Multifloraflavone and polyphenols from Garcinia multiflora with antioxidant, anti-acetylcholinesterase, and anti-Helicobacter pylori activities

A new tetraflavonoid, named multifloraflavone (1), along with garcinol (2), isogarcinol (3), aromadendrin (4), and morelloflavone (5) were isolated from the fruit pericarp of Garcinia multiflora collected in Vietnam. The three-dimensional arrangements of groups in this complex molecule were analysed using NOESY and CD spectroscopic methods. Compounds 1-5 were evaluated for their antioxidant, acetylcholinesterase inhibitory, and anti-Helicobacter pylori activities. Multifloraflavone (1) exhibited the strongest antioxidant activity in the DPPH scavenging assay (IC50 = 3.90 µM), surpassing the standard quercetin. Aromadendrin (4) and morelloflavone (5) displayed potent acetylcholinesterase inhibitory effects (IC50 = 0.66 and 1.13 µM, respectively), approaching the efficacy of the reference drug donepezil (IC50 = 0.076 µM). Notably, compounds 1 and 3-5 exhibited activity against H. pylori strains. Compound 4, with MIC values of 0.1-0.5 mg/mL, showed the strongest inhibition against a H. pylori HP-6.250224 clinical isolate strain, which is ­resistant to amoxicillin, metronidazole, and clarithromycin.