Department of Analytical Chemistry, Medical University of Gdansk, Al. Gen. Hallera 107, 80-416, Gdansk, Poland.
Plant Foods Hum Nutr. 2021 Dec;76(4):458-465. doi: 10.1007/s11130-021-00922-7. Epub 2021 Sep 27.
Bioactivity of mulberry has been widely described, but mostly related to its fruits, while studies with leaves are scarce. Herein, in this study leaves of two mulberry species (Morus alba L. and Morus nigra L.) were characterized, compared, and evaluated in terms of their phenolic composition and antioxidant activity. Aiming to valorize mulberry leaves extracts which can be included in modern diet four different extracts (infusions, decoctions, tinctures and hydromethanolic) were examined. The chemical characterization was done by quantifying total phenolics (TPC), flavonoids (TFC) and phenolic acids (TPAC) content, L( +)ascorbic acid (ASA) and individual phenolic compounds in the extracts by HPLC technique. Moreover, DPPH and FRAP assays were used to assess the antioxidant activity of white and black mulberry leaves. Findings of these studies revealed that black mulberry leaves were richer in TFC and TPAC, while white mulberry leaves contained higher levels of individual phenolic compounds in water extracts. Gallic acid was found in the highest concentrations in two mulberry leave extracts. Correlation analysis showed strong relationships between antioxidant activity and TPC and TFC. This fact suggests the crucial role of phenolic compounds as antioxidant agents in white and black mulberry leaves. The results obtained in this study demonstrate that leaves of both white and black mulberry can be used as a valuable source of phenolic compounds with bioactive potential, which can be applied in the food sector, as foods and as promising source of natural ingredients.
桑树的生物活性已被广泛描述，但大多与它的果实有关，而关于其叶子的研究则很少。在此，本研究对两种桑树（白桑和黑桑）的叶子进行了特征描述、比较，并从其酚类成分和抗氧化活性方面进行了评估。为了实现桑树叶提取物的增值，使其可以包含在现代饮食中，研究了四种不同的提取物（浸液、煎剂、酊剂和水-甲醇提取物）。通过定量测定总酚（TPC）、类黄酮（TFC）和酚酸（TPAC）含量、L(+)抗坏血酸（ASA）和HPLC 技术测定提取物中的单个酚类化合物，对提取物进行了化学表征。此外，还使用 DPPH 和 FRAP 测定法评估了白桑和黑桑树叶的抗氧化活性。这些研究的结果表明，黑桑树叶的 TFC 和 TPAC 含量更高，而白桑树叶的水提取物中含有更高水平的单个酚类化合物。两种桑树叶提取物中均发现了较高浓度的没食子酸。相关分析表明，抗氧化活性与 TPC 和 TFC 之间存在很强的关系。这一事实表明，酚类化合物作为白桑和黑桑树叶中抗氧化剂的关键作用。本研究的结果表明，白桑和黑桑的叶子都可以作为具有生物活性潜力的酚类化合物的有价值来源，可应用于食品领域，作为食品和有前景的天然成分来源。
