Two new biologically active steroids from Costus lucanusianus (Costaceae)

A phytochemical investigation of the leaf extract of Costus lucanusianus J. Braun & K. Schum (Family Costaceae) a tropical African medicinal plant known for curing several infectious diseases such as venereal disease, cough and urinary tract infection led to the isolation of two new steroids. The identification of these isolates was achieved by modern spectroscopic methods, including 2D NMR. The in vitro antimicrobial activity and Minimum Inhibition Concentration (MIC) values of the isolated compounds against six bacterial and four fungi strains were evaluated. Compound Xp named 3,27-dihydroxy-1-methoxy-22-cholest-5-enone and compound 1 named β-sitosterol-3-O-β-D-3-deoxyxylo-4-hydroxy4,5-dimethyl-pent-2-one displayed broad antimicrobial activity at concentration 12.5 µg/mL-100 µg/mL. Compound Xp displayed MIC value 25.0 µg/mL against tested micro-organisms except for P. notatum and R. stolonifer which showed no prominent growth. Compound 1 was insufficient to determine the MIC value. This present study may be helpful in discovering new chemical groups of antimicrobial compounds that could be useful as an agent against infectious diseases.