(Poly)phenols of apples contribute to in vitro antidiabetic properties: Assessment of Canada's Apple Biodiversity Collection

Abstract

Societal Impact Statement Apples are affordable and accessible fruit with tremendous biodiversity. Among over 10,000 identified apple cultivars, only a few are commercially available. Habitual fruit consumption is correlated with the prevention of Type 2 diabetes and related complications. Particularly, (poly)phenols found in apples are major contributors to their antidiabetic properties. Here, we have screened (poly)phenol‐rich extracts of 476 apple accessions in Canada's Apple Biodiversity Collection for antidiabetic properties. The results of this work provide insights into the prevention and management of Type 2 diabetes by identifying high (poly)phenol‐containing specialty apples for use in fresh fruit form or value‐added functional food ingredients. Summary The recent trend in sedentary lifestyles and nutritionally‐imbalanced diets has elevated the prevalence of Type 2 diabetes in many parts of the world. Some pharmacological glycemic management can cause undesirable gastrointestinal side effects or hypoglycemia. Thus, there is a growing interest in safe glycemic management using dietary (poly)phenols. In this study, (poly)phenol‐rich extracts of 476 apple accessions from Canada's Apple Biodiversity Collection (ABC) and six major apple (poly)phenols were assessed for in vitro antidiabetic properties against the activities of α‐glucosidase, α‐amylase, and dipeptidyl peptidase‐4 (DPP‐4) and the formation of advanced glycation end products (AGE). Apple (poly)phenol extracts varied in their antidiabetic activities in a dose‐dependent manner. High (poly)phenol‐containing apples demonstrated that their total phenolic contents (TPC) were inversely correlated with the IC50 values of α‐glucosidase, α‐amylase, and AGE formation, but not DPP‐4. Concentrations of major (poly)phenol compounds such as procyanidin B2, phloridzin, and epicatechin in apples were significantly inversely correlated with IC50 values of α‐glucosidase in the high (poly)phenol‐containing apples. High TPC apples are not suitable for marketing for fresh fruit consumption due to bitterness and astringency; however, these apples show potential to use in the development of value‐added functional food ingredients or nutraceuticals for blood glucose management. The high TPC apple, “S23‐03‐749,” an advanced breeding line of dessert apple, presents a novel option as a specialty apple cultivar for the dietary management of glycemia.

Keywords

• α‐amylase
• α‐glucosidase
• advanced glycation end products
• dietary (poly)phenols, dipeptidyl peptidase‐4
• functional food
• Malus species