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Rice husk (RH) is an agricultural waste obtained from rice milling process. Our previous study demonstrated the optimized process of extracting xylooligosaccharides (XOS), a prebiotic that can support the growth and activity of beneficial gut microbiota, from RH. Accumulated evidences indicate that the composition of gut microbiota is involved in the progression of insulin resistance and diabetes. This study aims to evaluate the antihyperglycemic effect and putative mechanisms of RH-XOS using a diabetic rat model induced by high-fat diet and streptozotocin injection. Diabetic rats were randomly assigned to receive vehicle (DMC), XOS (DM-XOS), metformin (DMM), and a combination of XOS and metformin (DMM-XOS). An additional group of rats were fed with normal diet plus vehicle (NDC) and normal diet plus XOS (ND-XOS). Supplementation with RH-XOS for 12 weeks successfully decreased the fasting plasma glucose, insulin, leptin, and LPS levels in DM-XOS compared with DMC. Likewise, the insulin-stimulated glucose uptake assessed by in vitro study was significantly enhanced in DM-XOS, DMM, and DMM-XOS. The diminished protein expressions of GLUT4 and pAkt Ser473 as well as pAMPK Thr172 were significantly modulated in DM-XOS, DMM, and DMM-XOS groups. Interestingly, RH-XOS supplementation reversed the changed gut permeability, elevated the number of beneficial bacteria, both Lactobacillus and Bifidobacterium spp., and increased SCFAs production. Taken together, the results confirm the efficacy of RH-XOS in achieving good glycemic control in diabetes by maintenance of gut microbiota and attenuation of endotoxemia.The findings reveal the benefits of RH-XOS and open an opportunity to improve its value by its development as a nutraceutical for diabetes. K E Y W O R D Santihyperglycemia, diabetes mellitus, gut microbiota, prebiotic, rice husk, xylooligosaccharides | 429 KHAT-UDOMKIRI eT Al.

Despite the updated knowledge of the impact of gut dysbiosis on diabetes, investigations into the beneficial effects of individual bacteria are still required. This study evaluates the antihyperglycemic efficacy of Lactobacillus paracasei HII01 and its possible mechanisms in diabetic rats. Diabetic rats were assigned to receive vehicle, L. paracasei HII01 (108 CFU/day), metformin 30 (mg/kg) or a combination of L. paracasei HII01 and metformin. Normal rats given vehicle and L. paracasei HII01 were included. Metabolic parameters, including in vitro hemi-diaphragm glucose uptake, skeletal insulin-signaling proteins, plasma lipopolysaccharide (LPS), gut permeability, composition of gut microbiota and its metabolites, as well as short-chain fatty acids (SCFAs), were assessed after 12 weeks of experiment. The results clearly demonstrated that L. paracasei HII01 improved glycemic parameters, glucose uptake, insulin-signaling proteins including pAktSer473, glucose transporter 4 (GLUT4) and phosphorylation of AMP-activated protein kinase (pAMPKThr172), tumor necrosis factor (TNF-α) and nuclear factor-κB (NF-kB) in diabetic rats. Modulation of gut microbiota was found together with improvement in leaky gut, endotoxemia and SCFAs in diabetic rats administered L. paracasei HII01. In conclusion, L. paracasei HII01 alleviated hyperglycemia in diabetic rats primarily by modulating gut microbiota along with lessening leaky gut, leading to improvement in endotoxemia and inflammation-disturbed insulin signaling, which was mediated partly by PI3K/Akt signaling and AMPK activation.

The use of biotransformation has become a popular trend in the food and cosmetic industry. Lactic acid bacteria (LAB) are widely used due to their safety and beneficial effects on human health. Coffee pulp, a by-product obtained from coffee production, has antioxidant activity because it contains different classes of phenolic compounds. To investigate the factors affecting the biotransformation process of coffee pulp using L. plantarum TISTR 543, a systematic study using 23 factorial designs in a completely randomized design (CRD) was done. After the coffee pulp was bio-transformed, its bacterial count, pH, phenol contents, flavonoid contents, tannin contents, changes in bioactive compounds by LC-QQQ, and antioxidant properties were studied. The highest phenolic content was obtained in the sample containing the substrate, water, and sugar in the ratio of 3:10:3 with a 5% starter. After the fermentation was done, for 24–72 h, total bacteria count, total phenol contents, and antioxidant activities significantly increased compared to their initial values. Protocatechuic acid also markedly increased after 24 h of the biotransformation process. Hence, the fermentation of coffee pulp with L. plantarum TISTR 543 can produce substances with a higher biological activity which can be further studied and used as functional foods or active ingredients in cosmetic application.

Rice husk (RH) is the major agricultural waste obtained during rice hulling process, which can be a sustainable source of xylooligosaccharide (XOS). The current study deals with the production of XOS from Thai rice husk using alkaline pretreatment and enzyme hydrolysis method. The response surface methodology consisted of central composite design and Box–Behnken design was employed to achieve the maximum response in alkaline pretreatment and XOS production, respectively. The optimum conditions for alkaline pretreatment to recover maximum xylan yield were 12–18% of alkaline concentration, the temperature at 110–120 °C, and steaming time for 37.5–40 min. The FTIR results suggested that the extracted sample was the xylan fraction. The maximum XOS production of 17.35 ± 0.31 mg XOS per mL xylan was observed in the run conditions of 6.25 mg enzyme per g xylan, 9 h of incubation time, and 5% of xylan. The results revealed that the xylan extracted from RH by using an effective base couple with the steam application and the enzymatic hydrolysis help to maximize the yield of XOS, which can be further used in functional foods and dietary supplements.

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The research aims to assess the yield of bioactive compounds and their antioxidant activities obtained from tea flowers using an ultrasound-assisted extraction method with butylene glycol (BG-UAE) through Box−Behnken design. It investigates the bioactive compounds including the total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC) and analyzes their antioxidant activities, bioactive compound composition by liquid chromatography triple quadrupole tandem mass spectrometry, and their cellular activities via UAE and maceration using BG or ethanol as the solvent. Under optimal conditions, the values of the TPC, TFC, TTC, 1,1-diphenyl-2-picrylhydrazil radical scavenging assay, 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical scavenging assay, and ferric reducing antioxidant power assay (FRAP) of the BG-UAE extract were 54.00 ± 1.19 mg GAE/g sample, 291.47 ± 3.34 mg QE/g sample, 65.37 ± 1.78 mg TAE/g sample, 106.45 ± 1.21 mg TEAC/g sample, 163.58 ± 2.76 mg TEAC/g sample, and 121.31 ± 4.75 mg FeSO 4 /g sample, respectively. Except for FRAP, BG-UAE exhibited the highest values in all parameters compared to the other extraction methods. Catechins and caffeine were predominantly detected in tea flower extracts through UAE with BG and ethanol (EtOH-UAE). BG-UAE exhibited greater cell viability and cellular antioxidant activity than EtOH-UAE. The researcher expects that this research will contribute to the emergence of a green extraction technique that will offer larger functional components with economic and environmental benefits and minimal chemicals and energy use.