海绵来源链霉菌S52-B中氨酰胺天然产物的分离与鉴定

【背景】海洋微生物是复杂海洋生态环境中重要的生物资源之一。海洋微生物所产生的活性天然产物极为丰富,是药物或药物先导化合物的重要来源。【目的】探索海洋中海绵来源链霉菌Streptomycessp.S52-B的优势生长条件,挖掘其次级代谢产物,以期分离具有良好生物活性的天然产物。【方法】根据"One Strain Many Compounds"(OSMAC)策略,寻找利于Streptomyces sp. S52-B生长和次级代谢产物产生的优势培养基,结合质谱及特征性的紫外吸收谱图,选择培养基进行大量发酵。利用正相硅胶柱色谱、葡聚糖凝胶柱色谱和制备型高效液相色谱等进行分离纯化,并应用高分辨质谱和核磁共振光谱进行化合物结构解析。【结果】确定培养基A–D为海洋链霉菌S52-B的优势培养基,基于紫外吸收光谱与质谱分析,从培养基A的大量发酵物中分离鉴定3个具有吡咯并[4,3,2-de]喹啉核心结构的含氯化合物,属于氨酰胺类天然产物,其中Ammosalic acid为新结构化合物。【结论】已知含有吡咯并喹啉母核的氨酰胺类家族化合物具有优良的抗癌活性。本研究从海绵来源链霉菌S52-B中分离鉴定了3个氨酰胺类化合物,其中一个是新结构化合物,不仅丰富了此类化合物家族的结构类型,也为研究其生物合成途径中的未知机理奠定了基础,还有利于结合培养条件和基因组信息从这株海绵来源链霉菌中挖掘新结构的活性天然产物。     

Physiological activities and the active constituents of potentially medicinal plants used by wild chimpanzees of the Mahale mountains,Tanzania

Potential medicinal plants for wild chimpanzees have been studied in order to discover their physiologically active compounds. Tests of the physiological activity of 3 plant species—Vernonia amygdalina, Aspilia mossambicensis, andFicus exasperata—indicate that they contain a variety of active compounds. From one species,V. amygdalina, an antitumor agent and 2 possible antitumor promoters are identified. Furthermore, steroid glucosides were isolated as the bitter substances. These structurally new compounds are expected to exhibit a number of significant physiological activities. The chemical investigation of possible medicinal plants used by chimpanzees should be helpful in recovering naturally occurring compounds of medicinal significance for human use.     

Microbial functionalization of (–)-ambroxide by filamentous fungi

Abstract

Biocatalysis is a very useful tool for organic chemists to functionalize organic compounds under working conditions milder than chemical ones. This methodology has special significance since it can be an easy way to introduce a functional group in a non-reactive carbon, regio- and stereoselectively. In order to look for new compounds with antioxidant activity we report the transformation of the natural substrate (–)-ambroxide using the enzyme potential of pure strains of the filamentous fungi Alternaria alternata and Cunninghamella sp., following a protocol with growing cell cultures, which produced the new compound 1β-hydroxyambroxide and the previously known compound 3β-hydroxyambroxide. After purification their structures were elucidated by spectroscopic methods. These two metabolites are the products of oxidation of ring A of the starting material, without evidence of other compounds with different functionalization. Both compounds were tested for their activity as free radical scavengers in vitro, using the assay of DPPH (1,1-diphenyl-2-picrylhydrazyl) radical trapping. The results demonstrated that hydroxylation of carbons C-1 and C-3 of (–)-ambroxide with β stereochemistry had no effect on biological activity as an antioxidant compared with the starting material and a reference substance.     

Enzymatic assays and molecular modeling studies of Schisandra chinensis lignans and phenolics from fruit and leaf extracts

Abstract

Considerable interest has been shown in natural sources and their compounds in developing new therapeutically agents for different diseases. In this framework, investigations performed on this topic play a central role for human health and drug development process. Schisandra chinensis (Turcz.) Baill is a medicinal and edible plant showing highly advantageous bioactivity and nutritional value. The main bioactive compounds from its fruits are lignans, derivatives of dibenzocyclooctadiene whereas concerning its leaves, phenolic acids, and flavonoids are dominant. The purpose of this study was to investigate the enzyme inhibitory potential on selected carbohydrate hydrolases, cholinesterases, and tyrosinase of extracts from fruits and leaves of Schisandra in relation with their main bioactive compounds. Furthermore, the interactions between dominant compounds (schisandrol A, schisandrol B, schisandrin B, and cinnamic acid) from extracts and selected enzymes were investigated by molecular modeling and molecular dynamic studies in order to explain at a molecular level our findings.     

Microwave-assisted synthesis of antimicrobial agents based on pyridazine moiety

An efficient and simple microwave assisted synthesis of sulfonamide derivatives incorporating the pyridazine moiety has been developed. These sulfonamides were used for the preparation of new heterocyclic compounds via reaction with different reagents using a microwave irradiation technique. The structures of the newly synthesized compounds were confirmed on the basis of FTIR, ¹H and ¹³C-NMR, mass spectral techniques and elemental analyses. Some of the new synthesized compounds were assayed for their in vitro antibacterial activity against Gram-positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis, Gram-negative bacteria, Escherichia coli and Klebsiella pneumonia and antifungal activity against Aspergillus fumigatus and Candida albicans. Most of the new compounds showed significant antibacterial and antifungal activity.     

Design,synthesis and evaluation of 3-(imidazol- 1-ylmethyl)indoles as antileishmanial agents. Part II

A new series of 1-benzyl-3-(imidazol-1-ylmethyl)indoles were synthesized according to a previous 3D-QSAR predictive model and assayed for their antiparasitic activity upon Leishmania mexicana promastigotes. The biological results obtained for these twelve molecules showed an IC₅₀ ranging from 2.3 to 32 μM and mainly illustrated the importance of the hydrophobic parameter the para-position of the benzyl group. In order to improve the activities of these compounds and to check the potential influence of the electronic parameter on this particular position, a Craig diagram was used to select original electro-donating and lipophilic substituents. Synthesis and biological evaluation of ten new compounds (IC₅₀ between 2.5 and 5.4 μM) confirmed that only the hydrophobic field is essential for a high level of activity.     

Electroantennogram responses to plant volatiles in two species of Pieris butterflies

Electroantennogram (EAG) responses were recorded from females of two related butterfly species, Pieris brassicae L. and P. rapae L. (Lepidoptera: Pieridae) to 23 volatiles of plant origin, 19 of which have been reported to occur in the headspace of their preferred host plants, Brassica and Sinapis species (Cruciferae). In both species, selective responses were observed and the most effective compounds were the 6-carbon fatty acid derivatives trans-hex-2-enal, hexan-1-ol and hexanal, which are common green leaf volatiles. Of the 6 isoprenoids tested, myrcene and geraniol were most effective. Of the 4 crucifer-specific compounds tested, phenylacetonitrile was a distinctly stronger stimulant than the three isothiocyanates in both species. The rank order of mean stimulating effectiveness of all compounds tested was strongly correlated between the two species. Statistical analysis of dose-response relationships for 6 compounds revealed significant differences between compounds. The rank order of effectiveness changed with dose. Exclusive exposure to Sinapis arvensis during larval life and young adulthood resulted in quantitative changes in EAG responses to several compounds in both species, although the overall rank order of effectiveness was strongly correlated between the groups reared on the two host plants.     

Water-Soluble Constituents of Cudrania tricuspidata （Carr.） Bur.

In order to find new structural and biologically active compounds, the constituents of the bark of Cudrania tricuspidata （Carr.） Bur. were investigated and a new 6-p-hydroxybenzyltaxifolin glucoside, named tricusposide （compound 1）, together with 16 known compounds, was isolated by solvent partition, macroporous adsorption resin AB-8, silica gel, Sephadex LH-20 chromatography. Using spectroscopic methods, the structures of the compounds were elucidated as 6-p-hydroxybenzyl taxifolin-7-O-β-D-glucoside （compound 1）, dihydroquerctin-7-O-β-D-glucoside （compound 2）, dihydrokaempferol-3-O-β-D-glucoside （compound 3）, dihydroquercetin （compound 4）, peonoside （compound 5）, sphaerobioside （compound 6）, quercimeritrin （compound 7）, genistein （compound 8）, aromadendrin （compound 9）, kaempferol （compound 10）, genistin （compound 11）, 3,4-dihydroxystyryl alcohol （compound 12）, sucrose （compound 13）, 1,3,5,6-tetrahydroxyxanthone （compound 14）, gericudranin E （compound 15）, gericudranin C （compound 16）, and orobol （compound 17）. Compounds 2-6, 8, 9, 12-14, and 17 were isolated from this genus for the first time.     

Virtual screening,docking, and dynamics of potential new inhibitors of dihydrofolate reductase from Yersinia pestis

In the present work, we propose to design drugs that target the enzyme dihydrofolate redutase (DHFR) as a means of a novel drug therapy against plague. Potential inhibitors of DHFR from Yersinia pestis (YpDHFR) were selected by virtual screening and subjected to docking, molecular dynamics (MD) simulations, and Poisson–Boltzmann surface area method, in order to evaluate their interactions in the active sites of YpDHFR and human DHFR (HssDHFR). The results suggested selectivity for three compounds that were further used to propose the structures of six new potential selective inhibitors for YpDHFR.     

Analysis of Bacillus anthracis nucleoside hydrolase via in silico docking with inhibitors and molecular dynamics simulation

As the enzyme nucleoside hydrolase (NH) is widely found in nature but has not yet been detected in mammals, it is considered an ideal target in the development of chemotherapy against parasitic diseases and bacterial infections like anthrax. Considering the risk that this biological warfare agent represents nowadays, the search for new drugs and new molecular targets in the development of chemotherapy against anthrax is imperative. On this basis, we performed docking studies of six known NH inhibitors at the active site of NH from Bacillus anthracis (BaNH). Subsequently, molecular dynamics (MD) simulations of these compounds inside BaNH were carried out in order to complement the docking studies and select the most promising compounds as leads for the design of potential BaNH inhibitors. Most of the docking and MD results obtained agreed well with each other and showed good correlation with experimental data.     

Nucleophilic substitution at C-2 of S-alkylated 2-thiocytidines by cysteine and lysine : A new method for specific covalent linking of peptides to nucleic acids

S-Alkylated 2-thiocytidine can be substituted at C-2 by nucleophilic agents. This reaction has been investigated with model compounds as well as with tRNA using the amino acids cysteine and lysine in order to develop a new affinity label linking covalently tRNA and a protein. Reaction with N-protected cysteine gives 2-S-alkyl-pyrimidines, while unprotected cysteine yields an N-alkyl-pyrimidine, after intramolecular substitution. With the -amino group of lysine a fast replacement at C-2 is observed, leading to an unstable 2-N-alkyl-pyrimidine. All products have been characterized both chemically and spectroscopically.     

Chemical ecology of oribatid mites III. Chemical composition of oil gland exudates from two oribatid mites, Trhypochthoniellus sp. and Trhypochthonius japonicus (Acari: Trhypochthoniidae)

The composition of oil gland exudates from two oribatid mites, Trhypochthoniellus sp. and Trhypochthonius japonicus, was studied with reference to the related species Trhypochthoniellus crassus. Trhypochthoniellus sp. contained a mixture of seven compounds; (Z,Z)-6,9-heptadecadiene, geranial, 3-hydroxybenzene-1,2-dicarbaldehyde (γ-acaridial), neryl formate, neral, (Z)-8-heptadecene and geranyl formate in decreasing order of abundance. The profile of the components from T. japonicus consisted of two types depending on the locality of sampling with unknown reason; one possessing a mixture of eight compounds [(Z,E)-farnesal, γ-acaridial, (Z,Z)-6,9-heptadecadiene, (E,E)-farnesal, (Z)-8-heptadecene and geranial in decreasing order] together with two unknown compounds, and the other composed of the same set of compounds together with 2-hydroxy-6-methylbenzaldehyde as the most abundant component. Relative abundance among common components was consistent between the two types of T. japonicus. Profiles of components differed among three species including T. crasus. The phylogenetic relationship between Oribatida and Astigmata was discussed based on secretory compounds commonly distributed between these two suborders. This revised version was published online in July 2006 with corrections to the Cover Date.     

Anti-tumor-initiating effects of phenolic compounds isolated from the bark of Picea jezoensis var. jezoensis

We have previously reported the isolation of nine phenolic compounds including three new flavonostilbenes, jezonocinols A, B, and C, from the MeOH extract of the bark of Picea jezoensis var. jezoensis. Further investigation of the MeOH extract led to the isolation of three new stilbene-type compounds and one new 1,4-benzodioxane-type compound, together with seven known phenolic compounds. These compounds were tested for their inhibitory effects on the activation of (±)-(E)-methyl-2-[(E)-hydroxy-imino]-5-nitro-6-methoxy-3-hexemide (NOR 1), a nitric oxide (NO) donor, as a primary screening test for anti-tumor initiators. All compounds tested exhibited potent inhibitory effects on NOR 1 activation. Furthermore, jezonocinol B, the most potent inhibitor of NOR 1 activation, showed remarkable anti-tumor-initiating activity in the in vivo two-stage mouse skin carcinogenesis test using peroxynitrite (ONOO⁻; PN) as the initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as the promoter.     

Synthesis,structure, antimycobacterial and anticancer evaluation of new pyrrolo-phenanthroline derivatives

A study concerning design, synthesis, structure and in vitro antimycobacterial and anticancer evaluation of new fused derivatives with pyrrolo[2,1-c][4,7]phenanthroline skeleton is described. The strategy adopted for synthesis involves a [3?+?2] dipolar cycloaddition of several in situ generated 4,7-phenanthrolin-4-ium ylides to different substituted alkynes and alkenes. Stereo- and regiochemistry of cycloaddition reactions were discussed. The structure of the new compounds was proven unambiguously, single-crystal X-ray diffraction studies including. The antimycobacterial and anticancer activity of a selection of new synthesized compounds was evaluated against Mycobacterium tuberculosis H37Rv under aerobic conditions and 60 human tumour cell line panel, respectively. Five of the tested compounds possess a moderate antimycobacterial activity, while two of the compounds have a significant antitumor activity against renal cancer and breast cancer.     

Ammonium‐Charged Sterically Hindered Phenols with Antioxidant and Selective Anti‐Gram‐Positive Bacterial Activity

The increase in the resistance of pathogens, in particular Staphylococcus aureus, to the action of antibiotics necessitates the search for new readily available and non‐toxic drugs. In solving this problem, phenolic acylhydrazones have high potential. In this communication, the synthesis of quaternary ammonium compounds containing a differently substituted phenolic moiety has been performed. An initial study of antimicrobial activity showed that these compounds are highly selective against S. aureus and B. cereus. The highest activity (MIC 2.0 μm ) was shown by hydrazones containing a catechol fragment. These compounds are more than 3‐fold more active against S. aureus and 3–10‐fold more active against B. cereus than norfloxacin. Low hemolytic and high antioxidant activities of all new compounds were also established.     

Activity of Fluorinated Curcuminoids against Leishmania major and Toxoplasma gondii Parasites

A new 3,4-difluorobenzylidene analog of curcumin, CDF, was recently reported, which demonstrated significantly enhanced bioavailability and in vivo anticancer activity compared with curcumin. For highlighting the antiparasitic behavior of CDF, we tested this compound together with its new O-methylated analog MeCDF against Leishmania major and Toxoplasma gondii parasites. Both CDF and MeCDF were tested in vitro against L. major and T. gondii. In addition, the in vitro cytotoxicity against Vero cells and macrophages was determined and selectivity indices were calculated. The DPPH radical scavenging activity assay was carried out in order to determine the antioxidant activity of the test compounds. Both compounds showed high activities against both parasite forms with EC₅₀ values in the (sub-)micromolar range (0.35 to 0.8 μM for CDF, 0.31 to 1.2 μM for MeCDF). The higher activity of CDF against L. major amastigotes when compared with MeCDF can in parts be attributed to the antioxidant activity of CDF while MeCDF lacking any antioxidant activity was more active than CDF against T. gondii parasites. In conclusion, CDF and MeCDF are promising antiparasitic drug candidates due to their high activities against L. major and T. gondii parasites.     

Diterpenoids and Flavonoids from the Twigs of Cephalotaxus fortunei var. alpina

Three new diterpenoids (a cephalotane, an abietane and a 9(10→20)‐abeo‐abietane) and one new flavonoid, together with 11 known compounds, were isolated from the twigs of Cephalotaxus fortunei var. alpina. The new compounds were identified by comprehensive spectroscopic (including 1D and 2D‐NMR and HR‐ESI‐MS) analysis. Anti‐inflammatory, immunosuppressive and cytotoxic activities of three new compounds were evaluated. 3β,20‐epoxyabieta‐8,11,13‐triene‐3α,12‐diol showed weak cytotoxicity against tumor cell lines NCI?H1975, HepG2, MCF‐7, while fortalpinoid R and 3‐acetonyl‐3,5,7,4′‐tetrahydroxy‐2‐methoxyflavanone were not active at 80 μM. None of these compounds showed anti‐inflammatory and immunosuppressive activities.     

New semicarbazones as gorge-spanning ligands of acetylcholinesterase and potential new drugs against Alzheimer’s disease: Synthesis,molecular modeling,NMR, and biological evaluation

Two new compounds (E)-2-(5,7-dibromo-3,3-dimethyl-3,4-dihydroacridin-1(2H)-ylidene)hydrazinecarbothiomide (3) and (E)-2-(5,7-dibromo-3,3-dimethyl-3,4-dhihydroacridin-1(2H)-ylidene)hydrazinecarboxamide (4) were synthesized and evaluated for their anticholinesterase activities. In vitro tests performed by NMR and Ellman’s tests, pointed to a mixed kinetic mechanism for the inhibition of acetylcholinesterase (AChE). This result was corroborated through further docking and molecular dynamics studies, suggesting that the new compounds can work as gorge-spanning ligands by interacting with two different binding sites inside AChE. Also, in silico toxicity evaluation suggested that these new compounds can be less toxic than tacrine.     

Screening for anticoagulant activity in marine algae from the Northwest Mexican Pacific coast

Disorders in blood coagulation can lead to an increased risk of bleeding (hemorrhage) or clotting (thrombosis). These illnesses have increased over the last decades and no useful new substances have been discovered to remediate them. In search of new compounds from marine natural resources, macroalgae from the Northwest Mexican Pacific coast were investigated in order to detect anticoagulant activity. Egregia menziesii, Ulva neumatoidea, Porphyra perforata, Silvetia compressa, and Codium fragile were collected from Ensenada coasts. Collected materials were cleaned, dried, milled, and stored until use. Proximate chemical composition and sulfate content were determined in dried powder. Hot and cold aqueous extracts were obtained from the dried algae in order to isolate polysaccharides and similar compounds. Methanol-soluble compounds were separated by means of Soxhlet extraction. Organic and aqueous extracts were screened for anticoagulant activity in both intrinsic and extrinsic pathways of clot formation. Clotting activity was studied by standardized plasma coagulation tests (activated partial thromboplastin time (aPTT) and prothrombin time (PT)). Heparin, a sulfated glycosaminoglycan widely used in anticoagulant therapy, was used as reference. Effects were defined either as aPTT index (Sample aPTT/Control aPTT ratio) or PT index (Sample PT/Control PT ratio). Some of the fractions showed anticoagulant activity over intrinsic pathways, whereas they were found to be coagulants on the extrinsic pathway. The highest aPTT index was 1.8 for U. nematoidea (1 μg mL⁻¹). Hot aqueous extracts from E. menziesii (1 μg mL⁻¹) showed the highest potency, with an aPTT index of 1.4. Sulfate content and anticoagulant activity were not correlated.