Changes in the Polyphenol Content of Red Raspberry Fruits during Ripening

Ryo Kobori,Akiko Saito,Syuichi Yakami,Takashi Kawasaki

doi:10.3390/horticulturae7120569

Abstract

Berry fruits that contain large amounts of polyphenol compounds are expected to exhibit health and anti-aging effects due to the antioxidant activities of these components. Among the various polyphenols, flavan-3-ol derivatives are known to have a particularly high functionality. In this study, the maturity of red raspberry fruits is classified into eight stages based on the polyphenol content at each stage. Quantification of the various compounds and investigation of the DPPH and ABTS radical scavenging activities were carried out. The total polyphenol content, including that of the flavan-3-ol derivatives, was the highest in immature fruits, gradually decreasing during fruit maturation, during which the radical scavenging activity also decreased. Based on our quantitative results, it was considered that the decrease in the flavan-3-ol derivative content due to fruit ripening was largely related to the increase in the amount of anthocyanin derivatives. Considering that the decreased contents of these compounds were related to the expression levels of polyphenol biosynthetic enzymes, quantification was performed using the semi-quantitative polymerase chain reaction, but the only change observed was the increased expression of the enzyme that synthesizes anthocyanins during maturation. Therefore, it was suggested that it is necessary to inhibit anthocyanin synthesis to increase the contents of highly functional flavan-3-ol derivatives in the mature fruit.

Highlights

There is currently great interest in the functional and bioactive compounds present in food sources since they are generally considered to be safe due to their frequent consumption in the daily diet
We previously developed a stereoselective route to flavan-3-ol derivatives, oligomeric compounds [3,4,5,6,7,8], galloyled derivatives [9,10,11,12,13], and acylated derivatives [14,15,16], to permit structure-activity relationship (SAR) studies to be carried out, including those related to the anti-oxidative activities [5,6,7,8,9], radical scavenging activities [10,11], HeLa S3 proliferation-inhibitory activities [7,12,13,16], and anti-viral activities [17] of these compounds
For the other enzymes examined, no significant differences were observed during maturation, and so our results suggest that the decrease in the amount of flavan-3-ol derivatives was caused by an increase in the expression of ANS, the expression level of the external biosynthetic enzyme of the flavan-3-ol derivative did not change

Summary

Introduction

There is currently great interest in the functional and bioactive compounds present in food sources since they are generally considered to be safe due to their frequent consumption in the daily diet. Biological activity evaluations and elucidation of the mechanisms of action require large quantities of the corresponding compounds to obtain structure-activity relationship (SAR) profiles, and currently, it is difficult to obtain such quantities of polyphenol compounds from plants To address this issue, we previously developed a stereoselective route to flavan-3-ol derivatives, oligomeric compounds [3,4,5,6,7,8], galloyled derivatives [9,10,11,12,13], and acylated derivatives [14,15,16], to permit SAR studies to be carried out, including those related to the anti-oxidative activities [5,6,7,8,9], radical scavenging activities [10,11], HeLa S3 proliferation-inhibitory activities [7,12,13,16], and anti-viral activities [17] of these compounds.

Methods

Results

Conclusion