Tue Jul 19, 2016 4:27 am by vairclair1
The Use of Botanical Extracts as Topical Skin-Lightening Agents Mon Jan 18, 2010 12:47 am
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The Use of Botanical Extracts as Topical Skin-Lightening Agents
Arbutin:
Arbutin, a naturally occurring [You must be registered and logged in to see this image.]-D-glucopyranoside derivative of hydroquinone, exists in the dried leaves of certain plant species, such as bearberry. The mode of action appears to be by inhibition of melanosomal tyrosinase and DHICA (5,6-dihydroxyindole-2-carboxylic acid) polymerase activities at noncytotoxic concentrations rather than by suppression of the synthesis and expression of this enzyme ([You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]). It is thought that the activity of arbutin is driven by the structural homologies that it shares with the substrate tyrosine, which leads to the competitive inhibition of the catalytic function of tyrosinase. Studies have shown that [You must be registered and logged in to see this image.]-arbutin (4-hydroxyphenyl [You must be registered and logged in to see this image.]-glucopyranoside) demonstrates an even stronger inhibitory effect on human tyrosinase activity than arbutin itself. This effect was achieved without affecting mRNA expression of enzyme in cultured human melanoma cells and a three-dimensional human skin model ([You must be registered and logged in to see this link.]). Deoxyarbutin (dA, 4-[tetrahydrofuran-2-yl-oxy]-phenol) has also demonstrated effective inhibition of mushroom tyrosinase in vitro. In a human clinical trial, topical treatment with dA for 12 weeks resulted in a significant or a slight reduction in overall skin lightness and improvement of solar lentigines in a population of light-skinned or dark-skinned individuals, respectively ([You must be registered and logged in to see this link.]). [You must be registered and logged in to see this image.]-Arbutin has widely replaced arbutin as the chosen skin-lightening agent in topical skin preparations because it is more effective and stable in producing the desired effects on human skin.
Aloesin:
Aloesin, a compound isolated from the aloe plant, has been proven to competitively inhibit tyrosinase from human, mushroom, and murine sources. Studies have shown that tyrosine hydroxylase and DOPA (3,4-dihydroxyphenylalanine) oxidase activities (of tyrosinase from normal human melanocyte cell lysates) are inhibited by aloesin in a dose-dependent manner ([You must be registered and logged in to see this link.]). The topical application of aloesin on UV-irradiated (210 mJ) human volar forearm (four times a day for 15 days) showed pigmentation suppression in a dose-dependent manner ([You must be registered and logged in to see this link.]). Aloesin, along with arbutin, was observed to synergistically inhibit melanin production by combined mechanisms of noncompetitive and competitive inhibitions of tyrosinase activity ([You must be registered and logged in to see this link.]).
Flavonoids:
Bioflavonoids can be divided into flavones, flavonols, isoflavones, and flavanones. The effects of many flavonoids on the oxidation of L-DOPA have been studied. Isoflavones, including glycitein, daidzein, and genistein, showed little antityrosinase activity, but 6,7,4'-trihydroxyisoflavone has been identified as a potent tyrosinase inhibitor stronger than kojic acid. Flavanones, such as hesperidin, eriodictyol, and naringenin, have a structure that is similar to that of hydroquinone. When concentrated in nanocapsules, they are protected until they reach the active site of melanin synthesis, where they exert a powerful reducing action and antiradical activity, and act as a substrate competitor for tyrosinase ([You must be registered and logged in to see this link.]).
Hesperidin:
Hesperidin is a bioflavonoid existing extensively in the peel and membranes of citrus fruits. Studies by Zhu and colleagues have demonstrated hesperidin's potent ability to inhibit melanin synthesis without cytotoxicity. This work found dose-dependent inhibition of tyrosinase activity (vs control) of hesperidin in melanoma B16 cells and human primary melanocytes ([You must be registered and logged in to see this link.], [You must be registered and logged in to see this link.]). In addition, hesperidin was found to protect against UVA-induced damage of fibroblasts and oxidative damage of collagen ([You must be registered and logged in to see this link.]). Thus, hesperidin offers potential skin-lightening benefits, including improved overall skin tone and antiyellowing effects.
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Niacinamide:
Niacinamide is a biologically active form of niacin (vitamin B3) found widely in many root vegetables and yeasts, and it is also an important precursor of NADH (nicotinamide adenine dinucleotide) and NADPH (nicotinamide adenine dinucleotide phosphate). The large number of cellular enzyme reactions in which these cofactors participate may be the basis for the variety of cosmetic benefits, including barrier enhancement observed from the topical use of niacinamide ([You must be registered and logged in to see this link.]). Using cocultures of human melanocytes and keratinocytes, investigators have shown that niacinamide inhibits the transfer of melanosomes from melanocytes to keratinocytes. Results of clinical studies using topically applied niacinamide have demonstrated a reversible reduction in hyperpigmented lesions and increased skin lightness compared with vehicle alone after 4 weeks of use. In a separate clinical study, topical niacinamide was also shown to decrease collagen oxidation products and improve aging-induced yellowing or sallowness ([You must be registered and logged in to see this link.]).
Licorice extracts:
Licorice extracts have several active compounds that may stimulate or suppress melanogenesis. Glabridin, the main ingredient in the hydrophobic fraction of licorice extract, inhibits tyrosinase activity in cultured B16 murine melanoma cells, at concentrations from 0.1 to 1.0 [You must be registered and logged in to see this image.]g ml-1, without affecting DNA synthesis. Other active compounds, such as glabrene, isoliquiritigenin licuraside, isoliquiritin, and licochalcone A, isolated from licorice extracts, were also shown to inhibit tyrosinase activity ([You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]). Liquiritin has no effect on tyrosinase; however, it causes depigmentation by other mechanisms, and studies demonstrate that a 20% liquiritin cream applied at 1 g day-1 for 4 weeks is therapeutically effective in melasma ([You must be registered and logged in to see this link.]).
Mulberry:
Dried mulberry (Morus alba) leaves (85% ethanol extract) have been shown to inhibit tyrosinase activity. Additionally, several phenolic flavonoids, such as gallic acid and quercetin, and fatty acids, such as linoleic acid and palmitic acid, have been isolated from its leaves. Mulberroside F (moracin M-6, 3'-di-O-beta-D-glucopyranoside), the active component, showed inhibitory effects on tyrosinase activity and on melanin formation in melan-a cells. This compound also exhibited superoxide scavenging activity that is involved in the protection against auto-oxidation ([You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]), suggesting a role for Morus alba as a component of lightening cosmetics.
Polyphenols:
Polyphenols are a class of compound that have antioxidant capacity and are found widely within plants. The inhibition of melanogenesis has been observed with many types of polyphenol plant extracts. Proanthocyanidins or procyanidins, classified as polyphenols, exist in red wine and cranberry juice; grape seeds are another especially rich source. The antioxidative activities of proanthocyanidins were found to be much stronger than the activity of vitamin C or E in aqueous systems. Ellagic acid is another natural polyphenol that is widely found in fruits and vegetables. The extract of the rinds of pomegranate contains 90% ellagic acid and showed inhibitory activity against mushroom tyrosinase in vitro. The mechanism of action may be inhibition of the proliferation of melanocytes and melanin synthesis by tyrosinase in melanocytes ([You must be registered and logged in to see this link.]).
Ginseng:
P-coumaric acid, extracted from the fresh leaves of Panax ginseng, was shown to inhibit the oxidation of L-tyrosine more strongly than the inhibition of tyrosinase demonstrated by L-DOPA ([You must be registered and logged in to see this link.]). Treatment with Radix ginseng in the presence of various concentrations of Radix trichosanthis suppressed tyrosinase activity and melanin content but increased cell proliferation slightly in B16 melanoma cells, raising the possibility that this combination may be effective as a skin-lightening agent ([You must be registered and logged in to see this link.]).
Gingko:
Extracts from the leaves of the gingko tree have shown potent free radical scavenger activity when applied to the skin. Ginkgo flavone glycosides, mostly quercetin and kaempferol derivatives, can inhibit tyrosinase activity by chelating copper in the enzyme ([You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]).
Herbs used in traditional Chinese medicine:
There are many kinds of traditional Chinese medicine prescriptions aimed at the treatment of hyperpigmentary disorders. The inhibitory actions of the extracts of 219 different traditional Chinese medicine herbs on tyrosinase activity were studied, and 11 ethanolic extracts and 8 aqueous extracts showed inhibitory effects on tyrosinase superior or similar to that of arbutin ([You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]). Further research investigated the effects and mechanisms of action of screened herbs. Ammonium glycyrrhizinate (18[You must be registered and logged in to see this image.]-GL), aloesin, icariin, piceid, salidroside, and epigallocatechin-3-gallate were found to significantly inhibit melanogenesis without cytotoxic effects in vitro. Most of these worked primarily by inhibiting tyrosinase activities competitively or noncompetitively ([You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]; [You must be registered and logged in to see this link.]). A human trial is currently underway to study the effects of treatment with hesperidin and glycyrrhiza cinnamic acid, a naturally occurring aromatic fatty acid of low toxicity, which has a long history of human use. It is known that cinnamic acid does not influence fungal growth but decreases the yield of pigment from the mycelium. Cinnamic acid and aloesin are mixed-type inhibitors of tyrosinase activity, and sophorcarpidine functions as an uncompetitive inhibitor. [You must be registered and logged in to see this link.] demonstrated that sophorcarpidine, aloin, and cinnamic acid can bind not only to the enzyme but also to the enzyme–substrate complex, leading to inactivation of tyrosinase.
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