In Vitro Modulating Effects Of Bitter Melon Preparations On Structure And Metabolism Of Human Gut Microbiota

Bitter melon (Momordica charantia, MC) has been widely usedaround the world as an edible and medicinal plant. Being believed to beeffective in treating patients with obesity or type2diabetes, different MCpreparations show dissimilar effects and their action mechanisms are stillunclear. Recent studies found that MC may play a therapeutic role bymodulating human gut microbiota.This study was to evaluate the effects of two different bitter melonproducts (Bitter melon power, BMP; Bitter melon ethanol extract, BME)on the structure and metabolism of human gut microbiota. Fresh fecalsamples from a healthy individual and a T2D patient were separatelyco-cultivated with BMP or BME for0h,12h,24h and48h underanaerobic conditions. Gas chromatography was used to measure theproduction of short chain fatty acids (SCFAs) in the supernatant.454pyrosequencing combined with multivariate statistical analysis wasemployed to examine the overall structural changes of microbiota andidentify the spedific phylotypes responding to BMP (15mg/mL,7.5mg/mL)/BME (15mg/mL,7.5mg/mL,3.75mg/mL,1.875mg/mL). Quantitative PCR (qPCR) was chosen to target the dynamic relativeabundance of5specific bacterial groups.It was found that SCFAs were significantly accumulated in thesupernatant after BMP or BME treatment, wherein the highestconcentration was in the BMP15mg/mL group. Redundancy analysisshowed that both products could change the microbial communitystructure between which the effect of BMP was more stronger.82and80BMP/BME-responding key OTUs were identified using redundancyanalysis (RDA) from samples of the healthy individual and the T2Dpatient respectively. BMP and BME could enrich Blautia andFaecalibacterium but decrease Bilophila and Desulfovibrio in bothindividuals, among which Blautia was significantly positively correlatedwith SCFAs. Also, qPCR revealed that BMP and BME promoted thegrowth of Lactobacillus, Bifidobacterium and butyrate-producing bacteriawhile Enterobacteriaceae was significantly inhibited. However, onlyBMP15mg/mL consistently prevented the increase of sulphate-reducingbacteria. The relative abundance of Bifidobacterium were significantlypositively correlated with SCFAs in both samples.Bitter melon preparations could improve the structure andmetabolism of human gut microbiota by enriching SCFA-producingbacteria and inhibiting opportunistic pathogen, with BMP showed astronger modulating effect.