Two phenanthrenes were isolated from the aerial part of Dendrobium nobile Lindl. and their structures were identified to be 4,7-dihydroxy-2-methoxy-9,10-dihydrophenanthrene (1) and denbinobin (2), among which the former has been first isolated from this plant. These two compounds were found to be cytotoxic against A549 (human lung carcinoma), SK-OV-3 (human ovary adenocarcinoma), and HL-60 (human promyelocytic leukemia) cell lines. Compound 1 also showed antitumor activity on the life span of ICR mice intraperitoneally implanted with 1 x 10(6) cells of sarcoma 180.

In the search for antiangiogenic agents from medicinal plants used in Vietnam, a methanol extract of the stem barks of Bombax ceiba was found to exhibit a significant antiangiogenic activity on in vitro tube formation of human umbilical venous endothelial cells (HUVEC). Bioactivity-guided fractionation and isolation carried out on this extract afforded lupeol as an active principle. At 50 and 30 microg/mL lupeol showed a marked inhibitory activity on HUVEC tube formation while it did not affect the growth of tumor cell lines such as SK-MEL-2, A549, and B16-F10 melanoma.

Seventeen saponins isolated from the root of Pulsatilla koreana were examined for their in vitro cytotoxic activity against the human solid cancer cell lines, A-549, SK-OV-3, SK-MEL-2, and HCT15, using the SRB assay method, and their in vivo antitumor activity using BDF1 mice bearing Lewis lung carcinoma (LLC). The saponins 5-17, with a free acidic functional group at C-28 of aglycon, exhibited moderate to considerable cytotoxic activity, however, the saponins 1-4, esterified with a trisaccharide at C-28 of aglycon, did not exhibit cytotoxic activity (ED 50 ; Ͼ300 m mM). Among them, oleanolic acid 3 -a a-L-arabinopyranoside (17, IR; 50.3%) exhibited potent antitumor activity. These two saponins were identically comprised of a hederagenin aglycon moiety and a sugar sequence O-a a-Lrhamnopyranosyl-(1→ →2)-a a-L-arabinopyranoside at C-3 of the hederagenin, suggesting that the two elements are essential factors for the antitumor activity.

The petroleum ether fraction of Pulsatilla koreana (Ranunculaceae) was found to have an inhibitory effect on the tube-like formation of human umbilical venous endothelial (HUVE) cells and strong cytotoxic activity against five tumor cell lines. The active component isolated from the fraction was deoxypodophyllotoxin (DPT). The cytotoxic activity against the tumor cells comprising the A549, SK-OV-3, SK-MEL-2, HCT15, and B16F10 cell lines, expressed as ED50, ranged from 6 to 18 ng/ml. 3 ng/ml of DPT, a concentration considerably below the cytotoxic concentration, completely inhibited the tube-like formation of HUVE cells. Furthermore, DPT exhibited an inhibition ratio of 60 % on BDF1 mice bearing Lewis lung carcinoma cells. The inhibitory effect on the tube-like formation was suggested to play an important role in antitumor activity.

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