Isolation, biological evaluation and validated HPTLC-quantification of the marker constituent of the edible Saudi plant Sisymbrium irio L.

Phytochemical investigation and chromatographic purification of the n-hexane fraction of the aerial parts of the edible Saudi plant Sisymbrium irio led to the isolation of β-sitosterol (1), stigmasterol (2) and β-sitosterol-β-d-glucoside (3). The cytotoxic effects of the n-hexane, dichloromethane, ethyl acetate and n-butanol fractions were tested against three cancer cell lines viz., MCF-7, HCT-116 and HepG2, using the crystal violet staining (CVS) method, while the antibacterial activity against a number of pathogenic bacterial strains, was also estimated using the broth microdilution assay. The n-hexane fraction showed potent cytotoxic activities against all tested human cancer cell lines (IC(50): 11.7-13.4 μg/mL), while the dichloromethane fraction was particularly potent against HCT-116 cells (IC(50): 5.42 μg/mL). On the other hand, the n-hexane and EtOAc fractions demonstrated significant inhibitory activities against the Gram positive bacteria S. pyogenes and C. perfringens; and the Gram negative bacterium S. enteritidis. Our results warrant the therapeutic potential of S. irio as nutritional supplement to reduce the risk of contemporary diseases. Additionally, a validated high performance thin-layer chromatography (HPTLC) method was developed for the quantitative analysis of biomarker β-sitosterol glucoside (isolated in high quantity) from the n-hexane fraction. The system was found to furnish a compact, sharp, symmetrical and high resolution band for β-sitosterol glucoside (R(f)  = 0.43 ± 0.002). The limit of detection (LOD) and limit of quantification (LOQ) for β-sitosterol glucoside was found to be 21.84 and 66.18 ng band(-1), respectively. β-sitosterol glucoside was found to be present only in n-hexane fraction (2.10 μg/mg of dried fraction) while it was absent in the other fractions of S. irio which validated the high cytotoxic and antibacterial activity of n-hexane fraction of S. irio.