Isolation of some new steroids and evaluation of bio-activity of Cenchrus ciliaris

Abstract

Cenchrus ciliaris L. (Poaceae) is most suitable and highly nutritive grass for desert environmental conditions; still no bioactive compound identified and no antimicrobial work yet have been done on this grass. To determine the possible bioactive components (steroids) of C. ciliaris and in vivo estimation of metabolites, photosynthetic pigments of seedlings and antimicrobial activity of extract in various polar solvents from the seeds of C. ciliaris. New compounds were isolated by GC-MS analysis. Antimicrobial activity was evaluated against Proteus merabilis, Klebsiella pnemoniae, Agerobacterium tumefaciens and Aspergillus niger; using disk diffusion method followed by MIC by broth dilution method. Estimation of metabolites (total soluble sugar, soluble protein, proline and total phenolics), photosynthetic pigments (chlorophyll-a, chlorophyll-b and carotenoids) of seedlings were done with well established methods. Four new steroids from C. ciliaris were first time identified in the isopropyl alcohol extract such as 4,22-Stigmastadiene-3-one (4.76%), fagarsterol (lupeol) (1.94%), δ4-sitosterol-3-one (stigmast-4-en-3-one) (1.93%) and ethyl iso-allocholate (0.49%). The highest antimicrobial activities (in terms of zone of inhibition in mm) were exhibited by the ethyl acetate and water extract against P. merabilis (18.50 ± 0.64 and 15.5 ± 0.64 respectively) after the glacial acetic acid extract. Total soluble sugar and chlorophyll-a showed highest content.