Synthesis of eudistomin D analogues and its effects on adenosine receptors

Six analogues (1-6) of eudistomin D, a beta-carboline alkaloid from a marine tunicate Eudistoma olivaceum, were synthesized, and their affinity and selectivity for adenosine receptors A(1), A(2A), and A(3) were examined. All the synthetic compounds 1-6 did not show affinity to the adenosine A(1) receptor. Delta-carboline 3 exhibited the most potent affinity to the adenosine receptor A(3) among compounds 1-6. Delta-carbolines 3 and 4 showed better affinity than the corresponding beta-carbolines 1 and 2, respectively, while N-methylation (2, 4, and 6, respectively) of the pyrrole ring in 1, 3, and 5 resulted in the reduced affinity to the adenosine A(3) receptor. On the other hand, an eudistomin D derivative, BED, exhibited modest affinity to all the receptors A(1), A(2A), and A(3) but no selectivity.     

Synthesis of hybrid molecules of caffeine and eudistomin D and its effects on adenosine receptors

Four hybrid molecules (1 and 12-14) of caffeine and eudistomin D, a beta-carboline alkaloid from a marine tunicate, were synthesized, and their affinity and selectivity for adenosine receptors A(1), A(2A), and A(3) were examined. It was found that all the compounds showed better potency as adenosine receptor ligands as compared with caffeine. Among them, a compound (13) possessing a nitrogen at the delta-position of the pyridine ring (delta-N type) showed the most potent affinity for adenosine receptor A(3) subtype, while N-methylation (14) of a pyrrole ring in 13 significantly lowered the potency as adenosine receptor ligands. Compounds (1 and 12) having a nitrogen at the beta-position of the pyridine ring (beta-N type) showed lower affinity than the corresponding delta-N type compounds (13 and 14), while compounds (10, 11, and 17) lacking a pyrrole ring between the pyridine and pyrimidine rings exhibited almost no affinity to the adenosine receptor subtypes examined.     

Bioactive metabolites from the endophytic fungus Ampelomyces sp. isolated from the medicinal plant Urospermum picroides

Extracts of cultures grown in liquid or on solid rice media of the fungal endophyte Ampelomyces sp. isolated from the medicinal plant Urospermum picroides exhibited considerable cytotoxic activity when tested in vitro against L5178Y cells. Chromatographic separation yielded 14 natural products that were unequivocally identified based on their ¹H and ¹³C NMR as well as mass spectra and comparison with previously published data. Six compounds (2, 4, 5, 7, 9 and 11) were natural products. Both fungal extracts differed considerably in their secondary metabolites. The extract obtained from liquid cultures afforded a pyrone (2) and sulfated anthraquinones (7 and 9) along with the known compounds 1, 3, 6 and 8. When grown on solid rice medium the fungus yielded three compounds 4, 5 and 11 in addition to several known metabolites including 6, 8, 10, 12, 13 and 14. Compounds 4, 8 and 10 showed the strongest cytotoxic activity against L5178Y cells with EC₅₀ values ranging from 0.2–7.3 μg/ml. Furthermore, 8 and 10 displayed antimicrobial activity against the Gram-positive pathogens, Staphylococcus aureus, S. epidermidis and Enterococcus faecalis at minimal inhibitory concentrations (MIC) of 12.5 μg/ml and 12.5–25 μg/ml, respectively. Interestingly, 6 and 8 were also identified as constituents of an extract derived from a healthy plant sample of the host plant U. picroides thereby indicating that the production of bioactive natural products by the endophyte proceeds also under in situ conditions within the host plant.     

Inhibitory effects of 2-substituted-1-naphthol derivatives on cyclooxygenase I and II

Naphthol derivatives, 2-(3'-hydroxypropyl)-naphthalen-1-ol (2), 2-(3'-hydroxy-2'-methylpropyl)-naphthalen-1-ol (3) and 2-(3'-hydroxy-2',2'-dimethylpropyl)-naphthalen-1-ol (7) were synthesized and already reported by our group. Therefore in this paper we described further synthesis of their ether derivatives, 3-(1-methoxy-naphthalen-2-yl)-propan-1-ol (4), 3-(1-methoxy-naphthalen-2-yl)-2methyl-propan-1-ol (5), 3-(1-methoxy-naphthalen-2-yl)-2,2-dimethyl-propan-1-ol (8), 2-(3-methoxy-propyl)-naphthalen-1-ol (10) and 2-(3-methoxy-2,2-dimethyl-propyl)-naphthalen-1-ol (13). Compounds 4, 5 and 8 were prepared by methylation of compounds 2, 3 and 7, respectively while compounds 10 and 13 were prepared in good yield from naphthols 2 and 7, respectively. When tested for inhibitory activity, five compounds (2, 3, 7, 10 and 13) showed preferential inhibition of COX-2 over COX-1, while compounds 4, 5 and 8 lacked inhibitory effect on either the COX-1 or COX-2 isozyme. The structure-activity relationships of these naphthols analyzed by docking experiments, indicated that the presence of hydroxyl group at C-1 position on the naphthalene nucleus enhanced the anti-inflammatory activity towards COX-2 via hydrogen bonding to the COX-2 Val 523 side chain. When this hydroxyl group was replaced by methoxy group, there was no inhibition. C-2' Dimethyl substituents on the propyl chain also increased the inhibitory activity. All active compounds have the C-1 hydroxyl group aligned so as to form hydrogen bond with Val 523. The results provide a model for the binding of the naphthol derivatives to COX-2 and facilitate the design of more potent or selective analogs prior to synthesis.     

8-Amino-5-nitro-6-phenoxyquinolines: potential non-peptidic neuropeptide Y receptor ligands

The synthesis and pharmacological evaluation of analogues of PD 160170, a neuropeptide Y1 (NPY) receptor antagonist are reported. Phamacomodulation of this 8-amino-5-nitro-6-phenylsulfonylquinoline was carried out by replacing the sulfone moiety by oxygen. The corresponding ethers 11-16 were obtained by nucleophilic substitution of 8-acetamido-6-chloro-5-nitroquinoline 4 with phenols, followed by acidic hydrolysis of the intermediary amides 5-10. The test compounds 11-16 exerted no appreciable Y1 activity and they were also inactive in terms of Y5 receptor binding; their IC50 values were >1 microM and 10 microM, respectively. The dramatic decrease in potency resulting from replacement of the sulfone function by an ether was confirmed by IP administration of 16 to ob/ob mice; after a 4-day administration, no decrease in food consumption or weight was observed.     

水稻品种中抗褐飞虱抗原次生物质的分析

借助高效液相色谱(HPLC)技术,研究了130份对褐飞虱生物型Ⅱ具有不同抗性水平的水稻样品(26个品种)中13个次生物质含量(峰面积)的差异;运用主成分分析和多元回归分析,建立了水稻品种抗性级别的预测模型：Y=3．4593-0．02491X1+0．08475X2-0．04227X8+0．1174X12结果表明,水稻的抗性水平与峰面积值之间极显著相关(r^2=0．84,P<0．01),峰1、峰2、峰8、峰12对应的次生化合物是影响水稻对褐飞虱生物型Ⅱ抗性水平的主要抗原次生化合物;水稻品种中起抗虫作用的抗原次生物质不止一种,而是几种的组合,而且它们对水稻抗虫性的贡献权重是不完全相同的．     

Synthesis and antitubercular activities of bis-glycosylated diamino alcohols

Conjugate addition of diamines to glycosyl olefinic esters 1a and 1b followed by reduction of resulting bis-glycosyl beta-amino esters (2-7 and 14-19) with lithium aluminium hydride led to the respective glycosyl amino alcohols (8-13 and 20-25) in moderate to good yields. All the compounds were evaluated for antitubercular activity against Mycobacterium tuberculosis H(37)Ra and H(37)Rv. Few of the compounds exhibited antitubercular activity with MIC as low as 6.25-3.12microg/mL in virulent and avirulent strains. Compound 13 was found to be active against MDR strain and showed mild protection in mice.     

Synthesis, antiviral and cytostatic activities, of carbocyclic nucleosides incorporating a modified cyclopentane ring. IV. Adenosine and uridine analogues

Eight new carbocyclic nucleosides were prepared by mounting a purine (compounds 8-10), 8-azapurine (12 and 13) or pyrimidine (15, 16 and 17b) on the amino group of (1S,3R)-3-aminomethyl-2,2,3-trimethylcyclopentylmethanol (6). All the compounds were evaluated as antiviral and antitumor agents in a variety of assay systems. Only compound 8 showed any cytostatic activity against the tumor cell lines examined.     

半枝莲抗肝癌活性部位的化学成分研究

前期研究发现,半枝莲(Scutellaria barbata)全草醇提物的乙酸乙酯萃取部位经大孔吸附树脂处理,其70%乙醇洗脱部位具有较好的抗肝癌活性。为明确其活性成分,该研究采用硅胶柱色谱、Sephadex LH-20柱色谱、制备TLC、半制备液相色谱等对活性部位进行分离和纯化,运用多种波谱分析方法鉴定了单体化合物结构,并利用CCK-8法评价了所有单体化合物对人肝癌HepG2细胞体外增殖抑制活性,同时利用分子对接技术考察了活性最好的化合物与肝癌靶标的结合情况。结果表明:(1)从该活性部位共分离得到14个化合物,包括12个新克罗烷型二萜类化合物和2个黄酮类化合物,分别鉴定为scutefolide C(1)、6-乙酰氧基-7-烟酸酰氧基半枝莲碱G(2)、scutestrigillosin D(3)、 scutehenanine D(4)、半枝莲碱A(5)、半枝莲碱B(6)、7-烟酸酰氧基半枝莲碱H(7)、半枝莲碱N(8)、半枝莲碱Y(9)、barbatin A(10)、barbatin B(11)、barbatin D(12)、5, 7, 6''-三羟基-2''-甲氧基黄酮醇(13)和5, 8-二羟基-6, 7-二甲氧基黄酮(14)。其中,化合物1-3、13、14为首次从该植物中分离得到。(2)活性测试结果显示,化合物4、7、10-12表现出较弱的HepG2细胞增殖抑制活性,化合物6的细胞增殖抑制活性和阳性对照(顺铂)活性接近,而化合物5表现出比顺铂更强的细胞增殖抑制活性。(3)分子对接结果显示,化合物5和化合物6与肝癌靶蛋白VEGF-2均具有良好的结合力。该研究结果不仅丰富了半枝莲的化学物质类群,也为进一步深入研究活性化合物抗肝癌的作用机制提供了参考。     

Characterization of yakju brewed from glutinous rice and wild-type yeast strains isolated from nuruks

Korean traditional rice wines yakju and takju are generally brewed with nuruk as the source of the saccharogenic enzymes by natural fermentation. To improve the quality of Korean rice wine, the microorganisms in the nuruk need to be studied. The objective of this research was to improve the quality of Korean wine with the wild-type yeast strains isolated from the fermentation starter, nuruk. Only strain YA-6 showed high activity in 20% ethanol. Precipitation of Y89-5-3 was similar to that of very flocculent yeast (?80%) at 75.95%. Using 18S rRNA sequencing, all 10 strains were identified as Saccharomyces cerevisiae. Volatile compounds present in yakju were analyzed by gas chromatography-mass selective detector. The principal component analysis (PCA) of the volatile compounds grouped long-chain esters on the right side of the first principal component, PC1; these compounds were found in yakju that was made with strains YA-6, Y89-5-3, Y89-5- 2, Y90-9, and Y89-1-1. On the other side of PC1 were short-chain esters; these compounds were found in wines that were brewed with strains Y183-2, Y268-3, Y54-3, Y98-4, and Y88-4. Overall, the results indicated that using different wild-type yeast strains in the fermentation process significantly affects the chemical characteristics of the glutinous rice wine.     

Bioactive polyhydroxylated steroids from the Hainan soft coral Sinularia depressa Tixier-Durivault

Two new steroids, (2β,3β,4α,5α,8β)-4-methylergost-24(28)-ene-2,3,8-triol (1) and (3β,7α)-24-methyl-7-hydroperoxycholest-5,24(28)-diene-3-ol (2), together with 13 known analogues (3–15) were isolated from the soft coral Sinularia depressa Tixier-Durivault. The structures of the new compounds were elucidated by detailed spectroscopic analysis and comparison with reported data. In the bioassay in vitro, compounds 3a, 4, and 14 exhibited potent PTP1B inhibitory activity, being similar as that of positive control oleanolic acid. Compound 14 also displayed a notable neuroprotective activity against both amyloid-β_25–35- and serum deprivation-induced injuries in SH-SY5Y cells while compound 11 showed a considerable antibacterial activity against Staphylococcus aureus. Preliminary structure–activity relationships of these steroids were discussed.     

Anti-atherosclerotic and anti-inflammatory activities of catecholic xanthones and flavonoids isolated from Cudrania tricuspidata

The catecholic xanthones and flavonoids 1-13 were isolated from the root bark of Cudrania tricuspidata. Compounds 1 and 3-8 exhibited significant antioxidant activity against low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substance (TBARS) assay. Among them, prenylated flavonoids 10-12 showed an inhibitory effect on the NO production and iNOS expression in RAW264.7 cells. Also, compounds 1, 2, 5, 7, 9, and 11 preferentially inhibited hACAT-2 than hACAT-1, whereas compounds 3, 4, 6, and 8 showed a similar specificity against hACAT-1 and -2. However, flavonoids 10, 12, and 13 dominantly inhibited hACAT-2, not hACAT-1.     

Synthesis and Antiviral and Cytostatic Activities of Carbocyclic Nucleosides Incorporating a Modified Cyclopentane Ring. I: Guanosine Analogues

Abstract

Six new carbocyclic nucleosides were prepared by constructing a guanine (compounds 6, 8 and 10) or 8-azaguanine (compounds 7, 9 and 11) base on the amino group of (1R, cis)-3-(aminomethyl)-1,2,2-trimethylcyclopentylmethanol (2), and their activities against 13 viruses and 3 tumor cell lines were determined. Compounds 9, 10 and 11 showed activity against human immunodeficiency virus type 1 (HIV-1), and compound 11 also against vaccina virus, whereas compounds 6 and 7 showed some inhibition of tumor cell proliferation.     

Discovery of novel EGFR tyrosine kinase inhibitors by structure-based virtual screening

By using of structure-based virtual screening, 13 novel epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors were discovered from 197,116 compounds in the SPECS database here. Among them, 8 compounds significantly inhibited EGFR kinase activity with IC(50) values lower than 10 μM. 3-{[1-(3-Chloro-4-fluorophenyl)-3,5-dioxo-4-pyrazolidinylidene]methyl}phenyl 2-thiophenecarboxylate (13), particularly, was the most potent inhibitor possessing the IC(50) value of 3.5 μM. The docking studies also provide some useful information that the docking models of the 13 compounds are beneficial to find a new path for designing novel EGFR inhibitors.     

Prolyl endopeptidase inhibitors from Syzygium samarangense (Blume) Merr. & L. M. Perry

Compounds isolated from the hexane extract of the leaves of Syzygium samarangense (Blume) Merr. & L. M. Perry were tested for inhibitory activity against the following serine proteases: trypsin, thrombin and prolyl endopeptidase. The compounds were identified as an intractable mixture of alpha-carotene and beta-carotene (1), lupeol (2), betulin (3), epi-betulinic acid (4), 2',4'-dihydroxy-6'-methoxy-3'-methylchalcone (5), 2'-hydroxy-4',6'-dimethoxy-3'-methylchalcone (6), 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (7), 2',4'-dihydroxy-6'-methoxy-3'-methyldihydrochalcone (8) and 7-hydroxy-5-methoxy-6,8-dimethylflavanone (9). Hydrogenation of compounds 5, 6 and 7 yielded compound 8, 2'-hydroxy-4',6'-dimethoxy-3'-methyldihydrochalcone (10) and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethyldihydrochalcone (11), respectively. The hydrogenated products of compounds 6 and 7 were also tested for enzyme inhibitory activity. In addition, beta-sitosterol (12) and beta-D-sitosterylglucoside (13) were also isolated. This is the first report of the isolation of compounds 1-6, 8 and 13 from this plant. Compounds 3-8 and 10 exhibited significant and selective inhibition against prolyl endopeptidase among three serine proteases. This is the first report of this kind of activity for all these compounds.     

Microbiological transformation of two labdane diterpenes, the main constituents of Madia species, by two fungi

Microbial transformation of 13R,14R,15-trihydroxylabd-7-ene (5) and 13R,14R,15-trihydroxylabd-8(17)-ene (6) by the fungus Debaryomyces hansenii gave 1 (13R,14R,15-trihydroxy-6-oxolabd-8-ene) and 3 (7alpha,13R,14R,15-tetrahydroxy-labd-8(17)-ene), respectively. While, microbial transformation of 5 by Aspergillus niger afforded 2 (3beta,13R,14R,15-tetrahydroxy-labd-7-ene), and 13R,14R,15-trihydroxylabd-8,17-ene (6) gave 3 and 4 (3R,14R,15-3-oxotetrahydroxy-labd-7-ene). The structures of the new compounds, 1 and 2, were assigned by 1D and 2D high-field NMR spectroscopic methods. Antimicrobial activity of these compounds were tested and their MIC were determined.     

Synthesis and biological evaluation of some new A,B-ring modified steroidal D-lactones

Starting from the D-homo lactones of androst-4-en-3-one 3 and 4, prepared from 1 and 2, the new 17a homolactones 5-12, 14 and 15, were synthesized. The 4-hydroxy compounds 9 and 10 were obtained through the reaction of 4alpha,5alpha- (5 and 7) and 4beta,5beta- (6 and 8) epoxides with formic acid. The epoxides 5 and 6 were prepared from compound 3, and epoxides 7 and 8 from compound 4 by oxidation with H(2)O(2) under basic conditions. Compound 1 served as a starting substance for obtaining lactones 11-13. Oxidation of compound 1 with m-chloroperbenzoic acid yielded 11 and 12, but compound 13 gave 14. Compound 15 was obtained from 13 by oxidation with H(2)O(2) under basic conditions. The structures of epoxides 6 and 14 were confirmed by X-ray structural analysis. Cytotoxic activity against three tumor cell lines (human breast adenocarcinoma ER+, MCF-7, human breast adenocarcinoma ER-, MDA-MB-231, and prostate cancer PC3) was evaluated. Compounds 6 and 14 showed strong activity against PC3, the IC(50) being 10.6 and 2.2 microM, respectively, whereas compounds 3 and 8 showed strong activity against MDA-MB-231 (IC(50) is 9.3 and 3.6 microM, respectively). Aromatase inhibition assay showed that the tested compounds 9, 10, and 14 possess lower activity compared to formestane.     

Inhibition of yeast adenylate cyclase by antibodies to ras p21.

Monoclonal antibody Y13-259 to ras p21 was shown to bind to the highly conserved residues in the region 63-73 and to neutralize ras action in the Saccharomyces cerevisiae adenylate cyclase system. Inhibition of adenylate cyclase activity in isolated membranes by antibody Y13-259 occurred after a lag period of 6 min. This lag corresponded to the time necessary for binding of antibody Y13-259 to the membranes in a ras-dependent manner. The mechanism of inhibition appeared to be steric in nature because antibody Y13-259 neutralized ras p21 bound to a stable GTP analogue. Monoclonal antibodies Y13-4 and Y13-128 also inhibited yeast adenylate cyclase activity, and the epitopes for both the these antibodies were localized to ras region 65-75. However, the ras residues essential for binding of antibodies Y13-4 and Y13-128 to ras p21 (positions 65, 66, 68 and 75) were different from those essential for binding of antibody Y13-259 (positions 63, 65, 66, 67, 70 and 73). These results indicate that residues 63-75 constitute a major neutralizing epitope on ras p21.     

Antioxidant and cytotoxic flavonols from Calotropis procera

Phytochemical investigations of Calotropis procera leaves have led to the isolation of two new compounds: quercetagetin-6-methyl ether 3-O-beta-D-4C1-galacturonopyranoside (3) and (E)-3-(4-methoxyphenyl-2-O-beta-D-4C1 -glucopyranoside)-methyl propenoate (4), along with eleven known metabolites: nine flavonol and two cinnamic acid derivatives. All metabolites were isolated for the first time from the genus Calotropis, except for 1 isolated previously from Calotropis gigantea. The structures were determined by spectroscopic methods (UV, ESI-MS, 1H, 13C NMR, 1H-1H COSY, HSQC, and HMBC). The radical scavenging activity of the aqueous methanol extract and compounds 8-13 was measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Cytotoxic screening of the same compounds was carried out on brine shrimps as well.     

Selective cholinesterase inhibition by lanostane triterpenes from fruiting bodies of Ganoderma lucidum

Two new lanostane triterpenes, named methyl ganoderate A acetonide (1) and n-butyl ganoderate H (2), were isolated from the fruiting bodies of Ganoderma lucidum together with 16 known compounds (3-18). Extensive spectroscopic and chemical studies established the structures of these compounds as methyl 7β,15α-isopropylidenedioxy-3,11,23-trioxo-5α-lanost-8-en-26-oate (1) and n-butyl 12β-acetoxy-3β-hydroxy-7,11,15,23-tetraoxo-5α-lanost-8-en-26-oate (2). Because new compounds exhibiting specific anti-acetylcholinesterase activity are being sought as possible drug candidates for the treatment of Alzheimer's and related neurodegenerative diseases, compounds 1-18 were examined for their inhibitory activities against acetylcholinesterase and butyrylcholinesterase. All of the compounds exhibited moderate acetylcholinesterase-inhibitory activity, with IC(50) values ranging from 9.40 to 31.03μM. In contrast, none of the compounds except lucidadiol (13) and lucidenic acid N (14) exhibited butyrylcholinesterase-inhibitory activity at concentrations up to 200μM. These results indicate that these lanostane triterpenes are preferential inhibitors of acetylcholinesterase and may be suitable drug candidates.