Diversity and chemical fingerprinting of endo-metabolomes from endophytes associated with Ampelopsis grossedentata (Hand.-Mazz.) W. T. Wang possessing antibacterial activity against multidrug resistant bacterial pathogens.

BACKGROUND: Serious infections caused by bacteria and their resistance to antibiotics are one of the biggest healthcare threats to mankind. Therefore, the present study aimed to isolate endophytes from medicinal plant Ampelopsis grossedentata, an endemic species of Western Hubei, China and to investigate its antibacterial efficacy and chemical diversity of the secondary metabolites. METHODS: The antibacterial potential of the endophytes was evaluated by disc diffusion method against a panel of eleven type strains and some multidrug resistant pathogenic bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were estimated by broth microdilution using iodonitrotetrazolium chloride assay. Further, the chemical diversity of the metabolites was estimated using LC-Q-TOF-MS/MS and GC-MS fingerprinting. RESULTS: Four endophytic fungi were isolated from the tender shoot of A. grossedentata; they were identified as Fusarium graminearum TC-1, Phomopsis mali TC-3, Pestalotiopsis maculans TC-5 and Alternaria alternata TC-11. Among the endophytes screened, A. alternata TC-11 exhibited significant antibacterial activity with the zones of inhibition ranging from 13.72 ± 0.30 to 21.76 ± 0.53 mm against all the tested type strains and multidrug resistant bacterial pathogens. Further, it showed significant antibacterial activity with MIC values ranging from 0.37 to 3.00 µg/mL. The combined LC-Q-TOF-MS/MS and GC-MS analyses of active extract revealed that alternarian acid, altertenuol, dimethyl sulfone, docosane, dodecane, duclauxin, ergosta-4,6,8(14),22-tetraen-3-one, ethyl 6-cyano-5-oxo-1-phenyl-7-thiophen-2-yl-[1,2,4]triazolo[4,3-a]pyrimidine-3-carboxylate, heptacosane, linoleic acid, neodecanoic acid, oxiranylmethyl ester, pentadecane, verrulactone E, 2,6,11-Trimethyldodecane and 4-[(E,4R,6R)-11-(furan-3-yl)-6-hydroxy-4,8-dimethylundec-8-enyl]-2-hydroxy-2H-furan-5-one were the most abundant compounds present which were responsible for the significant antibacterial activity. CONCLUSIONS: To our knowledge, this is the first report of fungal endophytes isolated from the tender shoot of A. grossedentata with bacteriostatic and bactericidal activities. Our finding provides a new insight into the antibacterial potential of endophytes and envisages the possibility of using them for drug discovery.

Poor vitamin D status and the risk of maternal depression: a dose-response meta-analysis of observational studies.

OBJECTIVE: The association between 25-hydroxyvitamin D (25(OH)D) and maternal depression (MD) is deemed to be inconclusive. The current analysis aimed to quantify the relationship between 25(OH)D serum concentrations, the main indicator of vitamin D nutritional status, and MD. DESIGN: Dose-response meta-analysis. SETTING: A systematic search in PubMed, Embase and Web of Science from inception to June 2019. PARTICIPANTS: Relevant observational studies reporting risk estimates and 95 % CI of random effects for 25(OH)D concentration on MD were identified. RESULTS: Twelve observational studies with thirteen independent reports involving 10 317 pregnant women were included. Compared with the lowest category of 25(OH)D, the pooled OR for the highest category of MD was 0·49 (95 % CI 0·35, 0·63); a high heterogeneity was observed (P = 0·001, I2 = 82·1 %). A non-linear association between 25(OH)D and MD was found (P for non-linearity = 0·001); the dose-response analysis indicated that the lowest pooled OR was at blood 25(OH)D concentrations of 90-110 nmol/l. Subgroup analyses suggested a stronger association between 25(OH)D and MD in summer time (OR 0·25, 95 % CI 0·08, 0·43) than in other seasons (OR 0·68, 95 % CI 0·52, 0·83) (P for interaction = 0·008). A visual inspection of funnel plot and Begg's and Egger's tests did not indicate any evidence of publication bias. CONCLUSIONS: Low circulating 25(OH)D is associated with MD, and our analysis suggests that they influence each other. Further randomised controlled trials would be needed to determine the direction of causation.