Synergy is now a widely recognized approach that has direct applicability for new pharmaceuticals. The ethanolic extract of the aerial parts of the herb Sophora moorcroftiana showed significant antibacterial activity against drug-resistant Staphylococcus aureus, and its minimum inhibitory concentration (MIC) was 8 µg/mL. In a phytochemical study of the extract, five flavonoids were obtained. However, the isolates exhibited antibacterial activity in the range of 32-128 µg/mL, which was weaker than the extract. In combination with antibiotics, the antibacterially inactive compound genistein (1) and diosmetin (4) showed significant synergistic activity against drug-resistant S. aureus. In combination with norfloxacin, genistein (1) reduced the MIC to 16 µg/mL and showed synergy against strain SA1199B with a fractional inhibitory concentration index (FICI) of 0.38. With the antibiotics norfloxacin, streptomycin and ciprofloxacin, diosmetin (4) showed synergy against SA1199B, RN4220 and EMRSA-15, with FICI values of 0.38, 0.38 and 0.09, respectively. In an efflux experiment to elucidate a plausible mechanism for the observed synergy, genistein showed marginal inhibition of the NorA efflux protein.

This study seeks to discover flavonoids from a traditional Chinese herb, Artemisia rupestris L., with synergistic antibacterial effects against multidrug-resistant Staphylococcus aureus.Five flavonoids, artemetin (1), chrysosplenetin (2), pachypodol (3), penduletin (4) and chrysoeriol (5) were obtained by various column chromatographic methods. Their chemical structures were determined on the basis of comprehensive spectroscopic analysis and comparison with literature data. Three of the compounds (2, 4 and 5) exhibited synergistic activity when combined with norfloxacin against SA1199B, an effluxing fluoroquinolone-resistant strain. The fractional inhibitory concentration indices (FICIs) of 2, 4 and 5 in combination with norfloxacin were 0.375, 0.079 and 0.266 respectively, suggesting synergy. Compound 5 also showed synergistic effects against EMRSA-15 and EMRSA-16 when combined with ciprofloxacin and oxacillin exhibiting FICIs of 0.024 and 0.375 respectively. Real time ethidium bromide (EtBr) efflux assay, qRT-PCR and molecular docking were employed to explore the mechanisms of the synergistic effects.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Valeriana jatamansi Jones is an aromatic medicinal herb and important alternative to V. officinalis, which is utilized for medicinal purposes in China and India and also as spices in India. Bioactive ingredients of V. jatamansi vary in different regions. However, no information is currently available on influence of genotype and environmental factors in the volatile compounds, especially when germplasms and planting locations need to be selected. Based on the results of SNP and volatile constituents from GC-MS analysis, this study found various genotypes and chemotypes of V. jatamansi for wild plants from seven regions in China and common-garden samples; correlations between genotype and chemotype were revealed for the plants. Two distinct populations (PX, FY) were distinguishable from five others (GJ, YL, SY, DD, DY) according to their genotypes and volatile profiles, the consistency of which was observed showing that genotype could significantly influence chemotype. Wild populations and common-garden samples were also separated in their volatile profiles, demonstrating that environmental factors strongly affected their chemotypes. Compounds contributing to the discrimination were identified as discriminatory compounds. This investigation has explored and provided essential information concerning the correlation between genotype and chemotype as well as environmental factors and chemotype of V. jatamansi in some regions of China. Feasible plantation and conservation strategies of V. jatamansi could be further explored based on these results.