Antioxidant and α-Glucosidase Inhibitory Activity of Polyphenols in Peel and Core from Five Different Pear Varieties

Abstract

This study was performed to compare polyphenol content, DPPH radical scavenging activity and αglucosidase inhibitory activity in peel, core and pulp of five different pear cultivars. Oligomeric polyphenols were the main polyphenols in core, which exhibited greater polyphenols, DPPH radical scavenging activity, and αglucosidase inhibitory activity, compared to peel and pulp. For the peel, Japanese pears including Yasato, 20-Seki and Shinko pear contained relatively more polyphenol content and α-glucosidase inhibitory activity, compared to European pears including Starkrimson and Purekosu pear. Monomeric polyphenols were the main polyphenols in the peel of European pears, in contrast, oligomeric polyphenols were the main polyphenols in those of Japanese pears. The peel of Yasato pear had high ratios of non-monomeric polyphenols, and showed highest DPPH radical scavenging activity and α-glucosidase inhibitory activity amongst five pear cultivars. Thus DPPH radical scavenging activity and α-glucosidase inhibitory activity may be related with non-monomeric polyphenols in pears. Moreover, as comparing with peel, pulp had lower polyphenol content, DPPH radical scavenging activity and α-glucosidase inhibitory activity. All of the observations suggested that peel and core of pear contained abundant polyphenols and possess potential the values of reusing.

Antioxidant Activity, and α-Glucosidase, α-Amylase and Lipase Inhibitory Activity of Polyphenols in Flesh, Peel, Core and Seed from Mini Apple

“…It indicated that more highly polymerized polyphenols exhibited more potent inhibitory activities on α-glucosidase. Consistent with this, we also observed that oligomeric and polymeric polyphenols exhibited stronger α-glucosidase inhibitory activity than monomeric polyphenols in pears and scarlet runner beans [18,21]. These results may be explain why seed polyphenols had the strongest inhibitory activity than the other parts on digestive enzymes.…”

“…Polyphenol content was much higher than in the flesh [17]. We also found peel of European pears and Japanese pears that peel had higher polyphenol content than those of flesh [18]. Moreover, Leontowicz et al [17] reported that polyphenol content was 1.07 ± 0.1 mg/g in apple peel and 0.62 ± 0.1 mg/g in apple flesh.…”

A Comparative Study of Ten Pear (Pyrus communis L.) Cultivars in Relation to the Content of Sugars, Organic Acids, and Polyphenol Compounds

“…The same phenolic subgroups were identified in the pulp, with the exception of flavonols. The content of all analyzed polyphenol compounds was higher in pear peel (574.93 mg kg −1 ) than in pulp (36.86 mg kg −1 ), which is in accordance with earlier reported results [10,33]. Traditional pear cultivars had higher total phenols in both peel and pulp than the commercial 'Président Drouard', with the exception of cultivars 'Takiša' and 'Ahmetova' (Table 4).…”