Oxabicyclo Isolate from the Leaves of Siparuna cymosa

In this research, the phytochemical study of extracts from the leaves of Siparuna cymosa, an endemic species in Brazil, was carried out for the first time, and evaluated the cytotoxic activity of this extract against leukemia cell lines. The dried leaves were powdered and subjected to extraction by exhaustive maceration with pure organic solvents. The chloroform and ethyl acetate extracts were purified by column chromatography, and the isolated compounds were identified by spectroscopic techniques. The cytotoxic activity of extracts and compounds against THP-1 (acute myeloid) and K-562 (chronic myeloid) leukemia lines was determined using 3-(4,5-dimethyl-2-thyazolyl)- 2,5-diphenyl-tetrazoliumbromide (MTT) assay. The isolated compounds were 1,5,6-trimethyl8-oxabicyclo[3.2.1]oct-6-en-3-ol, β-sitosterol-3-O-β-D-glucopyranoside, and kaempferol-3,7-diO-α-L-rhamnoside. This is the first report of isolation of oxabicyclo-octenol in plant species. β-Sitosterol-3-O-β-D-glucopyranoside and kaempferol-3,7-di-O-α-L-rhamnoside significantly reduced the viability of tumor cells after controlled exposure for 48 h. Moreover, selectivity was at least two times higher for such lineages compared to the results found for non-tumor peripheral blood cells (PBMC). Kaempferol-3,7-di-O-α-L-rhamnoside was the most active and selective. In conclusion, metabolites from S. cymosa showed to be of scientific interest. This study shows that the biodiversity of plant species in Brazil represents an important arsenal of organic compounds and, therefore, research should be motivated aiming at the isolation of secondary metabolites.