Chemical Constituents And Antimicrobial Activity Of Lunasia Amara Blanco And Zingiber Officinale Var. Rubrum Theilade






Lunasia amara Blanco, Zingiber officinale var. rubrum Theilade, chemical constituents, antimicrobial activity


Two species of medicinal plants, namely Lunasia amara Blanco and Zingiber officinale var. rubrum Theilade were studied for their chemical constituents and antimicrobial activity. L. amara contained mainly alkaloids and some terpenoids whereas various unsaturated terpenoids constituted the major components in the rhizomes of Z officinale var. rubrum. Antimicrobial activity was screened against some human pathogenic bacteria, yeasts and sporulated fungi. L. amara showed a pronounced and broad spectrum of antimicrobial activity whereas Z. officinale var. rubrum showed a slight activity. Petroleum ether extract was the most active extract of the rhizomes of Z. officinale var. rubrum that showed a strong activity against Trichophyton mentagrophytes. 32 components amounted to 68.21% of the extract were identified by GCMS. The extract contained mainly sesquiterpene hydrocarbons (53.88%) and ar-curcumene (13.80%) was present as the major component. Bioactivity-guided fractionation of L. amara leaves extracts, facilitated with Bioautographic Agar Overlay Assay led to the isolation of two antimicrobially active alkaloids. These alkaloids were identified as lunidonine and lunacrine by spectroscopic data analysis. Quantitative determination for antimicrobial activity of lunidonine against the susceptible organisms gave the minimum inhibitory concentration (MIC) values ranged between 3.13ug/ml and 200.0µg/ml. The MTCs of lunacrine ranged between 1.565µg/ml and 200µg/ml. The minimum bactericidal concentrations (MBCs) of lunidonine ranged between 50.0µg/ml and 200.0µg/ml whereas the values of lunacrine ranged between 12.5ug/ml and 25.0ug/ml.