Clonal variation in raspberry fruit phenolics and relevance for diabetes and hypertension management

The health-relevant functionality of fruit extracts from 12 Rubus cultivars was evaluated for potential diabetes and hypertension management. Inhibition of in vitro alpha-amylase, alpha-glucosidase and angiotensin-1-converting enzyme (ACE-1) activity was evaluated in conjunction with phenolic content and antioxidant activity. Black raspberries, Jewel and MacBlack cultivars, had the highest overall phenolic content and antioxidant activity. Red raspberry cultivars, Nova, Heritage and K81-6, showed the overall highest alpha-amylase inhibition in water and ethanol extracts. Jewel, a black raspberry cultivar, had the lowest alpha-amylase inhibitory activity of 40% or lower. Ethanol extracts of all 12 cultivars showed high inhibitory activity (above 85%) against alpha-glucosidase. The yellow raspberry, KCB-1, was the most effective at inhibiting alpha-glucosidase in both water and ethanol extracts. Fruit extracts of the yellow raspberries, KCB-1 and Kiwi Gold, showed the most potential for ACE-1 inhibition. Jewel and the red raspberry, Caroline, also had good activity against ACE-1.