莽草酸及其代谢产物在医药工业中的应用

莽草酸代谢途径是芳香族氨基酸合成过程中的一段共同代谢途径,广泛存在于植物和微生物中。莽草酸途径的代谢产物莽草酸、奎尼酸和没食子酸均含有多功能的六碳环状结构以及3个不对称的碳原子手性中心,可以在化学修饰下形成一系列具有潜在药理学活性的衍生物,广泛应用于医药工业。文章着重介绍莽草酸代谢途径的相关产物及其衍生物在抗病毒、抗肿瘤、抗菌、抗炎及抗血栓等方面的应用。     

利用重组大肠杆菌合成莽草酸的研究进展

莽草酸是芳香族氨基酸合成途径中的一种重要中间代谢产物。近年来,莽草酸作为临床上对抗禽流感的惟一有效药物达菲的合成前体而备受关注。通过改造大肠杆菌代谢通路使之能大量积累莽草酸是研究的热点之一。文章综述了莽草酸在重组大肠杆菌中生物合成的途径,并分析了莽草酸合成过程中的关键基因的改造及其对莽草酸积累的影响,最后还讨论了减少莽草酸产生菌培养过程中副产物产成的若干措施。     

莽草酸的研究现状

莽草酸（shikimic acid）,异名毒八角酸,它是可有效对付禽流感病毒和甲型H1N1流感病毒药物＂达菲＂的重要原料。莽草酸通过影响花生四烯酸代谢,抑制血小板聚集,抑制动、静脉血栓及脑血栓形成;其次,莽草酸具有有抗炎、镇痛作用;另外,莽草酸还可作为抗病毒和抗癌药物中间体。     

海洋源放线菌Streptomyces sp.SCSIO 10428中吩嗪生物碱类抗生素的分离鉴定

目的对从广西北海斜阳岛海域沉积物中分离的1株海洋源放线菌Streptomyces sp.SCSIO 10428进行次级代谢产物及活性研究。方法对海洋源放线菌Streptomyces sp.SCSIO 10428的发酵产物进行有机溶剂萃取,利用硅胶、凝胶柱层析等手段纯化次级代谢产物,通过波谱数据分析及文献比较对化合物进行结构鉴定,对化合物进行了抗菌、卤虫致死以及抗氧化活性评价。结果从海洋源放线菌Streptomyces sp.SCSIO10428发酵产物中分离得到3个生物碱类化合物,其结构分别鉴定为1-甲氧基吩嗪(1),1-羟基吩嗪(2),吩嗪-1-羧酸(3);活性结果显示化合物1~3对白色念珠...     

若干莽草酸衍生物的合成和生物活性研究

虽然对莽草酸(shikimic acid)的研究由来已久,但只是在陆续发现了具有生物活性的乙二醛酶Ⅰ抑制剂(glyoxalase Ⅰinhibitor 1)和二(口恶)霉素(dioxolamycin 2)等含莽草酸类母核的天然产物后,才有合成莽草酸衍生物进行生物活性研究的报道,即由莽草酸甲酯合成乙二醛酶Ⅰ抑制剂的类似物3。     

氯霉素生产的优化与遗传

氯霉素是由委瑞拉链霉菌产生的。氯霉素生物合成、调节和遗传已研究得相当详细。含乳酸、甘油和丝氨酸合成培养基生产氯霉素约150mg/升。加入芳香氨基酸能刺激氯霉素生产。即使乳酸代谢差,但它对于氯霉素生产是很需要的。大概培养基内乳酸使内源合成丙酮酸转向莽草酸途径。     

经Nrf2／ARE通路发挥化学防癌作用的天然化合物

消除各种内外源性致癌物对机体细胞和组织的侵害，是对癌症进行化学预防的有效方法，该过程与Ⅱ相代谢酶的作用有关，并主要受Nrf2／ARE通路调控。研究表明，某些天然化合物能通过Nrf2／ARE途径，诱导Ⅱ相代谢酶而发挥化学防癌作用。本文综述经上述途径发挥化学防癌作用的各种天然化合物。     

表观遗传修饰法增加真菌次级代谢产物化学多样性的应用

真菌次级代谢产物结构新颖、活性显著,是药物先导化合物的重要来源.然而,大量已知化合物的重复分离限制了传统真菌天然产物研究的快速发展.化学表观遗传修饰法是1种真菌代谢调控的简便、有效方法,其通过在培养基中添加化学表观遗传修饰剂激活真菌的沉默代谢途径获得隐蔽天然产物.本文综述了 2016年至2020年间采用化学表观遗传修饰...     

水栀子果实化学成分的研究

目的研究水栀子（Gardenia jasminoidesEllis f.logicarpa）果实中化学成分。方法利用不同的色谱技术进行分离纯化,根据化合物的光谱数据解析鉴定化合物的结构。结果分离鉴定了4个化合物,分别为琥珀酸（succinic acid）（Ⅰ）、芥子酸（sinapinic acid）（Ⅱ）、莽草酸（shikimic acid）（Ⅲ）及D-甘露醇（D-mannitol）（Ⅳ）。结论化合物Ⅰ～Ⅲ为首次从该属植物中分离得到,化合物Ⅳ为首次从该植物中分离得到。     

五环三萜羽扇豆烷型天然产物抗肿瘤活性研究进展

天然产物是抗肿瘤药物的重要来源。三萜化合物是植物体内重要的次生代谢产物,具有广泛的生物活性,其中五环三萜羽扇豆烷型天然产物对多种肿瘤细胞生长均表现出很强地抑制活性,同时由于毒性较低且作用机制独特,使其成为优秀的抗肿瘤先导化合物。近年来,针对羽扇豆烷型天然产物的抗肿瘤机制研究越发深入,对其结构进行衍生化从而提升活性、改善成药性的研究也越来越多。本文综述了五环三萜中白桦酸、23-羟基白桦酸、桦木醇和羽扇豆醇4个天然活性化合物的来源、抗肿瘤活性、作用机制及结构衍生化等方面国内外的研究进展。     

Chemosensitizer effect of cisplatin-treated bladder cancer cells by phenazine-5,10-dioxides

We determined the chemosensitizer effect of phenazine dioxide derivatives to cisplatin and the possible mechanism of action on bladder cancer cells. Anti-proliferative activity of nine phenazine dioxide derivatives in presence or absence of cisplatin was evaluated in two bladder tumor human cells T24 and 253 J and one non tumor cell line V79-4.The sensitizer effect of the combined treatment was determined by chromosomal aberrations and micronucleus test. A possible mechanism of action of the sensitizer compounds as HDACi was also investigated.The phenazine dioxide 2c combined with cisplatin induced a cell cycle arrest on bladder cancer cells and resensitize the invasive and cisplatin resistant 253 J cell line. The HDAC inhibitory activity appears as one of the mechanism of action of the compound. The low toxicity levels against normal cells point out the phenazine dioxide derivative 2c as a very good scaffold for further design of HDACi sensitizer agents.     

Multicomponent synthesis of poly-substituted benzo[a]pyrano[2,3-c]phenazine derivatives under microwave heating

A new one-pot two-step tandem synthesis of highly functionalized benzo[a]pyrano[2,3-c]phenazine derivatives via microwave-assisted multicomponent reactions of 2-hydroxynaphthalene-1,4-dione, diamines, aldehydes, and malononitrile is reported. The procedures are facile, avoiding time-consuming and costly syntheses, tedious workup, and purifications of precursors, as well as protection/deprotection of functional groups. The method is expected to find application in the combinatorial synthesis of biologically active compounds, since phenazine and chromene motifs have a broad spectrum of biological activities.     

Differential enzymatic reductions governing the differential hypoxia-selective cytotoxicities of phenazine 5,10-dioxides

Some derivatives of phenazine 5,10-dioxide are selectively toxic to hypoxic cells commonly found in solid tumors. Previous studies of the phenazine 5,10-dioxide mechanism of action indicated that a bioreduction process could be involved in its selective toxicities, maybe as result of its potential H(*)-releasing capability in hypoxia. The major unresolved aspect of the mechanism of phenazine 5,10-dioxides is the identity of the reductase(s) in the cell responsible for activating the drug to its toxic form and metabolites. We have studied the metabolism in both hypoxia and oxia of some selected 2-amino and 2-hydroxyphenazine 5,10-dioxides, 1- 5, using rat liver microsomal and cytosol fractions. Differential hypoxic/oxic metabolism was found to be correlated to a compound's cytotoxic selectivity but, in general, without metabolic differences between liver microsomal or cytosolic enzymes. Dicoumarol and ketoconazole were found to inhibit the hypoxic metabolism of the most selective phenazine 5,10-dioxide, 1, inferring a role for DT-diaphorase and cytochrome P450. The least hypoxic selective agents, 4 and 5, possess different hypoxia-metabolic profiles as compared to derivative 1, explaining the differential cytotoxic biological behavior. The nonselective derivative, 2, suffered bioreduction in both conditions and, according to the inhibition studies with dicoumarol and ketoconazole, involves both DT-diaphorase and cytochrome P450. The nontoxic derivative, 3, showed poor bioreductive behavior.     

Antitumoral effect of phenazine N5,N10-dioxide derivatives on Caco-2 cells

We studied the in vitro antitumoral effect of a series of phenazine di- N-oxide derivatives, named 2-chloroacetylamino-7(8)-nitrophenazine N(5), N(10)-dioxide (1), 2-amino-7(8)-(1,3-dioxol-2-yl)phenazine N(5), N(10)-dioxide (2), 2-chloroacetylamino-7(8)-(1,3-dioxol-2-yl)phenazine N(5), N(10)-dioxide (3), and 2-amino-7(8)-methoxyphenazine N(5), N(10)-dioxide (4), on Caco-2 cells. These phenazine N(5), N(10)-dioxide derivatives belong to our in-house chemical library. The products were selected according to their stereoelectronic characteristics and taking into account their differential cytotoxicity against V79 cells. Human colorectal adenocarcinoma cell line Caco-2 was used to study the cell growth inhibition capacity of these compounds, their capacity of altering the cell cycle and possible induction of apoptosis, DNA fragmentation, and genotoxic damage. The IC 50 after 24 h of incubation was lower for 1, 2, and 3 (4.8, 46.8, and 8.2 microM, respectively) than for 4 (474.7 microM). Compound 1 induced arrest in the G2/M phase at 24 and 48 h of treatment and apoptosis at the highest doses at 24 h of treatment. These facts were corroborated with caspase 3, caspase 9, and cytochrome c activation and DNA fragmentation at 24 h of treatment. The derivatives studied induced neither significant single strand breaks nor oxidative damage at the different studied times. We concluded that among the series of N(5), N(10)-dioxide phenazine derivatives analyzed, 1, which contains a nitro moiety and a chloroacetamide group, is the most promising as an antitumoral compound.     

Signal Transduction Events Elicited by Natural Products that Function as Cancer Chemopreventive Agents

Cancer chemoprevention is a rapidly emerging paradigm for slowing, stopping or reversing the carcinogenic process. A multiplicity of biological mechanisms, functioning as complex interactions of gene products and regulatory pathways, are stimulated or inhibited by cancer chemopreventive agents. Several natural products and dietary components have been shown to function as chemopreventive agents. Screening chemical libraries of natural products for properties associated with cancer chemoprevention provides important insight into structural motifs driving rational design of more effective agents. In this review, the signal transduction pathways that are modulated by chemopreventive natural products are summarized. The activation of several signal transduction pathways triggered by polyphenolic antioxidants, flavonoids, retinoids, phytoestrogens and isothiocyanates are illustrated. These natural products may disrupt many signaling pathways, including transduction of cell surface (epidermal growth factor) or nuclear (estrogen) receptors via inhibition of their associated tyrosine kinase activities that regulate mitogenic signaling cascades (e.g., c-Raf-1). Alternatively, cytoprotective signal transduction pathways may be activated in a concentration- and time-dependent manner. The consequences of the modulation of signal transduction pathways by administration of these cancer chemopreventive compounds, singly or in combination, are the inhibition of cell cycle activating cascades and induction of cell survival / protection genes. Understanding the activation of signal transduction events elicited by various drugs and chemicals may yield insights into the regulation of the expression of genes coordinating cell proliferation, death, as well as, drug metabolizing and other cytoprotective enzymes. Monitoring the activation or inhibition of these pathways may serve as endpoints for rapid screening of effective cancer chemopreventive agents.     

Endophenazines A-D,new phenazine antibiotics from the arthropod associated endosymbiont Streptomyces anulatus. I. Taxonomy,fermentation, isolation and biological activities

Four new members of the phenazine family, endophenazines A-D, and the already known phenazine-1-carboxylic acid (tubermycin B) were detected in the culture broth of various endosymbiotic Streptomyces anulatus strains by chemical screening in a combination of TLC-staining reagents and HPLC-diode array analysis. The endosymbiotic strains were isolated from four different arthropod hosts at various sites. The new phenazine compounds showed antimicrobial activities against Gram-positive bacteria and some filamentous fungi, and herbicidal activity against Lemna minor (duckweed).     

Structure-activity relationships for pyrido-, imidazo-, pyrazolo-, pyrazino-, and pyrrolophenazinecarboxamides as topoisomerase-targeted anticancer agents.

Heterocyclic phenazinecarboxamides were prepared by condensation of aminoheterocycles and 2-halo-3-nitrobenzoic acids, followed by reductive ring closure and amidation. They showed similar inhibition of paired cell lines that underexpressed topo II or overexpressed P-glycoprotein, indicating a non topo II mechanism of cytotoxicity and indifference to P-glycoprotein mediated multidrug resistance. Compounds with a fused five-membered heterocyclic ring were generally less potent than the pyrido[4,3-a]phenazines. A 4-methoxypyrido[4,3-a]phenazine (IC(50)s 2.5-26 nM) gave modest (ca. 5 day) growth delays in H69/P xenografts with oral dosing.     

Antitubercular 2,8-bis(alkylaminomethyl)phenazines

The preparation and antitubercular properties of a series of 2,8-bis(alkylaminomethyl)phenazines are described. These compounds all inhibited the growth of Mycobacterium smegmatis ATCC 607 in vitro. 2,8-Bis(dibutylaminomethyl)phenazine (5c) was also active against a lethal Mycobacterium tuberculosis H37Rv infection in mice.     

Potential chemopreventive agents based on the structure of the lead compound 2-bromo-1-hydroxyphenazine, isolated from Streptomyces species, strain CNS284

The isolation of 2-bromo-1-hydroxyphenazine from a marine Streptomyces species, strain CNS284, and its activity against NF-κB, suggested that a short and flexible route for the synthesis of this metabolite and a variety of phenazine analogues should be developed. Numerous phenazines were subsequently prepared and evaluated as inducers of quinone reductase 1 (QR1) and inhibitors of quinone reductase 2 (QR2), NF-κB, and inducible nitric oxide synthase (iNOS). Several of the active phenazine derivatives displayed IC?? values vs QR1 induction and QR2 inhibition in the nanomolar range, suggesting that they may find utility as cancer chemopreventive agents.     

Effects of N-heterocyclic polyaromatic hydrocarbons on survival, reproduction, and biochemical parameters in Daphnia magna

N-heterocyclic polycyclic aromatic hydrocarbons (N-PAHs) belong among newly identified classes of environmental pollutants with relatively high toxic potential. N-PAHs have been detected in air, soil, marine environments, and freshwater sediments. The N-PAHs are present at lower concentrations than their nonsubstituted analogues but their greater solubility would lead to greater bioavailibity and potential for toxic effects. Here we present results of acute and chronic toxicity in traditional aquatic invertebrate ecotoxicological model (Daphnia magna) along with assessment of biochemical responses. Studied biomarkers in D. magna exposed to N-heterocyclic derivatives included glutathione levels and activities of detoxication and antioxidative enzymes glutathione S-transferase and glutathione peroxidase. Phenanthrene and 1,10-phenathroline were the most toxic of all tested compounds (EC50 < 6 microM after 48 h exposure) and all tested N-PAHs suppressed reproduction of Daphnia magna. The data suggest that N-PAHs can induce oxidative stress in D. magna. The significant decline of glutathione content was found in animals treated with acridine, 1,10-phenanthroline, benzo(h)quinoline, phenantridine, and phenazine. Significant decrease of GPx activities relative to controls was found for all tested compounds except of phenanthrene and phenazine. Activities of GST increased after exposure to phenanthridine, phenazine, and benzo(h)quinoline, and declined in D. magna treated with phenanthrene (significant at one concentration) or anthracene (not significant). Our results confirmed significant acute as well as chronic toxicities of N-PAHs as well as potential of biochemical parameters to be used as early warning signals of toxicity in Daphnia magna.