Anti-diabetic activity in type 2 diabetic mice and α-glucosidase inhibitory, antioxidant and anti-inflammatory potential of chemically profiled pear peel and pulp extracts (Pyrus spp.)

• Hypoglycemic activity of pear peel in streptozocin-induced type 2 diabetic mice.
• Inhibitory activity of pear peel in α-glucosidase in vitro.
• Evaluation of 8 pear varieties' antioxidant and anti-inflammatory potential.
• Analysis of total polyphenols, total triterpenes, and main monomeric compounds.

Total phenolic acids, total flavonoids, total triterpenes contents, and eleven monomeric compounds, derived from eight different pears' peel and pulp, were qualitatively and quantitively profiled utilizing HPLC and HPLC-MS. All the chemical components found in the peel were approximately 2 to 18 folds concentrated than those in the pulp. Their antioxidant (reducing power and 2, 2-diphenyl-1-picrylhydrazyl/DPPH assay) and anti-inflammatory (xylene-induced mouse ear edema assay) activities were comparatively evaluated. Correlation analysis and principal component analysis were utilized to seek bioactive components in antioxidant and anti-inflammatory activities. Subsequently, Yaguang pear (Pyrus ussuriensis Maxim, with high polyphenols content) was selected to investigate in vitro and in vivo anti-diabetic potential (α-glucosidase inhibition assay and hypoglycemic assay in streptozocin-induced type 2 diabetic mice). Eleven monomeric compounds were seriatim examined for α-glucosidase inhibitory activity to fish out anti-diabetic components. For the first time, this study delineated pear peel's anti-diabetic prospect of treatment for type 2 diabetes.