A comparative analysis of the antimicrobial activities of Andrographis paniculata (Burm. f.) Wall. ex Nees plant extracts and its pure diterpenoids: Andrographolide and neoandrographolide

Abstract

The current study assesses the comparative potency of Andrographis paniculata crude extracts and their pure bioactive compounds against gram-positive, gram-negative and fungal pathogens. This study also estimated the polyphenolic contents present in different solvent extracts. A total of four solvent extracts of different polarities isolated from Andrographis paniculata and its major bioactive compounds were investigated against human pathogenic microbes. The antibacterial activities and minimum inhibitory concentrations were assessed by the broth dilution assay. The total phenolic and flavonoid contents were estimated by using the Folin–Ciocalteu reagent method and Aluminum chloride colorimetric method, respectively. Andrographolide and neoandrographolide both have significant antibacterial activities against all bacteria, but are completely inactive against Candida albicans. Ethanolic and ethyl acetate extracts demonstrated antimicrobial activity against each microbe investigated in this study. Both diterpenoids and ethanolic extract were effective against Staphylococcus aureus. This study tried to conclude that most of the solvent extracts contain anti bacterial activity, but andrographlide and neoandrographolide are not the only antibacterial agents present in the crude of Andrographis paniculata and there are also other phytochemicals present which have great activity as an antifungal agent.