Cytotoxic phytochemicals

Six pure compounds were isolated and showed potent growth inhibition; vulgarin (1), isolated from Artemisia judaica, inhibited the growth of human colorectal cancer cells (27–100%, IC₅₀ =14µg/ml) and human melanoma cells (24–100%, IC₅₀=12µg/ml) with 7–14% growth inhibition of the normal human fibroblasts. Saudinolide (2), isolated from Cluytia richardiana, inhibited the growth of colorectal cancer cells (16–100%, IC₅₀=15µg/ml) and melanoma cells (26–100%, IC₅₀=12µg/ml) with 14–18% growth inhibition of normal fibroblast cells. Psoralen (3), isolated from Ruta chalepensis, inhibited the growth of colorectal cancer cells (22–100%, IC₅₀=20µg/ml) and melanoma cells (41–100%, IC₅₀=12µg/ml) with 6–23% growth inhibition of normal fibroblasts. On the other hand, 2β-angeloyloxy-5β,8β-dihydroxypresilphiperfolane (4), isolated from Senecio hadiensis, inhibited the growth of colorectal cancer cells (28–100%, IC₅₀=12µg/ml) and melanoma cells (26–100%, IC₅₀=12µg/ml) while exerting 6–34% growth inhibitory effect on normal human fibroblasts. Moreover, plectranthone (5) and casticin (6) were both isolated from Plectranthus cylindraceus. Compound 5 inhibited the growth of colorectal cancer cells (15–100%, IC₅₀=20µg/ml) and melanoma cells (39–100%, IC₅₀=12µg/ml) with 8–25% growth inhibition of normal fibroblasts, while compound 6 had very potent growth inhibitory effects on both colorectal cancer cells and melanoma cells (80–100%, IC₉₀=10 and 12µg/ml, respectively) with 4–35% effect on normal human fibroblasts.