Estudo fitoquímico das folhas de Psychotria viridis (Rubiaceae) e avaliação da atividade biológica de extratos e constituintes

Abstract

Phytochemical study of the hexane, chloroformic and methanolic extracts from the leaves of Psychotria viridis resulted in the isolation of: a mixture of two pentacyclic triterpenes, ursolic and oleanolic acid; three steroids , 24-methylenecycloartanol and a mixture of stigmasterol and -sitosterol; a mixture of two steroid glucoside, 3-O--D-glucosyl--sitosterol e 3-O--D-glucosyl--stigmasterol; the polyunsaturated triterpene, squalene; two esters of glycerol, the monoacylglycerol monopalmitin and a triacylglycerol; a mixture of long chain hydrocarbons; an aldehyde, nonacosanal; three long chain fat acids, the hentriacontanoic, hexadecanoic and heptadenoic acids; a methyl ester, methyl heptadecanoate; a quinic acid derivate, the methyl 4-epi-quinate and two indole alkaloids, N,N-dimethyltryptamine and Nmethyltryptamine. The chemical structures were determined by spectroscopic (IR, 1H and 13 C NMR, HSQC, HMBC and NOESY) and spectrometric (CG-EM e LCMS-ESI-ITTOF) methods. The study of the biological activity consisted of activity of the capacity to inhibit acetylcholinesterase, antimicrobial activity and evaluation of citotoxic activity. The hexane, chloroformic, ethyl acetate and methanolic extracts, the substances 24-methylenecycloartanol, N,N-dimethyltryptamine (DMT) and a mixture of 3-O--Dglucosyl--sitosterol e 3-O--D-glucosyl--stigmasterol showed cholinesterase inhibiting activity. Wherein the chloroformic and ethyl acetate extracts showed cholinesterase inhibiting activity higher than 90%. Tryptamine (DMT precursors) was active against S. aureus, B. cereus, E. coli, K. oxytoca e K. pneumoniae. The methanolic extract showed antioxidant activity (oxygen radical scavenging capacity) higher than 85%, at concentration above 125,00 µg/mL. The methanolic and ethyl acetate extracts were able to inhibit the growth and/or induce the death of the tumoral cell strains B16F10 and 4T1, without damaging of the integrity of the normal cell strain BHK and CHO. The DMT also demonstrated a pronounced activity against tumoral cell strains B16F10 and 4T1.