Blood glucose-lowering effect of Tectona grandis flowers in type 2 diabetic rats: a study on identification of active constituents and mechanisms for antidiabetic action

Tectona grandis L.f: A comprehensive review on its patents, chemical constituents, and biological activities

Tectona grandis L.f is a timber plant that is commonly referred to as teak. Its wide use as a medicine in the various indigenous systems makes it a plant of importance. A wide gamut of phytoconstituents like alkaloids, phenolic glycosides, steroids, etc. has been reported. A renewed interest in this plant has resulted in scientific investigations by various researchers towards the isolation and identification of active constituents along with scientific proof of its biological activities. The different parts of the plant have been scientifically evaluated for their antioxidant, antipyretic, analgesic, hypoglycemic, wound healing, cytotoxic, and many more biological activities. Documentation of this scientific knowledge is of importance to have consolidated precise information encompassing the various aspects of this plant, which could provide a base for future studies. This review is a compilation of the salient reports on these investigations concerning phytochemistry, the methods used to identify and quantify the constituents, the evaluation methods of the biological activity, toxicological studies, allergies and the patent/patent applications. This will further help researchers to find an area of the gap for future studies.

Medicinal plants utilized in Thai Traditional Medicine for diabetes treatment: Ethnobotanical surveys, scientific evidence and phytochemicals

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus remains the most lethal metabolic disease of contemporaneous times and despite the therapeutic arsenal currently available, research on new antidiabetic agents remains a priority. In recent years, the revitalization of Thai Traditional Medicine (TTM) became a clear priority for the Thai government, and many efforts have been undertaken to accelerate research on herbal medicines and their use in medical services in various hospitals. Additionally, and particularly in rural areas, treatment of diabetes and associated symptomatology frequently relies on herbal preparations recommended by practitioners of TTM. In the current work, medicinal plants used in Thailand for treating diabetes, as well as their hypoglycaemic pharmacological evidences and potential therapeutic use for diabetes-related complications were reviewed.

MATERIALS AND METHODS

Ethnopharmacological information on the plant materials used in TTM for diabetes treatment was collected through literature search in a range of scientific databases using the search terms: diabetes, folk medicine, Thailand medicinal plants, traditional medicine. Information regarding scientific evidence on the antidiabetic effects of surveyed species was obtained considering not only the most common taxonomic designation, but also taxonomic synonyms, and including the keywords 'diabetes' and 'hypoglycaemic effect'.

RESULTS

A total of 183 species known to be used for diabetes management in TTM were reviewed, with 30% of them still lacking experimental evidences to support claims regarding the mechanisms and phytochemicals underlying their antidiabetic properties. Moreover, a total of 46 bioactives displaying effective antidiabetic effects have been isolated from 24 species, their underlying mechanism(s) of action being fully or partially disclosed.

CONCLUSIONS

We deliver the most extensive survey dealing with the ethnomedicinal knowledge of Thai medicinal plants utilized on diabetes management. We are certain that the current review will spark further research on Thai plants for the development of new standardized phytomedicines through drug discovery programmes.

Evaluation of antidiabetic activity of biologically synthesized silver nanoparticles using Pouteria sapota in streptozotocin-induced diabetic rats

BACKGROUND

Medicinal plants and green synthesis of silver nanoparticles (AgNPs) have proven to be good sources of agents effective in the treatment of diabetes mellitus. The present study focused on the green synthesis of AgNPs from the aqueous leaf extract of Pouteria sapota in order to evaluate the in vitro and in vivo antidiabetic properties of this extract and the synthesized AgNPs.

METHODS

The AgNPs were biologically synthesized under ambient conditions from an aqueous leaf extract of P. sapota using the hot percolation method and were characterized using spectroscopic methods, X-ray diffraction, and scanning electron microscopy. The in vitro antidiabetic activity of the aqueous leaf extract and AgNPs was confirmed by non-enzymatic glycosylation of hemoglobin, glucose uptake by yeast cells following exposure of cells to 5 or 10 mmol/L glucose solution, and inhibition of α-amylase. Further, in vivo antidiabetic activity was assessed in streptozotocin-induced rats. Rats were treated with aqueous leaf extract (100 mg/kg) or AgNPs (10 mg/kg) for 28 days. Following treatment, rats were killed for biochemical and histopathological analysis of kidney and liver samples.

RESULTS

A significant reduction in blood sugar levels was noted in rats treated with leaf extract or AgNPs. Results of in vitro and in vivo analyses in rats treated with leaf extract or AgNPs show that both the extract and the biologically synthesized AgNPs have antidiabetic activity.

CONCLUSION

The aqueous leaf extract of P. sapota and AgNPs exhibited efficient antidiabetic activity in the rat model of diabetes and therefore could have potential for development for medical applications in the future.