Phytochemistry and DNA˗Based Authentication of Medicinal Lasianthus stipularis Blume (Rubiaceae) Species Against Human Pathogenic Bacteria:(TJPS-2020-0180.R1)

Abstract

Lasianthus stipularis Blume is a medicinal plant found in the tropical rainforests of peninsular Thailand and Malaysia. Its leaves are used in traditional medicine to treat a condition called “noise in the head” (i.e., ear infections). As such infections are often caused by gram-negative bacteria, this species of Lasianthus may have antibacterial effects. In this study, we examined the non-polar fractions from the leaves and stem bark of L. stipularis using thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The non-polar fractions exhibited a high coumarin content, while stem bark extracts showed a high concentration of 7-hydroxy-6-methoxycoumarin when isolated by column chromatography. The antibacterial activity of these extracts was evaluated by disk diffusion and broth microdilution against seven gram-negative bacteria include Escherichia coli ATCC 25922, Pseudomonas aeruginosaDMSC 37166, P. aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC–BAA 1705, K. pneumoniae ATCC–BAA 1706, Acinetobacter baumannii ATCC 19606, and A. baumannii DMSC 3487 . The DNA of L. stipularis was sequenced to support species identification and authentication. The minimum inhibitory concentration (MIC) of fractions and pure compounds against pathogenic bacteria ranged from 100–200 µg/ml. Both strains of Pseudomonas aeruginosa revealed the highest antibacterial activity at 100 µg/ml and 400 µg/ml concentration effect on Acinetobacter baumannii. In conclusion, leaf and stem bark non-polar extracts of L. stipularis have clear antibacterial activities.
:TJPS-2020-0180.R1