Seasonal changes in essential oil composition of Aristolochia longa L. ssp. paucinervis Batt. (Aristolochiaceae) roots and its antimicrobial activity

The composition of essential oil is known to depend on intrinsic and extrinsic factors, including season harvest and climate condition among others. Experiments were conducted to study the variation in the essential oil composition of Aristolochia longa ssp. paucinervis harvested at different period (August, 2009; September, 2011; March, 2012; and April, 2013). The essential oil composition was assessed by GC-FID and GC-MS analyses, which revealed the presence of 103 molecules. Hence, samples collected in April 2013 showed the most complex composition (51 compounds) when compared with those collected in September 2011 (42 compounds), August 2009 (37 compounds) and March 2012 (35 compounds). Further, oxygenated sesquiterpenes (50.2-81.1%) and oxygenated monoterpenes (5.9-28.0%) are the major chemical groups.The antimicrobial properties of essential oils were evaluated against six microorganisms by the disc diffusion method. The highest activity is observed against all the Gram-positive bacteria. Increasingly, the essential oil isolated from roots collected in September (2011), exhibited the highest antimicrobial activity against Streptococcus agalactiae and Enterococcus faecium.