INFLUENCE OF MATURITY STAGE ON TRYPTOPHAN, PHENOLIC, FLAVONOID, AND ANTHOCYANIN CONTENT, AND ANTIOXIDANT ACTIVITY OF Morus alba L. FRUIT

Abstract

Mulberry (Morus alba L.) fruits have been suggested to be a good nutritional source of alkaloids, phenolic compounds, flavonoids, and anthocyanins, which can provide health benefits. However, limited studies have addressed how changes in health promotion compounds and mulberry fruit quality are affected by harvest season. Therefore, phytochemical profiles of mulberry fruit at different maturity stages were determined by liquid chromatographytandem mass spectrometry (LC-MS/MS). Mulberry fruit extracts were also analyzed for their antioxidant potential and total phenolic, flavonoid, and anthocyanin contents. The results established that purple fruit had the highest total phenolic, flavonoid, and anthocyanin contents (608.87±8.07 mg GAE/g DW, 11.39±0.17 mg GAE/g DW, and 22.04±0.54 mg/ 100 g DW, respectively). Purple fruit also exhibited the strongest antioxidant activity in DPPH, ABTS, and FRAP assays. Quantitative analysis by LC-MS/MS revealed that purple fruit had the highest cyanidin-3- O-glucoside, rutin, gentisic acid, protocatechuic acid, and gallic acid contents, whereas green fruit had the highest caffeic acid, chlorogenic acid, and tryptophan contents. Our result suggests that later developmental stages of mulberry fruit have increased phenolic, flavonoid, and anthocyanin contents, and antioxidant capacity while tryptophan content was high in both green and purple mulberry fruits.