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Diabetes mellitus, linked with insulin resistance and hyperglycaemia, is a leading cause of mortality. Glucose uptake through glucose transporter type 4, especially in skeletal muscle, is crucial for maintaining euglycaemia and is a key pathway targeted by antidiabetic medication. Abrus precatorius is a medicinal plant with demonstrated antihyperglycaemic activity in animal models, but its mechanisms are unclear. This study evaluated the effect of a 50% ethanolic (v/v) A. precatorius leaf extract on (1) insulin-stimulated glucose uptake and (2) related gene expression in differentiated C2C12 myotubes using rosiglitazone as a positive control, and (3) generated a comprehensive phytochemical profile of A. precatorius leaf extract using liquid chromatography-high resolution mass spectrometry to elucidate its antidiabetic compounds. A. precatorius leaf extract significantly increased insulin-stimulated glucose uptake, and insulin receptor substrate 1 and Akt substrate of 160 kDa gene expression; however, it had no effect on glucose transporter type 4 gene expression. At 250 µg/mL A. precatorius leaf extract, the increase in glucose uptake was significantly higher than 1 µM rosiglitazone. Fifty-five phytochemicals (primarily polyphenols, triterpenoids, saponins, and alkaloids) were putatively identified, including 24 that have not previously been reported from A. precatorius leaves. Abrusin, precatorin I, glycyrrhizin, hemiphloin, isohemiphloin, hispidulin 4′- O - β -D-glucopyranoside, homoplantaginin, and cirsimaritin were putatively identified as known major compounds previously reported from A. precatorius leaf extract. A. precatorius leaves contain antidiabetic phytochemicals and enhance insulin-stimulated glucose uptake in myotubes via the protein kinase B/phosphoinositide 3-kinase pathway by regulating insulin receptor substrate 1 and Akt substrate of 160 kDa gene expression. Therefore, A. precatorius leaves may improve skeletal muscle insulin sensitivity and hyperglycaemia. Additionally, it is a valuable source of bioactive phytochemicals with potential therapeutic use for diabetes. [ABSTRACT FROM AUTHOR]

Although considered an abundant source of agricultural by-products, avocado (Persea americana Mill.) seed, with several biological activities and bioactive components, might become a promising resource for phytopharmaceutical development. In this study, through bioassay-guided isolation of the main α -glucosidase inhibitors in avocado seed, we discovered the major α -glucosidase inhibitor to be avocado seed oligomeric proanthocyanidin complex (ASOPC). Thiolysis and UPLC-DAD-HRESIMS showed the presence of A- and B-type procyanidins, and B-type propelargonidin with (epi)afzelechin as extension unit. Mean degree of polymerization (mDP) of ASOPC was calculated as 7.3 ± 1. Furthermore, ASOPC appeared to be a strong, reversible, competitive inhibitor of α -glucosidase, with IC50 value of 0.1 µg/mL, which was significantly lower than Acarbose (IC50 = 75.6 µg/mL), indicated that ASOPC is a potential natural α -glucosidase inhibitor. These findings would contribute to the direction of utilizing avocado seed bioactive components with the possibility to be used as natural anti-diabetic agents. [ABSTRACT FROM AUTHOR]

As a kind of traditional Chinese medicine extract, curcumin has been proven to be effective in inhibiting inflammation and apoptosis in pancreatic islet β cells in the streptozotocin-induced diabetes mellitus rat model, although the underlying mechanism has not yet been clarified. To examine the effect of curcumin on inflammation and apoptosis in pancreatic islet β cells, we established a type 2 diabetes rat model by feeding the animals a high-fat diet and intraperitoneally injecting streptozotocin. The curcumin was administered by intraperitoneal injection. The rat body weight, fasting blood glucose, intraperitoneal glucose tolerance tests, and insulin tolerance tests were recorded and analyzed. Hematoxylin and eosin staining was used for morphological analysis, and a TUNEL assay was performed to detect the apoptotic cells. The expression levels of proteins related to oxidative stress, inflammation and apoptosis were detected by Western blotting and ELISA. Curcumin administration significantly decreased fasting blood glucose and promoted recovery of pancreas function in type 2 diabetes rats. In curcumin-treated rats, the pancreatic tissue destruction and apoptosis index were reduced. The expression of IL-1 β , IL-6, TNF- α , caspase-3, Bax, and malondialdehyde were significantly reduced, and Bcl-2, superoxide dismutase 2, and glutathione peroxidase were significantly increased. Curcumin inhibited the expression of phosphorylated JNK and NF- κ B proteins to block the RAGE/JNK/NF- κ B signaling pathway. In conclusion, these results indicate that curcumin blocks the phosphorylation of JNK and NF- κ B protein to inhibit this signaling pathway, thereby further inhibiting inflammation and apoptosis in pancreatic islet β cells. Curcumin has potential value for the treatment of diabetes. [ABSTRACT FROM AUTHOR]

PPARγ agonists are widely used medications in diabetes mellitus therapy. Their role in improving adipose tissue function contributes to antidiabetic effects. The extracts of Dodonaea viscosa have been reported to exert antidiabetic activity. However, the effective mediators and the underlying mechanisms were largely unknown. In this study, we investigated the action on PPARγ transactivation and adipocyte modulation of two typical flavonoid constituents from D. viscosa, 5,4'-dihydroxy-7,8-dimethoxyflavanone and aliarin. Our results showed that 5,4'-dihydroxy-7,8-dimethoxyflavanone and aliarin were potential partial PPARγ agonists. The compounds induced adipogenesis in 3T3-L1 cells, with an upregulated adiponectin mRNA level and enhanced insulin sensitivity. The favorable effects of 5,4'-dihydroxy-7,8-dimethoxyflavanone, aliarin, and other flavonoid constituents on adipocytes might contribute to the antidiabetic efficacy of D. viscosa. [ABSTRACT FROM AUTHOR]

Naringin, chemically 4',5,7- trihydroxyflavanone-7-rhamnoglucoside, is a major flavanone glycoside obtained from tomatoes, grapefruits, and many other citrus fruits. It has been experimentally documented to possess numerous biological properties such as antioxidant, anti-inflammatory, and antiapoptotic activities. In vitro and in vivo studies have further established the usefulness of naringin in various preclinical models of atherosclerosis, cardiovascular disorders, diabetes mellitus, neurodegenerative disorders, osteoporosis, and rheumatological disorders. Apart from this, naringin has also exerted chemopreventive and anticancer attributes in various models of oral, breast, colon, liver, lung, and ovarian cancer. This wide spectrum of biological expediency has been documented to be a result of either the upregulation of various cell survival proteins or the inhibition of inflammatory processes, or a combination of both. Due to the scarcity of human studies on naringin, this review focuses on the various established activities of naringin in in vitro and in vivo preclinical models, and its potential therapeutic applications using the available knowledge in the literature. Additionally, it also encompasses the pharmacokinetic properties of naringin and its inhibition of CYP isoenzymes, and the subsequent drug interactions. Moreover, further clinical research is evidently needed to provide significant insights into the mechanisms underlying the effects of naringin in humans. [ABSTRACT FROM AUTHOR]

Diabetes mellitus is one of the major health problems in Africa. The conventional oral synthetic antidiabetic drugs available to manage the disease are costly and not readily affordable to the majority of the affected population. Interestingly, the continent is endowed with a tremendous number of medicinal plants that have been explored for their folkloric treatment of diabetes mellitus. Scientific investigations have validated the antidiabetic potentials of a number of these medicinal plants but there is no repository with information on these scientifically investigated plants as a guide for future research. In this review article, all of the in vivo antidiabetic studies conducted between January 2000 and July 2013 on African plants are systematically compiled with a closer look at some relevant plants from the continent's subregions. Plants of the Asteraceae and Lamiaceae families are the most investigated, and West Africa has the highest number of investigated plants. Although promising results were reported in many cases, unfortunately, only a few studies reported the partial characterization of bioactive principles and/or mechanisms of action. It is hoped that government agencies, pharmaceutical industries, and the scientific community will have a look at some of these plants for future research and, if possible, subsequent commercialization. [ABSTRACT FROM AUTHOR]

Two new xanthones, 1,8-dihydroxy-3-methoxyxanthone 7-O-[α-L-rhamnopyranosyl(1→2)-β- D-glucopyranoside] (1) and 1,8- dihydroxy-3- methoxyxanthone 7-O-[α-L-rhamnopyranosyl (1→3)-α-L-rhamno-pyranosyl (1→2)-β-D-xylopyranoside] (2), together with 26 known xanthones (3-28), were isolated from the aqueous ethanol extract of the traditional Chinese herb Swertia mussotii. Their structures were elucidated via spectroscopic analyses including 2D NMR. The inhibition of α-glucosidase by the isolated xanthones was evaluated by an in vitro high-throughput screening assay. Our results indicated that 1,3,5,8-tetrahydroxyxanthone is the best inhibitor with an IC50 value of 5.33 ± 0.09 μM, while the O-glycosylated xanthones were poor α-glycosidase inhibitors. [ABSTRACT FROM AUTHOR]

There is a traditional belief among Eastern people that opium may have ameliorating effects on cardiovascular risk factors, especially diabetes; thus, it is widely used among diabetic patients. We attempted to investigate the association of opium consumption with coronary artery disease (CAD) in diabetic patients. A cross-sectional study was conducted on diabetic patients undergoing coronary angiography in our center. Out of 1925 diabetic patients included in the study, 228were opium users, and the remaining 1697 non-opium users were used as a pool of potential comparators. Propensity scores were used to match the 228 opium consumers with 228 matched comparators for age, sex, and smoking status. The Gensini score and extent score were respectively used to assess the angiographic severity and extent of CAD. The mean Gensini score (86.9 ± 62.7 vs. 59.6 ± 43.4, p < 0.0001) and extent score (7.1 ± 2.9 vs. 5.9 ± 2.9, p < 0.0001) were significantly higher in opium user diabetic patients than in non-opium users. After adjustment for potential confounders, a dose-response relationship was observed between dose of opium and the Gensini score (β = 0.27, p = 0.04). There were no significant differences between the routes of opium administration (inhalation vs. oral) regarding the severity and extent of CAD. In conclusion, exposure to opium in diabetic patients may be positively associated with the risk of CAD, and with the angiographically determined severity and extent of the disease. Furthermore, dosage of opium consumption may correlate with severity of CAD. [ABSTRACT FROM AUTHOR]

Diabetic hyperglycaemia promotes the production of advanced glycation end-products (AGEs), which play a significant role in the development of complications associated with type 2 diabetes mellitus. Vaccinium angustifolium, a medicinal plant used for the treatment of diabetes, produces a variety of phenolic metabolites with putative anti-diabetic activities. To assess optimal cultivation time, seasonal changes in the concentration of six phenolic compounds in leaves and twelve compounds in stems were examined using HPLC-DAD and examined in relation to seasonal changes in AGE inhibition activity, assessed with a fluorescence-based assay. A seasonal decline occurred in the concentration of chlorogenic acid, rutin, and quercetin 3-arabinoside in leaves and chlorogenic acid in stems. The concentration of (+)-catechin, and (−)-epicatechin in stems declined within two weeks before rising and fluctuating insignificantly. AGE inhibition activity of leaves was significantly greater at the final compared to the initial collection date whereas the activity of stems did not change significantly. Relative to the leaf extract, the stem was a more potent inhibitor of AGE formation, which could be a result of the unique phytochemistry of stems. Together, these results revealed significant seasonal variation in the phenolic profile and anti-glycation effects of V. angustifolium extracts and indicated late summer as the collection time yielding optimal activity. [ABSTRACT FROM AUTHOR]