Investigating the antibacterial mechanism of Ampelopsis cantoniensis extracts against methicillin-resistant Staphylococcus aureus via in vitro and in silico analysis.

Methicillin-resistant Staphylococcus aureus (MRSA) is a critical pathogen responsible for a wide variety of serious infectious diseases in humans. The accelerated phenomena of drug tolerance, drug resistance, and dysbacteriosis provoked by antibiotic misuse are impeding the effectiveness of contemporary antibiotic therapies primarily used to treat this common worldwide pathogen. In this study, the antibacterial activity of 70% ethanol extract and multiple polar solvents of Ampelopsis cantoniensis were measured against the clinical MRSA isolate. The agar diffusion technique was employed to determine the zone of inhibition (ZOI), accompanied by the use of a microdilution series to identify the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Our results revealed that the ethyl acetate fraction exhibited the most significant antibacterial activity, which was determined to be bacteriostatic based on the MBC/MIC ratio 8. A list of compounds isolated from A. cantoniensis was computationally studied to further investigate the mechanism of action with the bacterial membrane protein PBP2a. The combination of molecular docking and molecular dynamics methods showed that the main compound, dihydromyricetin (DHM), is expected to bind to PBP2a at allosteric site. In addition, DHM was identified as the major compound of ethyl acetate fraction, which accounts for 77.03 ± 2.44% by high performance liquid chromatography (HPLC) analysis. As a concluding remark, our study addressed the antibacterial mechanism and suggested the prioritization of natural products derived from A. cantoniensis as a potential therapy for MRSA.Communicated by Ramaswamy H. Sarma.

Pogostemins A-C, three new cytotoxic meroterpenoids from Pogostemon auricularius.

Pogostemins A-C (1-3), three new meroterpenoids with pyrone-sesquiterpenoid hybrid skeletons, were isolated from the aerial parts of Pogostemon auricularius. Their chemical structures were elucidated by 1D- and 2D-NMR and HRESIMS analyses. Compound 1 showed significant cytotoxicities against the human colon adenocarcinoma SW-480, epidermoid carcinoma KB, gastric cancer AGS, hepatoma cancer Hep-G2, and lung cancer LU-1 cell lines with IC50 values of 7.21, 8.49, 9.44, 11.75, and 12.76 µg/mL, respectively.