Anti-Hyperglycaemic Evaluation of Buddleia indica Leaves Using In Vitro, In Vivo and In Silico Studies and Its Correlation with the Major Phytoconstituents

Buddleia indica Lam. is an ornamental evergreen shrub with few reports concerning its phytoconstituents and biological activities. Herein, the antihyperglycaemic activity of B. indica leaves methanol extract (BIT) was evaluated for the first time using in vitro and in vivo studies. Molecular modelling was performed for its major phytoconstituents that were further subjected to ADME/TOPAKT (absorption, distribution, metabolism, excretion and toxicity) prediction. BIT revealed considerable reduction in glucose concentration by 9.93% at 50 μg/mL using 3T3-L1 adipocyte culture. It displayed substantial inhibition versus α-glucosidase and α-amylase with IC₅₀ 205.2 and 385.06 μg/mL, respectively. In vivo antihyperglycaemic activity of BIT and the ethyl acetate fraction (BIE) was performed using streptozotocin-induced diabetes in rat model. BIT and BIE effectively ameliorate oxidative stress markers in addition to reducing serum blood glucose by 56.08 and 54.00%, respectively, and are associated with a substantial increase in serum insulin by 4.1 and 12.7%, respectively. This can be attributed to its richness with polyphenolic compounds comprising flavonoids, phenolic acids, phenyl propanoids and iridoids. Molecular docking showed that verbascoside and kaempferol displayed the highest fitting within human α-amylase (HA) and human α-glucosidase (HG) active sites, respectively. They showed reasonable pharmacokinetic, pharmacodynamic and toxicity properties, as revealed by ADME/TOPKAT study.

Anti-hyperglycaemic effect of labdane diterpenes isolated from the rhizome of Amomum maximum Roxb., an edible plant in Southwest China

Amomum maximum Roxb. rhizome is a fork medicine mainly used in South and Southeast Asia. In present study, the hypoglycaemic effects of the ethanolic extract of A. maximum rhizome were demonstrated both on α-glucosidase assay in vitro and streptozotocin (STZ)-induced postprandial hyperglycaemia in mice. Furthermore, six labdane diterpenes, amoxanthin A (1), ottensinin (2), coronarin D (3), coronarin D methyl ether (4), isocoronarin D (5), and zerumin (6), were isolated from its ethyl acetate sub-fraction with the guidance of α-glucosidase inhibitory activity. Among these compounds, 2 and 6 exhibited significant inhibitory effect on α-glucosidase, as well as on STZ-induced high postprandial blood glucose levels in mice. Additionally, molecular docking analysis revealed that 2 and 6 could firmly bind to the active sites of α-glucosidase. These results suggest that compounds 2 and 6 are the main anti-hyperglycaemic agents present in A. maximum, which may demonstrate potential beneficial effects in diabetes management.

QSAR study of some anti-hyperglycaemic sulphonylurea drugs

Sulphonylureas are widely used anti-hyperglycaemic drugs for the treatment of type 2 diabetes. The only published quantitative structure-activity relationship (QSAR) models for sulphonylurea drugs have been found to be questionable, for a number of reasons. We have re-analysed the human anti-hyperglycaemic potencies, acute mouse intraperitoneal toxicities (LD50) and plasma protein-binding abilities of the 15 drugs using multiple linear regression and obtained good QSAR models for each endpoint. The obtained QSARs all comply well with the Organisation for Economic Co-operation and Development (OECD) Guidelines for the Validation of (Q)SARs. We could not carry out external validation of our models for acute toxicity and plasma protein-binding because of the very small datasets available.

Efficacy and safety of Stephania glabra: an alkaloid-rich traditional medicinal plant

Stephania glabra (Roxb.) Miers (Menispermaceae) has long been used for the treatment of asthma, tuberculosis, dysentery, hyperglycaemia, cancer, fever, intestinal complaints, sleep disturbances and inflammation in many Asian countries. It mainly contains alkaloids and, until now, over 30 alkaloids such as bisbenzylisoquinolines, hasubanalactams, berberines and aporphines have been isolated from its tuber. Most of its traditional medicinal activities are scientifically approved by various in vitro and in vivo studies. It shows remarkable anti-psychotic, anti-diabetic, antipyretic, analgesic, antimicrobial and anti-hypertensive activities. This work includes comprehensive information on the ethnobotany, chemistry and pharmacology of S. glabra. This review also focuses on the future perspectives with main emphasis on the establishment of therapeutic index and safety index of the plant. This review concludes that S. glabra has a great potential to treat various diseases, and could be used as a source for novel healthcare products in the near future, which needs further studies.