Diabetes mellitus (DM) is a severe chronic metabolic disease with increased mortality and morbidity. The pathological progression of DM is intimately connected with the formation and activation of oxidative stress (OS). Especially, the involvement of OS with hyperglycemia, insulin resistance, and inflammation has shown a vital role in the pathophysiological development of DM and related complications. Interestingly, accumulating studies have focused on the exploration of natural antioxidants for their improvement on DM. Of specific interest is gallic acid (GA), which is rich in many edible and herbal plants and has progressively demonstrated robust antioxidative and anti-inflammatory effects on metabolic disorders. To provide a better understanding of its potential therapeutic impacts and enhancement of human health care, the available research evidence supporting the effective antidiabetic properties of GA and relevant derivatives are needed to be summarized and discussed, with emphasis on its regulation on OS and inflammation against DM. This review aims to highlight the latest viewpoints and current research information on the role of OS in diabetes and to provide scientific support for GA as a potential antihypoglycemic agent for DM and its complications.

Nonalcoholic fatty liver diseases (NAFLD) represent a set of liver disorders progressing from steatosis to steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma, which induce huge burden to human health. Many pathophysiological factors are considered to influence NAFLD in a parallel pattern, involving insulin resistance, oxidative stress, lipotoxicity, mitochondrial dysfunction, endoplasmic reticulum stress, inflammatory cascades, fibrogenic reaction, etc. However, the underlying mechanisms, including those that induce NAFLD development, have not been fully understood. Specifically, oxidative stress, mainly mediated by excessive accumulation of reactive oxygen species, has participated in the multiple NAFLD-related signaling by serving as an accelerator. Ameliorating oxidative stress and maintaining redox homeostasis may be a promising approach for the management of NAFLD. Green tea is one of the most important dietary resources of natural antioxidants, above which epigallocatechin gallate (EGCG) notably contributes to its antioxidative action. Accumulative evidence from randomized clinical trials, systematic reviews, and meta-analysis has revealed the beneficial functions of green tea and EGCG in preventing and managing NAFLD, with acceptable safety in the patients. Abundant animal and cellular studies have demonstrated that green tea and EGCG may protect against NAFLD initiation and development by alleviating oxidative stress and the related metabolism dysfunction, inflammation, fibrosis, and tumorigenesis. The targeted signaling pathways may include, but are not limited to, NRF2, AMPK, SIRT1, NF-κB, TLR4/MYD88, TGF-β/SMAD, and PI3K/Akt/FoxO1, etc. In this review, we thoroughly discuss the oxidative stress-related mechanisms involved in NAFLD development, as well as summarize the protective effects and underlying mechanisms of green tea and EGCG against NAFLD.

Dietary natural products could ameliorate diabetes via inhibiting carbohydrate hydrolyzing enzymes, exerting antioxidant, anti-inflammatory and anti-glycation effects, activating the PI3K/AKT pathway, modulating the gut microbiota, and so on.

Kombucha is a fermented tea known for its health benefits. In this study, golden-flower tea (Camellia petelotii) and honeysuckle-flower tea (Lonicera japonica) were first used as raw materials to prepare kombucha beverages. The antioxidant activities, total phenolic contents, concentrations of bioactive components, and sensory scores of two kombucha beverages were assessed. Additionally, effects of fermentation with or without tea residues on kombucha beverages were compared. The results found that two kombucha beverages possessed strong antioxidant activities and high scores of sensory analysis. In addition, fermentation with golden-flower tea residues could remarkably enhance the antioxidant activity (maximum 2.83 times) and total phenolic contents (3.48 times), while fermentation with honeysuckle tea residues had a minor effect. Furthermore, concentrations of several bioactive compounds could be increased by fermentation with golden-flower tea residues, but fermentation with honeysuckle-flower tea residues had limited effects. Moreover, the fermentation with or without tea residues showed no significant difference on sensory scores of golden-flower tea kombucha and honeysuckle-flower tea kombucha, and golden-flower tea kombucha had higher sensory scores than honeysuckle-flower tea kombucha. Therefore, it might be a better strategy to produce golden-flower tea kombucha by fermentation with tea residues, while honeysuckle-flower tea kombucha could be prepared without tea residues.

Hepatobiliary diseases have a high prevalence worldwide, with a wide range of diseases involved in the liver and biliary system. Modifications in gut microbiota have been proven to have an association with unbalanced intestinal homeostasis and the dysfunction of host metabolism and the immune system, which can be the risk factors for many hepatobiliary diseases, such as nonalcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), nonalcoholic fatty steatohepatitis (NASH), hepatitis, cirrhosis, hepatocellular carcinoma (HCC) and cholestasis, as well as infection due to liver transplantation. Probiotics are commonly used gut microbiota-targeted strategies to treat dysbiosis and intestinal dysfunction, as well as the gut–liver axis, which can enhance the effectiveness of probiotics in the management of liver diseases. Recent studies have explored more potential single or mixed strains of probiotics, and bioinformatics methods can be used to investigate the potential mechanisms of probiotics on liver diseases. In this review, we summarize the preclinical and clinical studies on the role of probiotics in hepatobiliary diseases from 2018 to 2023, revealing the possible mechanism of probiotics in the treatment of hepatobiliary diseases and discussing the limitations of probiotics in treating hepatobiliary diseases. This review provides updated evidence for the development of probiotic products, exploration of new probiotic strains, and support for clinical studies. Further studies should focus on the safety, viability, and stability of probiotics, as well as medication dosage and duration in clinical practice.

Kombucha is a well-known fermented beverage traditionally made from black tea infusion. Recent studies have focused on finding alternative materials to create novel kombucha beverages with various health benefits. In this study, we prepared and evaluated two novel kombucha beverages using Rhodiola rosea and Salvia miltiorrhiza as materials. The effects of fermentation with the residue of these plants on the kombucha were also investigated. The antioxidant activities, total phenolic contents, and concentrations of the bioactive compounds of the kombucha beverages were determined by the Trolox equivalent antioxidant capacity test, ferric-reducing antioxidant power test, Folin–Ciocalteu method, and high-performance liquid chromatography, respectively. The results revealed that the kombucha beverages made with Rhodiola rosea and Salvia miltiorrhiza had strong antioxidant capacities and abundant phenolic contents. Additionally, the kombucha fermented with Rhodiola rosea residue had higher FRAP, TEAC and TPC values than that fermented without residue. On the other hand, the Salvia miltiorrhiza kombucha fermented with residue had similar FRAP and TEAC values but lower TPC values compared to that fermented without residue. The correlation analysis showed that gallic acid, salidroside, and tyrosol were responsible for the antioxidant abilities and total phenolic contents of the Rhodiola rosea kombucha, and salvianolic acid A and salvianolic acid B contributed to the antioxidant abilities of the Salvia miltiorrhiza kombucha. Furthermore, the kombucha fermented with Rhodiola rosea residue had the highest sensory scores among the kombucha beverages studied. These findings suggest that Rhodiola rosea and Salvia miltiorrhiza are suitable for making novel kombucha beverages with strong antioxidant abilities and abundant phenolic contents, which can be used in preventing and managing oxidative stress-related diseases.