Antifouling activity of a dibrominated cyclopeptide from the marine sponge Geodia barretti

Many sessile suspension-feeding marine organisms rely on chemical defense to keep their surfaces free from fouling organisms. The brominated cyclopeptides barettin (cyclo[(6-bromo-8-entryptophan)arginine]) ( 1) and 8,9-dihydrobarettin (cyclo[(6-bromotryptophan)arginine]) ( 2) from the cold-water sponge Geodia barretti have previously displayed settlement inhibition of barnacle larvae in a dose-dependent manner. In this paper, we describe a novel dibrominated cyclopeptide, bromobenzisoxazolone barettin (cyclo[(6-bromo-8-(6-bromobenzioxazol-3(1 H)-one)-8-hydroxy)tryptophan)]arginine) ( 3), which we have isolated from G. barretti and which displays settlement inhibition of barnacle larvae ( Balanus improvisus) with an EC 50 value of 15 nM. The chemical structure was determined using MS and 2D-NMR.     

Antifouling activity of brominated cyclopeptides from the marine sponge Geodia barretti

In this work, we show the potent antifouling effects of two compounds, barettin (cyclo[(6-bromo-8-entryptophan)arginine]) (1), isolated as a Z/E mixture (87/13), and 8,9-dihydrobarettin (cyclo[(6-bromotryptophan)arginine]) (2), isolated from the marine sponge Geodia barretti. The compounds were isolated guided by their ability to inhibit the settlement of cyprid larvae of the barnacle Balanusimprovisus, and their structures were determined by means of mass spectrometry, NMR, and quantitative amino acid analysis. The activities of these brominated diketopiperazine-like cyclic dipeptides are in the range of antifouling agents in use today, as shown by their EC(50) values of 0.9 and 7.9 microM, respectively. However, contrary to today's antifouling agents, the effects of barettin and 8,9-dihydrobarettin are nontoxic and reversible. A small set of synthetic analogues, including l-arginine, l-tryptophan, 5-bromo-d,l-tryptophan, 6-bromo-d,l-tryptophan, and 6-fluoro-d,l-tryptophan, were tested for possible structure-activity relationships. None of these compounds showed any effect at a concentration of 10 microM. We hypothesize that the isolated compounds are part of the sponge's chemical defense to deter fouling organisms. This theory is supported by the fact that barettin is found in water exposed to living specimens of G. barretti in concentrations that completely inhibit barnacles from settling.     

Mode of action of peppermint oil and (-)-menthol with respect to 5-HT3 receptor subtypes: binding studies, cation uptake by receptor channels and contraction of isolated rat ileum

Peppermint oil (Mentha × piperita L. (Lamiaceae) has been shown to exert potent antiemetic properties, but its mode of action has not yet been elucidated. Among its active constituents (-)-menthol is the most important. Three different in vitro models were used to investigate the effects on 5-HT(3) receptors (serotonin receptor subtype): [(14)C]guanidinium influx into N1E-115 cells which express 5-HT(3) receptors, isotonic contractions of the isolated rat ileum and equilibrium competition binding studies using a radioactively labelled 5-HT(3) receptor antagonist ([(3)H]GR65630) (3-(5-methyl-1H-imidazol-4-yl)-1-(1-methyl-1H-indol-3-yl)-1-propanone). Both peppermint oil and (-)-menthol inhibited [(14)C]guanidinium influx through 5-HT(3) receptor channels as well as contractions of the ileum induced by serotonin. Neither the peppermint oil nor (-)-menthol, however, was able to displace [(3)H]GR65630 from 5-HT(3) binding sites. It may be concluded that peppermint oil and (-)-menthol exert their antiemetic effect at least partly by acting on the 5-HT(3) receptor ion-channel complex, probably by binding to a modulatory site distinct from the serotonin binding site.     

In vitro pharmacological investigations of Sapindus trifoliatus in various migraine targets

Phytotherapies have offered alternative sources of therapy for migraine and gained much importance in prophylactic treatment. The aqueous extract of pericarp of fruits of Sapindus trifoliatus Linn (ST), family Sapindaceae was evaluated for its affinity for 5-HT(1B/1D) receptors in rabbit saphenous vein, alpha-adrenoceptors in rabbit aorta, GABA receptors in guinea pig ileum, 5-HT(2B) receptors in rat fundus and vanilloid receptors in guinea pig trachea. The calcium blocking effect was studied in rabbit aorta while the modulatory role of ST on platelet serotonin release was evaluated in human platelets. The aqueous extract of Sapindus trifoliatus exhibited significant 5-HT(2B) receptor inhibition and moderate platelet serotonin release inhibition.     

Alkaloids from Boophane disticha with affinity to the serotonin transporter in rat brain

Bulbs and leaves of Boophane disticha are used in South African traditional medicine in the treatment of anxiety. Crude extracts of the leaves have shown affinity to the SSRI site on the serotonin transporter in a radioligand binding assay. In this study, two compounds, buphanadrine and buphanamine, were isolated by bioassay-guided fractionation on VLC and preparative TLC. The structures of the compounds were determined by (1)H and (13)C NMR. Fractions were tested for affinity to the serotonin transporter in a binding assay using [(3)H]-citalopram as ligand. The IC(50) values of buphanidrine and buphanamine were 274 microM (K(i)=132 microM) and 1799 microM (K(i)=868 microM), respectively. The two alkaloids were also tested for affinity to the 5HT(1A) receptor, but only showed slight affinity.     

Affinity of Iresine herbstii and Brugmansia arborea extracts on different cerebral receptors

Iresine herbstii Hook. (Amaranthaceae) and Brugmansia arborea (L.) Lagerheim (Solanaceae) are used in the northern Peruvian Andes for magic-therapeutical purposes. The traditional healers use Iresine herbstii with the ritual aim to expel bad spirits from the body. Furthermore, Iresine herbstii was used in association with other plants, such as Trichocereus pachanoi Britt. et Rose, for divination, to diagnose diseases, and to take possession of another identity. Also, species of Brugmansia have been reported to be used during ritual practices for magical and curative purposes. Given the above evidence, the aim of the present study is to evaluate if the central effects of Iresine herbstii and Brugmansia arborea could be associated with interaction with SNC receptors. Two Iresine herbstii extracts (methanolic and aqueous) and one Brugmansia arborea aqueous extract were tested for in vitro affinity on 5-HT(1A), 5-HT(2A), 5-HT(2C), D1, D2, alpha(1), and alpha(2) receptors by radioligand binding assays. The biological materials for binding assay (cerebral cortex) were taken from male Sprague-Dawley rats. The extracts affinity for receptors is definite as inhibition percentage of radioligand/receptor binding and measured as the radioactivity of remaining complex radioligand/receptor. The data obtained for Iresine extracts have shown a low affinity for the 5-HT(1A) receptor and no affinity for 5-HT(2A) receptor. Otherwise the methanolic extract showed affinity for 5-HT(2C) receptor (IC(50): 34.78 microg/ml) and for D1 receptor (IC(50): 19.63 microg/ml), instead the Iresine aqueous extract displayed a lower affinity for D1 (48.3% at the maximum concentration tested) and a higher value of affinity for D2 receptors (IC(50): 32.08 microg/ml). The Brugmansia aqueous extract displayed affinity for D1 receptors (IC(50): 17.68 microg/ml), D2 receptors (IC(50): 15.95 microg/ml) and weak affinity for the serotoninergic receptors. None of the three extracts showed relevant affinity to the alpha(1), and alpha(2) receptors. The results of our experiments indicate that Iresine herbstii methanolic extract was able to interact with the central 5-HT(2C) and D1 receptors and Iresine herbstii aqueous extract showed affinity for D2 receptors, thus confirming their ritual use. Instead Brugmansia arborea was able to interact only with the central dopamine receptors tested. Parallel studies are currently in progress for evaluating the extracts affinity and active components towards these and other receptor types (GABAergic).     

5-Hydroxytryptamine2A receptor binding activity of compounds from Litsea sessilis

A 96-well microplate filtration based 5-HT(2A) receptor-radioligand binding assay was optimized and adopted to carry out a bioassay-guided fractionation of the methanol extract of the leaves of Litsea sessilis. This purification led to the isolation of two compounds identified as (+)-boldine (1) and (+)-dehydrovomifoliol (2). (+)-Boldine binds to 5-HT(2A) receptors at high concentrations with a K(i) value of 2.16 microm. However, (+)-dehydrovomifoliol showed minimal competitive inhibition on the binding of [(3)H]ketanserin to the same receptor with a K(i) value of 2.06 mm. These results suggest that (+)-boldine influences the activity of 5-HT(2A) receptors through competitive binding as an agonist or antagonist.     

罗布麻叶总黄酮抗抑郁作用参与5-HT能系统可能机制的研究

该研究采用经典抗抑郁模型强迫游泳实验对罗布麻叶总黄酮的抗抑郁活性进行了评价,同时选择相关5-HT受体阻断剂(5-HT1A→Way100635、5-HT2→赛庚啶、5-HT2A→酮舍林)采用小鼠悬尾实验来探讨罗布麻叶总黄酮的抗抑郁机制。结果表明罗布麻叶总黄酮具有明确的抗抑郁作用;同时,5-HT2A、5-HT2受体阻断剂酮舍林(5mg/kg)、赛庚啶(3mg/kg)与罗布麻叶总黄酮50mg/kg联合连续灌胃给药10天后与罗布麻叶总黄酮50mg/kg单独给药相比,能明显延长悬尾小鼠累计不动时间(P<0.05),表明罗布麻叶总黄酮的抗抑郁活性与5-羟色胺能系统(5-HT2A、5-HT2受体)有关。     

Binding studies for serotoninergic, dopaminergic and noradrenergic receptors of Valeriana adscendens Trel. extracts

Valeriana adscendens Trel. (Valerianaceae) is a psychoactive plant usually used in magical-therapeutic rituals in traditional practices of the Northern Peruvian Andes. Previous studies have been carried out on extracts of aerial parts in order to validate its traditional use. The results indicated that Valeriana adscendens exerts important effects on the central nervous system. Aim of the present study is to evaluate if the effects on the central nervous system of Valeriana adscendens extracts can be associated with interaction with some CNS receptors. In this work we examined affinity and selectivity of two Valeriana adscendens extracts (methanolic and aqueous) towards 5-HT(1A), 5-HT(2A), 5-HT(2C) serotononergic, D(1) and D(2) dopaminergic, alpha(1) and alpha(2) noradrenergic receptors by a preliminary binding screen. The results show weak affinity to 5-HT(1A) for the aqueous extract. Both extracts showed affinity for D(1) receptors, but only for the methanolic extract the IC(50) value was determinable (30.14 microg/ml). No affinity for 5-HT(2A), 5-HT(2C) serotononergic receptors, alpha(1) and alpha(2) noradrenergic receptors and D(2) receptors was recorded for the extracts.     

Estrogenic and serotonergic butenolides from the leaves of Piper hispidum Swingle (Piperaceae)

Ethnopharmacological relevance

Our previous work has demonstrated that several plants in the Piperaceae family are commonly used by the Q’eqchi Maya of Livingston, Guatemala to treat amenorrhea, dysmenorrhea, and pain. Extracts of Piper hispidum Swingle (Piperaceae), bound to the estrogen (ER) and serotonin (5-HT7) receptors.

Aim of the study

To investigate the estrogenic and serotonergic activities of Piper hispidum extracts in functionalized assays, identify the active chemical constituents in the leaf extract, and test these compounds as agonists or antagonists of ER and 5-HT7.

Materials and methods

The effects of the Piper hispidum leaf extracts were investigated in estrogen reporter gene and endogenous gene assays in MCF-7 cells to determine if the extracts acted as an estrogen agonist or antagonist. In addition, the active compounds were isolated using ER- and 5-HT7 receptor bioassay-guided fractionation. The structures of the purified compounds were identified using high-resolution LC–MS and NMR spectroscopic methods. The ER- and 5-HT7-agonist effects of the purified chemical constituents were tested in a 2ERE-reporter gene assay in MCF-7 cells and in serotonin binding and functionalized assays.

Results

Three butenolides including one new compound (1) were isolated from the leaves of Piper hispidum, and their structures were determined. Compound 1 bound to the serotonin receptor 5-HT₇ with IC₅₀ values of 16.1 and 8.3 μM, respectively, and using GTP shift assays, Compound 1 was found to be a partial agonist of the 5-HT₇ receptor. The Piper hispidum leaf extracts, as well as Compounds 2 and 3 enhanced the expression of estrogen responsive reporter and endogenous genes in MCF-7 cells, demonstrating estrogen agonist effects.

Conclusions

Extracts of Piper hispidum act as agonists of the ER and 5-HT₇ receptors. Compound 1, a new natural product, identified as 9,10-methylenedioxy-5,6-Z-fadyenolide, was isolated as the 5-HT₇ agonist. Compounds 2 and 3 are reported for the first time in Piper hispidum, and identified as the estrogen agonists. No inhibition of CYP450 was observed for any of these compounds in concentrations up to 1 μM. These activities are consistent with the Q’eqchi traditional use of the plant for the treatment of disorders associated with the female reproductive cycle.     

麻黄连翘赤小豆汤对5-HT所致瘙痒模型大鼠与不同细胞系中5-HT1A及GRPR表达的影响＊

目的 通过建立大鼠瘙痒模型结合体外细胞培养，探讨麻黄连翘赤小豆汤止痒效果及对5-HT1a受体（5-羟色胺1a受体，Serotonin 1a receptor）、GRPR（胃泌素释放肽受体，Gastrin-releasing peptide receptor）表达的影响。方法 以40只雄性SD大鼠为研究对象，随机分为空白组、模型组、麻黄连翘赤小豆汤低、中、高剂量组，每组8只。除正常组外，其余各组均采取颈背部部皮下注射12%5-羟色胺（5-hydroxytryptamine，5-HT）溶液建立大鼠瘙痒模型。造模完成1天后，药物干预组大鼠分别用浓度为4.3 g·kg^-1、8.6 g·kg^-1、17.2 g·kg^-1的麻黄连翘赤小豆汤灌胃治疗14天，正常组和模型组灌胃等量等体积的生理盐水，观察并记录大鼠造模当天、治疗第7天、治疗第14天各组大鼠搔抓次数。治疗14天后取大鼠脊髓，采用蛋白免疫印迹法（Western Blot，WB）和免疫组化法检测5-HT1a受体和GRPR的表达水平及组织内分布情况。同时选用2种不同类型细胞系，分别分为空白组，对照组与干预组，对照组与干预组采用生理盐水与麻黄连翘赤小豆汤处理，48h后采用实时荧光定量PCR技术（Quantitative real-time PCR，qPCR）检测5-HT1a受体与GRPR mRNA的表达情况。结果 麻黄连翘赤小豆汤对瘙痒模型大鼠有止痒作用（P < 0.05），其抑制5-HT1a受体及GRPR的表达水平（P < 0.05），在细胞层面也下调5-HT1a受体及GRPR的表达。结论 麻黄连翘赤小豆汤可通过抑制5-HT1a与GPRP的表达进而达到止痒作用。     

选择性5-羟色氨受体抑制剂——巴西苏木红素(英文)

目的:子宫平滑肌内存在多种5-HT受体,5-HT通过作用于5-HT受体实现其对子宫收缩活性的影响。本研究探讨巴西苏木红素对5-HT受体的作用及其特点。方法:小鼠分离子宫平滑肌条,采用受体拮抗实验和real time PCR方法,对巴西苏木红素的5-HT受体的抑制作用进行研究。结果:巴西苏木红素虽然对正常子宫平滑肌的收缩幅度和频率无影响,但能明显抑制5-HT2受体激动剂马来酸麦角新碱的收缩活性,其pA2为5.71±0.21。而5-HT亚型的选择性激动剂舒马普坦(5-HT1D)、AL34662(5-HT2A)、MCPP(5-HT2C)的收缩子宫活性同样能够被巴西苏木红素抑制,pA2分别为4.58±0.06;4.91±0.15;5.38±0.15。巴西苏木红素明显抑制了5-HT受体1D和2C亚型mRNA的表达。结论:巴西苏木红素能够阻滞小鼠子宫5-HT受体,并通过可能影响5-HT受体所介导的子宫功能。     

Inhibition of [3H]-LSD binding to 5-HT7 receptors by flavonoids from Scutellaria lateriflora

The hot water and 70% ethanol extracts of dried mad-dog skullcap (Scutellaria lateriflora) both bound to the 5-HT(7) receptor, with 87.2 +/- 6.2% and 56.7 +/- 1.3% inhibition of [(3)H]-LSD binding to the receptor at 100 microg/mL, respectively. The on-line analysis of a 70% ethanol extract by HPLC-UV/MS resulted in the identification of five flavones (1-5). Fractionation of the ethanol extract resulted in the isolation of three flavone-glucuronides (6-8) and a flavanone-glucuronide (9), including one new compound, lateriflorin (5,6,-dihydroxy-7-glucuronyloxy-2'-methoxyflavone) (8). The structure of 8 was determined by NMR ((1)H NMR, (13)C NMR, and NOESY experiments) and MS analysis. From the results obtained in the testing of the pure compounds, it is evident that the activity on the 5-HT(7) receptor is at least partly due to the presence of flavonoids. Scutellarin and ikonnikoside I showed the highest inhibition of [(3)H]-LSD binding with IC(50) values of 63.4 and 135.1 microM, respectively.     

外周5-羟色胺系统与针刺镇痛

<正> 5-羟色胺(5-HT)是体内一种重要的吲哚型生物活性单胺。因其不能透过血脑屏障,所以存在于中枢神经系统和外周的5-HT基本上分属两个独立的系统。在中枢神经的系统中,5-HT主要存在于中枢5-HT能系统,中缝核则是脑内5-HT能神经元胞体最集中的部位。中枢5-HT即是由这些神经元合成、分泌的神经激素,经其末梢释放,作为神经介质或突触传递调节物参与多种生理功能的调节。有人认为5-HT是中枢抑制性介质。     

Effects of Kaixin Powder on Expression of 5-HT Receptor in Hippocampus of Depressed Rats Induced by CUMS

Objective To observe the influence of Kaixin Powder on ethology,content of 5-HT in the hippocampus, expression of m RNA, and protein in 5-HT1 A and 5-HT2 A receptors in the hippocampus of depressed rats induced by chronic unpredictable mild stress(CUMS). Methods Twenty-four male Wistar rats were randomly divided into blank,model, Trazodone, and Kaixin Powder groups, six rats in each group. In addition to the blank control group, other groups were established the depression model induced by CUMS combined with isolated feeding. At the same time, Trazodone group and Kaixin Powder group were treated with corresponding drugs for 3 weeks. After 3 weeks of administration, the rats were sacrificed, and a series of indexes were measured such as the contents of 5-HT, m RNA expression levels of 5-HT1 A and 5-HT2 A receptors, protein expression levels of 5-HT1 A and 5-HT2 A receptors, and so on. Results A series of indexes in the model group were decreased significantly such as the body weight growth, the sugar water intake, the score of Open Field Test, the content of5-HT in the hippocampus, expression of m RNA, and protein in 5-HT1 A receptor, while the expression of m RNA and protein in 5-HT2 A receptor were increased significantly.Compared with the model group, the indexes were ameliorated in Trazodone and Kaixin Powder groups. Kaixin Powder is better than Trazodone in decreasing the level of protein in 5-HT2 A receptor. Conclusion The result indicated that the depression performance of depressed rats induced by CUMS can be ameliorated by Kaixin Powder,and the mechanism maybe concerned with increasing the contents of 5-HT, exciting 5-HT1 A receptor, and antagonising 5- HT2 A receptor.     

New antiinfective and human 5-HT2 receptor binding natural and semisynthetic compounds from the Jamaican sponge Smenospongia aurea

In addition to the sesquiterpene-phenol aureols (1), 6'-chloroaureol (2), and aureol acetate (3), eight indole alkaloids including the new N-3'-ethylaplysinopsin (9) have been isolated from the Jamaican sponge Smenospongia aurea. Makaluvamine O (10), a new member of the pyrroloiminoquinone class, was also isolated. The structures were characterized by spectroscopic methods, and two new derivatives of aureol were prepared to optimize the biological activity. Aureol N,N-dimethyl thiocarbamate (1a) and 6-bromoaplysinopsin (7) exhibit significant antimalarial and antimycobacterial activity in vitro. Compound 6 showed activity against the Plasmodium enzyme plasmepsin II. The 6-bromo-2'-de-N-methylaplysinopsin (6), 6-bromoaplysinopsin (7), and N-3'-ethylaplysinopsin (9) displaced high-affinity [(3)H]antagonist ligands from cloned human serotonin 5-HT(2) receptor subtypes, whereas the other compounds tested did not. Remarkably, the 6-bromo-2'-de-N-methylaplysinopsin (6) showed a > 40-fold selectivity for the 5-HT(2C) subtype over the 5-HT(2A) subtype.     

Nocardimicins A, B, C, D, E, and F, siderophores with muscarinic M3 receptor inhibiting activity from Nocardia sp. TP-A0674

In the screening for muscarinic M3 receptor binding inhibitors from microbial secondary metabolites, the extract of Nocardia sp. TP-A0674 was found to be highly active. Bioassay-guided fractionation of it led to the isolation of six new siderophores, nocardimicins A (1), B (2), C (3), D (4), E (5), and F (6), as active principles. Their chemical structures were determined by spectroscopic and degradation analysis. Of these congeners, nocardimicin B (2) inhibited the binding of tritium-labeled N-methylscopolamine to the muscarinic M3 receptor most potently with a Ki value of 0.13 microM. Compound 2 showed more selective activity to M3 and M4 receptors than other subtypes.     

Pulicatins A-E, neuroactive thiazoline metabolites from cone snail-associated bacteria

The cone snail Conus pulicarius from the Philippines provides a specific habitat for actinomycetes and other bacteria. A phenotypic screen using primary cultures of mouse dorsal root ganglion neurons revealed that one C. pulicarius associate, Streptomyces sp. CP32, produces a series of natural products that enhance or diminish whole-cell Ca(2+) flux. These compounds include known thiazoline compounds and a series of new derivatives, pulicatins A-E (6-10). Individual compounds were shown to bind to a series of human receptors, with selective binding to the human serotonin 5-HT(2B) receptor. Here, we report the structure elucidation of the new compounds and results of the neurological assays.     

Alkaloids from Eschscholzia californica and their capacity to inhibit binding of [3H]8-Hydroxy-2-(di-N-propylamino)tetralin to 5-HT1A receptors in Vitro

A 70% ethanol extract of California poppy (Eschscholzia californica) was able to bind to 5-HT(1A) and 5-HT(7) receptors at 100 mug/mL. The subsequent isolation procedure yielded the known alkaloids californidine (1), escholtzine (2), N-methyllaurotetanine (3), caryachine (4), and O-methylcaryachine (5), along with a new pavine alkaloid, 6S,12S-neocaryachine-7-O-methyl ether N-metho salt (7). The structure of 7 was determined by spectroscopic data interpretation, while the absolute stereochemistry was determined by means of circular dichroism. From the results obtained from the radioligand-binding assay of the pure compounds, including the commercially available protopine (6), it was evident that the activity on the 5-HT(1A) receptor was at least partly due to the presence of the aporphine alkaloid 3, which showed the highest inhibition of [(3)H]8-hydroxy-2-(di-N-propylamino)tetralin ([(3)H]8-OH-DPAT) binding with an EC(50) value of 155 nM and a K(i) of 85 nM.     

针刺镇痛中α和β受体的作用及其对脑内5—羟色胺代谢的影响

<正> 据报道,针刺镇痛时脑内去甲肾上腺素(NE)的含量明显降低;损毁 NE 能神经元胞体密集分布的蓝斑或上行途径,或者用双硫醒等抑制 NE 合成以降低脑内 NE 含量,均可增强针刺镇痛;刺激蓝斑或注射 NE 前体二羟基苯丝氨酸使脑内 NE 含量增加时,可对抗针刺