Taxinine B

Thromb Res. 2010 Jun;125(6):e281-4.

A comparative optical aggregometry study of antiplatelet activity of taxanes from Taxus cuspidata.[Pubmed: 20170941]

Platelets are highly reactive components of the circulatory system. The cytoskeleton of a platelet is an important structure for platelet aggregation as stimulated by several agonists. An anticancer agent, taxol, has been suggested to exert platelet anti-aggregating activity by stabilizing microtubules during the aggregation process.
METHODS AND RESULTS:
An activity-guided fractionation was performed with a methanol extract of the leaves and twigs of Taxus cuspidata to isolate taxanes with platelet anti-aggregating effects. Compounds 1 to 7 - taxinine (1), taxinine A (2), Taxinine B (3), 2-deacetoxyTaxinine B (4), taxacin (5), taxchinin B (6), and taxol (7) - were obtained as the antiplatelet components of this plant. These taxane compounds present the possibility of securing new antiplatelet compounds which differ from currently available antiplatelet agents in chemical structure and possibly in mechanisms of action.
CONCLUSIONS:
All compounds showed stronger inhibitory effects than acetylsalicylic acid (ASA) on platelet aggregation induced by arachidonic acid (AA) (IC(50): 14.4, 64.5, 35.5, 16.0, 21.9, 28.6 and 48.2 versus 63.0microM) or U46619 (IC(50): 34.8, 24.9, 36.2, 35.0, 46.9, 71.9 and 68.7 versus 340microM). Compounds 1, 3, 4 and 5, with a cinnamoyl group at the C(5) position, showed strong inhibitory effects against AA-induced aggregation compared to compound 2 (with an -OH group at C(5)) or compounds with an oxetane ring at C(4),(5), such as compounds 6 and 7. All of the seven compounds were 5-13-fold more strongly inhibitory than ASA against U46619-induced aggregation.

Tetrahedron, 1997, 53(13):4621-6.

Crystal and solution state conformations of two taxoids, taxinine and taxinine B[Reference: WebLink]

METHODS AND RESULTS:
Crystal and solution state conformations of two taxoids, taxinine and Taxinine B, inhibiting the drug transport by P-glycoprotein in multidrug-resistant cells, were analyzed by X-ray crystallographic analysis and ROE experiments. This study demonstrated that in solid state, both taxinine and Taxinine B took similar cage conformation in which A-ring and the cinnamoyl side chain at C-ring were specially very close to each other.
CONCLUSIONS:
These conformations were also observed in their solution conformations deduced by ROE correlations in CDCl3, Monte Carlo simulation using MM2∗ force field, and semiempirical molecular orbital calculation using PM3 method.