Antiproliferative activity of stilbene derivatives and other constituents from the stem bark of Morus nigra L

The antiproliferative activities of 2′,3,4′,5,5′-pentahydroxy-cis-stilbene 1, resveratrol 2, oxyresveratrol 3, norartocarpetin 4, kuwanon C 5, morusin 6, cudraflavone A7, kuwanon G 8, albafuran C 9, mulberrofuran G 10, 3-acetyl-O-α-amyrin 11, 3-acetyl-O-β-amyrin 12, ursolic acid-3-O-acetate 13 and uvaol 14, previously identified from the barks of Morus nigra L., were investigated against HepG2 and MCF-7 cell lines. In addition, a series of methylated stilbenes 15–19 were prepared using compounds 1–3 and their antiproliferative effects were similarly investigated. The structure of a new 2′,3,4′-trimethoxy-5-hydroxy-trans-stilbene 19 was elucidated using spectroscopic techniques. It showed remarkable activity against MCF-7 cells with IC₅₀ 12.5 μM. However, kuwanon C (5) showed the highest antiproliferative activity with IC₅₀ 3.92 and 9.54 μM against MCF-7 and HepG2, respectively.