Comparative Study of Bioactivities and Chemical Constituents of Cymbopogon jwarancusa subsp. olivieri (Boiss.) Soenarko Harvested in Spring and Winter

Essential oils and solvent extracts of Cymbopogon jwarancusa subsp. olivieri (Boiss.) Soenarko plants harvested during two different seasons were investigated in terms of chemical composition and biological activities. Piperitone was the major constituent of essential oil extracted from plants harvested in spring and winter (49.1 and 54.1 %, respectively). The highest total phenolic and flavonoid contents were measured in ethanol extract obtained from spring plants (31.72±0.08 mg gallic acid equivalents/g and 40.93±1.12 mg quercetin equivalents/g, respectively), and in acetone extract from plants collected in winter (31.24±0.17 mg GAE/g and 38.32±0.74 mg QE/g, respectively). Amongst the various extracts and essential oils, the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging capacity was recorded in ethanol extract (IC50 = 40.51±3.89 ppm) from plants collected in spring, in comparison with butylated hydroxytoluene (IC50 = 5.85±1.84 ppm) and ascorbic acid (IC50 = 1.28±0.06 ppm) as controls. Antibacterial and antifungal activities of all samples were tested by disc-diffusion, MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration) and MFC (minimum fungicidal concentration) tests. Diethyl ether extract from winter plants exhibited the highest inhibitory activity against Streptococcus pneumoniae (inhibition zone diameter, IZD = 19.28±1.51 mm), compared with gentamicin and penicillin (IZD = 19.87±0.37 and IZD = 13.61±1.84, respectively). Overall, the results showed that the essential oil of C. jwarancusa subsp. olivieri could be considered as a source of piperitone, whereas the diethyl ether extract of the plant could be developed as a promising antibacterial agent in food and pharmaceutical industries.