Antimicrobial, Cytotoxic and Phytochemical Analysis of Chloroform Extracts of Andrographis paniculata Root (Burm.F) and Parquetina nigrescens (Afzel) Aerial Part

Abstract

The menace of antibiotic resistance especially multi-drug resistant bacteria is increasing in the clinical setting. Therefore, the study investigated antimicrobial activity and phytochemical constituents of chloroform extracts of Andrographis paniculata root (Burm.F.) and Parquetina nigrescens (Afzel) aerial part. The extracts were screened for cytotoxic activity using brine shrimp (Artemia salina) lethality bioassay. The antimicrobial activity of the extracts was tested against Citrobacter diversus, Klebsiella pneumoniae, Proteus vulgaris and Shigella sonnei using tetrazolium microtitre-plate method. Analysis of chemical components of the extracts was done on Agilent Technologies 7890A gas chromatograph system s. GC-MS analysis of A. paniculata root extract and P. nigrescens aerial part extracts revealed a total of 32 and 22 compounds, respectively. The major components identified in these two extracts were fatty acid esters, alkaloids and terpenes. The lowest MIC observed with A. paniculata extract was 6.25 μg/ml for Citrobacter diversus and 12.5 μg/ml for Klebsiella pneumoniae. The lowest MIC recorded for Parquetina nigrescens extract was 3.125 μg/ml for Citrobacter diversus, Shigella sonnei and Proteus vulgaris while it was 12.5 μg/ml for Klebsiella pneumoniae. The susceptibility was compared with a clinical antibiotic (0.02 μg/ml) which served as the positive control. P. nigrescens with LC50 of 89.75 ± 0.18 μg/ml showed higher lethal toxicity than A. paniculata with LC50 of 167.5 ± 0.21 μg/ml. The observed toxicity might be due to presence of fatty acids and alkaloids in the extracts. The extract of the plants investigated in our study showed promising antimicrobial activity. Dhaka Univ. J. Pharm. Sci. 23(1): 43-51, 2024 (June)