FSK88, a forskolin derivative, was extracted and purified from cultured tropical plant roots, Coleus forskohlii. Our previous studies have demonstrated that FSK88 can inhibit HL-60 cell proliferation and induce the differentiation of HL-60 cells to monocyte macrophages. In this study, we showed that FSK88 can induce apoptotic death of human gastric cancer BGC823 cells in a dose- and time-dependent manner.Results showed that FSK88-induced apoptosis was accompanied by the mitochondrial release of cytochrome c and activation of caspase-3 in BGC823 cells. Furthermore, treatment with caspase-3 inhibitor (z-DEVD-fmk) was capable of preventing the FSK88-induced caspase-3 activity and apoptosis. FSK88-induced apoptosis in human gastric cancer BGC823 cells was also accompanied by the up-regulation of Bax, Bad and down-regulation of Bcl-2. Theses results clearly demonstrated that the induction of apoptosis by FSK88 involved multiple cellular and molecular pathways and strongly suggest that pro- and anti-apoptotic Bcl-2 family genes, mitochondrial membrane potential (Deltapsi(m)), cytochrome c, and caspase-3, participate in the FSK88-induced apoptotic process in human gastric cancer BGC823 cells.

The antiobesity effects of Coleus forskohlii were investigated in ovariectomized (ovx) rats. Eight-week-old female Wistar rats were assigned to four groups: a sham-operated group fed the control diet (MF, sham-m) ; an ovx-m group fed the control diet; a sham-operated group fed the control diet containing 50 g/kg of Coleus forskohlii extract (sham-c) ; and an ovx-c group fed the control diet containing 50 g/kg of Coleus forskohlii extract. The body weight, adipose tissues, and cell diameter were investigated in ovx rats after Coleus forskohlii extract treatment. Administration of Coleus forskohlii extracts reduced body weight, food intake, and fat accumulation in ovx rats. Our results suggest that Coleus forskohlii may be useful in the treatment of obesity.

Forskolin, a diterpene from the roots of an Indian plant, Coleus forskohlii, is a potent platelet aggregation inhibitor and has been examined for its effects on (a) tumor-induced human platelet aggregation and (b) pulmonary tumor colonization in mice. These studies employed a subline of B16 murine melanoma, B16-F10 (highly metastatic to lungs). Forskolin (2 microM) strongly inhibits the melanoma cell-induced human platelet aggregation. A single dose of forskolin (82 micrograms/mouse) administered intraperitoneally 30 or 60 min prior to tail vein injection of cultured B16-F10 cells (2 or 3 X 10(5) cells/mouse) reduced tumor colonization in the lungs by more than 70%. Similar results were obtained in three separate experiments. These findings raise the possibility that forskolin could prove of value in the clinic for the prevention of cancer metastasis.

Coleon C (6,11,12,14,16-pentahydroxyabieta-5,8,11,13-tetraen-7-one), extracted from Coleus forskohlii Briq., was investigated for its anti-tumor activity on eight human tumor cell lines (95-D, A375, HeLa, A431, MKN45, BEL7402, LoVo and HL60) and two normal ones (293, L02) by MTT and colony-forming assay in vitro. The results indicated that A375 was the most sensitive of all the cell lines. Hoechst 33258 staining showed fragmentation and condensation of chromatin. DNA ladder assay indicated the fragments of DNA because of apoptosis. Flow cytometric analysis demonstrated hypodiploid cells existed in A375 after Coleon C treatment. In the acute toxicity studies of C57BL/6 mice, LD(50 )of Coleon C was 1496+/-150 mg/kg. In the model of Lewis lung carcinoma, the average tumor weight in groups injected with 80 mg/kg Coleon C decreased by 48.9+/-14.3% compared with that of the control. These results indicate that Coleon C could effectively inhibit tumor cell proliferation and growth by inducing apoptosis with low toxicity. To our knowledge, this is the first report on the anti-tumor activity of Coleon C both in vitro and in vivo.