Plant pathogenic microbes are on rise and thus causing plants quality deterioration. Use of chemicals to lessen their effect, knowingly or unknowingly leaves their side effects. Natural product, a suitable alternative as antimicrobial agent to curb effect of such plant pathogenic microbes has led to study many rare and uncommon plants. Our study aimed to find some active constituents from invading alien species (IAS) predominant in Bihar region. Ageratum conyzoides (L.) L, Parthenium hysterophorus L., Eupatorium adenophorum Hort.Berol.ex Kunth, Galinsoga parviflora Cav. and Mikania micrantha (L.) Willd were chosen to study their active constituents using qualitative phytochemical analysis and GC-MS spectra. The extracts were evaluated to study their antimicrobial effect against plant pathogenic bacteria (S.aureus) and fungus (F.solani). The most significant results were observed in the case of Ageratum conyzoides L. extract (ACE) and Parthenium hysterophorus L.extract (PHE) against S.aureus and moderate activities against fungus by A.conyzoides (L.) L extract, E. adenophorum Hort. Berol. ex. Kunth extract and M.micrantha (L.) Willd extract. Thus these plants may be promising source as new antimicrobial drugs due to its efficacy
Keywords: Invasive alien species, Biodiversity, Chromatogram, and Retention time, Soxhlet, Inhibition, and Phytochemicals.