关键词: 越橘, 叶片, 多酚, 活性组分, 抗氧化能力

Abstract:

【Objective】The leaves of Vaccinium species are the main by-products in blueberry cultivation, which are rich in polyphenolic active compounds, but their resource values have not been fully developed and utilized. This study aimed to systematically investigate the accumulation patterns of polyphenolic components and their antioxidant activities in leaves at different developmental stages across 34 Vaccinium species, including wild resources and commercial cultivars. The objective was to identify germplasm with high nutritional value, thereby providing a theoretical basis for the high-value utilization of Vaccinium leaves and the development of functional products.【Method】Young (tender) leaves in spring, mature leaves and senescent leaves in winter from 34 Vaccinium species were used as experimental materials to detect the contents of total flavonoids, quercetin, anthocyanins, and proanthocyanidins. Antioxidant activities were comprehensively evaluated by three in vitro methods of hydroxyl radical (·OH) scavenging rates, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging rates, and ferric reducing antioxidant power (FRAP). Correlation analysis and principal component analysis (PCA) were applied to elucidate the relationships between polyphenolic components and antioxidant activities.【Result】Polyphenol contents and antioxidant activities in Vaccinium leaves were generally high and exhibited significant variations among species, cultivars, and leaf developmental stages. The average total flavonoid contents of young, mature, and senescent leaves were 189.92, 89.05 and 99.51 mg·g^-1 DW, respectively. Notably, young leaves of V. duclouxii (YNY316) exhibited an exceptionally high total flavonoid content of 561.43 mg·g^-1 DW. The average quercetin contents were 4.51, 12.56 and 8.95 mg·g^-1 DW, with mature leaves of V. mandarinorum (MFH4) showing the highest level (38.85 mg·g^-1 DW). The average anthocyanin contents were 0.83, 1.41 and 1.70 mg·g^-1 DW, while the average proanthocyanidin contents were 36.52, 38.45 and 44.42 mg·g^-1 DW. Antioxidant activity assessment revealed that senescent leaves showed the highest ·OH scavenging rate (65.14%) and FRAP value (1.23), whereas mature leaves exhibited the strongest ABTS radical scavenging capacity (33.66%). Correlation analysis indicated that quercetin contents in mature and senescent leaves were significantly positively correlated (P<0.01) with FRAP values and ABTS radical scavenging rates, indicating that quercetin is a major contributor to the antioxidant activity of Vaccinium leaves. Furthermore, wild resources such as V. duclouxii, V. trichophyllum, and V. mandarinorum, along with blueberry cultivars including ‘Eureka' ‘Beckyblue' and ‘Sringhigh', exhibited superior performance across multiple indices.【Conclusion】Wild Vaccinium germplasm and selected superior cultivars are rich in polyphenols, particularly flavonoids and proanthocyanidins, and exhibit remarkable antioxidant potential. The optimal developmental stages for leaf harvesting aimed at different functional components were clarified (e.g., young leaves for flavonoid extraction and mature leaves for quercetin extraction). These findings provide a theoretical foundation for the breeding of high-polyphenol blueberry cultivars and the high-value utilization of Vaccinium leaf resources.

Key words: Vaccinium spp., leaf, polyphenol, bioactive composition, antioxidant activity