Gas chromatography flame ionization detection of alkaloids, phytochemicals, antimicrobial and antifungal potential of Ageratum conyzoides leaf extract in vitro and in silico studies

Bacterial and fungal infections remain prevalent in the world especially African countries. Ageratum conyzoides is a plant with many medicinal uses found across many African countries. The aim of the present study was to evaluate the phytochemical, antibacterial, antifungal properties of methanolic extract of Ageratum conyzoides in vitro and molecular docking studies. Gas chromatographic flame ionization detection (GC-FID), spectrophotometric and antimicrobial assays were determined, also in silico methods were also carried out. The qualitative phytochemical results revealed the presence of tannins, saponins, alkaloids, phenols and flavonoids. Quantitative bioactives detected were tannins 10.76 ± 1.52 g/L, alkaloids 3.67 ± 1.07 %, phenols 39.42 ± 3.6 mg GAE/g, and flavonoids 24.34 ± 2.06 mg QE/g. The GC-FID analysis revealed many important alkaloids like camptothecin, jatrorrhizine, chelidonine, strychnine, stachdrine and leonurine which were docked against dihydrofolate reductase (PDB ID: 1AI9) and pectin lyase (PDB ID: 11DK).The extract (Ageratum conyzoides) inhibited Staph aureus, K. pneumoniae and P. aeruginosa at 100 mg/ml. A zone of inhibition of 11 mm, 8 mm and 7 mm respectively was recorded. The antifungal properties of Ageratum conyzoides revealed a zone of inhibition of 13 mm against Mucor sp at 100 mg/ml. Also the docking studies revealed high docking scores for leonurine −6.13 kcal/mol against pectin lyase, chelidonine −5.65 kcal/mol and Jatrorrhizine and camptothecin −6.81 and −6.40 kcal/mol respectively against dihydrofolate reductase. In conclusion, Ageratum conyzoides is a source of potential alkaloids useful as therapeutic agents against microbial infections.