Total Synthesis and Absolute Configuration Determination of the α-Glycosidase Inhibitor (3S,4R)-6-Acetyl-3-hydroxy-2,2-dimethylchroman-4-yl (Z)-2-Methylbut-2-enoate from Ageratina grandifolia.

Herein, we report the first total synthesis of α-glycosidase inhibitor (3R, 4S)-6-acetyl-3-hydroxy-2,2-dimethylchroman-4-yl (Z)-2-methylbut-2-enoate as well as its enantiomer. Our synthesis confirms the chromane structure separately proposed by Navarro-Vazquez and Mata, on the basis of DFT computations. Furthermore, our synthesis allowed us to determine the absolute configuration of the natural compound as (3S, 4R) and not (3R, 4S).

Protective Effects of Rifampicin and Its Analog Rifampicin Quinone in a Mouse Model of Obesity-Induced Type 2 Diabetes.

Advanced glycation end-products (AGEs) form when glucose reacts non-enzymatically with proteins, leading to abnormal protein function, oxidative stress, and inflammation. AGEs are associated with aging and age-related diseases; their formation is aggravated during diabetes. Therefore, drugs preventing AGE formation can potentially treat diabetic complications, positively affecting health. Earlier, we demonstrated that rifampicin and its analogs have potent anti-glycating activities and increase the life span of Caenorhabditis elegans. This study aimed to investigate the effects of rifampicin during hyperglycemia in C. elegans and in a mouse model of obesity-induced type 2 diabetes. The effects of rifampicin were assessed by determining the life span of C. elegans cultured in the presence of glucose and by measuring HbA1c, AGE levels, and glucose excursions in the diabetic mouse model. Our results show that rifampicin protects C. elegans from glucose-induced toxicity and increases life span. In mice, rifampicin reduces HbA1c and AGEs, improves insulin sensitivity, and reduces indications of diabetic nephropathy without inducing hepatotoxicity. Rifampicin quinone, an analog with lower anti-microbial activity, also reduces HbA1c levels, improves glucose homeostasis and insulin sensitivity, and lowers indications of diabetic nephropathy, without adversely affecting the liver of the diabetic mice. Altogether, our results indicate that rifampicin and its analog have protective roles during diabetes without inflicting hepatic damage and may potentially be considered for repositioning to treat hyperglycemia-related complications in patients.