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Two new compounds, along with two known compounds, were isolated from the barks of Parabarium huaitingii, and their structures were determined as 5α-pregn-6-ene-3β,17α,20(S)-triol-20-O-β-d-digitoxopyranoside (1), cymaropyranurolactone 4-O-β-d-digitalopyranosyl-(1 → 4)-O-β-d-cymaropyranosyl-(1 → 4)-O-β-d-oleandropyranosyl-(1 → 4)-O-β-d-cymaropyranoside (2), 3β,17α,20(S)-trihydroxy-5α-pregn-6-ene (3), and 5α-pregn-6-ene-3β,17α,20(S)-triol-3-O-β-d-digitalopyranoside (4) by spectroscopic methods.

The effects on guinea-pig heart muscle of extracts of Apocynum venetum L. leaf, root, stem, old stem and Venetron--a polyphenol-rich extract of leaves--were studied by recording the mechanical activity and heart rate of isolated right atria. Cymarin--a cardiac glycoside--was also determined in A. venetum extracts by LC-MS/MS analysis. All extracts examined here showed a weak cardiotonic effect, i.e., induced a contractile response of the isolated atria and increased the pulse at a concentration of 1 mg/mL, which was not inhibited by propranolol (1 microM)-a beta-adrenoceptor blocker. The cymarin content in extracts of A. venetum was ranked as follows: old stem >> stem > root > leaf >> Venetron. Since the cardiotonic effects of A. venetum extracts did not reflect the cymarin content, a possible mechanism other than that of cardiac glycosides was investigated. The inhibitory effects on phosphodiesterase 3 (PDE3) were studied in a cell-free enzyme assay; all extracts of various parts of A. venetum inhibited PDE purified from human platelets. These results suggest that PDE3 inhibition may contribute to the cardiotonic effects of A. venetum extracts.

Antiangiogenic activity-guided fractionation and isolation carried out on the methanol extract of Adonis amurensis led to the identification of three compounds, namely cymarin, cymarol, and cymarilic acid. Amongst the three compounds, cymarilic acid was isolated from this plant for the first time. This compound showed no significant cytotoxicity against tumor cell lines but was found to be strongly inhibitory toward tube formation induced by human umbilical venous endothelial (HUVE) cells. Cymarin and cymarol exhibited potent cytotoxicity against a human solid tumor cell line A549 (human lung carcinoma), while being inactive on murine leukemic cells (L1210)., (Copyright 2003 John Wiley & Sons, Ltd.)

Systematic fractionation of the cytotoxic extracts of the roots of Parquetina nigrescens (Afzel.) Bullock (Asclepiadaceae) on silica gel column chromatography led to the isolation of three cardenolides: cymarin, strophanthidin, and a strophanthidin glycoside (XS-89). Also isolated during the investigation were beta-sitosterol-beta-D-glucoside, a mixture of alpha- and beta-amyrins, a mixture of alkanols, and a mixture of plant sterols.

From the roots of Trachomitum sarmatiense Woodson (Apocynaceae) 5 cardial glycosides were isolated. Among them 4 substances were identified: cymarin and k-strophanthin-beta, and two derivatives of cannogen: apocannosid and apobiosid. In the overground part of the plant, the cardenolides were not found.