Potent water extracts of Indonesian medicinal plants against PTP1B

Objective: To examine the potent of water as a solvent agent in the preparation of traditional herbal medicine. Methods: Water extracts of 18 plants were prepared through reflux and examined (25 μg/mL) to evaluate their possibility for inhibiting protein tyrosine phosphatase 1B (PTP1B). The determination of IC₅₀ values was performed for the samples possessing more than 80% inhibition. Meanwhile, those exhibiting IC₅₀ values more than 7.0 μg/mL were further profiled for their chemical constituents through nuclear magnetic resonance (NMR) measurement. Results: About 44% (8) of the examined samples showed more than 80% inhibition against PTP1B. The water extracts of Elephantopus scaber, Helicteres isora aerial parts, Elaeocarpus grandiflorus (E. grandiflorus) fruits, Melaleuca leucadendron leaves, and Quercus infectoria gum had IC₅₀ values ranging from 2.05 to 6.90 μg/mL. Meanwhile, Andropogon nardus and Centella asiatica were at the area of δ 3.0-4.0 ppm. Further, the ¹³C NMR observation of samples possessing the most intensive signals in their proton NMR Cinnamomum burmannii and E. grandiflorus showed the peaks at the area of δ 60-90 ppm as the supportive evidence for sugar group signals. Intriguingly, a disaccharide from E. grandiflorus could be an active inhibitor towards PTB1B. Conclusions: In contrast to the mainstream solvents currently used in modern herbal manufactures especially Jamu medicine in Indonesia, pure-water-extracted materials should be reconsidered and could be reemerged for future studies and for the manufacture of herbal medicines. In addition, the activity of Jamu components should be confirmed that their antidiabetes and antiobesity activities could be through the inhibition of PTP1B.