Anti-diabetic functional food with wasted litchi seed and standard of quality control

The prevalence of diabetes has become a huge health burden in parts of quality of life and economic cost for overcoming this chronic disease. We followed a bioactivity-guided isolation using α-glucosidase inhibitory assay, four major compounds were isolated, and their structures were elucidated using nuclear magnetic resonance, mass spectrometry, and ultra-performance liquid chromatography quadrupole time of flight mass spectrometry in litchi seed. As a result, the IC50of α-glucosidase inhibitory assay of the crude extract, sugar-removed layer, pavetannin B2, procyanidin A2, and acarbose was 0.691 μg/mL, 3.686 μg/mL, 0.04 μM, 0.08 μM, and 55.845 μg/mL, respectively. With those compounds, we examined the protein tyrosine phosphatase 1B inhibitory activity. And the IC50of pavetannin B2, procyanidin A2, and ursolic acid was 450.295, 338.257, and 19.686 μM, respectively. Contents analysis method for bioactive compounds, which can be used in manufacturing for extract preparations, was established. The findings of this study, litchi seed can be a cost-effective medicinal food in terms of recyclable resources in the litchi food industry and as a natural alternative medicine against type-2 diabetes.