Comparisons of phenolic components and anti-metabolic activities during different cultivars and growing conditions of blueberry leaves

Blueberry leaves (BBL), the primary byproduct of blueberry processing industry, are rich in polyphenolic compounds with significant nutritional and medicinal potential. This study established and optimized analytical methods to determine the major components and bioactivities in 110 BBL samples. The results indicated that chlorogenic acid (7.40-102.26 mg/g) was the predominant monomeric component in BBL, with TPC (245.22 ± 67.47 mg/g) generally exceeding TFC (19.61 ± 13.92 mg/g). In terms of cultivar varieties, rabbiteye BBL demonstrated the highest values in neochlorogenic acid (3.60 ± 1.28 mg/g), isoquercitrin (5.06 ± 2.88 mg/g), total phenolics (315.19 ± 52.74 mg/g), antioxidant activities (DPPH: 627.07 ± 150.25 μmol/g; ABTS: 654.90 ± 98.79 μmol/g), as well as α-glucosidase (90.33 % ± 8.64 %) and pancreatic lipase (53.77 % ± 8.64 %) inhibitory capacities. Southern highbush BBL exhibited higher hyperoside content (3.47 ± 3.10 mg/g) and xanthine oxidase inhibitory activity (62.01 % ± 8.97 %), while northern highbush BBL were characterized by elevated levels of chlorogenic acid (52.89 ± 19.24 mg/g), rutin (2.22 ± 1.01 mg/g), and TFC (20.31 ± 12.54 mg/g). The statistical analysis results revealed significant positive correlations between antioxidant activity and the contents of neochlorogenic acid, chlorogenic acid, total phenolics, and total flavonoids. Specifically, a positive correlation was observed between α-glucosidase inhibition and the contents of total phenolics and flavonoids, while a negative correlation existed between pancreatic lipase inhibition and hyperoside content. The entropy weight method confirmed rabbiteye BBL exhibited superior quality compared to highbush types, and open-field BBL significantly surpassed greenhouse-grown samples. This study investigated the characteristic chemical components and metabolism-related bioactivities of BBL across different cultivars and growing environments. By integrating chemometric analysis for correlation assessment, it provides a scientific basis for the resource utilization and high-value exploitation of BBL.