Estudo fitoquimico e atividades biológicas de extratos de Goupia glabra aublet (Cupiúba)

Abstract

The species Goupia glabra Aublet (Goupiaceae), popularly known as cupiúba is used in popular medicine against several diseases. Their barks are used as dental analgesic, as a vermifuge, to treat malaria, chickenpox and eczema. The leaves are used against syphilis, ocular disorders, migraine, smallpox and as healing. This study aimed to quantify the phenolic compounds and evaluate the antioxidant, inhibiting acetylcholinesterase, brine shrimp toxicity, antitumor and antimicrobial activities of extracts of leaves, thin and thick branches of cupiúba. The dry material was crushed and subjected to Soxhlet extraction using solvents in increasing order of polarity (hexane, ethyl acetate and methanol). The phytochemical screening was performed for different classes of metabolites, observed positive results for sterols in all extracts and terpenoids and some classes of flavonoids in the extracts obtained in ethyl acetate and methanol. The fractionation of the hexane extract of leaves (EHF) resulted in the isolation of a mixture composed by β-sitosterol and stigmasterol. From ethyl acetate extract of leaves (EAF) was isolated catechol, a simple phenol with restricted distribution in nature. The total phenolic content of extracts was determined using the Folin-Ciocalteau and the result was expressed as gallic acid equivalents (GAE). The antioxidant activity was assessed by the ability of capturing the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH ), using quercetin as external standard, expressed as value of the effective concentration (EC50). We observed a positive correlation between total phenolics and EC50, ie as greater the amount of phenolics smaller is the EC50. The ethyl acetate extract of the leaves (EAF) presented the highest antioxidant potential [EC50 = 9.76 ± 0.42 μg/mL (quartz cuvette) and EC50 = 19.87 ± 0.31 μg/mL (microplate)]. The toxicity of the extracts was verified by bioassays with microcrustacea A. salina and expressed in percentual mortality of nauplius. Qualitative analysis of anticholinesterase activity was performed according to the method of Ellman (modified), presenting negative results. The antitumor activity was evaluated against four cell lines (leukemia, breast, colon and glioblastoma) using colorimetric analysis method based on conversion of salt 3-(4,5-dimethyl-2-thiazole)-2,5-diphenyl-2-H-tetrazonium bromide (MTT) into blue formazam by the method of Mossman. The best results were observed for the ethyl acetate extracts, especially for cells HCT-8 (colon) that ranged from 58.35 to 77.12%. The ethyl acetate extract obtained from thick branches (EAGg) showed values of IC50 = 13.73 μg/mL for strain HL-60 (leukemia). This extract was fractionated and the fraction EAGg5 showed the percentage of cell growth inhibition of 85.37 and 101.37% for the lines SF-295 (glioblastoma) and MDAMB-435 (breast), respectively. The antimicrobial activity was conducted using the minimum inhibitory concentration (MIC) that was determined by microdilution in Mueller-Hinton broth for bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and in liquid Sabouraud for fungi (Candida albicans, C. tropicalis and C. parapsilosis). All extracts showed some degree of bacterial and fungicidal activity, especially the ethyl acetate extracts which showed moderate inhibition of microbial growth. The effect of extracts on growth of protozoa in vitro study was evaluated with promastigotes of Leishmania amazonensis and epimastigotes of Trypanosoma cruzi. EAGg extract showed antiproliferative activity against both L. amazonensis and T. cruzi, with IC50 values of 86 and 40 μg/mL, respectively. The significant antioxidant, antitumor and antimicrobial activities observed in the extracts of cupiuba detaches its high potential for obtaining of biotechnological products.