Ya-Nan Yang

NMR Solution Structure Study of the Representative Component Hydroxysafflor Yellow A and Other Quinochalcone C-Glycosides from Carthamus tinctorius

Hydroxysafflor yellow A (HSYA), a representative component of Carthamus tinctorius, has attracted much attention because of its remarkable cardiovascular activities. Its structure was originally reported in 1993 and has been widely cited to date. In our experiments, its solution structure was studied using NMR techniques in different solvents, including DMSO-d(6), pyridine-d(5), and CD(3)OH. The results indicate that the structure of HSYA is different than the previously described 1b, with 3-enol-1,7-diketo form. The structure has two keto-enol tautomers (2a and 2b), and 2a, with the 1-enol-3,7-diketo form, is the preferred tautomer. On the basis of this finding, other published quinochalcone C-glycoside structures were revised. Furthermore, a trend in the (13)C NMR data of the (E)-olefinic carbons of quinochalcone C-glycosides is summarized, and a hypothesis is proposed for the relationship between the features of the molecular structure and the preferred keto-enol tautomer.

Hepatoprotective glycosides from Leonurus japonicus Houtt.

Two new phenylethanoid glycosides 1 and 2 named leonoside E and leonoside F, and one new sesquiterpene glycoside (3) identified as 7α (H)-eudesmane-4,11 (12)-diene-3-one-2β-hydroxy-13-β-d-glucopyranoside, together with seven known glycosides (4-10), were isolated from the aerial part of Leonurus japonicus Houtt. Their structures were elucidated on the basis of spectroscopic data and chemical evidence. When tested in in vitro assays, compounds 1, 2, 4, and 6 exhibited potent hepatoprotective activity against d-galactosamine-induced toxicity in HL-7702 cells at concentration of 1×10(-5) M.

New polyacetylene glucosides from the florets of Carthamus tinctorius and their weak anti-inflammatory activities

Eight new linear polyacetylene glucosides (1-8), containing two C(10)-, one C(13)- and five C(14)-acetylenes, together with three known polyacetylenes (9-11) were isolated from the florets of Carthamus tinctorius L. Their structures were elucidated by means of spectroscopic methods and chemical evidence. The absolute configurations of compounds 3-9 were confirmed by Snatzke and Gerardss method, observing the induced circular dichroism after addition of dirhodium tetrakis (trifluoroacetate) [Rh(2)(OCOCF(3))(4)] in CHCl(3). All the isolated compounds (1-11) were also tested for inhibitory activities against LPS-induced NO production in murine macrophages and just showed weak activities at concentrations of 1×10(-5)M.

Dibenzoyl and Isoflavonoid Glycosides from Sophora flavescens: Inhibition of the Cytotoxic Effect of d-Galactosamine on Human Hepatocyte HL-7702

Twelve new dibenzoyl derivatives sophodibenzoside A-L (1-12) and five new isoflavone glycosides (13-17) have been isolated from the roots of Sophora flavescens together with eight known compounds (18-25). Notably, the use of acetic acid-d4 was required to enable identification of the dibenzoyl glycoside structures. Compounds 1, 2, 13, 14, and 19 exhibited weak inhibition of the cytotoxic effect of d-galactosamine on the human hepatic cell line HL-7702.

Acyl glycosides with rare β-d-apiofuranosyl-β-d-glucopyranosyl-β-d-apiofuranosyl from Erycibe hainanesis

Three new acyl glycosides with rare β-D-apiofuranosyl-(1→2)-[β-D-apiofuranosyl-(1→6)]-β-D-glucopyranosyl moieties, 2-O-[2,6-O-bis(5-O-syringoyl-β-D-apiofuranosyl)-β-D-glucopyranosyl]-isopropyl alcohol (1), 1-O-[2,6-O-bis(5-O-syringoyl-β-D-apiofuranosyl)-β-D-glucopyranosyl]-isoamyl alcohol (2), and 1-O-[2,6-O-bis(5-O-vanilloyl-β-D-apiofuranosyl)-β-D-glucopyranosyl]-3,4,5-trimethoxyphenol (3) were obtained from Erycibe hainanesis. Their structures were determined by UV, IR, HRESIMS, (1)D and (2)D NMR data, and by chemical methods. Compounds 1-3 were evaluated against D-galactosamine induced toxicity in WB-F344 rat hepatic epithelial stem-like cells, and compounds 1 and 3 showed moderate hepatoprotective activities.

Bioactive Sesquiterpenoid and Polyacetylene Glycosides from Atractylodes lancea.

Nine new sesquiterpenoids (1-9), five new polyacetylenes (10-14), and six known compounds were isolated from the rhizomes of Atractylodes lancea. These new chemical structures were established using NMR, MS, and ECD data. Notably, compounds 3-5, the aglycone of which possesses two stereogenic centers (C-5 and C-7), exhibited similar ECD spectra to compounds 1 and 2, the aglycone of which possesses one stereogenic center (C-7). Such a difference was supported by the experimental and calculated ECD data and single-crystallographic analyses of 3a. In addition, compound 3 inhibited lipopolysaccharide-induced NO production in BV2 cells with an IC50 value of 11.39 μM (positive control curcumin, IC50 = 4.77 μM); compound 4 showed better hepatoprotective activity against N-acetyl-p-aminophenol-induced HepG2 cell injury than the positive drug (bicyclol) at a concentration of 10 μM (p < 0.001).

Polyflavanostilbene A, a New Flavanol-Fused Stilbene Glycoside from Polygonum cuspidatum

Polyflavanostilbene A, a new flavanol-fused stilbene glycoside, was isolated from the rhizome of Polygonum cuspidatum. Its unusual structure, including its absolute stereochemistry, was determined by UV, IR, HRESIMS, and 1D and 2D NMR data and by the comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Polyflavanostilbene A has an unprecedented rearranged flavanol skeleton fused to stilbene via a hexahydrocyclopenta[c]furan moiety. Polyflavanostilbene A showed strong inhibitory activity against α-glucosidase with an IC(50) value of 17.7 μM.

Bioactive Octahydroxylated C21 Steroids from the Root Bark of Lycium chinense.

Lyciumsterols A-K (1-11), 11 new octahydroxylated C21 steroids, were isolated from the root bark of Lycium chinense, along with 15 known compounds. Characterization of these C21 steroids showed the presence of eight hydroxy groups on the C21 steroid skeleton with a (2E,4E)-5-phenyl-2,4-pentadienoate group at C-12 or C-20 and various 2,6-deoxy sugar residues at C-3. The structures of these compounds were elucidated using spectroscopic data interpretation. Compounds 2, 3, and 7 exhibited dose-dependent protective effects on pancreatic islet cells and may help to improve cell viability. In addition, it was found that compounds 7, 8, 9, and 11 exhibited autophagy activation.

Forsythoneosides A–D, Neuroprotective Phenethanoid and Flavone Glycoside Heterodimers from the Fruits of Forsythia suspensa

Forsythoneosides A-D (1-4), four unusual adducts of a flavonoid unit fused to a phenylethanoid glycoside through a pyran ring or carbon-carbon bond, and four new phenylethanoid glycosides (5-8) were isolated from the fruits of Forsythia suspensa, together with nine known compounds. The structures of 1-8, including their absolute configurations, were elucidated by spectroscopic data as well as experimental and calculated electronic circular dichroism analysis. Compounds 2 and 4 inhibited PC12 cell damage induced by rotenone, and increased cell viability from 53.9 ± 7.1% to 70.1 ± 4.0% and 67.9 ± 5.2% at 0.1 μM, respectively.

Acyl glycosides lignans, coumarins, and terpenes from the stems of Erycibe obtusifolia

Nine new acyl glycosides, obtusifosides A-I (1-9), and eight known compounds have been isolated from an EtOH extract of the stems of Erycibe obtusifolia. Their structures were elucidated on the basis of a spectroscopic data analysis (NMR, HRESIMS, and CD) and chemical evidence. The hepatoprotective effects of some of the compounds from d-galactosamine-induced cytotoxicity in HL-7702 hepatic cells were evaluated. Compounds 1, 10, 11, 13, 16, and 17 showed significant hepatoprotective activities compared with the positive control bicyclol at concentrations of 1×10(-5)M.