New coumarins from Pterocaulon virgatum (L.) DC

Three new coumarins, 5-hydroxy-6,7-methylenedioxycoumarin, 5-(2-hydroxy-3-methoxy-3-methylbutoxy)-6,7-methylenedioxycoumarin and 5-(2-hydroxy-3-methyl-3-butenyloxy)coumarin, were isolated from the petrol ether extract of the aerial parts of Pterocaulon virgatum. Their structures were elucidated based on spectroscopic evidence.     

Flemiphyllin,an isoflavone from stems of Flemingia macrophylla

A new isoflavone, designated flemiphyllin, was isolated from a petrol extract of the stems of Flemingia macrophylla. Its structure was established as 5,7,4′-trihydroxy-3′,5′,8-tri(3-methylbut-2-enyl) isoflavone on the basis of physical and chemical evidence.     

Lignans of Piper clusii

From the petrol extract of Piper clusii five lignans were isolated. One of the lignans (?)-clusin is assigned the structure (?)-2-furanol-4(1,3-benzodioxol-5-ylmethyl) tetrahydro-3(3,4,5-trimethoxyphenyl) methyl. This is the first report of this compound from a natural source. Asaronaldehyde and sitosterol were also present.     

6,7,4'-Trihydroxyisoflavan: a potent and selective inhibitor of 5-lipoxygenase in human and porcine peripheral blood leukocytes

The effect of 6,7,4'-trihydroxyisoflavan on human platelet 12-lipoxygenase and human and porcine PMNL 5-lipoxygenase activities has been studied. 6,7,4'-Trihydroxyisoflavan was found to inhibit 5-lipoxygenase more strongly than 12-lipoxygenase; its concentration for 50% inhibition (IC50) was 1.6 microM for human and porcine 5-lipoxygenase and 22 microM for human platelet 12-lipoxygenase. Inhibition of microsomal cyclooxygenase from ram seminal vesicles is exhibited at much higher concentrations of 6,7,4'-trihydroxyisoflavan (IC50 = 200 microM).     

Siderone,a diterpene from Sideritis syriaca

Siderone, a new keto-diterpene, has been isolated from the petrol extract of the inflorescence of Sideritis syriaca. Its structure and stereochemis     

Isocrotocaudin,A new norclerodane-type diterpene from Croton caudatus

Isocrotocaudin, a new furanoid norditerpene (norclerodane type), has been isolated from the petrol extract of the stem-bark of Croton caudatus (Eup     

A new alkamide from Piper sylvaticum

Sylvamide, a new amide derivative, has been isolated from the petrol extract of the seeds of Piper sylvaticum (Roxb.). From spectral and chemical s     

Inhibition of lipoxygenase activity and HL60 leukemic cell proliferation by ursolic acid isolated from heather flowers (Calluna vulgaris).

A compound was isolated and purified from heather flowers (Calluna vulgaris) based on its ability to inhibit lipoxygenase activity. This molecule was characterized as ursolic acid by GC-MS. Ursolic acid was found to be an inhibitor of both potato tuber 5-lipoxygenase and soybean 15-lipoxygenase with IC50 values of 0.3 mM. Ursolic acid also inhibits lipoxygenase activity in mouse peritoneal macrophages at 1 microM and HL60 leukemic cells growth (IC50 = 0.85 microM) as well as their DNA synthesis (IC50 = 1 microM). The possible role of lipoxygenase inhibition in the proliferation of leukemic cells is discussed.     

Studies on the Chemical Constituents of Arnebia guttata Bunge

Four naphthoquinones were isolated from the petrol ether extract of the root of Arnebia guttata Bunge. They were identified as deoxyshikonin, acetylshikonin, shikonin, and β-hydroxyisovalerylshikonin by IR, HPLC, NMR, etc.     

虎耳草石油醚提取物的化学成分分析

目的:对虎耳草微波辅助-石油醚提取物的化学成分进行研究。方法:采用气相色谱-质谱-数据系统联用技术对虎耳草微波辅助-石油醚提取物的化学成分进行分析鉴定。结果:石油醚提取物共鉴定出102种成分。结论:采用气相色谱-质谱-数据系统联用技术能够对低极性部位的化学成分快捷、简便、准确分析。     

Translocation of HL-60 cell 5-lipoxygenase. Inhibition of A23187- or N-formyl-methionyl-leucyl-phenylalanine-induced translocation by indole and quinoline leukotriene synthesis inhibitors.

We have demonstrated translocation of HL-60 cell 5-lipoxygenase to a membrane compartment in response to both the calcium ionophore A23187 and the receptor-mediated stimulus, N-formyl-methionyl-leucyl-phenylalanine (fMLP). In addition, we have shown inhibition of A23187- and fMLP-induced 5-lipoxygenase translocation by an indole and a quinoline leukotriene synthesis inhibitor, MK-886 and L-674,573, respectively. Selectivity of inhibition of 5-lipoxygenase translocation in both fMLP- or A23187-challenged cells is shown using the indole L-583,916 and quinoline L-671,480, which neither inhibit leukotriene synthesis nor inhibit 5-lipoxygenase translocation. The present study in HL-60 cells is the first demonstration of the selective inhibition of 5-lipoxygenase translocation by quinoline leukotriene synthesis inhibitors, exemplified by L-674,573. Also described here is the first demonstration of 5-lipoxygenase translocation and inhibition in response to a stimulus other than A23187, namely the receptor-mediated stimulus, fMLP.     

Effect of tocopherol and tocopherol quinone complexes with proteins on activity of leukotriene B4 lipoxygenase

While estimating the effect of tocopherol, tocopherylquinone and their complexes with the tocopherol-binding proteins from the rat liver cytosole on arachidonate 5-lipoxygenase from peritoneal-lymphocytes and soybean linoleate-5-lipoxygenase alpha-tocopherol and especially its complex with tocopherol-binding protein was defined to inhibit the activity of both vegetative- and animal nature-lipoxygenase.     

Effects of tenuiorin and methyl orsellinate from the lichen Peltigera leucophlebia on 5-/15-lipoxygenases and proliferation of malignant cell lines in vitro.

The orcinol derivatives tenuiorin (1) and methyl orsellinate (2) were identified as active components of an extract from the lichen Peltigera leucophlebia (Nyl.) Gyeln. showing in vitro inhibitory activity against 15-lipoxygenase from soybeans. The compounds were subsequently tested for in vitro activity against 5-lipoxygenase from porcine leucocytes and proved to be moderately active, with IC50 values of 41.6 microM and 59.6 microM respectively. Tenuiorin is a known constituent of several Peltigera species but has not previously been isolated from P. leucophlebia. As correlation between 5-lipoxygenase inhibition and antiproliferative effects has earlier been witnessed for related lichen metabolites, tenuiorin and methyl orsellinate were further tested for antiproliferative activity on cultured human breast (T-47D)-, pancreatic (PANC-1)- and colon (WIDR) cancer cell lines. The monomeric methyl orsellinate exhibited no detectable antiproliferative activity whereas the trimeric tenuiorin caused moderate/weak reduction in [3H]-thymidine uptake of the pancreatic- and colon cancer cells, with ED50 values of 87.9 and 98.3 microM respectively.     

Arachidonate 15-lipoxygenase from human eosinophil-enriched leukocytes: partial purification and properties

Arachidonate 15-lipoxygenase was purified from human eosinophil-enriched leukocytes after showing that 15-lipoxygenase activity was 100-fold greater in eosinophils than in neutrophils. Partial purification was achieved using ammonium sulfate precipitation, cation-exchange and hydrophobic-interaction chromatography. New evidence is presented suggesting that 15-lipoxygenase has electrostatic and hydrophobic properties distinct from 5-lipoxygenase. In addition, ATP is shown to inhibit, and phosphatidylcholine is shown to stimulate, 15-lipoxygenase, suggesting a regulatory role for these compounds in the lipoxygenation of arachidonic acid.     

Characterization of monoclonal antibodies against human leukocyte 5-lipoxygenase

Four mouse monoclonal IgG1 antibody-producing cell lines (5LO-1, 5LO-2, 5LO-3, 5LO-4), produced against highly purified human leukocyte 5-lipoxygenase have been characterized. The monoclonal antibodies produced by these cell lines exhibited differential reactivity against 5-lipoxygenase as determined by ELISA and immunoprecipitation analyses. Monoclonal antibodies 5LO-2 and 5LO-3 inhibited the activity of recombinant human leukocyte 5-lipoxygenase in a dose-dependent manner. This inhibition was selective for 5-lipoxygenase activity since these monoclonal antibodies did not inhibit human leukocyte 15-lipoxygenase or porcine leukocyte 12-lipoxygenase.     

Hydroalcoholic plant extracts with anti-inflammatory activity

The aim of the present study was to investigate if standardized hydroalcoholic plant extracts such as Calendula officinalis, Hypericum perforatum, Plantago lanceolata and Glycyrrhiza glabra can suppress in cell-free systems the activities of 5-lipoxygenase (5-LO) and cyclooxygenase-2 (COX-2), key enzymes in the formation of proinflammatory eicosanoids from arachidonic acid (AA). Studies were undertaken to compare the above mentioned plant extracts to a known NSAID (nimesulide) in their ability to inhibit both cyclooxygenase (COX-2) and lipoxygenase (5-LO) activities in cell-free systems. We report on 2 vegetal extracts (Hypericum perforatum and Glycyrrhiza glabra) that inhibit 5-LO activity and 2 vegetal extracts (Plantago lanceolata and Glycyrrhiza glabra) that inhibit COX-2 activity. In this study, we demonstrate for the first time that Glycyrrhiza glabra extract efficiently suppresses both eicosanoids and leukotrienes formation in cell-free systems, implying that this extract directly acts as a dual inhibitor of 5-LO and COX-2 activities. With regard to the properties of dual COX-2/5-LO inhibitors, Glycyrrhiza glabra extract might be a potential drug possessing anti-inflammatory activity devoid of the most troublesome (gastric) side effects seen for drugs used as COX-2 and 5-LO inhibitors. Hypericum perforatum, Plantago lanceolata and Glycyrrhiza glabra extracts can be added to an already impressive list of these species that have anti-inflammatory activity.     

(−)-3β-Acetoxydrimenin from the leaves of Drimys winteri

A new natural product, 3β-acetoxydrimenin was isolated from the petrol extract of the leaves of Drimys winteri which also contains the known compounds safrol, drimenol and polygodial. The structure of the new compound was determined by chemical and spectroscopic methods.     

6,7,4′-trihydroxyisoflavan: A potent and selective inhibitor of 5-lipoxygenase in human and porcine peripheral blood leukocytes

The effect of 6,74′-trihydroxyisoflavan on human platelet 12-lipoxygenase and human and porcine PMNL 5-lipoxygenase activities has been studied. 6,7,4′-Trihydroxyisoflavan was found to inhibit 5-lipoxygenase more strongly than 12-lipoxygenase; its concentration for 50% inhibition (IC₅₀) was 1.6 μm for human and porcine 5-lipoxygenase adn 22 μM for human platelet 12-lipoxygenase. Inhibition of microsomal cyclooxygenase from ram seminal vesicles is exhibited at much higher concentrations of 6,7,4′-trihydroxyisoflavan (IC₅₀ = 200 μM).     

Inhibition of mammalian 5-lipoxygenase by 2-benzylaminophenols

A number of 2-benzylaminophenols, prepared from the corresponding 2-aminophenols by reductive alkylation, have been identified as highly potent inhibitors of 5-lipoxygenase with IC50 values in the nanomolar range. Most compounds were also shown to inhibit the release of the peptidoleukotrienes when administered intraperitoneally in a rat model of peritoneal anaphylaxis. Two compounds evaluated for their effects on anaphylactic contractions in isolated human lung were shown to attenuate the leukotriene-induced component of the response.     

Triacylbenzenes and long-chain volatile ketones from Cochlospermum tinctorium rhizome

The composition of the volatile fraction from Cochlospermum tinctorium rhizome was investigated by GC and GC-MS; among 11 constituents detected, eight were identified as straight chain ketonic compounds. In addition, five triacylbenzenes were isolated from a petrol extract of the rhizome, separated by HPLC and identified by their spectral data.