Estudos fitoquímicos, biológicos e dos efeitos da radiação gama na descontaminação microbiana e na integridade dos princípios ativos das cascas do caule de Luehea Ochrophylla Mart

Abstract

Luehea ochrophylla (Malvaceae) is a tree known popularly as "açoita-cavalo." Representatives of L. ochrophylla are found in Brazil, Paraguay, and Argentina. In Brazil, Luehea ochrophylla occurs in the North, Northeast, and Southeast regions. Its bark is used in the treatment of inflammations, rheumatism and arthritis, while its flowers and leaves are used to treat bleeding, gonorrhea, cough, and diarrhea. Considering these informations and the lack of studies about L. ochrophylla, this present work aimed perform phytochemical studies and pharmacological essay to prove scientifically its popular use. L. ochropylla stem bark was acquired in Belo Horizonte Central Market, having been collected in August 2012 in the city of Esmeraldas (MG). After grinding of the plant material, it was performed the maceration with hexane and posteriorly ethanol. The extracts obtained were fractionated using solvents in order of increasing polarity using hexane, DCM, EtOAc, EtOH, and MeOH as eluents. An aqueous extract was also prepared from the decoction with water of the stem bark, being posteriorly performed a methodological sequence to obtain the phenolic, saponinic, and alkaloidal fractions. Phytochemical investigation of the hexane extract obtained from stem bark of L. ochrophylla provides isolation of triterpenoids friedelin, -friedelinol, lupeol, pseudotaraxasterol, and betulinic acid in addition to -sitosterol. From the ethanolic extract were identified triterpenes lupeol and taraxasterol besides the -sitosterol-3-O--D- glucopyranoside steroid. From this extract, the flavonoids (-)-epicatechin and (+)-epicatechin- (4-8)-epicatechin, known as procyanidin B2, were also isolated. With exception of lupeol, - sitosterol-3-O--D-glucopyranoside, and (-)-epicatechin, all compounds were first described for Luehea genus. The phytochemical study of aqueous extract of stem bark of L. ochrophylla was performed by preparative HPLC analysis. As a result, was isolated and identified the trans-aconitic acid. L. ochrophylla analyzes were performed to verify sufficient gamma radiation dosage to promote the microbiological decontamination and possible chemical changes after use of gamma rays. As a result, it was noticed that the incidence of gamma radiation at doses equal to or greater than 5.0 kGy had to be sufficient for the total elimination of Lecythophora iv decumbens and Eurotium chevalieri L. Mangin, fungi species predominant in stem bark of plant studied. It was found that most of phytochemicals of the phenolic fraction had its concentration decreased when the plant material was exposed to even the smallest dose of radiation used range (1.0 kGy). The trans-aconitic acid was the most affected by gamma radiation with a reduction of 95.38% over the concentration by non-irradiated samples. It has been proposed that gamma radiation promotes hydration of the trans-aconitic acid to citric and isocitric acids by radical and ionic reactions, requiring the concomitant presence of the water during this exposure to ionizing radiation. The fraction in ethyl acetate (FA) showed anti-inflammatory activity, in vitro, similar to activity presented by dexamethasone (positive pattern). In addition, hexane extract (EH), FA and betulinic acid promoted the restructuring of muscle fibers and decreased edema and inflammatory infiltrate regions when analyzing the topical anti-inflammatory activity in vivo. These observations confirm the anti-inflammatory activity ethnopharmacological alleged. An important and promising antitumor activity was presented by -sitosterol-3-O--D- glucopyranoside for the line of colorectal cancers cells. Ethanol extract (EE) showed activity against Staphylococcus sanguinis, Salmonella typhimurium e Candida albicans. The L. ochrophylla of stem bark also showed antioxidant activity similar to activity presented by ascorbic acid used as a positive standard.