Antibacterial Activity of Three Medicinal Lasianthus (Rubiaceae) Extracts on Human Resistant Pathogenic Bacteria

Aim: To evaluate the activity of medicinal Lasianthus extracts on bacteria and to determine the chemical characters among three medicinal Lasianthus (Rubiaceae) species. Materials and Methods: The phytochemical investigation of L. cyanocarpus, L. hirsutus and L. lucidus were performed using thin layer chromatography and high performance liquid chromatography (HPLC) techniques. Four antibacterial resistant strains including Staphylococcus aureus ATCC 43300 (MRSA), Klebsiella pneumoniae ATCC BAA 1705 (carbapenemase; KPC-producing strain) and Pseudomonas aeruginosa ATCC 27853 (AmpC β-lactamase producing strain) were used. The phytochemical investigation of L. cyanocarpus, L. hirsutus and L. lucidus were performed using thin layer chromatography and high performance liquid chromatography (HPLC) techniques. We also detected the effects of extracts on bacteria by using a scanning electron microscope. Results: The lipophilic extracts from the three plants revealed the terpenoids, coumarin and iridoid. HPLC showed similarities in the chemical profiles of both leaf and stem bark extracts. L. lucidus lipophilic extracts revealed the greatest effect against S. aureus and P. aeruginosa at 400 and 100 μg/mL respectively, whereas L. cyanocarpus extracts prominently affected K. pneumoniae at 400 μg/mL. Cell lysis and leakage of bacteria treated with extracts were observed. Conclusion: Our findings surprisingly showed the potential of antibacterial effect among resistant pathogenic bacteria. We also revealed the comparable signals of the chemical characters from the three Lasianthus. These findings support the traditional use related infectious diseases and it might be possible to further develop the antibiotic agents.