Isolation of new steroids of Kala Dhaman grass (Cenchrus setigerus) and evaluation of their bioactivity

Abstract

The present study was carried out to determine the possible bioactive components (steroids) of Cenchrus setigerus using GC-MS analysis and in vivo estimation of metabolites (total soluble sugar, soluble protein, proline and total phenolics), photosynthetic pigments (chlorophyll-a, chlorophyll-b and carotenoids) of seedlings and antimicrobial activity of extracts in various polar solvents from the leaves of C. setigerus. Antimicrobial activity was evaluated against three Gram-negative bacteria, including Proteusmirabilis, Klebsiella pneumonia and Agrobacterium tumefaciens andone fungus Aspergillus niger using 'disc diffusion' method, followed by the determination of minimum inhibitory concentrations (MIC) by broth dilution method. Results revealed the presence of some steroids in the isopropyl alcohol extract of C. setigerus:which are (22E)-stigmasta-4,22-dien-3-one(4.93%), δ4-sitosterol-3-one (stigmast-4-en-3-one) (4.31%), fagarsterol (lupeol) (1.25%) and ethyl iso-allocholate (0.32%). Total soluble sugars and chlorophyll-a were also recorded to be highest. The highest activity was exhibited by the isopropyl alcohol and ethyl acetate extract against P. mirabilis.