Metabolic and microbial modulation of phenolic compounds from raspberry leaf extract under in vitro digestion and fermentation

Abstract

Raspberry leaves, by-products in raspberry production, are also a rich source of bioactive phytochemicals. In this study, the changes of phenolic compounds in raspberries leaf extract (RLE) under in vitro digestion and colonic fermentation were further studied by HPLC-MS analysis and 16S rRNA. The results showed that the phenolic compounds in RLE were relatively stable during in vitro gastric digestion; however, in the subsequent intestinal digestion and colonic fermentation, their content decreased sharply. A large amount of hydroxyphenylpropionic acid, hydroxyphenylacetic acid and urolithins were produced under the action of gut microbiota. Moreover, compared with corresponding control, RLE significantly reduced the ratio of Firmicutes/Bacteroidetes in all volunteers, increased the relative abundances of some beneficial bacteria, Enterococcus, Prevotella, and decreased the relative abundances of potential pathogens, Clostridium and Faecalibacterium. These findings suggest that RLE during in vitro digestion and fermentation has positive effects on gut microbiota and potential value of maintaining intestinal health.

An Integrated Extraction–Purification Process for Raspberry Leaf Polyphenols and Their In Vitro Activities

“…Our previous results showed that raspberry leaf extract with 50% total phenolic content (TPC) had positive effects on gut microbiota during in vitro digestion and fermentation, and reduced the ratio of Firmicutes/Bacteroidetes and the relative abundance of potential pathogens in the feces of all volunteers. The extract also increased the relative abundance of some bacteria, e.g., Enterococcus and Prevotella, that have been shown to have beneficial value in maintaining intestinal health [6]. Moreover, it was shown to have a potential role in HFD-induced body weight control in mice [7].…”

“…Their adsorption kinetic properties were analyzed using pseudo-first-order (Equation ( 6)) and pseudo-second-order (Equation ( 7)) models. ln q t − q e = −k 1 t + lnq e (6) t q t = 1 k 2 q 2 e + t q e (7) q e is the adsorption equilibrium capacity (mg). q t is the adsorption capacity (mg) at interval time t. k 1 and k 2 are the rate constants of pseudo-first-order kinetic and pseudosecond-order kinetic models, respectively.…”

“…Among 25 kinds of ellagitannin from unripe raspberry (Rubus chingii), Chingiitannin A showed the best inhibitory activities against α-amylase and α-glucosidase [10]. Raspberry leaves are rich in polyphenols, ellagictannins, quercetin, and kaempferol derivatives, and have good antioxidant, anti-inflammatory, and anti-diabetic properties, as well as the ability to improve obesity and intestinal flora balance, thus being of high healthcare value and industrial value [6,[10][11][12][13].…”

Integrated 16s RNA sequencing and network pharmacology to explore the effects of polyphenol-rich raspberry leaf extract on weight control

“…In our previous studies, it was shown that the total phenolic content (TPC) of raspberry leaf extract (RLE) reached 540.32 ± 8.96 mg g −1 , and RLE supplementation reduced body weight and adipose percentage in mice after ingestion ( 19 ). In addition, the 16 s RNA sequencing results of co-cultivation of RLE with volunteer feces showed that RLE has potential value in maintaining intestinal health ( 20 ).…”