tetracycline and hydroquinone

Exogenous ochronosis is clinically and histologically similar to its endogenous counterpart; however, it exhibits no systemic effects and is not an inherited disorder. It is characterized by an asymptomatic hyperpigmentation of the face, sides and back of the neck, back, and extensor surfaces of the extremities. The associated ochronotic discoloration most commonly results from use of products containing hydroquinone. It also occurs following use of antimalarials and products containing resorcinol, phenol, mercury or picric acid. The etiology of hydroquinone-induced hyperpigmentation in exogenous ochronosis remains speculative. The majority of patients with this condition are Black, but it has been reported to occur in Hispanics and Caucasians. Exogenous ochronosis is prevalent among South African Blacks, but is believed relatively uncommon within the US. The reasons for this phenomenon are not clear, but it could be a result of the use of skin care products containing resorcinol in combination with hydroquinone or the use of hydroquinone in a hydroalcoholic lotion. Treatment of this condition is difficult. The offending agent must be avoided, but improvement occurs only slowly. A number of topical agents have been studied as have dermabrasion and the use of lasers. Controlled studies in larger numbers of patients are require to determine the true efficacy of newer treatments.

Topics: Adrenal Cortex Hormones; Adult; Aged; Anti-Bacterial Agents; Caustics; Cosmetics; Cryotherapy; Dermabrasion; Dermatologic Agents; Female; Humans; Hydroquinones; Incidence; Keratolytic Agents; Laser Therapy; Middle Aged; Ochronosis; Resorcinols; Skin Care; South Africa; Sunscreening Agents; Tetracycline; Time Factors; Tretinoin; Trichloroacetic Acid

The total synthesis of hibarimicinone, a potent v-Src tyrosine kinase inhibitor possessing thirteen stereogenic centers and an axial chirality, has been achieved. The key step to constructing the eight-ring skeleton was the double Michael–Dieckmann-type cyclization (Hauser annulation) using a thiolactone pseudo-dimer. These synthetic studies indicated the efficiency of the thiolactone-employed route to synthesize the multiply functionalized polycyclic compounds. The ABCD-ring moiety including the bridging ether was constructed by a strategy including oxidation of the C-ring hydroquinone and the subsequent transfer of the oxidation stage to the neighboring ring. The atropisomer of hibarimicinone was also synthesized to confirm the structure of the natural product.

Topics: Cyclization; Dimerization; Glycosides; Hydroquinones; Naphthacenes; Naphthalenes; Oxidation-Reduction; Protein Kinase Inhibitors; src-Family Kinases; Stereoisomerism; Tetracycline