This study isolated and identified a probiotic strain with hypoglycemic activity from naturally fermented sugarcane residue. The inhibitory effects of the strain and its cell-free supernatant against key digestive enzymes were assessed along with hypoglycemic effects in a mouse model of type 2 diabetes mellitus induced by a high-fat diet and streptozotocin. The results showed that six strains of Lactiplantibacillus plantarum were obtained from naturally fermented sugarcane residue. Among them, the cell-free supernatant of L. plantarum P6 inhibited 96.49% of α-glucosidase activity. The in vivo experiment showed that L. plantarum P6 and its cell-free supernatant could effectively alleviate symptoms such as excessive drinking, eating, and urination, as well as body mass loss and organ enlargement in mice. It could also significantly rescue glucose tolerance and abnormal insulin secretion, effectively reduce the serum levels of triglycerides, total cholesterol, low-density lipoprotein cholesterol, and inflammatory factors (interleukin (IL)-6, IL-10, tumor necrosis factor-α, and lipopolysaccharide), and promote the secretion of high-density lipoprotein cholesterol and glucagon-like peptide-1. Therefore, L. plantarum P6 and its cell-free supernatant have the potential to significantly reduce blood sugar levels and mitigate diabetes-related symptoms.

With the ongoing COVID-19, a significant increase in global depression rates has placed a considerable strain on healthcare systems. Conventional pharmaceutical methods have shown limitations in treating this rise in depression. Therefore, identifying new potential treatments for depression is crucial. Maintaining a balanced gut microbiota is vital for human health and immune system function due to its complex bidirectional relationship with the brain. Numerous studies have established a robust correlation between anxiety and depression disorders, as well as the composition of microbial communities in the gastrointestinal tract, providing a fresh perspective. Adjusting the balance of gut microbiota may help alleviate depression symptoms. Probiotics, live microorganisms in the human gut, can improve the microbial community, help maintain homeostasis and stress resilience to remission in patients with depression. It is essential to explore how probiotics affect gut microbiota since their impact can differ between animal experiments and clinical trials. The variation in results may be attributed to factors like the probiotic type, administered dosage, and treatment duration. The purpose of this review is to summarize the potential mechanisms by which probiotics affect gut microbiota, drawing from recent animal and clinical studies and observations on gut microbial ecology shifts. Additionally, this review will spotlight effective probiotic species for depression relief and discuss treatments centered on restoring gut microbial balance. Furthermore, it will also discuss the potential of probiotics on host microbiota in other organs to improve depressive symptoms and demonstrate the transient nature of the need for a more nuanced understanding of the safety and potential adverse effects of probiotics.

The role of gut microbiota in terms of host health is becoming increasingly important. In this study, the comparative effects of tea polyphenols (TPs) on weight loss and lipid metabolism on conventionalized mice (CVZ) and pseudo germ-free (PGF) mice (treated with antibiotics) were investigated. Our findings revealed that high fat (HF) diet considerably increased the body weight, total fat and upsurge lipid indices in CVZ mice but PGF mice were not sensitive to the effect of HF diet as CVZ mice. After the dietary administration of TP, body weight, perirenal fat and epididymal fat, liver weight, glucose (GLU) level, total chloestrol (TC level), high density lipoprotein-cholesterol (HDL-C) level significantly lowered in PGF mice as compared to CVZ mice group. However, the area of fat cells and triglyceride (TG) level were significantly increased in PGF mice. In CVZ mice, TP intervention resulted in a considerable drop in the Firmicutes/Bacteroides ratio as compared to PGF mice. The intestinal flora of PGF mice was severely reduced after antibiotic treatment, while TP administration restored intestinal diversity; the abundance of Akkermansia and Lactobacillus increased, whereas the abundance of Enterobacteriaceae and Prevotella reduced. Overall, we can assume that PGF obese mice administered with TP have less anti-obesity effects compared to obese CVZ mice.