Antiplatelet aggregation effects of phenanthrenes from Calanthe arisanensis.

Three phenanthrenes (1-3), four indole alkaloids (4-7) and one steroid (8) were isolated from the leaves of Calanthe arisanensis for the first time. In the antiplatelet aggregation assay, phenanthrenes 1 and 2 showed potential antiplatelet activity. We have reported and discussed here the antiplatelet aggregation properties of the eleven naturally-occurring phenanthrenes (1-2 and 9-17) isolated from the underground part of the plant and eighteen chemically synthesized phenanthrenes (18-35). Overall, our data demonstrated that 1,4-phenanthrenequinones 20, 21 and 22 (collagen, IC50 0.2, 0.2, 0.1 microg/mL; thrombin, IC50 0.8, 1.0, 1.1 microg/mL, respectively) could be promising lead candidates for further cardiovascular disease studies.

Cytotoxic phenanthrenequinones and 9,10-dihydrophenanthrenes from Calanthe arisanensis.

Two new phenanthrenequinones, calanquinones B and C (2 and 3) and four new 9,10-dihydrophenanthrenes, calanhydroquinones A-C (4-6) and calanphenanthrene A (7), along with five known compounds (1 and 8-11), were isolated from an EtOAc-soluble extract of Calanthe arisanensis through bioassay-guided fractionation. Their structures were identified from spectroscopic data, and the compounds were tested for in vitro cytotoxic activity against human lung (A549), prostate (PC-3 and DU145), colon (HCT-8), breast (MCF-7), nasopharyngeal (KB), and vincristine-resistant nasopharyngeal (KBVIN) cancer cell lines. Compound 1 showed the highest potency (EC(50) < 0.5 microg/mL) against all seven cancer cell lines, with the greatest activity against breast cancer MCF-7 cells (EC(50) < 0.02 microg/mL). Generally, except for 7, compounds 2-11 also showed significant cytotoxic activity (EC(50) < 4 microg/mL) against some cell lines (especially PC-3 and MCF-7) in the panel.

Cytotoxic withanolides from Tubocapsicum anomalum.

Fifteen new withanolides (1-8, 11-17) and two known withanolides, withanolide D (9) and 17alpha-hydroxywithanolide D (10), were isolated from the stems, roots, and leaves of Tubocapsicum anomalum using bioassay-directed fractionation. The structures were determined by spectroscopic and chemical methods, and the absolute configurations were established by CD analysis and by the Mosher ester method. The structure of 1 and 3 were further confirmed by X-ray crystallographic analysis. Compounds 1, 4-6, 8-10, and 13 showed significant cytotoxic activity against Hep G2, Hep 3B, A-549, MDA-MB-231, MCF-7, and MRC-5 cell lines.

New cytotoxic 6-oxygenated 8,9-dihydrofurocoumarins, hedyotiscone A - C, from Hedyotis biflora.

Using the bioactivity-guided fractionation method, three new 6-oxygenated 8,9-dihydrofurocoumarin-type compounds, hedyotiscones A, B, and C were isolated from the methanol extract of Hedyotis biflora together with seven known compounds. The structures of all isolated compounds were determined on the basis of mass and spectroscopic evidence. Compounds, oleanolic acid, and 6'-(beta-sitosteryl-3- O-beta- D-glucopyranosidyl) pentadecanoate showed marginal cytotoxicity against Hep G2 cells (human liver cancer cells) with IC50 values of 14.4, 17.4, 4.9, 8.0, and 9.2 microg/mL, respectively. Ursolic acid showed significant cytotoxicity against MDA-MB-231 cells (human breast carcinoma cells) with an IC50 value of 1.49 microg/mL.