The major cause of cutaneous aging is oxidation of skin structures from highly reactive oxygen molecules present in our oxygen rich environment. It is amazing to think that the live-giving oxygen that we need to survive is also the same oxygen that destroys our tissues with continued exposure. Yet, our environment is full of answers, since many living systems have evolved to deal with oxidation stress. The primary source of answers would have to come from plants, since all plants must protect themselves from oxidation following UV exposure in the outdoor environment in which they grow. These protective mechanisms have evolved over many years providing interesting chemicals that can be extracted and added to topical antioxidant preparations for human use in the treatment of benign photodamage. The cosmetics and skin care industry is spending tremendous resources searching for the botanical antioxidant that can provide human cutaneous protection from oxidative damage.
Basically, antioxidant botanicals quench singlet oxygen and reactive oxygen species, such as superoxide anions, hydroxyl radicals, fatty peroxy radicals, and hydroperoxides. There are many botanical antioxidants that have been commercialized and are available from raw material suppliers. This article will present these botanical antioxidants briefly and then continue on to discuss the currently popular botanical antioxidants, such as soy, kinetin, curcumin, silymarin and pycnogenol.
The botanical antioxidnats are too numerous to mention in one article. However, most botanical antioxidants can be classified into one of three categories as flavonoids, carotenoids, and polyphenols. Flavonoids possess a polyphenolic structure that accounts for their antioxidant, UV protectant, and metal chelation abilities. Carotenoids are chemically related to vitamin A, which encompasses all of the naturally occurring retinol derivatives. Lastly, polyphenols compose the largest category of botanical antioxidants.
Soybeans are a rich source of flavonoids called isoflavones, such as genistein and daidzein. These isoflavones function as phytoestrogens when orally consumed and have been credited with the decrease in cardiovascular disease and breast cancer seen in Asian women. Some of the cutaneous effects of soy have linked to its estrogenic effect in postmenopausal women. Topical estrogens have been shown to increase skin thickness and promote collagen synthesis. It is interesting to note that genistein increases collagen gene expression in cell culture, however there are no published reports of this collagen-stimulating effect in topical human trials. Genestein has also been reported to function and a potent antioxidant scavenging peroxyl radicals and protecting against lipid peroxidation in vivo.
Curcumin is a polyphenol antioxidant derived from the turmeric root. Tumeric is a popular natural yellow food coloring used in everything from prepackaged snack foods to meats. It is sometimes used in skin care products as a natural yellow coloring in products that claim to be free of artificial ingredients. Curcumin is consumed orally as an Asian spice, frequently found in rice dishes to color the otherwise white rice yellow. However, this yellow color is undesirable in cosmetic preparations, since yellowing of products is typically associated with oxidative spoilage. Tetrahydrocurcumin, a hydrogenated form of curcumin, is off-white in color and can be added to skin care product not only to function as a skin antioxidant, but also to prevent the lipids in the moisturizer from becoming rancid. The antioxidant effect of tetrahydrocurcumin is said to be greater than vitamin E by cosmetic chemists. Resveratrol, a related chemical to curcumin, is found in red wine accounting for the antioxidant effect of this beverage.
Silymarin is an extract of the milk thistle plant (Silbum marianum), which belongs to the aster family of plants including diasies, thistles, and artichokes. The extract consists of three flavinoids derived from the fruit, seeds, and leaves of the plant. These flavinoids are silybin, silydianin, and silychristine. Homeopathically, silymarin is used to treat liver disease, but it is a strong antioxidant preventing lipid peroxidation by scavenging free radical species. Its antioxidant effects have been demonstrated topically in hairline mice by the 92% reduction of skin tumors following UVB exposure. The mechanism for this decrease in tumor production is unknown, but topical silymarin has been shown to decrease the formation of pyrimidine dimers in a mouse model. Silymarin is found in a number of high-end moisturizer for benign photoaging to prevent cutaneous oxidative damage.
Pycnogenol is an extract of French marine pine bark (Pinus pinaster), which is said to function as a plant derived antioxidant. It is a water-soluble liquid that contains several phenolic constituents, including taxifolin, catechin, procyanidins. It also contains several phenolic acids, including p-hydroxybenzoic, protocatechuic, gallic, vanillic, p-couric, caffeic, and ferulic. It is a trademarked ingredient that is sold for oral consumption as a preventative for cardiovascular disease and as a topical skin antioxidant. It is a potent free radical scavenger that can reduce the vitamin C radical, returning the vitamin C to its active form. The active vitamin C in turn regenerates vitamin E to its active form maintaining the natural oxygen scavenging mechanisms of the skin intact.
Pycnogenol is the ideal antiaging additive since it demonstrates no chronic toxicity, no mutagenicity, no teratogenicity, and no allergenicity. It is consumed orally to enhance the production of nitric oxide, which inhibits platelet aggregation in coronary artery disease, thus it is also deemed safe for topical use. In short, pycnogenol is one of the new breed of oral supplements sold for improving the appearance of benign photoaged skin from the inside, while topical application is said to augment this effect. As with many trademarked dietary supplements, it is difficult to validate the purported benefits.
Kinetin is a not a naturally occurring plant substance, different from those previously discussed. It is a member of the N6-substituted adenine derivatives, known as cytokinins. In plants, this hormone has been shown to stimulate transcription and influence the cell cycle by stimulating growth. It is also a plant antioxidant. The specific cytokinin that is used in the commercial moisturizers currently marketed is N6-furfuryladenine. Kinetin is said to improve benign photoaging by decreasing fine wrinkles, improving pigmentation, and increasing skin smoothness. It is typically compared to the retinoids, discussed under vitamin agents for benign photoaging, but human cells do not contain kinetin receptors while they do contain retinoid receptors. It is currently unknown whether moisturizers containing this active agent provide benefits above and beyond those attributed to moisturization alone.
Plant antioxidants are an important reservoir of actives in the search for relevant human antioxidants. This article has discussed some of the plant derivatives currently popular in the marketplace. While there is not enough scientific data to determine which botanical antioxidant shows the most promise, it is worthwhile to become familiar with these actives in terms of their purported function and activity.
Plants are generally considered healthy and good. This consumer concept has led to the development of a burgeoning natural supplement market. Any ailment known to man can be treated with an herb or extract of some sort. In dermatology, patients commonly present with a variety of herbals and vitamins for the treatment of incurable diseases such as psoriasis and lupus, where modern medicine has left patients desiring better and more complete remedies. Recently, the herbal market has come under greater FDA scrutiny as herbals are making medicinal claims. Yet, questions remain as to whether botanicals are truly safe and effective. I would like to further examine this question using tea and pomegranate supplements as timely examples.
Both tea and pomegranate are felt to be potent antioxidants, representing the largest category of botanical supplements. Antioxidants currently popular since the major cause of cutaneous aging is oxidation of skin structures from highly reactive oxygen molecules present in the oxygen rich environment. Botanical extracts are antioxidant rich, since all plants must protect themselves from oxidation following UV exposure. Antioxidant botanicals function by quenching singlet oxygen and reactive oxygen species, such as superoxide anions, hydroxyl radicals, fatty peroxy radicals, and hydroperoxides.
One of the most popular topical and oral antioxidants is tea. Tea, also known as Camellia sinensis, is botanical used in the Orient for 5000 years. Teas are a rich part of the Oriental culture used to stay alert during extended meditation. An Indian legend tells of a Prince Siddhartha Guatama, the founder of Buddhism, who tore off his eyelids in frustration over his inability to stay awake during meditation. A tea plant is said to have sprouted from where his eyelids fell providing the ability to stay awake, meditate, and reach enlightenment. Tea reached western cultures during the 6th century from Turkish traders.
There are several different types of teas: green, black, oolong, and white. The different teas come from the same plant, but different processing imparts different properties. Green tea is made from unfermented tea leaves and contains the highest concentration of polyphenol antioxidants. Black tea leaves are fermented days before heating. Oolong tea originates in the Fukien province of China and the leaves are treated much like black tea, except the withering and fermentation times are minimized. White tea comes from young tea leaves that are harvested for a few days each spring when the plant emerges from the ground. These leaves are said to be very high in antioxidants. The highest quality white tea is obtained from buds that are just ready to open known as needles or tips.
The FDA was recently presented with data to support the anticancer benefits of topical and oral green tea. On June 30, 2005, the FDA concluded, “that there is no credible evidence to support qualified health claims for green tea consumption and a reduced risk of gastric, lung, colon/rectal, esophageal, pancreatic, ovarian, and combined cancers.” The FDA also concluded that there was very limited credible evidence for qualified health claims regarding green tea in the prevention of breast and prostate cancer. On May 9, 2006, in response to “Green Tea and Reduced Risk of Cardiovascular Disease,” the FDA concluded, “there is no evidence to support qualified health claims for green tea or green tea extract and a reduction in a number of risk factors associated with cardiovascular disease.”
Why did the FDA deny these claims? Many papers have been published on the benefits of green tea, but other issues intervened. Some FDA advisers voiced concern that teas may contain high levels of pesticides and heavy metals. Indeed, an analysis of several types of tea leaves confirmed this concern. Are botanicals truly safe and effective?
Green tea is still felt to be of health benefit when consumed orally because it is rich in antioxidant polyphenols, such as epicatechin, epicatechin-3-gallate, epigllocatechin, and eigallocatechin-3-gallate (EGCG). EGCG is the most potent of the polyphenols and sold in health food stores as a white caffeine-free powder. Oral studies with 300mg of EGCG have demonstrated increased fat oxidation, heart rate improvement, and reduced serum glucose levels.,
Green tea can be easily added to topical creams and lotions designed to combat the signs of photoaging, but it must be stabilized itself with an antioxidant, such as butylated hydroxytoluene (BHT). BHT is not a natural ingredient. Are botanicals still natural even though they require “synthetic chemicals” for preservation?
Green tea has also been touted as a natural photoprotectant and possibly a natural sunscreen alternative, however the Mayo Clinic Drugs and Supplements rates the evidence to support green tea as a photoprotectant as a C. Most of the studies to validate the topical benefits of green tea in photoprotection are on rodent models. A study by Katiyar, et al, demonstrated the anti-inflammatory effects of topical green tea application on C3H mice. A topically applied green tea extract containing GTP ((-)-epigallocatechin-3-gallate) was found to reduce UVB-induced inflammation as measured by double skin-fold swelling. The application of topical green tea polyphenols prior to UV exposure has also been shown to decrease the formation of cyclobutane pyrimidine dimers. These dimers are critical in initiating UV-induced mutagenesis and carcinogenesis, which represent the end stage of the aging process.
One human study applied GTP to the back of humans 30 minutes prior to UV irradiation, which resulted in decreased myeloperoxidase activity and decreased infiltration of leukocytes as compared to untreated skin. This observation certainly holds promise for the use of green tea as a photoprotectant, but much further work remains to be done to demonstrate the safety of topical green tea formulations.
Another popular botanical is pomegranate extract. Pomegranate, botanically known as Punica granatum, is a deciduous tree bearing a red fruit native to Afghanistan, Pakistan, Iran, and northern India. It was brought to California by the Spanish settlers in 1769 and is commercially cultivated for its juice. The pomegranate became famous in Greek mythology when Persephone was kidnapped by Hades and taken to the Underworld to be his wife. Persephone had consumed four pomegranate seeds while in the Underworld and thus had to spend four months every year in Hades, during which time nothing would grow. This gave rise to the season of winter.
Pomegranate juice, commonly consumed in the Middle East, provides about 16% of the adult requirement of Vitamin C per 100mg serving. It also contains pantothenic acid, also known as Vitamin B5, potassium, and antioxidant polyphenols. These substances have been demonstrated to protect against UVA and UVB induced cell damage in SKU-1064 human skin fibroblasts. Pomegranate juice has also been purported to reduce oxidative stress, affect LDL, and platelet aggregation in humans and apolipoprotein e-deficient mice., It has also been studied for improving hyperlipidemia in diabetic patients.
Pomegranate, much like tea, is a supplement with far reaching benefits and claims. Yet, both botanicals need validation to prove they are safe and effective. One of the biggest problems with botanicals is the inability to determine the exact dose necessary for optimal results. How much is too much and how much is too little? Furthermore, is it possible to produce pesticide free and contaminant free extracts? Since extracts are concentrated from dried botanical materials, it is possible that anything present on the leaf would have an increased presence in the final product. Who will test and certify that the botanical extracts are pure and contaminant free? Until these questions are answered, it is not possible to state that botanicals are truly safe and effective.
Botanicals formed the basis of all medical treatments at the time settlers were coming to America. The American Indians had an extensive pharmacopeia based on native plants that was passed from generation to generation through the wisdom of the medicine man in each community. These plant concoctions were mastered by the settlers and transported back to England and incorporated into some of the earliest books on medical treatment. Increased understanding of human physiology, disease processes, and chemistry led to the extraction and synthesis of many medically important substances from these early botanical remedies. Recently, there has been a resurgence in botanical preparations found in the modern drug store. These concoctions are nonprescription, unregulated remedies that appeal to the current popular trend of natural healing. Interestingly, many of these “modern” botanicals are variations of American Indian folk remedies.
Some of these botanical preparations were used by the English settlers and American Indians to treat skin diseases. Practitioners of naturopathic and homeopathic medicine are reviving these preparations and the media is popularizing their use. This article discusses some of the plants of dermatologic significance to acquaint the physician with their purported value, chemical constituents, and interesting details. The dermatologist may find this information of value when evaluating skin moisturizers containing botanical cocktails or when responding to popular press articles regarding botanical supplements for skin disease.
Echinacea, also known as black susans or American cone flower, is native to Kansas, Nebraska, and Missouri, but can be propagated as an annual in any environment with ample water. Every part of the plant was used for medicinal purposes by the American Indians. The fresh leaves were ground to produce an antiseptic and pain reliever for wounds and bites. The juice of the roots was used to bathe burns. The plant was introduced into medicine and documented in 1871 by a patent medicine vendor in Nebraska.
Echinacea purpurea species is currently advocated for its value in treating psoriasis. It can be applied topically or taken orally. The plant contains anti-inflammatory substances that may be of use in psoriasis. In current pill preparations, it is unclear from reading the label whether the leaves, stems, or roots are included in the bottle.
Thuja, also known as cedarwood or arborvitae, is also used in psoriasis for its anti-inflammatory properties. American Indians used the ground wood as a salve for warts. It was also noted to have antifungal effects and used by herbalists to treat tinea corporis and oral candidiasis.
Sasparilla is well known in the modern world as a flavoring. It contains a number of plant sterols and saponins to account for its medicinal effects. Sasparilla has both antiseptic and antipruritic properties and is used in topical preparations for both eczema and psoriasis. It may also be consumed orally.
Prickly pear, a native plant to the southwestern desert, is a cactus also known as cactus pear, Indian pear, or tuna fig. It is was imported to Europe in the 16th century and became a part of a salve designed to sooth cutaneous wounds and burns. The fleshy pad of the prickly pear contains 83% water and 10% sucrose with small amounts of tartaric acid, citric acid, and other mucopolysaccharides. American Indians would rub the mucilage from the broken pad over the skin surface to act as a sunscreen and moisturizer. An extract of prickly pear is found in some moisturizer formulations, however, the extract is added as a dried powder and not as a mucilage.
Sagebrush was used widely by the Indians of the southwestern United States, such as the Navajo, as a powder to sprinkle onto cuts and wounds. It was felt to have both antibiotic and skin soothing effects. Today, the leaves of the plant are sometimes cooked and mixed with olive oil and applied to irritated skin by practitioners of herbal dermatology.
Jojoba oil is a common cosmetic additive to many herbal and mass market preparations. The plant is native to the drier climates of Mexico and Arizona. The American Indians used jojoba oil for a hair conditioner and to speed the healing of wounds. The oil may also be consumed internally and is felt to act as a topical, as well as systemic, anti-inflammatory agent for the skin. Oral consumption of the oil is used by the Mexicans in the treatment of skin cancer.
It is important to recognize that the jojoba oil that is used in many commercial preparations bares little resemblance to the oil squeezed from the leaves of the plant. Chemical houses produce a powdered additive and liquid additive labelled as the oil, but it is a mixture of a variety of extracts designed to compliment skin and hair moisturizers. The small amount added to products in this manner probably has little anti-inflammatory properties.
Some practitioners of aromatherapy and trichotherapy are using the pure jojoba oil in the treatment of seborrheic dermatitis and scalp psoriasis. It is unclear whether the oil accompanied by massage loosens the skin scale, or whether the reduction in inflammation from the oil application itself is the beneficial part of the scalp treatment.
Feverwort, also known as boneset and Indain sage, is found in wet areas of the United States. The leaves of the plants were collected and made into a poultice that was applied topically for the treatment of skin cancers by the North American Indians. It was also used orally as a treatment for the high fevers accompanying influenza. It contains the glycoside eupatorin and other volatile oils.
Bloodroot is found in wooded areas from Florida to Arkansas. It is also known as sanguinaria. The whole plant from leaves to roots can be used to make a preparation used by the North American Indians around Lake Superior to treat skin cancer. The plant derives it name from the red juice obtained from the root, which contains red resin.
Extracts from the root were popularized in England for the treatment of cancers when combined with zinc chloride, flour, and water. It was also used as an early treatment for warts. It does have some analgesic properties, from the sanguinarine present in the root, and was listed in the US Pharmacopoeia until 1926. Bloodroot is currently attracting renewed interest from herbalists.
Witch hazel is a botanical extract well known to the dermatologist. It is most commonly used as an astringent in persons with oily skin. The plant was originally discovered by the Indians of the New England area of the United States. An extract is prepared by boiling the twigs and leaves of the plant, which grows as a low bush. The leaves can also be crushed and applied to the skin as a paste. The astringent action of witch hazel is probably due to the high tannin content of the plant.
There currently is a varicose vein treatment sold through infomericals based on a witch hazel extract. The tannins of the plant also function as venous vasoconstrictors. Whether this function can be achieved through topical application to such a degree that poor venous return is enhanced remains unknown. Another presently marketed formulation combined witch hazel with glycolic acid to treat acne by reducing inflammatory papules and pustules. Witch hazel ointments, known as Hamamelis ointments after the botanical name, are sold by herbalists for the treatment of atopic dermatitis.
Apache plume is found in the southwestern United States and was used by the Hopi Indians as a hair rinse. It was felt to also encourage the growth of hair. It is unclear whether there is any basis for this claim; however, I have seen some infomercial products that claim to grow hair through the use of apache plume.
Latex from the unripened fruit of the papaya plant, also known as the paw paw plant, is used by the Indians of New Guinea to treat fungal infections of the skin. Amazingly, the latex has been shown to have anti-fungal properties. This extract is actually undergoing further investigation for its use as a topical agent in the herbal market.
The latex extract contains papain, which is a proteolytic enzyme valuable in clearing epithelial debris in wound healing. It is similar to bromelain found in pineapple. Some dermatologic surgeons are recommending the use of oral bromelain to prevent and speed the resolution of bruising following liposuction.
Many botanical additives are available for use in skin and hair care products. The difficulty lies in the identification of medically useful botanicals. The purported use for a botanical extract seldom has a double-blind placebo controlled trial to support its benefits. Problems arise when assessing skin soothing or enhanced healing claims since the skin heals expediently if protected from further damage. It is impossible to know what might have happened if the botanical had not been used. Many of the skin uses for botanicals are based on folklore and word of mouth.
Note: This article is adapted from several of the writings of Anthony C. Dweck, an expert in the use of herbal extracts. More details can be found in the following reference:
Plants are an amazing source of ingredients that can be placed on the skin. These plants are labeled as botanicals. It is interesting to note that botanicals formed the basis of all medical treatments at the time European settlers were first coming to America. These Europeans learned that the American Indians had an extensive medical knowledge, based on native plants, that was passed from generation to generation through the wisdom of the medicine man in each community. These plant concoctions were mastered by the settlers, transported back to England, and incorporated into some of the earliest books on medical treatment. When the new English settlers were learning about North American plant extracts, a large body of knowledge utilizing plants from the Orient was also being developed. The richness of plant material in the tropical Orient led to different plant extracts of great diversity that were used in Oriental medicine and religious practices. Today cosmetic formulators have access to plant materials worldwide for incorporation into topical preparations.
Botanicals are complex skin care additives. There are many sources and types of plant materials, which may or may not provide topical skin benefits. First, the source of the plant material is important. The chemicals that can be obtained can from the leaves, berries, stems, roots, and flowers. Many natural plant extracts are difficult to characterize chemically, since over 200 individual chemicals may be present in any one plant extract. Furthermore, the season in which the plant material was gathered may also greatly influence its chemical composition. Certain substances are present only in fall when the leaves are shedding while other substances are only present in early spring when immature leaves are present on the branches.
Second, it is important to realize that a tremendous amount of processing must occur before a plant extract can be placed in a skin care product. Raw crushed leaves added to a moisturizer will not provide an aesthetically pleasing result. Usually, the plant material is heated or processed to obtain an oil or other liquid that can be easily added to a cosmetic formulation. It must be determined whether heating or processing concentrates or destroys the active chemical providing the skin benefit.
Third, the amount of the plant extract is important to determining efficacy. Sometimes the plant is added in such small amounts that it provides more marketing benefit than skin benefit. Ingredients are listed in order of decreasing amount, yet a concentrated plant extract may only be required in low concentration to provide the desired effect.
Yes, many plants can reduce inflammation and make skin feel better. The plants that can reduce inflammation include Ginkgo biloba, green tea, Echinacea, Thuja, and Sarsaparilla.
Ginkgo biloba is a plant with numerous purported benefits that is a common part of homeopathic medicine in the Orient. The plant leaves are said to contain unique polyphenols such as terpenoids (ginkgolides, bilobalides), flavinoids, and flavonol glycosides that have anti-inflammatory effects. These anti-inflammatory effects have been linked to antiradical and antilipoperoxidant effects in experimental fibroblast models. Ginkgo flavonoid fractions containing quercetin, kaempferol, sciadopitysin, ginkgetin, and isoginkgetin have been demonstrated to induce human skin fibroblast proliferation in vitro. Increased collagen and extracellular fibronectin were also demonstrated by radioisotope assay.
Various unknown Ginkgo fractions are added to skin moisturizers for anti-aging benefits, even though no controlled trials exist regarding cutaneous benefits. Since Ginkgo is added to products considered cosmetics, no anti-aging claims can be made. Generally, Ginkgo is claimed to “enhance the skin appearance,” which is a cosmetic claim not requiring validation, since appearance is a subjective assessment.
Green tea is another botanical popular in the Orient for both topical application and oral ingestion. Orally, green tea is said to contain beneficial flavonoids that act as potent antioxidants. Current claims on green tea packaging claims that it enhances energy levels, not that it reverses aging.
A topically applied green tea extract containing GTP ((-)-epigallocatechin-3-gallate) was found to reduce UVB-induced inflammation as measured by double skin-fold swelling. At present, green tea remains a nutritional supplement and not an approved sun protective agent.
Echinacea, also known as black-eyed susans or American cone flower, is native to Kansas, Nebraska, and Missouri, but can be propagated as an annual in any environment with ample water. It was a common botanical homeopathic remedy used by the American Indians that is currently seeing renewed topical popularity. The American Indians used every part of the plant for medicinal purposes. The fresh leaves were ground to produce an antiseptic and pain reliever for wounds and bites. The juice of the roots was used to bathe burns.
Echinacea purpurea species is currently advocated for its value in treating psoriasis and reducing the inflammation associated with a variety of dermatologic conditions. An oral Echinacea purpurea extract is sold as a homeopathic remedy for psoriasis, however the mechanism of action is unknown. Echinacea is listed as a botanical additive in many moisturizers designed for sensitive skin.
Thuja, also known as cedarwood or arborvitae, is another American Indian homeopathic remedy for psoriasis. It too is found in moisturizing preparations for skin that is sensitive or easily irritated. Interestingly, Thuja is also incorporated into homeopathic salves used in the treatment of warts. Other homeopathic uses include the treatment of tinea corporis and oral candidiasis, however the antifungal effects of Thuja have never been demonstrated clinically.
Many botanical extracts that were once considered medications are still used as modern day flavorings, perhaps with some additional homeopathic benefits. An example of such a botanical is Sarsaparilla. Sarsaparilla was used as a flavoring in sodas sold in pharmacies to children and adults. It is still possible to purchase sarsaparilla candy and sodas in gourmet food establishments.
Sarsaparilla is also claimed to possess topical benefits due the presence of plant sterols and saponins. It is said to have both antiseptic and antipruritic properties. For this reason, it is incorporated into homeopathic topical preparations to treat both eczema and psoriasis.
Another common dermatologic use of botanical extracts is to providing skin soothing benefits. Many products that claim to calm, normalize, replenish, or relax the skin incorporate botanical ingredients such as prickly pear, sagebrush, jojoba, aloe vera, or allantoin.
Prickly pear, a plant native to the southwestern desert, is a cactus also known as cactus pear, Indian pear, or tuna fig. It is was imported to Europe in the 16th century and became a part of a salve designed to soothe cutaneous wounds and burns. The fleshy pad of the prickly pear contains 83% water and 10% sucrose with small amounts of tartaric acid, citric acid, and other mucopolysaccharides. American Indians would rub the mucilage from the broken pad over the skin surface to act as a sunscreen and moisturizer.
Mucilages in general have a soothing cooling effect on the skin, due to evaporation of water, when the plant juice is rubbed over the skin. Additionally, the mucopolysaccharides dry to form a protective coating over wounded or dermatitis skin. An extract of prickly pear is found in some moisturizer formulations, however, the extract is added as a dried powder and not as a mucilage. This defeats the skin soothing benefits for the most part. Nevertheless, prickly pear juice is found in a variety of skin care products.
Sagebrush is another desert plant that was used widely by the Indians of the southwestern United States, such as the Navajo, as a powder to sprinkle onto cuts and wounds. The powder was felt to have both antibiotic and skin soothing effects. Ground sagebrush leaves cooked and mixed with olive oil are still applied to irritated skin by homeopathic healers in Mexico and the southwestern United States. This is the rationale behind the incorporation of sagebrush extract into night creams designed to soothe irritated skin.
Jojoba is currently a protected endangered plant in the southwestern United States. The plant is valued for the light- weight oil obtained from its fruit that is highly desirable in the skin care industry. Jojoba is difficult to domesticate thus it is an expensive botanical additive. Jojoba oil was first used by the American Indians and Mexicans for its ability to soothe and heal wounds. The oil is now finding its way into botanical moisturizers as a specialty additive, an ingredient designed to capture consumer attention.
Probably the most widely used botanical additive to soothe the skin is aloe vera. The mucilage is released from the plant leaves as a colorless gel and contains 99.5% water and a complex mixture of mucopolysaccharides, amino acids, hydroxy quinone glycosides, and minerals. Compounds isolated from aloe vera juice include: aloin, aloe emodin, aletinic acid, choline, and choline salicylate. The reported cutaneous effects of aloe vera include increased blood flow, reduced inflammation, decreased skin bacterial colonization, and enhanced wound healing.
In most skin preparations, aloe vera is added as a powder, not as a mucilage. The composition of aloe vera powder may not be the same as aloe vera juice that oozes from the freshly broken plant leaf. Aloe vera extract is found in soaps, hair shampoos, hand lotions, body moisturizers, etc. It is estimated that aloe vera must be present at a concentration of 10% to have a moisturizing effect in products designed to remain on the skin for extended periods of time. Concentration and formulation are important considerations when determining whether or not a botanical additive has a skin benefit.
Allantoin is a currently popular botanical extract that is obtained from common comfrey root. It is the basis for sensitive skin claims made for a number of moisturizers marketed to dermatologists. Most allantoin currently used in skin care products is not botanically derived, but rather manufacturered by the alkaline oxidation of uric acid in a cold environment. It is a white crystalline powder that is readily soluble in hot water, making it easy to formulate in a variety of products. Allantoin is felt to induce cell proliferation and is also incorporated into botanical healing salves.
A variety of botanicals have also been identified for their ability to treat and prevent skin cancer based on folk medicine. These substances, such as feverwort and bloodroot, are entering many topical anti-aging products designed to prevent skin cancer.
Feverwort, also known as boneset and Indain sage, is found in wet areas of the United States. The leaves of the plants were collected and made into a poultice that was applied topically for the treatment of skin cancers by the North American Indians. It was also used orally as a treatment for the high fevers accompanying influenza. It contains the glycoside eupatorin and other volatile oils.
Bloodroot is found in wooded areas from Florida to Arkansas. It is also known as sanguinaria. The whole plant from leaves to roots can be used to make a preparation used by the North American Indians around Lake Superior to treat skin cancer. The plant derives it name from the red juice obtained from the root, which contains red resin.
Extracts from the root were popularized in England for the treatment of cancers when combined with zinc chloride, flour, and water. It was also used as an early treatment for warts. It does have some analgesic properties, from the sanguinarine present in the root, and was listed in the US Pharmacopoeia until 1926. Bloodroot is currently attracting renewed interest from herbalists.
Witch hazel is a botanical extract well known to the dermatologist. It is most commonly used as an astringent in persons with oily skin. The plant was originally discovered by the Indians of the New England area of the United States. An extract is prepared by boiling the twigs and leaves of the plant, which grows as a low bush. The leaves can also be crushed and applied to the skin as a paste. The astringent action of witch hazel is probably due to the high tannin content of the plant.
There currently is a varicose vein treatment sold through infomericals based on a witch hazel extract. The tannins of the plant also function as venous vasoconstrictors. Whether this function can be achieved through topical application to such a degree that poor venous return is enhanced remains unknown. Another presently marketed formulation combined witch hazel with glycolic acid to treat acne by reducing inflammatory papules and pustules. Witch hazel ointments, known as Hamamelis ointments after the botanical name, are sold by herbalists for the treatment of atopic dermatitis.
Apache plume is found in the southwestern United States and was used by the Hopi Indians as a hair rinse. It was felt to also encourage the growth of hair. It is unclear whether there is any basis for this claim; however, I have seen some infomercial products that claim to grow hair through the use of apache plume.
Latex from the unripened fruit of the papaya plant, also known as the paw paw plant, is used by the Indians of New Guinea to treat fungal infections of the skin. Amazingly, the latex has been shown to have anti-fungal properties. This extract is actually undergoing further investigation for its use as a topical agent in the herbal market.
The latex extract contains papain, which is a proteolytic enzyme valuable in clearing epithelial debris in wound healing. It is similar to bromelain found in pineapple. Some dermatologic surgeons are recommending the use of oral bromelain to prevent and speed the resolution of bruising following liposuction.
Do cosmeceuticals work? How many times has the dermatologist been asked this question? How many times has the dermatologist wished an answer were available? Unfortunately, it is not easy to compose a succinct answer to this question. I think a correct answer might be “cosmeceuticals work sometimes depending ingredients and user expectations.” If the consumer is looking for increased tactile softness, cosmeceuticals are fabulous. But, if the consumer is looking for a reversal of facial folds, cosmeceuticals are ineffective.
Cosmeceuticals represent an ever-expanding field in dermatology with perhaps much yet unrealized promise. Cosmeceuticals extend beyond cosmetics to enhance skin functioning, usually aiming to return the skin to a more youthful state. For example, wrinkle reducing moisturizers, antioxidant serums, and skin lightening salves all fall into this category. Cosmeceuticals are somewhat confusing, however, as both prescription and OTC products have been labeled by this term. Drug cosmeceuticals include topical retinoids for improving dermal collagen production, topical minoxidil for enhanced scalp hair growth, and eflornithine for facial hair growth reduction. Cosmeceuticals also include OTC drugs, such as sunscreens and antiperspirants. This article discusses only cosmeceuticals for appearance improvement.
A discussion of the efficacy of all cosmeceutical ingredients would be impossible, thus I have chosen to focus on the category of flavonoids and the published evidence available to demonstrate their efficacy. Flavonoids are aromatic compounds, frequently with a yellow color, that occur in higher plants. 5000 flavonoids have been identified with a similar chemical structure possessing 15 carbon atoms and possessing a variety of biologic activities. Flavonoids can be divided into flavones, flavonols, isoflavones, and flavanones, each with a slightly different chemical structure.
Currently, the most common isoflavones are derived from soy, curcumin, silymarin, pycnogenol, and gingko. Each of these sources will be discussed presenting studies from the literature to support their efficacy.
Fermented soy contained two primary isoflavones: genistein and daidzein. These isoflavones function as phytoestrogens when orally consumed and have been credited with the decrease in cardiovascular disease and breast cancer seen in Asian women., Other purported systemic benefits include improvement in immunity, reduction of prostate cancer, and improvement in cognition. Some of the cutaneous effects of soy have linked to its estrogenic effect in postmenopausal women. Topical estrogens have been shown to increase skin thickness and promote collagen synthesis. Genestein has also been reported to function as a potent antioxidant scavenging peroxyl radicals and protecting against lipid peroxidation in vivo. These are the best designed human studies that have been published to date.
The other interesting soy research was performed on rodents. A study in mice documented the ability of soy to protect against UVB-induced skin damage where a topical application of nondenatured soy extracts reduced UVB-induced cyclooxygenase-2 expression, prostaglandin-E2 secretion, and inhibited p38 MAP kinase activation. It is unknown whether this rodent data translates into UVB photoprotection in humans.
Genestein and daidzein are found in postmenopausal antiaging oral supplements. It is interesting that many gynecologists are hesitant to allow breast cancer patients to take oral soy supplements to prevent hot flashes if they have an estrogen positive cancer receptor. While there are no studies to confirm that oral fermented soy promotes the growth of breast cancer, there are enough concerns to wonder if phytoestrogens are biologically active in the human. Here is where the data ends and the supposition begins.
Curcumin is an old ingredient recently rediscovered as a potent antioxidant. It is found as the primary ingredient in skin care line designed for atopic dermatitis. Curcumin is a popular natural yellow food coloring used in everything from prepackaged snack foods to meats. It is sometimes used in skin care products as a natural yellow coloring in products that claim to be free of artificial ingredients. Curcumin comes from the rhizome of the tumeric plant and is consumed orally as an Asian spice, frequently found in rice dishes to color the otherwise white rice yellow. However, this yellow color is undesirable in cosmetic preparations, since yellowing of products is typically associated with oxidative spoilage.
Tetrahydrocurcumin, a hydrogenated form of curcumin, is off-white in color and can be added to skin care product not only to function as a skin antioxidant, but also to prevent the lipids in the moisturizer from becoming rancid. The antioxidant effect of tetrahydrocurcumin is said to be greater than vitamin E by cosmetic chemists. Published reviews purport that the antioxidant skin benefits arise when curcumin quenches oxygen radicals and inhibits nuclear factor-KB. The effects of curcumin as a topical antioxidant in the skin have not been as well studied as its oral ingestion in rodents for the correction of cystic fibrosis defects and inhibition of tumor proliferation.
The only problem with topical application of tetrahydrocurcumin is the smell of the product, which is pungent, and the stinging induced when applied on open wounds. For this reason, curcumin is used in more therapeutic rather cosmetic product formulations.
Another family of flavonoids comes from the milk thistle plant (Silbum marianum), which belongs to the aster family of plants including diasies, thistles, and artichokes. The plant is named milk thistle because the oldest recorded use of the extract was to enhance human lactation and the plant produces a white milky sap. The cosmeceutical extract is termed silymarin and contains three flavinoids derived from the fruit, seeds, and leaves of the plant. These flavonoids are silybin, silydianin, and silychristine.
Homeopathically, silymarin is used to treat liver disease, but it is a strong antioxidant preventing lipid peroxidation by scavenging free radical species. Its antioxidant effects have been demonstrated topically in hairline mice by the 92% reduction of skin tumors following UVB exposure. The mechanism for this decrease in tumor production is unknown, but topical silymarin has been shown to decrease the formation of pyrimidine dimers in a mouse model. It has also been found to improve the healing of burns in albino rats.
Silymarin is found in a number of high-end moisturizer for benign photoaging to prevent cutaneous oxidative damage and to reduce facial redness. A double-blind placebo-controlled study in 46 subjects with stage I-III rosacea found improvement in skin redness, papules, itching, hydration, and skin color. This was felt to be due to its direct activity on modulating cytokines and angiokines. Other well-controlled human trials are lacking.
Pycnogenol is an extract of French marine pine bark (Pinus pinaster), which grows only on the southwest coast of France in Les Landes de Gascongne. The extract is a water-soluble liquid containing several phenolic constituents, including taxifolin, catechin, procyanidins. It also contains several phenolic acids, including p-hydroxybenzoic, protocatechuic, gallic, vanillic, p-couric, caffeic, and ferulic. It is a trademarked ingredient that is sold for oral consumption as a preventative for cardiovascular disease, a treatment for diabetic microangiopathy, and a pain reliever for muscle cramps. It is a potent free radical scavenger that can reduce the vitamin C radical, returning the vitamin C to its active form. The active vitamin C in turn regenerates vitamin E to its active form maintaining the natural oxygen scavenging mechanisms of the skin intact.
Pycnogenol is consumed orally to enhance the production of nitric oxide, which inhibits platelet aggregation in coronary artery disease. In B16 melanoma cells, it was shown to inhibit tyrosinase activity and melanin biosynthesis. Many discussions of antioxidant flavonoids include a mention of pycnogenol, but little quality data is presented.
Ginkgo biloba, also named the maidenhair tree, is the last member of the Ginkgoaceae family, which grew on earth some 200-250 million years ago. For this reason, ginkgo contains flavonoids not found in other botanicals. It possesses bilobalide (a sequiterpene), ginkgolides (diterpenes with 20 carbon atoms), and other aromatic substances such as ginkgol, bilobdol, and ginkgolic acid. It is a plant with numerous purported benefits that is a common part of homeopathic medicine in the Orient for 4000 years.
The plant leaves are said to contain unique polyphenols such as terpenoids (ginkgolides, bilobalides), flavinoids, and flavonol glycosides that have anti-inflammatory effects. These anti-inflammatory effects have been linked to antiradical and antilipoperoxidant effects in experimental fibroblast models. Ginkgo flavonoid fractions containing quercetin, kaempferol, sciadopitysin, ginkgetin, and isoginkgetin have been demonstrated to induce human skin fibroblast proliferation in vitro. Increased collagen and extracellular fibronectin were also demonstrated by radioisotope assay. Thus, ginkgo extracts are added to many cosmeceuticals to function as antioxidants and promoters of collagen synthesis based on nonhuman models of oxidative damage.
This article was written based on a December 2008 Medline and Google Scholar search. It was truly amazing to realize how few serious scientific studies had been conducted on the flavonoids discussed. With the widespread use of these ingredients, many more studies should have been conducted. Perhaps this is why it is so hard to tell patients which cosmeceuticals actually work. For the most case, medical science really does not know.