Phytochemical analysis and evaluation of the phytotoxic effect of the hexane fraction from the leaves of smilax brasiliensis (smilacaceae)

Abstract

The species of Smilax genus are known as sarsaparilla or japecanga, being widely used in folk medicine as a tonic, antirheumatic, anti-syphilitic, antihypertensive and diuretic and for sweating, arthritis and skin conditions. Thus, the aim of this study was to evaluate the phytotoxic activity and to identify the main classes of secondary metabolites present in the hexane fraction obtained from Smilax brasiliensis. The leaves were collected, dried, crushed and extracted by percolation with ethanol, obtaining the ethanol extract. Part of this extract was partitioned with hexane, resulting in the hexane (HEX) fraction. The best results by the phytotoxic activity in Lactuca sativa seeds were for the HEX4 and HEX5 sub-fractions, at concentration of 250 μg per plate. When evaluating the phytotoxicity in Allium cepa seeds, the best results were found for the HEX1 sub-fraction for the radicle and the HEX2 sub-fraction for the hypocotyl, both at concentration of 125 μg per plate. Phytochemical analysis revealed the presence of coumarins, steroids and flavonoids in the hexane fraction, suggesting that the phytotoxic activity may be attributed at least partially to these compounds; however, additional studies are needed. These results suggest that in the future, the hexane fraction of S. brasiliensis leaves can be used as a natural herbicide.