Unit 4 lec

• Skin Whitening Products are popular among female patients
• Efficiency of skin whitening products leads to intense marketing through various platforms
• Regulation of skin whitening products under FDA is essential
• Skin product regulations depend on the regulatory framework of each country/territory
• Skin whitening products in different countries are classified differently:

  • China: Special-purpose cosmetics
  • Taiwan: Mediated cosmetics
  • Japan: Quasi-drugs
  • South Korea: Functional cosmetics
  • United States: Over-the-counter drugs
  • Europe: Cosmetics
• Skin whitening products in the Philippines or ASEAN member countries can be classified as drugs or cosmetics
• Melanocytes are specialized cells in the basal layer of the epidermis that produce melanin
• Melanin prevents UV-induced nuclear DNA damage by screening out harmful UV radiation
• Melanocytes produce organelles called melanosomes, which transfer melanin to neighboring keratinocytes
• Three types of melanin:

  • Eumelanin: Found in skin, eyes, and hair
  • Pheomelanin: Found in lips, nipples, and pinkish regions
  • Neuromelanin: Responsible for the color of neurons
• If veins appear blue or purple, the individual has a cool skin tone; if veins look green or greenish-blue, the individual has a warm skin tone
• Biosynthetic pathway of melanin involves eumelanogenesis and pheomelanogenesis:

  • Eumelanogenesis: Creation of dark pigment
  • Pheomelanogenesis: Creation of lighter pigment
• DHICA can be converted to ICAQ with the help of TRP1
• Leukodopachrome can be converted to ICAQ (indole-2-carboxylic acid-quinone) to EUMELANIN directly
• Enzymes and the conversion of compounds to melanin (either eumelanin or pheomelanin) are crucial for manufacturers
• Hyperpigmentation is often due to too much melanin or abnormal pigment distribution
• Heavy metals or drug metabolites can also change skin color
• Constitutive pigmentation is the genetically-determined level of melanin in the skin not influenced by external factors
• Facultative pigmentation is the induced increase in epidermal melanin content due to environmental factors like solar radiation or hormones
• Tyrosinase inhibition lessens production of eumelanin (dark complexion)
• Types of inhibition:

  • Competitive inhibition
  • Non-competitive inhibition
  • Uncompetitive inhibition
• Tyrosinase inhibitors are important in preventing melanin accumulation in the skin
• Interruption on melanosome transfer involves blocking sAPP and inhibiting PAR-2 to influence melanin transfer
• Skin-whitening topical agents do not provide instant whitening mechanisms and are temporary
• Increased epidermal turnover and desquamation can result in skin lightening
• Skin-whitening actives ingredients and their mechanisms of action:

  • Hydroquinone: Inhibition of tyrosinase activity
  • Arbutin: Inhibition of tyrosinase activity
  • Kojic Acid: Inhibition of catecholase activity of tyrosinase
  • Azelaic acid: Melanin inhibition in melanoma cells
  • Niacinamide: Inhibition of melanosome transfer
  • Soyabean: Inhibits protease-activated receptor 2 cleavage
  • a-Hydroxy acid: Promotes skin desquamation
  • Retinoic acid: Promotes skin desquamation
  • Vitamin C: Inhibition of tyrosinase activity
• Skin color measurements:

  • Mexameter: Measures light reflection and absorption for melanin and hemoglobin
  • Chromameter: Evaluates skin tone, detects erythematous and tanning responses, assesses bruises, scarring, and treatment efficacy