Vitamin A or Retinoids are the gold standard of topical anti-aging therapy. It increases the epidermal proliferation and differentiation leading to thicker and healthier epidermis. This effect also causes improvement in the yellowish color of aging skin and correction of dyschromia such as sun spots. It also stimulates the production of epidermal glycosaminoglycans and extracellular dermal matrixcomponents, thus leading to thickening of dermis. It inhibits collagenases and metalloproteinases which degrade the collagen. This leads to improvement in elasticity of the skin and attenuation of fine lines and wrinkles. It protects the skin from UV induced damage and by itself has the power of SPF 20. It improves the healing time of aged skin and has mild anti carcinogenic effect. Seems like a wonder molecule to me!! I have detailed the biochemistry of Retinoids in the image below using powerpoint slide!