Saturday, August 22, 2015

Retinoids

Retinoids such as tretinoin, adapalene, tazarotene and isotretinoin are derivatives of vitamin A. Itis an important nutrient obtained exclusively from the environment having many important and diverse functions throughout the body including roles in vision, regulation of cell proliferation and differentiation, growth of bone tissue, immune function, and activation of tumor suppressor genes. Research is also being done into their ability to treat skin cancers. retinoids are a common treatment option used to ameliorate acne, photodamage and post inflammatory hyperpigmentation. Retinoids causes inhibition of enzymes from breaking down collagen, acts as penetration enhancers when used with other lightening agents such as hydroquinone.

Mechanism of Action: The mechanisms for reducing pigmentation include inhibition of tyrosinase induction, interference with pigment transfer, and acceleration of epidermal turnover. Tretinoin (retinoic acid) increases keratinocyte proliferation and epidermal cell turnover by impairing glutathione-dependent cytoprotection via inhibition of glutathione S-transferase, which results in accentuation of melanin loss from the epidermis.They also have the ability to disperse pigment granules within keratinocytes.

The most common adverse effects include burning, stinging, erythema, dryness, and scaling. Although the adverse effects are reversible, retinoid dermatitis may itself lead to hyperpigmentation, especially in dark-skinned individuals. Tretinoin is available at different strengths ranging from 0.01% to 0.1%. Adapalene is a viable alternative for patients unable to tolerate tretinoin. It is a synthetic retinoid with greater selectivity than tretinoin.

Phenolic thioethers

N-acetyl-4-S-cysteaminylphenol and N-propionyl-4-S-cysteaminylphenol are derived from homologues of phenols with melanocytotoxic activity. Like Hydroquinone and Monobenzyl Ether of Hydroquinone, these belongs to the phenol/catechols class. N-acetyl-4-S-cysteaminylphenol is a tyrosine-amine derivative analogue that is less irritating than hydroquinone. As an alternative substrate of tyrosinase, it may therefore inhibit tyrosinase activity. By decreasing intracellular glutathione, it favors the pathway of forming pheomelanin rather than eumelanin. A clinical study using 4% preparation of N -acetyl-4-S-cysteaminyphenol for melasma showed marked-to-moderate improvement after 2-4 weeks of application, with minimal adverse effects. N -propionyl-4-S-cysteaminylphenol is more potent and has more cytotoxic properties as compared to the N-acetyl form.

Thursday, August 20, 2015

Niacinamide

Niacinamide is the biologically active form of vitamin B-3. It regulates the melanogenesis, suppresses the transfer of melanosomes from melanocytes to keratinocytes. In addition, niacinamide is also a tyrosinase inhibitor. It also promotes acne reduction, increases skin moisture, improves the appearance of aged, hyperpigmented and photodamaged skin. Research shows that it has potential to reduce appearance of wrinkles and fine lines by stimulating collagen & ceramide synthesis, and has soothing activity. Can improve functional & structural integrity of the skin barrier. Combined with vitamin A palmitate shows enhanced skin lightening properties. Niacinamide with retinyl palmitate has been shown to improve hyperpigmentation and increase skin lightening after 4 weeks of treatment compared with vehicle alone.

N-acetyl glucosamine

N-acetyl glucosamine is an amino-monosaccharide that was developed as a pigment-lightening cosmeceutical. It lightens skin by inhibiting the glycosylation of tyrosinase a step necessary for the formation of melanin. NAG is required by fibroblasts which are carpenter cells that synthesize collagen and connective tissue to regenerate body structure. They are highly concentrated in skin to assist the continual process of skin rejuvenation, which slows and becomes inefficient with age. A randomized double-blind study reported that the application of 2% N -acetyl glucosamine twice daily for 5 weeks provided a lightening effect. NAG (3%) applied topically to skin equivalent cell cultures significantly inhibits melanin content in a dose-dependent manner. Clinically, treatment with a 4% niacinamide plus 2% NAG combination for 8 weeks was significantly more effective at reducing hyperpigmentation than niacinamide alone. Thus, it can be an important ingredient in skin lightening products, particularly when combined with niacinamide.

Monobenzone

Monobenzone is the monobenzyl ether of hydroquinone a depigmenting agent. Similar to hydroquinone, monobenzyl ether of hydroquinone (MBEH) belongs to the phenol/catechol class of chemical agents. Genarally monobenzone is used on skin to permanently lighten skin in people with vitiligo. Depigmenting darker skin around the areas of vitiligo helps even out coloring and appearance of the skin. Due to its depigmenting effect, it is also used for skin whitening.

Mechanism of Action: Exact mechanisn is unknown but it is theorized that It works by eliminating melanin (pigment molecules) from skin cells by selective melanocytic destruction through free-radical formation and competitive inhibition of the tyrosinase enzyme system. Unlike hydroquinone, MBEH almost always causes nearly irreversible depigmentation of the skin.

It may take up to 4 months to complete the depigmentation of treated skin. It causes uneven pigmentation on skin when applied topically. So users have to use it carefully with expert’s advice. Skin treated with monobenzone makes skin sensitive to sunlight which leads to easy sunburn. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors. In dermatology, MBEH is only used to eliminate residual areas of normally pigmented skin in patients with generalized vitiligo.

Monday, August 17, 2015

Magnesium Ascorbyl Phosphate

Magnesium Ascorbyl Phosphate is a water-soluble, non-irritating, stable derivative of Vitamin C. This form of Vitamin C when used was shown to suppress melanin formation, increase skin’s hydration levels and improve its elasticity. It has the same potential as vitamin C to boost skin collagen synthesis but is effective in significantly lower concentrations, and can be used at concentrations as low as 10% to suppress melanin formation in skin-whitening solutions. It is also important to note that Magnesuim Ascorbyl Phosphate may be better choice than Vitamin C for people with sensitive skin and those wishing to avoid any exfoliating effects since many Vitamin C formulas are highly acidic and therefore produce exfoliating effects. In skin care products, Magnesium Ascorbyl Phosphate (MAP) is also used for UV protection and repair, collagen production, skin lightening and brightening, and as an anti-inflammatory. It is also a potent antioxidant. It is considered an excellent non-irritating skin whitening agent that inhibits skin cells to produce melanin and lightens age spots, and is a great alternative to Quinone. Magnesium Ascorbyl Phosphate is a also a potent anti-oxidant that can protect skin from oxidation and UV rays, and is used as an anti-inflammatory. Furthermore, MAP has been shown to have a protective effect against skin damage induced by UV-B irradiation. The latter protective effect is theorized to be due to the conversion of MAP to ascorbic acid.

Kojic acid

A fungal metabolic product produced by various fungal species such as Aspergillus and Penicillium.. In addition to its skin-lightening abilities, kojic acid is classified as an antioxidant. It has the ability to counteract the effects of particles in the air called free radicals, which have the potential to cause oxidative damage to the skin cells. By limiting the effects of free radicals, kojic acid helps to prevent the formation of signs of aging that occur when the cells that produce the skin's vital structural proteins become damaged. Kojic acid is also an antibacterial agent, meaning. disrupts the processes the processes that bacteria cells must perform to thrive and reproduce, leading to the death of bacteria.

Mechanism of Action: When kojic acid is applied to the skin in concentrated amounts, the chemicals in the ingredient work on the melanocytes, interfering with the production of melanin. It inhibits the catecholase activity of tyrosinase by chelating copper at the active site of the tyrosinase enzyme, which is the rate-limiting, essential enzyme in the biosynthesis of the skin pigment melanin. Melanocytes treated with kojic acid become nondendritic, with a decreased melanin content.

Kojic acid is also consumed widely in the Japanese diet, with the belief that it is of benefit to health. It scavenges reactive oxygen species released excessively from cells or generated in tissue or blood. Kojic acid is used in concentrations ranging from 1-4%. Although effective as a skin-lightening gel, it has been reported to have high sensitizing potential and may cause irritant contact dermatitis. In a study comparing glycolic acid/kojic acid combination with glycolic acid/hydroquinone, no statistical difference in efficacy was reported between kojic acid and hydroquinone; however, the kojic acid preparation was reported to be more irritating. To decrease the irritation from kojic acid, it is combined with a topical corticosteroid. In a comparison study, 2% hydroquinone, 10% glycolic acid, and 2% kojic acid decreased hyperpigmentation in patients with melasma better than the same combination without kojic acid.