Structural characteristics and in vitro fermentation patterns of polysaccharides from Boletus mushrooms

Digestive characteristics of Gastrodia elata Blume polysaccharide and related impacts on human gut microbiota in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Blume is a traditional Chinese medicine with the effects of improving the deficiency of the body and maintaining health, and polysaccharide (GEP) is one of the effective ingredients to play these activities of G. elata. Traditionally, G. elata is orally administered, so the activities of GEP are associated with digestive and intestinal metabolism. However, the digestive behavior of GEP and its effects on the human gut microbiota are unclear and need to be fully studied.

AIM OF THE STUDY

This study aimed to investigate the changes in structural characteristics of GEP during digestion and the related impacts of its digestive product on gut microbiota in human fecal fermentation, and to explain the beneficial mechanism of GEP on human health from the perspective of digestive characteristics and "gut" axis.

MATERIALS AND METHODS

The changes of reducing sugars, free monosaccharides and physicochemical properties of GEP during digestion were investigated by GPC, HPLC, FT-IR, CD, NMR, SEM, and TGA. Moreover, polysaccharide consumption, pH value changes, SCFAs production, and changes in gut microbiota during fermentation were also discussed.

RESULTS

During digestion of GEP, glucose was partially released causing a decrease in molecular weight, and a change in monosaccharide composition. In addition, the characteristics of GEP before and after digestion, including configuration, morphology, and stability, were different. The digestive product of GEP was polysaccharide (GEP-I), which actively participated in the fecal fermentation process. As the fermentation time increased, the utilization of GEP-I by the microbiota gradually increased. The abundance of probiotics such as Bifidobacterium, Collinsella, Prevotella, and Faecalibacterium was significantly increased, and the abundance of pathogenic Shigella, Dorea, Desulfovibrio, and Blautia was significantly inhibited, thereby suggesting that GEP has the potential to maintain human health through the "gut" axis. In addition, the beneficial health effects of GEP-I have also been observed in the influence of microbial metabolites. During the fermentation of GEP-I, the pH value gradually decreased, and the contents of beneficial metabolites such as acetic acid, propionic acid, and caproic acid significantly increased.

CONCLUSION

The structure of GEP changed significantly during digestion, and its digestive product had the potential to maintain human health by regulating gut microbiota, which may be one of the active mechanisms of GEP.

In vitro digestion and fermentation behaviors of polysaccharides from Choerospondias axillaris fruit and its effect on human gut microbiota

Choerospondias axillaris fruit has attracted more and more attention due to its various pharmacological activities, which are rich in polysaccharides. This study investigated the in vitro saliva-gastrointestinal digestion and fecal fermentation behaviors of polysaccharides from Choerospondias axillaris fruit (CAP), as well as its impact on human gut microbiota. The results showed that CAP could be partially degraded during the gastrointestinal digestion. The FT-IR spectra of the digested CAP didn't change significantly, however, the morphological feature of SEM changed to disordered flocculent and rod-like structures. 16S rRNA sequencing analysis found that after in vitro fermentation, CAP could increase the relative abundances of beneficial bacteria including Megasphaera, Megamonas and Bifidobacterium to produce short-chain fatty acids (SCFAs), while it can also reduce the abundances of harmful bacteria of Collinsella, Gemmiger, Klebsiella and Citrobacter, suggesting that CAP could modulate the composition and abundance of gut microbiota. These results implied that CAP can be developed as a potential prebiotic in the future.

In vivo absorption, in vitro simulated digestion and fecal fermentation properties of polysaccharides from Pinelliae Rhizoma Praeparatum Cum Alumine and their effects on human gut microbiota

Polysaccharides from Pinelliae Rhizoma Praeparatum Cum Alumine (PPA) have various biological activities, but their properties after oral administration are not clear. In this study, the absorption, digestion and fermentation properties of PPA were studied using in vivo fluorescence tracking, in vitro simulated digestion and fecal fermentation experiments. The absorption experiment showed that fluorescence was only observed in the gastrointestinal system, indicating that PPA could not be absorbed. Simulated digestion results showed that there were no significant changes in the molecular weight, Fourier transform infrared spectroscopy (FT-IR) spectrum, monosaccharides and reducing sugar of PPA during the digestion process, showing that the overall structure of PPA was not damaged. However, the carbohydrate gel electrophoresis bands of PPA enzymatic hydrolysates after simulated digestion were significantly changed, indicating that simulated digestion might impact the configuration of PPA. In vitro fermentation showed that PPA could be degraded by microorganisms to produce short chain fatty acids, leading to a decrease in pH value. PPA can promote the proliferation of Bacteroideaceae, Megasphaera, Bacteroideaceae, and Bifidobacteriaceae, and inhibit the growth of Desulfobacteriota and Enterobacteriaceae. The results indicated that PPA could treat diseases by regulating gut microbiota, providing a scientific basis for the application and development of PPA.

Fermentation characteristics and prebiotic potential of enzymatically synthesized butyryl-fructooligosaccharides

Existing prebiotics, such as fructo-oligosaccharides (FOSs), can be modified to enhance their functionality or introduce additional functionalities. This study aimed to investigate the fermentation characteristics and prebiotic potential of enzymatically synthesized butyryl-FOSs. The esters were successfully synthesized through the reaction of butyric acid and FOSs using both chemical and enzymatic methods, denoted as A-FOSs and B-FOSs, respectively, for comparative analysis. The esterification degree of each component in A-FOSs was significantly higher than that of B-FOSs. Subsequently, the obtained esters were characterized for their fermentation properties, degradation mode and potential prebiotic effects using an in vitro simulated colonic fermentation model. Enzymes of human gut microbiota were found to preferentially cleave the glycosidic bond to the unit without butyryl group and release the sugars for utilization. A significant increase in butyric acid levels was observed during fermentation after the supplementation of B-FOSs. The 16S rRNA gene sequencing, absolute quantification of microbiota, and selected probiotic strains culture showed that B-FOSs supplementation promoted the growth of beneficial bacteria while reducing harmful ones. These results suggest that B-FOSs hold promise as novel prebiotics, possessing dual functions of modulating gut microbiota and delivering butyric acid to the colon in a targeted manner, ultimately contributing to improved gut health.

Comparative analysis of the nutritional and biological properties between the pileus and stipe of Morchella sextelata

Morchella sextelata is a highly prized edible mushroom and is widely consumed for its distinctive taste and texture. The stipe of M. sextelata is significantly lower in priced compared to the pileus. The aim of this study was to conduct a comprehensive comparative analysis of the nutritional and biological properties between the pileus and stipe of M. sextelata. The results revealed that the stipe exhibited comparable levels of various nutrients and bioactive compounds to those found in the pileus. The stipe showed significantly higher levels of crude dietary fiber, various mineral elements, vitamins, amino acids, 5'-nucleotides, fatty acids, and specific sugars. Additionally, it also demonstrated significant abundance in bioactive compounds such as total flavonoids and ergothioneine. Overall, our study provides valuable insights into unlocking further knowledge about M. sextelata's nutritional composition while highlighting its potential health benefits associated with different parts of this highly esteemed edible mushroom.