Convallatoxin

The cardenolides g-strophanthin (hRf 5-10), convallatoxin (hRj 30-35) and k-strophanthin (h/ j 50-55) immediately formed red-violet chromatogram zones that gradually faded. Hence, the reagent was not always suitable for quantitative work. 

Fig. 1 Chromatograms of reference substances (A) and of a lily of the valley extract (B) 1 g-strophanthin, 2 = convallatoxin, 3 = k-strophanthin...

Furthermore, it has been found that ouabain, convallatoxin, and cymarin inhibit the PTX-induced contraction of rabbit aortic vascular smooth muscle (79). These observations have also provided evidence for the involvement of Na ,K -ATPase on the contractile effect of PTX in smooth muscle. 

Adonis brevistyla Franch. A. chrysocyathus Hook F. T. Thoms. A. vernalis L. Fu Shou Cao (Amur adonis) (aerial part) Cymarol, adonilide, pergularin, corchoroside A, convallatoxin, isoramanone.33 This herb is toxic. Treat heart disease and depression, diuretic. 

China Convallaria keiskei Miq. Convallatoxin, convalloside, convallamarin, convallatoxol. This herb is toxic.33 Treat heart disease, detoxify the liver. 

In their synthesis of convallatoxin, Reichstein and coworkers16 made some minor modifications in the Meystre-Miescher procedure. Because of the low solubility of strophanthidin (2) in benzene, the anhydrous aglycon was dissolved in a small volume of absolute p-dioxitne. Pure, dry silver carbonate was introduced and, under efficient stirring, a solution of the halide in benzene was added over a period of three hours, while distillation was maintained at a rate equal to that of the addition, thus keeping the volume of the solution in the flask at a constant (and small) volume. After addition of the halide was complete, a small volume of absolute benzene was added dropwise over a period of one hour, with distillation maintained as in the foregoing. By this procedure, the yield of tri-O-acetylcopvalla-toxin amounted to 44%. 

Following this work, Reichstein and coworkers15 effected the first partial synthesis of a naturally occurring cardenolide, convallatoxin. Convalla-toxin [3/3-0-(6-deoxy-a-n-mannopyranosyl) strophanthidin (9)] is considered to be the most potent of all the known, naturally occurring cardenolides, and is obtained from the blossoms of the lily-of-the-valley (Convallaria majalis). The coupling of strophanthidin (2) with 2,3,4-tri-0- acetyl-6-deoxy-a- L-mannosyl bromide was performed using silver car-... 

In Reichstein s synthesis15 of convallatoxin (9), 2,3,4-tri-0-acetyl-6-deoxy-a-L-mannosyl bromide (13) (a 1,2-trans halide) was employed. In contrast to the preparation of simple glycosides, the use of silver carbonate did not lead to orthoester formation instead, glycoside formation took... 

In order to introduce the terminal hydroxyl group in convallatoxin (9), it was necessary to work with the non-naturally occurring l-mannose (28), which may be synthesized according to Sowden and Fischer.41 Acetylation of (28) under the usual conditions gave 1,2,3,4,6-penta- 0-acetyl-/3-L-... 

The dried roots and tops of lily of the valley, Convallaria majalis (Liliaceae/Convallariaceae), contain cardioactive glycosides (0.2-0.3%) and are used in some European countries rather than digitalis. The effects are similar, but the drug is less cumulative. This plant is widely cultivated as an ornamental, particularly for its intensely perfumed small white flowers, and must be considered potentially toxic. The major glycoside (40-50%) is convallatoxin (Figure 5.98), the rhamnoside of strophanthidin. 

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