Evaluation of the alkaloid, polyphenols, and antioxidant contents of various mulberry cultivars from different planting areas in eastern China

Mulberry (Maras alba L.), a traditional industrial crop, has various cultivars and a large planting area in China and consequently, high exploitation potential. The aim of this study was to systematically study the mulberry resources in eastern China. Twenty-four mulberry leaf samples of eight representative cultivars from five provinces in eastern China were investigated. The alkaloid and polyphenols contents were determined by HPLC-MS/MS, and the total polyphenols and flavonoid contents were also obtained. Then, FRAP, ABTS, and DPPH tests were used to determine the antioxidant activity of mulberry leaves. The results indicated that the content of 1-deoxynojirimycin was within the range of 0.438 +/- 0.010 mg/g-2.159 +/- 0.016 mg/g, and the content of fagomine ranged from 0.379 +/- 0.018 mg/g to 1.675 +/- 0.021 mg/g. The samples from Anhui had the best antioxidant activity, of which the DPPH free radical-scavenging capacity reached 70.837 +/- 1.246%, and the ferric reducing antioxidant power was 258.864 +/- 22.718 mmol Fe2+/g. The principal component analysis results showed that there was a good correlation between the total polyphenols content, total flavonoid content, chlorogenic acid content, and antioxidant activity. Considering the active ingredient contents and antioxidant activity, we found that Yu711 was the most economically valuable variety, and Anhui is the best location to promote mulberry cultivation in eastern China, which provides a basis for the rational utilization of mulberry industrial products.