Searching for flavonoids with tyrosinase inhibitory activity from extracts of Dalea pazensis.

SANTI MARIA D; PERALTA MARIANA A; OVEJERO MARIBEL; MENDOZA CATERINE S; CABRERA JOSE L.; ORTEGA, M. GABRIELA

Córdoba

Otro; 3° Reunión Internacional de Ciencias Farmacéuticas(RiCiFa); 2014

Tyrosinase enzyme (Tyr) participates in the biosynthesis of melanin, responsible for the color formation in the skin of mammals, catalyzing two reactions: hydroxylation of L-Tyrosine (monophenolase activity) and L-Dopa´s oxidation to o-dopaquinone (diphenolase activity). The inhibition kinetics for these reactions are different because Tyr presents two active sites. Tyr inhibitory compounds are important in the treatment with abnormal pigmentation diseases and as whitening agents in cosmetics, but they showed toxicity, so research for new inhibitors of Tyr becomes primary. In the plant kingdom, flavonoids are the polyphenols?s group more studied. Some of them were reported as Tyr inhibitors. The chemical and pharmacological study of the genus Dalea in Argentina has been performed by our group informing new prenylated flavonoids with important activity as Tyr inhibitors, antioxidant and antimicrobial. The promising results motivate us to study other species in the genus. Previously, we inform that different extracts of Dalea pazensis, Bolivian specie, showed significant inhibition of monophenolase activity. In the present study, the inhibitory activity of diphenolase by hexane, benzene, ethyl acetate and ethanol extracts are presented. Also, the isolation, identification and diphenolase inhibitory activity of 5,7,2 ´, 4´-tretrahydroxy-5´-(1´´´, 1´´ ´-dimethylallyl)-8-prenylflavanone (8PP), isolated from the benzene extract and informed in other species of the genus, are reported. The results show a benzene extract as the most active (82.6 ± 1.0) % at 1μg/mL. 8PP showed an inhibition with an IC50 (80.7 ± 0.4) mM, compared with reference inhibitor Kojic Acid (IC50 =129.6 ± 0.3) mM, showing two times more active than the reference inhibitor. Previously, 8PP had shown a significant inhibition on monophenolase activity. Thus, 8PP could be a new candidate with potential applications in the pharmaceutical and cosmetic industries, motivating us to search other components that could contribute to the significant activity observed for the benzene extract as Tyr inhibitors.