Changes in Radical-scavenging Activity and Components of Mulberry Fruit During Maturation

• Autores: Tomoyuki Oki, Mio Kobayashi, Taeko Nakamura, Akiko Okuyama, Mami Masuda, Hideki Shiratsuchi, Ikuo Suda
• Localización: Journal of food science, ISSN 0022-1147, Vol. 71, Nº 1, 2006
• Idioma: inglés
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• Resumen

  • Extracts of mulberry fruits (Morus sp.) were prepared from 8 cultivars harvested at 4 stages of maturity, and their radicalscavenging activity, anthocyanin content, and total phenolic content were measured. The radical-scavenging activity was evaluated by a spectrophotometric assay using the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) in a 96-well microplate. Mulberry fruit extracts exhibited the DPPH-scavenging activities, ranging from 2.5 to 20.3 μmol-Trolox equiv/g-FW. Their activities were variable during maturation, and the highest activity was observed in the fully mature mulberry fruit in all cultivars. Anthocyanin was scarcely present in the immature mulberry fruits; however, its content increased as the fruit matured in all cultivars. On the other hand, all immature mulberry fruits contained non-anthocyanin phenolic compound. An on-line high-performance liquid chromatography (HPLC) method for the detection of DPPH-scavenging compounds revealed the difference in predominant radical scavengers between the immature and fully mature stages in the Miran 5 cultivar. Four major radical scavengers in the Miran 5 cultivar were assigned to 2 caffeoylquinic acids (chlorogenic acid and its isomer) and 2 anthocyanins (cyanidin 3-glucoside and cyanidin 3-rutinoside) in the immature and fully mature stages, respectively, by LC-ESI-MS/MS analysis. The change in the content of 4 compounds in mulberry fruits during maturation demonstrated that the most likely contributors to the DPPH-scavenging activity were caffeoylquinic acids in the immature mulberry and anthocyanins in the mature and fully mature mulberry.