Stereochemistry and biological activities of constituents from Cynanchum taiwanianum

Synergistic silver/scandium catalytic spiroketalization of β-alkynyl ketones for the atom economical synthesis of skeletally diverse spirocyclic isochromenes

Two types of new synergistic silver/scandium catalytic spiroketalizations of β-alkynyl ketones have been achieved, delivering a variety of skeletally diverse spirocyclic isochromenes in generally good yields.

Benzannulated spiroketal natural products: isolation, biological activity, biosynthesis, and total synthesis

A review discussing the isolation, biological activity, biosynthesis, and total synthesis of naturally occurring benzannulated spiroketals.

Ethnobotany, Phytochemistry and Pharmacological Effects of Plants in Genus Cynanchum Linn. (Asclepiadaceae)

Genus Cynanchum L. belongs to the family Asclepiadaceae, which comprise more than 200 species distributed worldwide. In Chinese medical practice, numerous drugs (such as tablets and powders) containing different parts of plants of this genus are used to treat snake bites, bruises, osteoblasts, rheumatoid arthritis and tumors. A search for original articles published on the cynanchum genus was performed by using several resources, including Flora of China Official Website and various scientific databases, such as PubMed, SciFinder, the Web of Science, Science Direct, and China Knowledge Resource Integrated (CNKI). Advances in the botanical, ethnomedicinal, phytochemical, and pharmacological studies of this genus are reviewed in this paper. Results showed that more than 440 compounds, including C21 steroids, steroidal saponins, alkaloids, flavonoids and terpene, have been isolated and identified from Cynanchum plants up to now. In vivo and in vitro studies have shown that plants possess an array of biological activities, including anti-tumor, neuroprotective and anti-fungal effects. Popular traditional prescription of Cynanchum sp. was also summed up in this paper. However, many Cynanchum species have received little or no attention. Moreover, few reports on the clinical use and toxic effects of Cynanchum sp. are available. Further attention should be focused on the study of these species to gather information on their respective toxicology data and relevant quality-control measures and clinical value of the crude extracts, active compounds, and bioactive metabolites from this genus. Further research on Cynanchum sp. should be conducted, and bioactivity-guided isolation strategies should be emphasized. In addition, systematic studies of the chemical composition of plants should be enhanced.

Synergistic silver/scandium catalysis for divergent synthesis of skeletally diverse chromene derivatives

The combination of AgTFA and Sc(OTf)₃ enables the bimetallic synergistic catalysis of β-alkynyl ketones and o-hydroxybenzyl alcohols, allowing divergent synthesis of three classes of skeletally diverse chromene derivatives with generally high diastereoselectivity through dehydroxylated bi- and tri-cyclization cascades.

Synthesis and X-Ray Crystal Structure of Cynandione B Analogues

The synthesis of analogues of cynandione B, a phenolic acetophenone from Cynanchum taiwanianum, is described. The one-step conversion of benzochromenones to the heptacyclic spiroacetal core of cynandione B using methylmagnesium bromide is investigated and structural requirements for this novel transformation established. X-ray crystal structure analysis has established the relative configuration in these unusual heterocycles.

Anti-inflammatory effects of Cynanchum taiwanianum rhizome aqueous extract in IL-1β-induced NRK-52E cells

CONTEXT

Cynanchum taiwanianum T. Yamaza (Asclepiadaceae) is a medicinal herb used in folk medicine for the treatment of several inflammation-related diseases such as hepatitis and dermatitis in Taiwan.

OBJECTIVE

In the present study, we investigated the anti-inflammatory effect of C. taiwanianum T. Yamaza rhizome aqueous extract (CTAE).

MATERIALS AND METHODS

The present study investigated the anti-inflammatory effect of CTAE using IL-1β-induced NRK-52E cells. Production of NO and PGE(2) by ELISA, the mRNA and protein expression of iNOS and COX-2, phosphorylation of IκBα, and activation of NF-κB by RT-PCR and western blotting were determined.

RESULTS

The CTAE significantly (P < 0.05) inhibited NO and PGE(2) production (decreased by 46.1% and 51%, respectively), and also significantly (P < 0.05) attenuated protein and mRNA expression of iNOS and COX-2 (decreased by 90% and 55% for iNOS and by 72% and 74%% for COX-2, respectively) in IL-1β-induced NRK-52E cells, in a dose-dependent manner, without obvious cytotoxic effects. Furthermore, the CTAE suppressed the NF-κB nuclear translocation, in terms of inhibition of IκBα phosphorylation.

DISCUSSION AND CONCLUSION

Our results provided evidence for its folkloric uses and suggest that the anti-inflammatory activities of CTAE may result from the inhibition of inflammatory mediators, such as NO and PGE(2), and an upstream suppression of a NF-κB-dependent mechanism, might be involved.

A Serendipitous Synthesis of the Novel Spiroacetal Core of Cynandione B

The novel spiroacetal core of cynandione B 2 is prepared from the isochromenone (S)-mellein 4 by treatment with methylmagnesium bromide. The expected lactol product undergoes spontaneous dimerization to form the spiroacetal system 8 as a single diastereoisomer, the stereochemistry of which is established from a single crystal X-ray structure analysis of a methanol solvate.