Chemical Characterization and Antibacterial Properties of Anthraquinones from Senna didymobotrya

Abstract

Bacterial infections remain a critical global health challenge intensified by the rising bacterial resistance to conventional medicines. This study evaluated the antibacterial activity of anthraquinones from Senna didymobotrya. Thin layer chromatography-direct bioautography (TLC-DB), chromatographic separations, and spectroscopic techniques proved vital research methods. The crude extracts from the plant were screened through TLC-DB method which revealed terpenoids, alkaloids, flavonoids, and phenolics. Three anthraquinones were isolated, identified, and verified by UV-Visible spectrophotometer and Nuclear Magnetic Resonance, and ESI-MS Spectrometry methods. TLC-DB bioassay method showed noTable inhibition of Pseudomonas aeruginosa of up to 13±0.00 mm for seedpod extracts and Staphylococcus aureus of 11±0.00 mm to 13±0.00 mm across samples from leaf, stem bark, and seedpod extract. Escherichia coli and Salmonella typhimurium were not inhibited. Among the isolated compounds, 1, 8-dihydroxy-3-methoxy-6 methylanthracene-9, 10-dione and 1, 8-dihydroxy-3-methylanthracene-9, 10-dione produced zones of 11±0.10 mm and 12±0.15 mm, respectively, while 1, 5-dihydroxy 3-methylanthracene-9, 10-dione showed weaker activity of 9±0.12 mm against P. aeruginosa. Due to the observed anthraquinone antibacterial activity, it is recommended for use in phytotherapy, particularly in formulations aimed at treating various ailments, including tumour cancer. These findings scientifically validated the traditional use of S. didymobotrya and highlighted the anthraquinones as promising leads against antibiotic-resistant pathogens deserving further pharmacological assessments.