Investigation of in vitro toxicity of jet fuels JP-8 and Jet A

The in vitro cytotoxicity and electrophysiological toxicity of Jet Propulsion-8 (JP-8 jet fuel) on four cell types: H4IIE liver cell line, NIH Swiss 3T3 cell line, neuroblastoma x glioma NG108-15 cells, and embryonic hippocampal neurons were investigated. H4IIE cells exposed to Jet A (a commercial fuel) and JP-8 demonstrated identical toxicity with an IC50 of 12.6 +/- 0.4 micrograms/ml for the two fuels. Comparison of H4IIE and NIH/3T3 toxicity to JP-8 revealed that NIH/3T3 cells were more sensitive to JP-8 than H4IIE cells, with an IC50 8.5 +/- 0.1 micrograms/ml. JP-8 exposure for the hippocampal neurons proved to be highly toxic (IC50 of < 2 micrograms/ml), while in contrast, the NG108-15 cells were much less sensitive. Electrophysiological examination of NG108-15 cells showed that administration of JP-8 at 1 microgram/ml did not alter significantly any of the electrophysiological properties. However, exposure to JP-8 at 10 micrograms/ml during a current stimulus of +46 pA decreased the amplitude of the action potential to 83 +/- 7% (n = 4), the rate of rise, dV/dtMAX to 50 +/- 8% (n = 4), and the spiking rate to 25 +/- 11% (n = 4) of the corresponding control levels. These results demonstrate JP-8 induced cytotoxic varies among cell types. The possible mechanisms underlying these observations are presented.     

The mycotoxin beauvericin induces apoptotic cell death in H4IIE hepatoma cells accompanied by an inhibition of NF-κB-activity and modulation of MAP-kinases

Beauvericin is a world-spread mycotoxin with a high toxicity in mammalian cells. However, its molecular mechanism of action is not fully understood. Using different cancer cell lines (HepG2, C6, Hct116 and H4IIE), we could show that the cyclic peptide is highly toxic (MTT assay) with IC₅₀ values in low micromolar range. As a molecular mechanism of cell death, necrosis was detected in C6 glioma cells (PI staining), but apoptosis prevails in H4IIE hepatoma cells (caspase 3/7 activity, nuclear fragmentation). In H4IIE cells, beauvericin rapidly decreases the phosphorylation of ERK and strongly increases JNK phosphorylation, while p38 phosphorylation was not affected. Furthermore, a strong inhibition of NF-κB signalling was detectable in H4IIE cells. A screening of 21 protein kinases involved in signal transduction pathways (cell proliferation, survival, angiogenesis and metastasis) showed a selective inhibition of src kinase by beauvericin (IC₅₀ = 9.8 μg/ml). We suggest that beauvericin mediates its toxic effects in H4IIE cells, at least in parts, by a distinct modulation of intracellular signalling molecules.     

乙酰天麻素对血管平滑肌的解痉作用

天麻属兰科植物,近年来从天麻中提出一个有效成分天麻素,经实验及临床观察认为是安全有效的镇静药。对神经衰弱,血管神经性头痛等可使症状减轻或消除。昆明制药厂对天麻素的结构进行了改造,合成了一系列的衍生物,其中乙酰天麻素(acetagastrodine,G2)作用比天麻素强,本文研究乙酰天麻素对血管平滑肌的影响。     

Synthesis and kinetics studies of N′‐(2‐(3,5‐disubstituted‐4H‐1,2,4‐triazol‐4‐yl)acetyl)‐6/7/8‐substituted‐2‐oxo‐2H‐chromen‐3‐carbohydrazide derivatives as potent antidiabetic agents

A novel series of N′‐(2‐(3,5‐disubstituted‐4H‐1,2,4‐triazol‐4‐yl)acetyl)‐6/7/8‐substituted‐2‐oxo‐2H‐chromen‐3‐carbohydrazides were synthesized and studied for their α‐glucosidase inhibition activity. Most of the synthesized compounds exhibited potential α‐glucosidase inhibition activity with IC₅₀ values ranging from 0.96 ± 0.02 to 32.86 ± 0.73 µg/ml. Among them, compounds 3e and 4e , having a methoxy group on the coumarin ring, proved to be the most potent ones, showing an enzyme inhibition activity with IC₅₀ = 0.96 ± 0.02 and 1.44 ± 0.06 µg/ml, respectively. The kinetic study through Lineweaver–Burk plots revealed that the inhibition mechanism of the most active compounds 3d, 3e, 4d , and 4e , on the α‐glucosidase activity, was found to be in the competitive mode.     

INVESTIGATION OF CLASS I ANTI-ARRHYTHMIC DRUG ACTIONS ON GUINEA-PIG CARDIAC MITOCHONDRIAL LACTATE DEHYDROGENASE ACTIVITY

1. The effects of the Class I anti-arrhythmic drugs quinidine, procainamide, lidocaine, phenytoin and tocainide on mitochondrial lactate dehydrogenase activity were compared in guinea-pig heart preparations. 2. All the tested drugs inhibited the enzyme activity in a concentration-dependent fashion, exhibiting varying profiles in their actions. Lidocaine exhibited inhibitory concentration 20% (IC₂₀) and IC₅₀ values of 0.52 ± 0.02 mmol/L and 25.6 ± 0.5 mmol/ L, procainamide 6.0 ± 0.2 mmol/ L and 108 ± 7.2 mmol/L, phenytoin 3.4 ± 0.06 μmol/L and 0.34 ± 0.02 mmol/L, quinidine 39.2 ± 1.2 μmol/L and 9.8 ± 0.8 mmol/L and tocainide 2.7 ± 0.3 mmol/L and 44.6 ± 2.5 mmol/L. 3. According to the IC₅₀ values, this is the order of their inhibitory potencies: phenytoin > quinidine > lidocaine > tocainide > procainamide. This trend is in general agreement with the lipophilicity rank of the drugs. 4. It is concluded, therefore, that inhibition of mitochondrial lactate dehydrogenase is a property shared by most Class I anti-arrhythmic drugs which may depend on their lipophilicity and possibly their membrane stabilizing effects.     

几种血卟啉衍生物对肿瘤细胞光动力学灭活作用的比较

本文用小鼠L₁₂₁₀淋巴白血病细胞和B₁₆黑色素瘤细胞研究了几种国内试制的血卟啉衍生物制剂对肿瘤细胞的光动力学灭活作用。与国外新一代血卟啉衍生物Photofrin Ⅱ(DHE)相比,LF-019和扬州光卟啉(Y-HPEI)的活性更显著。本文采用了Trypan blue排斥试验与注射瘤细胞后观察小鼠存活时间两种评价药物作用的方法,发现两者的结果是一致的。     

Development and radiosterilization of new hydrazono-quinoline hybrids as DNA gyrase and topoisomerase IV inhibitors: Antimicrobial and hemolytic activities against uropathogenic isolates with molecular docking study

This study aimed to synthesize new potent quinoline derivatives based on hydrazone moieties and evaluate their antimicrobial activity. The newly synthesized hydrazono-quinoline derivatives 2 , 5a , 9 , and 10b showed the highest antimicrobial activity with MIC values ≤1.0 μg/ml against bacteria and ≤8.0 μg/ml against the fungi. Further, these derivatives exhibited bactericidal and fungicidal effects with MBC/MIC and MFC/MIC ratio ≤4. Surprisingly, the most active compounds displayed good inhibition to biofilm formation with MBEC values ranging between (40.0 ± 10.0 – 230.0 ± 31.0) and (67.0 ± 24.0 – 347.0 ± 15.0) μg/ml against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. The hemolytic assays confirmed that the hydrazono-quinoline derivatives are non-toxic with low % lysis values ranging from 4.62% to 14.4% at a 1.0 mg/ml concentration. Besides, compound 5a exhibited the lowest hemolytic activity value of ~4.62%. Furthermore, the study suggests that the hydrazono-quinoline analogs exert their antibacterial activity as dual inhibitors for DNA gyrase and DNA topoisomerase IV enzymes with IC₅₀ values ranging between (4.56 ± 0.3 – 21.67 ± 0.45) and (6.77 ± 0.4 – 20.41 ± 0.32) μM, respectively. Additionally, the recent work advocated that compound 5a showed the reference SAL at the ɣ-radiation dose of 10.0 kGy in the sterilization process without affecting its chemical structure. Finally, the in silico drug-likeness, toxicity properties, and molecular docking simulation were performed. Besides, the result exhibited good oral-bioavailability, lower toxicity prediction, and lower binding energy with good binding mode rather than the positive control.     

Synthesis,cytotoxicity, and molecular docking of substituted 3-(2-methylbenzofuran-3-yl)-5-(phenoxymethyl)-1,2,4-oxadiazoles

A series of new benzofuran/oxadiazole hybrids ( 8a – n ) was synthesized from 2H-chromene-3-carbonitriles ( 3a – c ) through the multistep synthetic methodology, and these hybrids are known to exhibit anticancer activities. All the compounds were evaluated for their in vitro cytotoxicity against the HCT116 and MIA PaCa2 cell lines. Compounds 6a (IC₅₀: 9.71 ± 1.9 μM), 6b (IC₅₀: 7.48 ± 0.6 μM), and 6c (IC₅₀: 3.27 ± 1.1 μM) displayed a significant cytotoxic activity, whereas compounds 8d and 8e exhibited good activity against both cell lines. The depletion of glycogen synthase kinase-3β (GSK3β) induces apoptosis through the inhibition of basal NF-κB activity in HCT116 colon cancer cells and MIA PaCa2 pancreatic cancer cells. Molecular docking of compounds 6a , 6b , 6c , 8d , and 8e with GSK3β demonstrated the best binding affinity, correlating with the biological activity assay. Furthermore, the structure–activity relationship of these novel compounds reveals promising features for their use in anticancer therapy.     

In vivo and in vitro toxicological evaluations of aqueous extract from Cecropia pachystachya leaves

ABSTRACT

Cecropia pachystachya

leaves are popularly used to treat asthma and diabetes. Despite the widespread consumption of this plant, there are few scientific studies regarding its toxicological potential. In order to conduct a thorough study concerning the potential adverse effects, the aim of this study was to assess acute and subacute toxicity tests of crude aqueous extract from C. pachystachya leaves (CAE-Cp) using in vivomodel, as well as in vitro cytotoxicity, genotoxicity and antioxidant activity. In addition, genotoxicity, and cytotoxicity of chlorogenic acid (CGA) and cytotoxicity of isoorientin (ISOO) were also evaluated. The antioxidant activity was verified by DPPH, cytotoxicity using sulforhodamine B (SRB) assay and genotoxicity by comet assay on V79 cells. The phytochemical analysis of CAE-Cp detected flavonoids and tannins, CGA and ISOO as the major compounds utilizing HPLC. The total flavonoid content (6.52 mg/g EQ) and antioxidant activity (EC₅₀ = 62.15 µg/ml) of CAE-Cp were determined. In vitro evaluations with CAE-Cp showed genotoxic effects at 0.31 to 2.5 mg/ml and an expressive cytotoxicity on HT-29 (IC₅₀ = 4.43 µg/ml) cells. CGA was genotoxic against V79 cells at 0.07 mg/ml and cytotoxic against to HT-29 (IC₅₀ = 71.70 µg/ml), OVCAR-3 (IC₅₀ = 80.07 µg/ml), MCF-7 (IC₅₀ = 45.58 µg/ml) and, NCI-H460 (IC₅₀ = 71.89 µg/ml) cancer cell lines. Wistar rats treated with a single dose (2,000 mg/kg) CAE-Cp decreased hemoglobin levels after 14 days, although no significant toxicity was observed in animals after 28 days. In view of the in vitro cytotoxicity and genotoxicity detected, further studies are necessary to establish the safe use of CAE-Cp.     

维拉帕米对抗阿霉素的中国仓鼠卵巢上皮细胞抗药性的逆转作用

非细胞毒性剂量的维拉帕米(Ver)3μg/ml,增强阿霉素(ADM)对抗阿霉素的中国仓鼠卵巢上皮细胞(RC₁)的生长抑制达10倍。用集落形成法测定表明:Ver 3μg/ml能降低RC₁的IC₅₀值,即从1.2μg/ml降至0.08μg/ml,逆转抗药性达15倍。由于Ver增强ADM在RC₁细胞的积累,从而增强ADM对RC₁细胞的毒性,用流式细胞光度计,研究Ver逆转抗药性机制,发现Ver与ADM合用,能阻断RC₁细胞在G₂+M期。     

Anticancer effect of Cenchrus ciliaris L

Cenchrus ciliaris L total alcohol and successive extracts of both aerial and root parts were tested for their anticancer activities against lung (A-549), intestinal (CACO), colon (HCT-116), cervical (Hela), hepatocellular (HepG-2), and breast (MCF-7) (PC3) cell lines and compared with the standard drug vinblastine sulphate. The obtained results exhibited direct cytotoxic effect with variable inhibiting effect on the growth of the listed cell lines comparing to vinblastine sulphate as reference standard drug, these effects showed different IC₅₀ ranged from 11.1?±?0.3 to 267?±?µg/ml.All root extracts showed the best activities against most of the tested cell lines specially HepG-2 (Hepatocellular carcinoma) (9?±?2.1?µg/ml) which was somewhat closely related to the effect of vinblastine sulphate (2.93?±?0.3?µg/ml).The highest anticancer effect of Cenchrus ciliaris L aerial parts and root extracts were recorded on HepG-2 (Hepatocellular carcinoma) their IC₅₀ were 12?±?0.8 & 9?±?2.1 respectively, CACO (colorectal carcinoma) their IC₅₀ were 27.2?±?1.6 & 20.5?±?0.6 respectively, A-549 (Lung carcinoma) their IC₅₀ were 14.5?±?0.7& 11.1?±?0.3 respectively which were better than the standard drug especially in case the anticancer effect on CACO (colorectal carcinoma) and A-549 (Lung carcinoma). Chloroform extracts of both aerial and roots achieved the best anticancer activities on all of the cell lines especially with colorectal (CACO) and Lung carcinoma (A-549). Cenchrus ciliaris could be a promising source of new chemical moieties used to target cancer cells.     

In Vitro Protective Effect of Hypericum androsaemum Extract Against Oxygen and Nitrogen Reactive Species

Abstract: Hypericum androsaemum L. (Gutiferae) is a medicinal plant growing in Western Europe that has been used in traditional medicine in the prevention or treatment of liver diseases. Oxidative stress and nitrosative stress are common pathogenetic mechanisms contributing to initiation and progression of hepatic damage in several liver disorders. In the present study, an ethanol:water (4:6) extract from H. androsaemum branches and leaves were evaluated for its putative in vitro scavenging effects on 1,1‐diphenyl‐2‐picrylhydrazil radical, on reactive oxygen species, namely HO^?, O₂^??, ROO^?, ¹O₂ and H₂O₂ and on reactive nitrogen species, namely ^?NO and ONOO^?. The hypericum extract presented a remarkable capacity to scavenge all the tested reactive species, all the IC₅₀ values being found at the μg/ml level. IC₅₀ values for 1,1‐diphenyl‐2‐picrylhydrazil, and for the reactive oxygen species O₂^??, H₂O_2, HO^? and ¹O₂ were 11.3 ± 0.7, 32.7 ± 3.4, 944 ± 47, 595 ± 82, 28.3 ± 1.2 μg/ml respectively. The oxygen radical absorbance capacity value obtained for ROO^? was 1.5 ± 0.1 μmol Trolox equivalents/mg extract. The IC₅₀ values for ^?NO and ONOO^? were 2.2 ± 0.2 and 1.2 ± 0.1 μg/ml respectively. The content of total phenolics was 281 ± 2 mg of gallic acid equivalents/g of lyophilized extract. The observed antioxidant activity provides scientific support for the reported therapeutic use of H. androsaemum, though further in vitro and in vivo studies are required to ascertain the risk/benefit score at therapeutic concentrations.     

抗心律失常药常咯啉的临床药代动力学

11名心律失常患者,静脉滴注CRL(55 μg/kg/min)60min的峰浓度为3.6±0.6μg/ml。其中8名PVBs患者滴注后26±9 min,PVBs完全消失,血浆中CRL有效浓度为2.6±0.7μg/ml。停滴后血药浓度迅速下降,降至2.0±0.6μg/ml时PVBs又复出现。3名结性早搏病人无效。药代动力学特性表征为单室模型,动力学参数:K=0.032±0.011 min^-1;t_1/2=24±13 min;V_d=0.43±0.19 L/kg。健康志愿者6人,一次iv常咯啉50 mg,继以40μg/kg/min静滴55 min,血药浓度的范围在2.7～3.2μg/ml。对ECG和血压无明显变化。     

Acute toxicity test of CuO nanoparticles using human mesenchymal stem cells

Despite the growing interest in nanoparticles (NPs), standardized procedures for the evaluation of their toxicity have not been defined. The risk of human exposure is rapidly increasing and reliable toxicity test systems are urgently needed. In vitro methods are ideal in toxicology research because they can rapidly provide reproducible results while preventing the use of animals. Recently, a new test for acute toxicity based on the use of human bone marrow mesenchymal stem cells (hBMMSCs) has been developed and successfully tested in our laboratory following the Interagency Coordinating Committee on the Validation of Alternative Methods guidelines. Along these lines, the aim of this study is to evaluate the acute cytotoxicity of copper oxide (CuO) NPs using the new toxicity test based on hBMMSCs. Our results show that CuO NPs are much more toxic compared to micrometer ones. Specifically, CuO NP exposure exhibits a significant cytotoxicity at all the concentrations used, with an IC₅₀ value of 2.5?±?0.53?µg/ml. On the other hand, CuO microsized particle exposure exhibits a very low cytotoxicity at the same concentrations, with an IC₅₀ value of 72.13?±?16.2?µg/ml.     

Steroid glycosides from the starfish Pentaceraster gracilis

Using combined chromatographic separations, two new steroid glycosides namely pentacerosides A (1) and B (2), and four known compounds were isolated from the methanol extract of the starfish Pentaceraster gracilis. Their structures were determined on the basis of spectroscopic data (¹H and ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, ROESY, and FT-ICR-MS) and by comparing obtained results to the literature values. Among the isolated compounds, only maculatoside (5) showed significant cytotoxic effect against Hep-G2 (IC₅₀ = 16.75 ± 0.69 μM) and SK-Mel2 (IC₅₀ = 19.44 ± 1.45 μM) cell lines and moderate effect on KB (IC₅₀ = 36.53 ± 0.78 μM), LNCaP (IC₅₀ = 39.75 ± 3.34 μM), and MCF7 (IC₅₀ = 47.34 ± 7.01 μM) cell lines.     

Design,synthesis, and modelling study of new 1,2,3-triazole/chalcone hybrids with antiproliferative action as epidermal growth factor receptor inhibitors

A novel series of 1,2,3-triazole/chalcone hybrids 6a–n was designed and synthesized using a molecular hybridization approach to develop a new cytotoxic agent capable of targeting epidermal growth factor receptor (EGFR) and/or BRAF. The antiproliferative effect of the novel hybrids was investigated against four cancer cells using doxorubicin as a reference. Hybrids 6a , 6d , 6f–h , and 6n have the highest antiproliferative activity (IC₅₀ values 0.95–1.80 μM) compared to doxorubicin (IC₅₀ 1.14 μM). The most potent antiproliferative derivative, compound 6d , was also the most potent EGFR inhibitor with an IC₅₀ of 0.09 ± 0.05 μM, which is comparable to the reference Erlotinib (IC₅₀ = 0.05 ± 0.03 μM). 6d has modest BRAF inhibitory action with an IC₅₀ of 0.90 ± 0.10 μM. The findings were also related to molecular docking studies, which provided models of strong interactions with the EGFR-TK domain for the inhibitors. In cell cycle analysis, hybrid 6d caused a cell cycle arrest at the G1 transition phase.     

Acute toxicity and biochemical effects of azinphos methyl in the amphipod Hyalella curvispina

We evaluated the acute toxicity and biochemical effects of the organophosphorus pesticide azinphos methyl (AM) in the amphipod Hyalella curvispina that inhabits ponds and irrigation channels of an intensive fruit‐producing region in Rio Negro and Neuquén valley, North Patagonia, Argentina. The analysis by nonlinear regression of data from the 96 h‐acute toxicity tests indicated the coexistence of two subpopulations of H. curvispina with different susceptibilities to AM. The 96 h‐LC₅₀ for the resistant subpopulation (166 ± 56 μg/L) was 216‐fold higher than the 96h‐LC₅₀ value for the susceptible one (0.77 ± 1.33 μg/L).The two subpopulations could not be distinguished based on the biochemical measurements in control amphipods. Cholinesterase activity was significantly inhibited in AM‐exposed amphipods in a concentration‐dependent manner. The IC₅₀ value obtained after 96 h of exposure (2.18 ± 1.95 μg/L) was significantly lower than the 48 h‐IC₅₀ value (29.6 ± 17.4 μg/L). Carboxylesterase activity was significantly inhibited after 48 h of exposure to 12.5 and 62.5 μg/L AM (inhibition, 51%). This enzyme was thus able to protect cholinesterase from inhibition at 12.5 μg/L AM. Reduced glutathione and catalase showed a significant increase after 24 h of exposure as an adaptive response to AM, whereas glutathione S‐transferase activity was not significantly modified. The analysis of species sensitivity distribution showed that both subpopulations of H. curvispina were more tolerant to AM than most amphipod species, and that the susceptible subpopulation was more sensitive to AM than the other local aquatic species analyzed. The maximum concentration of AM in drainage water within the fruit‐producing area reported by other studies would affect most of the amphipod species (99%) and also a 44% of local aquatic ones. The results obtained in this study point out the usefulness of including amphipods like H. curvispina in ecotoxicity studies and monitoring programs to perform pesticide risk assessments. 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 1043–1053, 2014.     

6-(αα-二苯基乙酰哌嗪基苯基)-4,5-二氢-5-甲基-3(2H)-哒嗪酮对兔血小板聚集及TXB2,cAMP的影响

6-(αα-二苯基乙酰哌嗪基苯基)-4,5-二氢-5-甲基-3(2H)-哒嗪酮(简称DMDP)是我院新合成的哒嗪酮的衍生物。DMDP可以显著抑制由花生四烯酸(AA(?),ADP和血小板活化因子(PAF)诱导的免血小板聚集,其IC₅₀分别为1.12±0.1.4.19±0.5和2.97±0.1μmol/L。实验还表明DMDP在1～500 μmol/L浓度范围内呈剂量依赖性地抑制兔血小板内血栓素B₂含量,但升高兔血小板内环腺苷酸水平,这可能是其抑制血小板聚集的作用机理之一。     

Novel pyridine‐2,4,6‐tricarbohydrazide thiourea compounds as small key organic molecules for the potential treatment of type‐2 diabetes mellitus: In vitro studies against yeast α‐ and β‐glucosidase and in silico molecular modeling

A range of novel pyridine‐2,4,6‐tricarbohydrazide thiourea compounds ( 4a–i ) were synthesized in good to excellent yields (63–92%). The enzyme inhibitory potentials of these compounds were investigated against α‐ and β‐glucosidases because these enzymes play a crucial role in treating type‐2 diabetes mellitus (T2DM). As compared to the reference compound acarbose (IC₅₀ 38.22 ± 0.12 μM), compounds 4i (IC₅₀ 25.49 ± 0.67 μM), 4f (IC₅₀ 28.91 ± 0.43 μM), 4h (IC₅₀ 30.66 ± 0.52 μM), and 4e (IC₅₀ 35.01 ± 0.45 μM) delivered better inhibition against α‐glucosidase and were quite inactive/completely inactive against β‐glucosidase. The structure–activity relationship of these compounds was developed and elaborated with the help of molecular docking studies.     

Inhibition of benzodiazepine binding in vitro by amentoflavone,a constituent of various species of Hypericum

Flower extracts of Hypericum perforatum, Hypericum hirsutum, Hypericum patulum and Hypericum olympicum efficiently inhibited binding of [³H]flumazenil to rat brain benzodiazepine binding sites of the GABA_A-receptor in vitro with IC₅₀ values of 6.83, 6.97, 13.2 and 6.14 μg/ml, respectively. Single constituents of the extracts like hypericin, the flavones quercetin and luteolin, the glycosylated flavonoides rutin, hyperoside and quercitrin and the biflavone I3, II8-biapigenin did not inhibit binding up to concentrations of 1 μM. In contrast, amentoflavone revealed an IC₅₀ = 14.9 ± 1.9 nM on benzodiazepine binding in vitro. Comparative HPLC analyses of hypericin and amentoflavone in extracts of different Hypericum species revealed a possible correlation between the amentoflavone concentration and the inhibition of flumazenil binding. For hypericin no such correlation was observed. Our experimental data demonstrate that amentoflavone, in contrast to hypericin, presents a very active compound with regard to the inhibition of [³H]-flumazenil binding in vitro and thus might be involved in the antidepressant effects of Hypericum perforatum extracts.