School of Pharmaceutical Science, Guangzhou University of Chinese Medicine, Guangzhou, 510006, People's Republic of China.
J Nat Med. 2023 Sep;77(4):858-866. doi: 10.1007/s11418-023-01727-5. Epub 2023 Jul 18.
Four new stilbenes (1-4) and one new flavonoid (5), named cajanines D-H, together with three known stilbenes (6-8) were isolated from the leaves of Cajanus cajan (L.) Millsp. (pigeon pea). The structures of these compounds were elucidated unambiguously on the basis of IR, 1D, and 2D NMR, as well as HRESIMS data. Structurally, stilbenes 1-4 bore an isopentyl side chain, and further hydroxylation of compounds 1-3 generated a greater variety of structural forms. Compound 5 was a flavonoid owning an isopentyl side chain. Besides, antibacterial activity of the isolated compounds against Staphylococcus aureus, Bacillus cereus, and Escherichia coli was studied in vitro. Compounds 1-8 were endowed with profound antibacterial activity. Among them, the MIC values of compounds 4, 6, and 7 against S. aureus were 1.56, 0.78, and 0.78 µg/mL, respectively, among which 6 and 7 had better antibacterial activity than the positive control Vancomycin with the MIC values of 1.56 µg/mL. Additionally, the anti-SARS-CoV-2 main protease activity of all the isolated compounds was evaluated, and it was worth mentioning that the IC values of compounds 5-7 were 8.27, 4.65, and 8.30 µM, respectively, being comparable to the positive control Ebselen. Our findings may provide valuable guidance for the application of stilbenes as lead compounds in the future for the development of drugs with antibacterial or anti-COVID-19 activity.
从落花生属植物（相思豆）的叶子中分离得到四个新的二苯乙烯（1-4）和一个新的类黄酮（5），分别命名为 cajanines D-H，以及三个已知的二苯乙烯（6-8）。这些化合物的结构是根据 IR、1D 和 2D NMR 以及 HRESIMS 数据明确阐明的。结构上，二苯乙烯 1-4 带有异戊基侧链，并且化合物 1-3 的进一步羟基化产生了更多种类的结构形式。化合物 5 是一种带有异戊基侧链的类黄酮。此外，还研究了分离得到的化合物对金黄色葡萄球菌、蜡状芽孢杆菌和大肠杆菌的体外抗菌活性。化合物 1-8 具有很强的抗菌活性。其中，化合物 4、6 和 7 对金黄色葡萄球菌的 MIC 值分别为 1.56、0.78 和 0.78µg/mL，其中 6 和 7 的抗菌活性优于阳性对照万古霉素（MIC 值为 1.56µg/mL）。此外，还评估了所有分离得到的化合物对 SARS-CoV-2 主要蛋白酶的活性，值得注意的是，化合物 5-7 的 IC 值分别为 8.27、4.65 和 8.30µM，与阳性对照 Ebselen 相当。我们的研究结果可能为未来将二苯乙烯作为抗菌或抗 COVID-19 药物的先导化合物的应用提供有价值的指导。
