The increased incidence of metabolic diseases (e.g., diabetes and obesity) has seriously affected human health and life safety worldwide. It is of great significance to find effective drugs from natural compounds to treat metabolic diseases. Berberine (BBR), an important quaternary benzylisoquinoline alkaloid, exists in many traditional medicinal plants. In recent years, BBR has received widespread attention due to its good potential in the treatment of metabolic diseases. In order to promote the basic research and clinical application of BBR, this review provides a timely and comprehensive summary of the pharmacological and clinical advances of BBR in the treatment of five metabolic diseases, including type 2 diabetes mellitus, obesity, non-alcoholic fatty liver disease, hyperlipidemia, and gout. Both animal and clinical studies have proved that BBR has good therapeutic effects on these five metabolic diseases. The therapeutic effects of BBR are based on regulating various metabolic aspects and pathophysiological procedures. For example, it can promote insulin secretion, improve insulin resistance, inhibit lipogenesis, alleviate adipose tissue fibrosis, reduce hepatic steatosis, and improve gut microbiota disorders. Collectively, BBR may be a good and promising drug candidate for the treatment of metabolic diseases. More studies, especially clinical trials, are needed to further confirm its molecular mechanisms and targets. In addition, large-scale, long-term and multi-center clinical trials are necessary to evaluate the efficacy and safety of BBR in the treatment of these metabolic diseases.

Metabolic diseases have become major public health issues worldwide. Searching for effective drugs for treating metabolic diseases from natural compounds has attracted increasing attention. Quercetin, an important natural flavonoid, is extensively present in fruits, vegetables, and medicinal plants. Due to its potentially beneficial effects on human health, quercetin has become the focus of medicinal attention. In this review, we provide a timely and comprehensive summary of the pharmacological advances and clinical data of quercetin in the treatment of three metabolic diseases, including diabetes, hyperlipidemia, and nonalcoholic fatty liver disease (NAFLD). Accumulating evidences obtained from animal experiments prove that quercetin has beneficial effects on these three diseases. It can promote insulin secretion, improve insulin resistance, lower blood lipid levels, inhibit inflammation and oxidative stress, alleviate hepatic lipid accumulation, and regulate gut microbiota disorders in animal models. However, human clinical studies on the effects of quercetin in diabetes, hyperlipidemia, and NAFLD remain scarce. More clinical trials with larger sample sizes and longer trial durations are needed to verify its true effectiveness in human subjects. Moreover, another important issue that needs to be resolved in future research is to improve the bioavailability of quercetin. This review may provide valuable information for the basic research, drug development, and clinical application of quercetin in the treatment of metabolic diseases.

Type 2 diabetes mellitus (T2DM) is one of the most risk factors threatening human health. Although genetic and environmental factors contribute to the development of T2DM, gut microbiota has also been found to be involved. Gut microbiota-derived metabolites are a key factor in host-microbe crosstalk, and have been revealed to play a central role in the physiology and physiopathology of T2DM. In this review, we provide a timely and comprehensive summary of the microbial metabolites that are protective or causative for T2DM, including some amino acids-derived metabolites, short-chain fatty acids, trimethylamine N-oxide, and bile acids. The mechanisms by which metabolites affect T2DM have been elaborated. Knowing more about these processes will increase our understanding of the causal relationship between gut microbiota and T2DM. Moreover, some frontier therapies that target gut microbes and their metabolites to improve T2DM, including dietary intervention, fecal microbiota transplantation, probiotics, prebiotics or synbiotics intervention, and drugging microbial metabolism, have been critically discussed. This review may provide novel insights for the development of targeted and personalized treatments for T2DM based on gut microbial metabolites. More high-quality clinical trials are needed to accelerate the clinical translation of gut-targeted therapies for T2DM.

Liver disease is one of the most risk factors threatening human health. It is of great significance to find drugs that can treat liver diseases, especially for acute and chronic hepatitis, non-alcoholic fatty liver disease, and liver cancer. The search for drugs with good efficacy from traditional natural medicines has attracted more and more attention. Tibetan medicine, one of the China's traditional medical systems, has been widely used by the Tibetan people for the prevention and treatment of liver diseases for hundreds of years. The present paper summarized the natural Tibetan medicines that have been used in Tibetan traditional system of medicine to treat liver diseases by bibliographic investigation of 22 Tibetan medicine monographs and drug standards. One hundred and ninety three species including 181 plants, 7 animals, and 5 minerals were found to treat liver diseases in traditional Tibetan medicine system. The most frequently used species are Carthamus tinctorius, Brag-zhun, Swertia chirayita, Swertia mussotii, Halenia elliptica, Herpetospermum pedunculosum, and Phyllanthus emblica. Their names, families, medicinal parts, traditional uses, phytochemicals information, and pharmacological activities were described in detail. These natural medicines might be a valuable gift from the old Tibetan medicine to the world, and would be potential drug candidates for the treatment of liver diseases. Further studies are needed to prove their medicinal values in liver diseases treatment, identify bioactive compounds, elucidate the underlying mechanism of action, and clarify their side effects or toxicity with the help of modern phytochemical, pharmacological, metabonomics, and/or clinical trial methods.

Although changes in gut microbiome have been associated with the development of T2D and its complications, the role of the gut virome remains largely unknown. Here, we characterized the gut virome alterations in T2D and its complications diabetic nephropathy (DN) by metagenomic sequencing of fecal viral-like particles. Compared with controls, T2D subjects, especially those with DN, had significantly lower viral richness and diversity. 81 viral species were identified to be significantly altered in T2D subjects, including a decrease in some phages (e.g. Flavobacterium phage and Cellulophaga phaga). DN subjects were depleted of 12 viral species, including Bacteroides phage, Anoxybacillus virus and Brevibacillus phage, and enriched in 2 phages (Shigella phage and Xylella phage). Multiple viral functions, particularly those of phage lysing host bacteria, were markedly reduced in T2D and DN. Strong viral-bacterial interactions in healthy controls were disrupted in both T2D and DN. Moreover, the combined use of gut viral and bacterial markers achieved a powerful diagnostic performance for T2D and DN, with AUC of 99.03% and 98.19%, respectively. Our results suggest that T2D and its complication DN are characterized by a significant decrease in gut viral diversity, changes in specific virus species, loss of multiple viral functions, and disruption of viral-bacterial correlations. The combined gut viral and bacterial markers have diagnostic potential for T2D and DN.