The Chemotaxonomy of Cynanchum and Its Allied Genera

Li De-Zhu, Qiu Sheng-Xiang, Wu Cheng-Yih

Received:1900-01-01 Revised:1900-01-01 Online:1990-11-10 Published:1990-11-10
Contact: Li De-Zhu

Abstract:

This paper is a continuation of “Chemotaxonomy of Cynanchum and Its Allied

Genera with Notes on the Generic Characteristics of Vincetoxicum”, published in Acta Bota-

nica Yunnanica (11: 41-50, 1989).

There are other three sections of Cynanchum in “Flora Reipublicae Popularis Sinicae”

(Vol. 63), which were considered as separate genera by some authors. These sections are Cy-

nanchum Sect. Rhodostegiella, Sect. Seutera and Sect. Cyathella, also of a single corona. They

were not given generic rank as chemical data of Sect. Rhodostegiella were inavailable. It is

for this reason that we have studied the chemical constituents of this section. A very marvel-

lous result was obtained. No C₂₁ steroidal compounds but flavonols were identified from the

section Rhodostegiella. Some flavones were isolated from Hoya bella of Asclepiadaceae (Bass

et al., 1979), but no report has been given from Cynanchum and the tribe Asclepiadeae up to

now. The family Asclepiadaceae mainly contains C21 steroids, but some genera contain card-

enolides or terpenoids, and only a few genera, such as Cryptolepis and Tylophora, have alka-

loids. The genus Cynanchum sensu Tsiang et P. T. Li, like most members of Asclepiadaceae,

has C₂₁ steroids except the section Rhodostegiella. Flavonols, therefore, may be the characteri-

stic of the section. Considering the corona characteristics and geographical distribution, we

suggest that the section Rhodostegiella be given generic rank.

Because of the separation of Vincetoxicum Wolf and Rhodostegiella (Pobed.) C. Y. Wu

et D. Z. Li from Cynanchum sensu Tsiang et P.T. Li, the rank of the sections Seutera and

Cyathella should be reconsidered. Obviously, the problem of evolution of the sections of Cyn-

anchum sensu Tsiang et P. T. Li is complicated. The corona, chemical constituents, habit, ro-

ot-type are not congruent with one another in evolution.

The authors support the establishment of the genera Seutera and Cyathella by Reichen-

bach (1828) and Decne (1838) respectively.

Taxonomic treatments, including a new status, Rhodostegiella (Pobed.) C.Y. Wu et D.

Z. Li, and 12 new combinations, are given.

Key words Cynanchum Linn.; Rhodostegiella (Pobed.) C. Y. Wu et D. Z. Li; Seutera Reichb.; Cyathella Decne.; Flavonols; Chemotaxonomy; New combination

Li De-Zhu, Qiu Sheng-Xiang, Wu Cheng-Yih. The Chemotaxonomy of Cynanchum and Its Allied Genera[J]. .

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