Steroidal glycosides from Cynanchum forrestii Schlechter

Anticancer properties of caudatin and related C-21 steroidal glycosides from Cynanchum plants

Numerous C-21 steroidal glycosides have been isolated from Cynanchum plants. Many of them derive from the aglycone caudatin (CDT) which includes a tetracyclic deacylmetaplexigenin unit and an ikemaoyl ester side chain. CDT can be found in diverse traditional medicines, such as Baishouwu radix used to treat gastro-intestinal disorders. The compound has revealed marked anticancer properties, reviewed here. CDT and its mono-glycoside analogue CDMC display antiproliferative activities against different cancer cell lines in vitro and have revealed significant anticancer effects in tumor xenograft models in vivo. Their mechanism of action is multifactorial, implicating several signaling pathways (Wnt/GSK3/β-catenin, TRAIL/DR5/ER and TNFAIP1/NFκB) which contribute to the antiproliferative, antiangiogenic, antimetastatic and proapoptotic effects of the natural products. CDT also modulates DNA replication, is antioxidant and targets some cancer stem cells. CDT and CDMC are interesting anticancer products, while other CDT glycoside derivatives display antiviral and antifungal activities. Altogether, the present review provides a survey of the pharmacological profiles of CDT and derivatives. The lack of knowledge about the molecular targets of CDT currently limits drug development but the natural product, orally active, warrants further pharmacology and toxicology studies.

Two new C21 steroidal glycosides isolated from Cynanchum komarovii

The present study was designed to further investigate the C₂₁ steroidal glycosides in Cynanchum plants. Two new steroidal glycosides based on a 13, 14:14, 15-disecopregnane-type aglycone, komaroside P (1) and komaroside Q (2), together with three known compounds (3-5) were isolated from the whole herbs of Cynanchum komarovii. The aglycones of compounds 1 and 2 were two new disecopregnane. Their structures were elucidated on the basis of 1D, 2D NMR spectroscopic data and acid hydrolysis. All the compounds (1-5) showed potent inhibitory activities against human leukemia cell lines (HL-60) with IC₅₀ values ranging from 16.6 to 26.3 μmol·L^-1, compared to the positive control 5-fluorouracil (6.4 μmol·L^-1).

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.

14,15-Secopregnane-type C21-steriosides from the roots of Cynanchum stauntonii

Nine 14,15-secopregnane-type C₂₁-steriosides, stauntosides U, V, V₁-V₃, W and C₁-C₃, as well as two known C₂₁-steriosides, were isolated from the roots of Cynanchum stauntonii. Stauntosides U, V and V₁-V₃ share the same basic structural features of 8α:14α,14:16,15:20,18:20-tetraepoxy-14,15-secopregn-6-ene-3β,5α,9α-triol, with the numbering system following that of C₂₁-pregnanes. The aglycones of stauntosides U, V and V₁-V₃ are classified into two subcategories, the 5,9-dihydroxy groups and 5α:9α-peroxy bridge, according to the oxidative states of the two hydroxy groups at the C-5 and C-9 positions. The anti-inflammatory activity of the major compounds was assessed in an in vitro inflammatory model of mouse peritoneal macrophages using IC₅₀ values of the inhibition of nitric oxide (NO) production as an indicator. Stauntosides V₁ and V₃ exhibited target activity with IC₅₀ values of 9.3 μM and 12.4 μM, respectively, compared with dexamethasone, which was used as a positive control.

Sixteen novel C-21 steroidal glycosides from the roots of Cynanchum mooreanum

Fourteen novel 14,15-diseco-18-nor-pregnane-type steroidal glycosides, mooreanoside A-C (1-3) and mooreanoside F-P (6-16) and two new 14,15-diseco-pregnane-type steroidal glycosides, mooreanoside D-E (4-5) were isolated from the roots of Cynanchum mooreanum Hemsl. Their structures were determined on the basis of spectroscopic and chemical analysis. Compounds 1-6, 8-10, 12-14 and 16 were tested for their immunological activities in vitro against Con-A induced proliferation of mice splenocytes.

Seco-pregnane steroidal glycosides from the roots of Cynanchum atratum and their anti-TMV activity

Fifteen new seco-pregnane steroidal glycosides cynanosides A-O (1-15) together with twenty-seven known ones were isolated from the roots of Cynanchum atratum. The structures of 1-15 were determined by extensive analysis of spectroscopic data. The anti-tobacco mosaic virus (TMV) activity of these steroidal glycosides was screened by the conventional half-leaf method, enzyme-linked immunosorbent assay, and Western blot methods, most of them showed potent anti-TMV activity. Among them, compounds 1, 7, 13, 28 and 31 showed significantly anti-TMV activity with an IC50 value of 20.5, 18.6, 22.0, 19.2 and 22.2 μg/mL, respectively, and were much more effective than the positive control, ningnanmycin (IC50=49.6 μg/mL).

Twelve pregnane glycosides from Cynanchum atratum

Eleven new 14,15-seco-pregnane-type steroidal glycosides, cynanosides P1-P5, Q1-Q3, R1-R3, and a novel 12,13-seco-14,18-nor-pregnane-type steroidal glycoside, cynanoside S, were isolated from the roots of Cynanchum atratum, together with four known compounds, atratoside C, sublanceoside E3, chekiangensoside C and cynatroside B. Their structures were determined on the basis of spectroscopic analysis and chemical evidence.

Steroidal glycosides from the roots of Cynanchum amplexicaule Sieb. et Zucc

Seven new steroidal glycosides (amplexicosides A (4), B (7), C (8), D (9), E (10), F (11), and G (12)), along with six known compounds (cynatratoside A (1), tylophoside A (2), cynatratoside B (3), glaucogenin A (5), glaucoside A (6), and hancoside A (13)) were isolated from the 95% ethanol extract of the roots of Cynanchum amplexicaule (Sieb. et Zucc.). Their structures were determined based on spectral and chemical evidence. Compound 12 has a 14, 15-secopregnane-type skeleton aglycone, which has not been reported in literature.

Eight new C-21 steroidal glycosides from Dregea sinensis var. corrugata

Eight new steroidal glycosides, dresiosides were isolated from the stems of Dregea sinensis var. corrugate and their structures were deduced on the basis of chemical and spectral evidence. The sugar units of dresiosides were determined as deoxysugars after hydrolysis and isolation from natural glycosides. The absolute configurations of deoxysugars were determined as D on the basis of their optical rotation values in comparison with appropriate standards.

Seven new steroidal glycosides from the roots of Cynanchum forrestii

Seven new steroidal glycosides, cynaforrosides K (1), L (2), M (3), N (4), and Q (7), based on a 13,14:14,15-disecopregnane-type aglycone, and cynaforrosides O (5) and P (6) with a 14,15-secopregnane-type aglycone, were isolated from the 95% ethanol extract of the roots of Cynanchum forrestii Schlechter. The structures of new compounds were determined on the basis of spectroscopic and chemical evidence. The sugar units of cynaforrosides K-P contained two moieties of glucoses with the mode of 1-->4 linkage and those of cynaforrosides K-O contained six moieties of sugars.