Planta Med. 1991 Aug; 57(4): 380-3.

Cytotoxic clerodane diterpenes from Polyalthia longifolia.

Zhao GX, Jung JH, Smith DL, Wood KV, McLaughlin JL.

Nanjing College of Traditional Chinese Medicine, W.H.O. Nanjing Collaborative Center of Traditional Medicine, People's Republic of China.

Bioassay-directed chemical investigation of the stem bark of Polyalthia longifolia Thw. (Annonaceae) has led to a novel clerodane diterpene, 16-oxo-cleroda-3, 13(14)Z-dien-15-oic acid, which was named polyalthialdoic acid (3). The bioassays also led to the previously known related diterpenes, kolavenic acid (2) which has not been reported as a constituent of this plant, and 16 alpha-hydroxy-cleroda-3,13(14)Z-dien-15,16-olide (1) which is previously known to be in this plant. These structures were identified by chemical and spectroscopic methods. All three compounds (1-3) were significantly bioactive in the brine shrimp bioassay; they strongly inhibited the growth of crown gall tumors on potato discs; and they were cytotoxic in three human tumor cell lines. These activities suggest potential antitumor applications. Compound 3 was the most active (ED50 values ca. 6 x 10(-1) micrograms/ml in the human tumor cell culture systems).