Chemical constituents isolated from Disporum viridescens leaves and their inhibitory effect on nitric oxide production in BV2 microglial cells

Excessive NO (nitric oxide) has been associated with the pathogenesis of various neurodegenerative diseases including Alzheimer’s disease (AD). In our screening system using LPS-activated BV2 microglial cells, the methanolic extract of Disporum viridescens leaves was found to have significant NO inhibitory activity. Bioactivity-guided isolation yielded a new phenylpropanoid characterized as 4-ally-2,6-dimethoxyphenyl 1-O-β-d-apiofuranosyl (1 → 6)-β-d-glucopyranoside (12) with 21 known compounds from the leaves of D. viridescens. Among them, compounds 2 and 4 significantly inhibited NO production. Thus, we further elucidated the anti-inflammatory mechanism of these lignans. Especially, compound 4 inhibited the expression of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) through the suppression of the MAPK signaling pathway. Taken together, the anti-inflammatory activities of the active constituents isolated from D. viridescens leaves could have therapeutic potential against neurodegenerative diseases.     

Lignan glycosides from the Rhizomes of Smilax trinervula and their Biological activities

Phytochemical investigation of the rhizomes of Smilax trinervula led to isolation and structure elucidation of eight lignan glycosides, including five new lignans, namely, (7S, 8R, 8′R)-4, 4′, 9-trihydroxy-3, 3′, 5, 5′-tetramethoxy-7, 9′-epoxylignan-7′-one 4′-O-β-d-glucopyranoside (1), (7S, 8R, 8′R)-4, 4′, 9-trihydroxy-3, 3′, 5, 5′-tetramethoxy-7, 9′-epoxylignan-7′-one 4-O-β-d- glucopyranoside (2) (7S, 8R)-4, 9, 9′-trihydroxy-3, 3′, 5-trimethoxy-4′, 7-epoxy-8, 5′-neolignan 9′-O-β-d-glucopyranoside (3), (7R, 8R)-4, 9, 9′-trihydroxy-3, 5-dimethoxy-7.O.4′, 8.O.3′- neolignan 9′-O-β-d-glucopyranoside (4), and (7S, 8R)-4, 9, 9′-trihydroxy-3, 3′, 5-trimethoxy-8, 4′-oxy-neolignan 4-O-β-d-glucopyranoside (5), along with three known compounds (6-8). Their structures were established mainly on the basis of 1D and 2D NMR spectral data, ESI–MS and comparison with the literature. Compounds 1-8 were tested in vitro for their cytotoxic activity against four human tumor cell lines (SH-SY5Y, SGC-7901, HCT-116, Lovo). Compounds 3 and 5 exhibited cytotoxic activity against Lovo cells, with IC₅₀ value of 10.4 μM and 8.5 μM, respectively.     

Hypoglycemic effects of the wood of Taxus yunnanensis on streptozotocin-induced diabetic rats and its active components

Hypoglycemic effects of the H(2)O and MeOH extracts of the wood of Taxus yunnanensis were examined in streptozotocin (STZ)-induced diabetic rats. The H(2)O extract significantly lowered the fasting blood glucose level by 33.7% at a 100mg/kg dose on intraperitoneal administration. From the active H(2)O extract of the wood, three lignans, i.e., isotaxiresinol (1), secoisolariciresinol (2) and taxiresinol (3), were isolated as major components. These lignans were further tested for their hypoglycemic effects on the same experimental model. At a dose of 100mg/kg (i.p.), isotaxiresinol (1) reduced the fasting blood glucose level of diabetic rats by 34.5%, while secoisolariciresinol (2) and taxiresinol (3) reduced by 33.4% and 20.9%, respectively. The blood glucose lowering effects of 1 and 2 were stronger than the mixture of tolbutamide (200mg/kg) and buformin (1mg/kg) used as a positive control, which lowered fasting blood glucose level by 24.0%.     

New ellagitannin and galloyl esters of phenolic glycosides from sapwood of Quercus mongolica var. crispula (Japanese oak)

Two novel glycosides, 4,5-dimethoxy-3-hydroxyphenol 1-O-β-(6′-O-galloyl)-glucopyranoside (1) and (+)-2α-O-galloyl lyoniresinol 3α-O-β-d-xylopyranoside (2), as well as a novel ellagitannin named epiquisqualin B (3), were isolated from sapwood of Quercus mongolica var. crispula along with 19 known phenolic compounds. The structures of the novel compounds were elucidated on the basis of chemical and spectroscopic investigation. Compound 2 is the first example of a lignan galloyl ester, and 3 is the oxidation product of vescalagin, which is the major ellagitannin of this plant.     

亚麻籽木酚素预防乳腺癌的作用及机制研究

目的:探讨亚麻籽木酚素预防乳腺癌的作用及机制。方法:分别采用基础饲料(BD组)和添加亚麻籽木酚素的饲料(FS组)喂养大鼠两周后,通过二甲基苯蒽灌胃复制乳腺癌模型大鼠,连续观察并测定两组大鼠瘤体的体积和重量,采用免疫组织化学技术分别检测和比较两组大鼠乳腺癌组织中PCNA、Her-2、Ki-67的表达。结果:BD组大鼠乳腺癌的发生率及瘤体重量和体积均较FS组更高(P0.05)。FS组乳腺癌组织中Ki-67、Her-2、PCNA阳性表达率均较BD组显著降低(P0.010)。结论:亚麻籽木酚素可发挥预防乳腺癌的效应,该效用可能与其降低Ki-67、Her-2、PCNA的表达有关。     

鹿角蕨化学成分的研究

从鹿角蕨（Platycerium wallichii Hook.)的干燥叶中分离得到七个成分,利用UV、IR、^13C-NMR、^1H-NMR、MS等光谱方法鉴定出它们的结构,分别为β－谷甾醇（I）、谷甾醇β-D-吡喃葡萄糖苷（Ⅱ）、2－propenoic acid,3-[2,3-dihydro-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-5-benzofuramyl]-(Ⅲ）、松脂素（Ⅳ）、松脂素－4′－O－β－D－葡萄糖苷（Ⅴ）、2,5－二羟基苯甲酸甲酯（Ⅵ）、槲皮素3－O－β－吡喃半乳糖苷（Ⅶ）。七个成分均为首次从该种植物中获得。     

Syntheses of all eight stereoisomers of conidendrin

ABSTRACT

All eight stereoisomers of conidendrin were synthesized from (1 R,2 S,3 S)-1-(4-benzyloxy-3-methoxyphenyl)-3-(4-benzyloxy-3-methoxybenzyl)-2- hydroxymethyl-1,4-butanediol ((+)-4) and its enantiomer with high optical purity. The configurations at 4-positions of the conidendrin stereoisomers were constructed by intramolecular Friedel-Crafts reaction of protected 4. After conversion to tetrahydronaphthalene intermediate 7a, the 2- and 3-position of tetrahydronaphthalene structure 7a were converted to 3a- and 9a-position of (+)-α-conidendrin (3a), respectively. By the epimerization process of 2- or 3-position of 7a, the other diastereomers were obtained. All enantiomers were also synthesized from (?)-4.     

Two lignan dimers from bamboo stems (Phyllostachys edulis)

Phyllostadimers A and B, two bis-lignans in which the two lignan units are directly connected by a C-C bond, were isolated from stems of bamboo, Phyllostachys edulis. Their structures were determined on the basis of spectral evidence. In addition, 14 known compounds were also obtained throughout the investigation. Phyllostadimer A significantly inhibited liposomal lipid peroxidation.     

Constituents from the stems of Actinodaphne lancifolia

Two C(16)-lactonic compounds, actinolides A-B (1-2), were isolated from the stems of Actinodaphne lancifolia, together with five known lactones (3-7) and three known lignans (8-10). Their structures were determined spectroscopically, which included 2D NMR spectroscopic analysis.