Hypoglycemic natural products with in vivo activities and their mechanisms: a review

Advances in the treatment of type 2 diabetes mellitus by natural plant polysaccharides through regulation of gut microbiota and metabolism: A review

The prevalence and impact of type 2 diabetes mellitus (T2DM) is a major global health problem. The treatment process of T2DM is long and difficult to cure. Therefore, it is necessary to explore alternative or complementary methods to deal with the various challenges brought by T2DM. Natural plant polysaccharides (NPPs) have certain potential in the treatment of T2DM. However, many studies have not considered the relationship between the structure of NPPs and their anti-T2DM activity. This paper reviews the relevant anti-T2DM mechanisms of NPPs, including modulation of insulin action, promotion of glucose metabolism and modulation of postprandial glucose levels, anti-inflammation and modulation of gut microbiota (GM) and metabolism. This paper provides an in-depth study of the conformational relationships of NPPs and facilitates the development of anti-T2DM drugs or dietary supplements with NPPs.

Exploring the Anti-Diabetic Potential of Quercetagitrin through Dual Inhibition of PTPN6 and PTPN9

Protein tyrosine phosphatases (PTPs) are pivotal contributors to the development of type 2 diabetes (T2DM). Hence, directing interventions towards PTPs emerges as a valuable therapeutic approach for managing type 2 diabetes. In particular, PTPN6 and PTPN9 are targets for anti-diabetic effects. Through high-throughput drug screening, quercetagitrin (QG) was recognized as a dual-target inhibitor of PTPN6 and PTPN9. We observed that QG suppressed the catalytic activity of PTPN6 (IC50 = 1 μM) and PTPN9 (IC50 = 1.7 μM) in vitro and enhanced glucose uptake by mature C2C12 myoblasts. Additionally, QG increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and insulin-dependent phosphorylation of Akt in mature C2C12 myoblasts. It further promoted the phosphorylation of Akt in the presence of palmitic acid, suggesting the attenuation of insulin resistance. In summary, our results indicate QG's role as a potent inhibitor targeting both PTPN6 and PTPN9, showcasing its potential as a promising treatment avenue for T2DM.

Therapeutic potential of enzymatically extracted eumelanin from squid ink in type 2 diabetes mellitus ICR mice: Multifaceted intervention against hyperglycemia, oxidative stress and depression

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a prevalent metabolic disease that poses significant health risks due to its numerous complications. However, the effects of eumelanin on oxidative stress, hyperglycemia and depression in diabetic mice have not been extensively studied.

RESULTS

Our study employed an enzymatic approach to extract eumelanin from squid ink and characterized it using spectroscopic techniques. Remarkably, eumelanin extracted with alkaline-neutral-flavor protease (ANF) displayed superior inhibitory activity against α-glucosidase and α-amylase, while enhancing glucose utilization and hepatic glycogen synthesis in human hepatocellular carcinoma cell line (HepG2) insulin resistance model. Further evaluation of ANF in a T2DM ICR mouse model demonstrated its significant potential in alleviating hyperglycemia, reducing glycosylated serum protein levels, improving glucose tolerance and modulating total cholesterol and low-density lipoprotein levels, as well as antioxidant indices at a dosage of 0.04 g kg-1 . Additionally, ANF exhibited positive effects on energy levels and reduced immobility time in antidepressant behavioral experiments. Moreover, ANF positively influenced the density and infiltration state of renal cells, while mitigating inflammatory enlargement and deformation of liver cells, without inducing any adverse effects in mice.

CONCLUSION

Overall, these findings underscore the significant therapeutic potential of ANF in the treatment of T2DM and its associated complications. By augmenting lipid and glucose metabolism, mitigating oxidative stress and alleviating depression, ANF emerges as a promising candidate for multifaceted intervention. © 2023 Society of Chemical Industry.

Identification of Novel Alkaloids from Portulaca oleracea L. and Characterization of Their Pharmacokinetics and GLP-1 Secretion-Promoting Activity in STC-1 Cells

Six new alkaloids (compounds 1-6) were isolated from Portulaca oleracea L. The compounds were triple pair (1 and 2, 3 and 4, and 5 and 6) enantiomers, with 1, 3, and 5 in the R-configuration and 2, 4, and 6 in the S-configuration, and all could bind to SUR1 according to molecular docking analysis. Treatment of STC-1 cells with each compound led to an influx of intracellular Ca2+, eventually leading to the secretion of glucagon-like peptide-1 (GLP-1), with compound 3 giving the highest secretion, resulting in 24.3 ± 7.03% more GLP-1 than nateglinide-treated cells, suggesting that these alkaloids may be able to reduce blood glucose based on their ability to stimulate the release of GLP-1. Furthermore, compound 3 also exhibited slightly faster absorption than nateglinide, as shown by pharmacokinetic analysis conducted in rats. Therefore, the results showed that some purslane alkaloids (such as compound 3) had good pharmacological activity in vivo and may have preventive and therapeutic effects on diabetes.

Elucidation of Geniposide and Crocin Accumulation and Their Biosysnthsis-Related Key Enzymes during Gardenia jasminoides Fruit Growth

Gardenia jasminoides fruits are extensively grown worldwide, with a large harvest, and its major medicinal ingredients are geniposide and crocins. Research on their accumulation and biosynthsis-related enzymes is rare. In this study, the accumulation of geniposide and crocin of G. jasminoides fruits at different developmental stages were clarified by HPLC. The highest cumulative amount of geniposide was 2.035% during the unripe-fruit period, and the highest content of crocin was 1.098% during the mature-fruit period. Furthermore, transcriptome sequencing was performed. A total of 50 unigenes encoding 4 key enzymes related in geniposide biosynthsis pathways were screened, and 41 unigenes encoding 7 key enzymes in the pathways of crocin were elucidated. It was found that the expression levels of differentially expressed genes of DN67890_c0_g1_i2-encoding GGPS, which is highly related to geniposide biosynthesis, and DN81253_c0_g1_i1-encoding lcyB, DN79477_c0_g1_i2-encoding lcyE, and DN84975_c1_g7_i11-encoding CCD, which are highly related to crocin biosynthesis, were consistent with the accumulation of geniposide and crocin content, respectively. The qRT-PCR results showed that the trends of relative expression were consistent with transcribed genes. This study provides insights for understanding the geniposide and crocin accumulation and biosynthsis during fruit development in G. jasminoides.

System pharmacology analysis to decipher the effect and mechanism of active ingredients combination from Duhuo Jisheng decoction on osteoarthritis in rats

ETHNOPHARMACOLOGY RELEVANCE

Duhuo Jisheng decoction is a traditional Chinese formula that has been widely used in clinical practice to treat osteoarthritis, which has the effects of removing invaded cold and dampness, relieving joint pain. However, it is difficult to determine the effective substances and mechanisms due to assorted herbs and components, and further research is needed.

AIM OF THE STUDY

This study was designed to explore and verify the mechanism and targets of DHJSD in the treatment of OA via network analysis and experiments.

METHOD

In this study, the active ingredients of DHJSD were qualitatively analyzed by UPLC-QDA. Network analysis was used to identify common targets and pathways. Next, we explored the therapeutic mechanism of DHJSD through a rat model of knee osteoarthritis. HE staining was used to judge the establishment of the animal model. ELISA and Western blotting were used to verify the expression of key pathway proteins.

CONCLUSION

In this study, seventeen chemical constituents in DHJSD were identified. According to the network analysis, we obtained the potential associated pathways of action. Then, molecular docking and SPR experiments showed that the sixteen identified components had high binding energies to IL-6. HE staining showed that the high-dose group of DHJSD had an obvious therapeutic effect on model rats. Compared with the model group, the levels of IL-1β, TNF-α, IL-6, MMP3, MMP13, ADAMTS4 and ADAMTS5 in serum and the expression of STAT3 and p-STAT3 protein in administration groups were significantly decreased. This result indicated that the IL-6/STAT3 signaling pathway was one of the important pathways regulated by DHJSD to improve OA.

New iridoids from Patrinia scabiosaefolia and their hypoglycemic effects by activating PI3K/Akt signaling pathway

Growing in regions of Asia and North America, Patrinia scabiosaefolia is a wild vegetable and herb that has demonstrated health-promoting properties. Iridoids are one of the most bioactive phytochemicals in P. scabiosaefolia but the in-depth study is scarce. Herein we reported the separation and characterization of nine iridoids (compounds 1-9) from P. scabiosaefolia, and two compounds (2 and 6) were new. All the structures of the nine iridoids were characterized and confirmed with NMR (1D & 2D), HRMS, IR and UV. Compound 2 is a five-member ring iridoid, reminiscent of a broken C-1 and C-2 bond. Compound 6 has a typical monoene valerian iridoid, but the 5-deoxyglucose moiety at C-11 position is uncommon in this genus. The anti-diabetic evaluation of the isolated compounds revealed that compounds 1, 2, and 9 significantly increased the glucose absorption in 3 T3-L1 cells (P < 0.01). Further mechanism investigations have demonstrated that compound 1 promoted glucose uptake in dexamethasone-treated 3 T3-L1 adipocytes by activating PI3K/Akt signaling pathway. The expression of GLUT4 mRNA and protein was also upregulated. These results provide scientific references for the potential use of P. scabiosaefolia as a functional food to manage hyperglycemia.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.