GC-MS analysis and in vitro bioactivity of fixed oil and fatty acid fraction obtained from seeds of Simira gardneriana, a Rubiaceae from Brazilian Caatinga Biome

Rubiaceae family includes many species with biological activity, highlighting the genus Simira. In the Caatinga, this genus is represented by six species, and among them, Simira gardneriana is the only endemic species. Previous studies with this plant have shown that extracts from the aerial parts have antioxidant and antimicrobial activity. Thus, the aim of this study was to investigate the chemical composition, antibacterial and cytotoxic activities of fixed oil and fatty acids fraction obtained from seeds of the plant. For this, the fixed oil (Si-FO) was obtained through an extraction with petroleum ether. Subsequently, the fraction of fatty acids (Si-FA) was obtained and then esterified to facilitate analysis by gas chromatography-mass spectrometry GC-MS. Si-FO and Si-FA were evaluated for their antibacterial (MIC and MBC determination) and cytotoxic (MTS assays) properties. The GC-MS analysis identified squalene (39.95%), β-sitosterol (13.82%) and palmitic aldehyde (7.02%) as the major components of Si-FO. Meanwhile, the major compounds identified for the methylated fatty acids fraction were oleic (51.17%), 5,6-octadecadienoic (16.22%) and stearic acids (10.47%). In terms of biological activity, Si-FO and Si-FA exhibited relevant antibacterial activity against Enterococcus faecalis, Escherichia coli and Bacillus cereus strains. In addition, Si-FO showed moderate cytotoxicity against Sarcome S-180 cells, reaching 50.58% of cytotoxic activity in the highest concentration tested (400 μg/ml). These results can be explained by the chemical composition of the samples, since previous studies reported antibacterial and cytotoxic effects of the major compounds identified in Si-FO and Si-FA. Key words: Fixed oil, fatty acids, antibacterial, cytotoxic, Rubiaceae, Simira, Caatinga.