Guo-Cai Wang

Phenolic compounds from Origanum vulgare and their antioxidant and antiviral activities

In the present study, six new phenolic compounds (1-6) along with five known ones were isolated from the ethanol extract of the whole plants of Origanum vulgare. The structures of the new compounds were identified on the basis of extensive spectroscopic analyses (UV, IR, NMR, and HRESIMS) and acid hydrolysis. Twenty-one phenolic compounds isolated from O. vulgare in our previous and present studies were evaluated for their in vitro antioxidant activity using 2,2-diphenyl-1-picryhydrazyl (DPPH) radical-scavenging and ferric-reducing antioxidant power (FRAP) assays; twelve of them including two new compounds exhibited significant antioxidant activity comparable to that of ascorbic acid. In addition, the antiviral effects against respiratory syncytial virus (RSV), Coxsackie virus B3 (CVB3) and herpes simplex virus type 1 (HSV-1) were tested by cytopathic effect (CPE) reduction assay.

Flueggines A and B, Two New Dimeric Indolizidine Alkaloids from Flueggea virosa

Two unprecedented C,C-linked dimeric indolizidine alkaloids, flueggines A (1) and B (2), were isolated from the twigs and leaves of Flueggea virosa. The structures and absolute configurations were elucidated by means of NMR, single-crystal X-ray diffraction, and CD analyses. Compound 1 is the first example of Securinega alkaloids bearing an isoxazolidine ring, the plausible biogenetic pathway of which is also proposed. Compound 2 exhibited growth inhibitory activity against MCF-7 and MDA-MB-231 human breast cancer cells.

Clerodane diterpenoids from Croton crassifolius.

Seven new clerodane diterpenoids (1-7) were isolated from roots of Croton crassifolius, along with six known compounds. The structures were elucidated by extensive spectroscopic methods (IR, UV, HRESIMS, 1D NMR, and 2D NMR), and the structures of 1, 3, 4, and 7 were confirmed by single-crystal X-ray diffraction analyses. Compounds 1-13 were evaluated for in vitro antiviral activity against herpes simplex virus type 1 using the cytopathic effect reduction assay.

Cytotoxic dimeric indole alkaloids from Catharanthus roseus

Three new dimeric indole alkaloids (1-3), together with five known ones (4-8), were isolated from the whole plants of Catharanthus roseus. The structures and absolute configurations of new compounds were elucidated by means of NMR and CD analyses. All these compounds were evaluated for their in vitro cytotoxic activities against human breast cancer cell line MDA-MB-231.

Diterpenoids from the roots of Croton crassifolius and their anti-angiogenic activity

Six diterpenoids [crassifolin J, K, L, M, N and O] along with eleven known ones were isolated from the supercritical fluid extract (SFE) of the roots of Croton crassifolius (Euphorbiaceae). Their structures were elucidated using spectroscopic methods (IR, UV, HRESIMS, 1D and 2D NMR). The structure and stereochemistry of crassifolin J was confirmed by single-crystal X-ray diffraction analysis, and the absolute configurations of crassifolin K-M were determined by CD spectra. Twenty-three diterpenoids from this plant were screened for their anti-angiogenic activity using a wild-type zebrafish in vivo model. Four of the known compounds were active, of which penduliflaworosin possessed the best activity relative to the positive control (SU5416). Further study demonstrated that penduliflaworosin could inhibit vessel formation on Tg(fli1a:EGFP)y1-type zebrafish embryos.

Five new phenolic glycosides from Hedyotis scandens.

Five new phenolic glycosides, hedyotosides A-E (1-5), including a new cyanogenic glycoside (1), along with 10 known compounds (6-15) were isolated from the whole plants of Hedyotis scandens. The structures of compounds 1-5 were established by extensive spectroscopic analyses and acid hydrolysis. All the isolated compounds were evaluated for their in vitro antiviral activity against respiratory syncytial virus (RSV) with cytopathic effect (CPE) reduction assay. Compounds 6 and 15 showed anti-RSV effects with IC(50) values of 20 and 25 μg/mL, respectively.

Potent anti-angiogenic component in Croton crassifolius and its mechanism of action

ETHNOPHARMACOLOGICAL RELEVANCE The root of Croton crassifolius Geisel is traditionally used in China for the treatment of snake bites, stomach ache, sternalgia, joint pain, pharyngitis, jaundice and rheumatoid arthritis, while in Thailand, it has been used as an anticancer herbal medicine by the indigenous people. Yet, its pharmacological studies are still limited, especially towards its anticancer property. Anti-angiogenesis is a promising therapeutic strategy in the anti-cancer treatment. Previous studies have shown strong anti-angiogenic activity in the low polar fraction of the herb. Nevertheless, the potent compound which is responsible for the anti-angiogenesis, and its molecular mechanism have never been reported. AIM OF THE STUDY To determine the potent anti-angiogenic component in C. crassifolius and its molecular mechanism of action. MATERIALS AND METHODS C. crassifolius was extracted using supercritical fluid extraction and steam distillation. The anti-angiogenic activities of the two extracts were evaluated in the zebrafish model by quantitative endogenous alkaline phosphatase assay. The chemical compounds in the active extract were isolated using chromatographic methods, and their structures were elucidated using different spectroscopic techniques. The content/quantity of the active compounds in this extract was determined with HPLC analysis. The molecular mechanism of the most active compound was further studied using the real-time PCR assay. Besides, its cytotoxicity on various cancer and normal cell lines was evaluated using the cell-counting kit. RESULTS Supercritical fluid extract (SFE) of C. crassifolius showed better anti-angiogenic activity than that of steam distillation extract (SDE). Three sesquiterpenes, namely, cyperenoic acid, 8-hydroxy-α-guaiene and (+)-guaia-l(10),ll-dien-9-one, were isolated and identified in the SFE. Among them, cyperenoic acid displayed the strongest anti-angiogenic activity by 51.7% of the control at 10μM, while the others showed little effect. HPLC results showed that cyperenoic acid was the major component in the SFE with 9.97% (w/w). Results of the real-time PCR assay suggested that the cyperenoic acid affected multiple molecular targets related to angiogenesis including vascular endothelial growth factor (Vegfa), angpiopoietin (Angpt), and their receptors. Cytotoxicity assay showed cyperenoic acid possessed little toxicity toward cancer and normal cells. CONCLUSIONS Cyperenoic acid is an important anti-angiogenic component present in C. crassifolius and serve as a potent inhibitor in the angiogenesis in the zebrafish embryo model. The anti-angiogenic property, but not the cytotoxicity, of C. crassifolius provides a scientific basis for its traditional use in cancer treatment.

New steroidal saponins and sterol glycosides from Paris polyphylla var. yunnanensis.

Four new steroidal saponins, pariposides A-D (1-4), and two new sterol glycosides, pariposides E-F (5-6), along with eight known steroidal saponins (7-14), two known sterol glycosides (15-16), and two known ecdysteroids (17-18), were isolated from the roots of Paris polyphylla var. yunnanensis. Among them, compounds 1-4 are the first spirostanol saponins with a peroxy group located between C-5 and C-8 of the aglycone. Their structures were determined by detailed spectroscopic analyses and chemical methods. All the isolated compounds were evaluated for their in vitro cytotoxicities against human nasopharyngeal carcinoma epithelial (CNE) cells, and steroidal saponins 7, 11, 13, and 14 showed a potent antiproliferative effect on CNE cells with IC₅₀ values of 9.2, 4.7, 11.1, and 2.7 µM, respectively.

Triterpenoid saponins from rhizomes of Paris polyphylla var. yunnanensis.

Phytochemical investigation of the rhizomes of Paris polyphylla var. yunnanensis resulted in the isolation of six new oleanane-type triterpenoid saponins, paritrisides A-F (1-6), along with nine known triterpenoid saponins (7-15). The structures of the new compounds were elucidated on the basis of spectroscopic analysis and acid hydrolysis. All the triterpenoid saponins are obtained for the first time from the genus Paris. The isolated compounds were assayed for their cytotoxic activities against human nasopharyngeal carcinoma epithelial (CNE) cells, and compounds 7, 8, and 10 exhibited inhibitory effects on CNE cell growth with IC50 values of 16.53, 16.77, and 12.69 μm, respectively.

Three new glycosides from Hylocereus undatus

Three new glycosides, undatusides A–C (1–3), and 11 known compounds (4–14) were isolated from the flowers of Hylocereus undatus. Their structures were elucidated on the basis of spectroscopic data and chemical method.