Prolonged
insulin resistance is considered one of the reasons for
Type 2 Diabetes Mellitus. Upregulation of
Protein tyrosine phosphatase 1B (PTP1B), a negative regulator of
insulin signalling, has been well studied as a key regulator in prognosis to
insulin resistance. It has been widely studied as a desirable molecular therapeutic target. The study aimed to evaluate the efficacy of leaf extract of the medicinal plants Silybum marianum on the inhibition of PTP1B activity. It also explored the synergistic effect with extracts of Gymnema sylvestre (leaves), Momordica charantia (seeds), and Trigonella foenum graecum (seeds). The S. marianum leaves showed dose-dependent inhibition of PTP1B ranging from 9.48-47.95% (25-1000 μg mL-1). Assay with individual
plant extracts showed comparatively lesser inhibition of PTP1B as compared to
metformin as a control (38% inhibition). However, a synergistic effect showed nearly 45% PTP1B inhibition (higher than
metformin) after the assay was done with selected four
plant extracts in combination. The effect of leaf extracts of S. marianum was studied for
glucose uptake efficiency in yeast cell lines which was found to be increased by 23% as compared to the control (without extract).
Metformin improves
glucose upake by yeast cells by ~15-31%. GC-MS analysis revealed 23
phytochemicals, some of which possessed anti-diabetic properties. A dose-dependent increase in
antioxidant activity of S. marianum leaves extracts was observed (40-53%). The findings of the study highlighted the presence of various
phytochemicals in leaves extracts that are effective against PTP1B inhibition and may help in reinvigorating
drug development.