Superior Chemotherapeutic Efficacy of Amphotericin B in Tuftsin-bearing Liposomes against Leishmania Donovani Infection in Hamsters

Chemotherapeutic efficacy of the amphotericin B (Amp B), which is the drug of choice for treatment of the leishmanial infections (kala-azar) that become resistant to the conventional chemotherapy using antimonials, has been examined in the Leishmania donovani infected hamsters after encapsulating the drug in tuftsin-free as well as tuftsin-bearing liposomes. The activity was significantly increased (p <0.05) by delivering Amp B in tuftsin-free liposomes. This antileishmanial effect of the liposomized Amp B was further increased (p <0.05) by grafting the natural macrophage-activator tetrapeptide, tuftsin (Thr-Lys-Pro-Arg), on the liposome's surface. This could possibly be attributed to both the enhanced drug tolerance after liposomization as well as to the increased uptake of tuftsin-bearing Amp B-laden liposomes by the macrophages. In addition to the increased efficacy, encapsulation of Amp B in the tuftsin-bearing liposomes also enhanced the drug accessibility to areas (e.g. bone marrow) that are otherwise inaccessible to the free drug. These results further demonstrate the usefulness of tuftsin-bearing liposomes as drug vehicles in treatment of the macrophage-based infections that have been reviewed recently (Agrawal, A.K. and Gupta, C.M. (2000). Tuftsin-bearing liposomes in treatment of macrophage-based infections, Adv. Drug Deliv. Rev., 41, 135-146).     

Enhanced Immunostimulant Activity and Protective Effect of a Synthetic Lipopeptide after Liposomization Against Plasmodium berghei Infection in Mice

The immunostimulant activity of non-pyrogenic, sugar-free immunomodulator lipopeptide, Ala-D-Glu(Gly-Lys-CO. C₁₁H₂₃)-NH₂ (comp. no 84/201), and its iiposomized formulation has been studied. Liposomization of this lipopeptide significantly enhanced its antigen specific as well as nonspecific immune responses, as compared to the free lipopeptide. The liposomized formulation of lipopeptide significantly stimulated both the antibody and delayed-type hypersensitivity responses in Balb/c mice, and also enhanced nonspecifically the macrophage migration index, phagocytic activity and incorporation of ¹⁴C glucosamine in peritoneal macrophages of the mice that received pretreatment with this preparation. Further, the mice that received pretreatment with the liposomized preparation strongly resisted lethal P. berghei infection and consequently survived for longer period of times. These results indicate that liposomization of the compound no 84/201 significantly improves its ability to enhance not only antigen-specific immune response but also the nonspesific host's resistance against infections.     

Synthesis and in vitro Screening of 29, 30-Dibromo-28-oxoallobetulin against Parasitic Protozoans,Leishmania donovani and Leishmania Major

A simple synthesis and in vitro antileishmanial activity of 29,30-dibromo-28-oxoallobetulin against the parasitic protozoans, Leishmania donovani and Leishmania major is described. The structure of the compound is established on the basis of spectral data (IR, NMR, MS). Both the antiproliferative effect and the cell cycle progression were studied.     

In vitro and in vivo activities of three acridine thioethers against Leishmania donovani

The lack of definitive chemotherapeutic agents to fight against visceral leishmaniasis has lead to the testing of numerous compounds. In the present work, we carry out an in-depth study of the activity against Leishmania donovani of three acridine derivatives both in vitro and in vivo. These compounds have proven to be highly effective at medium and high concentrations of 10 microg/ml, against both flagellate and nonflagellate forms of the parasite, which, though obtained in vitro, closely resemble natural intracellular amastigotes. The in vivo assays showed a significant reduction in the percentage of parasitation versus control, for all the compounds tested. In addition, we have studied the possible mechanism by which these acridine derivatives act: they displayed a greater inhibitory effect against macromolecule synthesis in treated flagellates, yet alterations are also caused in the production of end metabolites and in the activity of different enzymes. The data obtained indicate that the acridine derivatives had several targets, one of them is the synthesis of nucleic acids and proteins, while the second one might be interaction with the carbohydrate and energy-production processes in the parasite. This conclusion is consistent with our observations concerning the ultrastructural changes induced in the parasite by these compounds principally at the mitochondrial level.     

Antileishmanial Activity,Cytotoxicity and Mechanism of Action of Clioquinol Against Leishmania infantum and Leishmania amazonensis Species

In this study, a quinoline derivate, clioquinol (5‐chloro‐7‐iodoquinolin‐8‐ol), was evaluated against Leishmania amazonensis and Leishmania infantum promastigotes and amastigotes. The cytotoxicity in murine macrophages and human red blood cells, as well as the efficacy in treating infected macrophages and the inhibition of infection using pre‐treated parasites were also evaluated. Results showed that clioquinol inhibited L. amazonensis and L. infantum promastigotes with effective concentration 50% (EC₅₀) values of 2.55 ± 0.25 and 1.44 ± 0.35 μg/mL, respectively, and of 1.88 ± 0.13 and 0.98 ± 0.17 μg/mL against axenic amastigotes, respectively. The cytotoxic EC₅₀ concentrations of clioquinol in murine macrophages and human red blood cells were, respectively, 255 ± 23 and 489 ± 20 μg/mL. With these results, the selectivity index was calculated, showing values of 99.9 and 177.1 against promastigotes, respectively, and of 135.6 and 260.1 against axenic amastigotes, respectively. Significant reductions in the percentage of infected macrophages after treatment using clioquinol were also observed, as well as when parasites were pre‐treated with clioquinol and used to infect murine macrophages. The mechanism of action of clioquinol was investigated in L. amazonensis, and results revealed morphological and biochemical alterations in the clioquinol‐treated parasites, including reduction in cell volume, loss of mitochondrial membrane potential, increase in the ROS production and rupture of the plasma membrane. The externalization of phosphatidylserine (PS) at the cell surface was evaluated in treated parasites that had been doubly labelled with annexin and propidium iodide (PI). The results showed no significant difference for PS exposure when compared to the untreated control, although a significant increase in the PI/annexin V‐labelled cell population was found in the treated parasites. Results suggest that clioquinol induces a discontinuity of the parasite membrane, possibly related to a characteristic event of cell death caused by necrosis. This study demonstrates, for the first time, the antileishmanial activity of clioquinol against two relevant Leishmania species and suggests that the mitochondria of the parasites may be a possible biological target leading to parasite necrosis. Our findings suggest that clioquinol may have a potential application in treatment of leishmaniasis and further studies should be performed in infected mammalian hosts.     

Effects of picroliv, the active principle of Picrorhiza kurroa, on biochemical changes in rat liver poisoned by Amanita phalloides.

The efficacy of Picroliv, a standardized iridoid glycoside fraction of Picrorhiza kurroa, was studied against the Amanita phalloides-induced biochemical changes in rat liver. A phalloides (50 mg.kg-1) caused significant increases in the activities of hepatic 5'-nucleotidase, gamma-glutamyl transpeptidase, acid ribonuclease, and succinate dehydrogenase, but a decrease in glucose-6-phosphatase. The level of cytochrome P-450 in microsomal fraction and content of glycogen in liver showed significant depletions. Picroliv (25 mg.kg-1.d-1 x 10 d) provided significant restorations of all the biochemical changes poisoned by A phalloides except cytochrome P-450 and glycogen. These results demonstrated the protective effect of Picroliv against A phalloides-induced hepatotoxicity in rats.     

In vitro and in vivo activity of new rhodium (III) complexes against Leishmania donovani

The activities of 17 new rhodium drug complexes were determined against Leishmania donovani promastigotes. The five most active salts were selected: [Rh(III)(2-amino-6-ethoxybenzothiazole)(4)Br(2)](+)Br(-); [Rh(III)(2-bromothiazole)(4)(Br)(2)](+)Br(-); [Rh(III)(mefloquine)(4)(Cl)(2)](+)Cl(-); [Rh(III)(2-mepacrine)(4)(Cl)(2)](+)Cl(-), and [Rh(III)(oxamniquine)(4)(Cl)(2)](+)Cl(-), which induced growth-inhibition rates of more than 50% at 24 h of treatment and at the maximum dosage tested. The cytotoxicity assays on the macrophage cell line J-774 showed high cytotoxicity for the salts [Rh(III) (mefloquine)(4)(Cl)(2)](+)Cl(-), [Rh(III)(2-mepacrine)(4)(Cl)(2)](+)Cl(-) and [Rh(III)(oxaminquine)(4)(Cl)(2)](+)Cl(-) with a percentage of specific (15)Cr release of 49.3, 64.8 and 53.2% at 24 h of incubation and 100 microg/ml. Meanwhile, assays of the other compounds showed practically no cytotoxicity. The ultrastructural studies in the flagellates treated with the salt [Rh(III)(2-amino-6-ethoxybenzothiazole)(4)Br(2)](+)Br(-) showed some alterations in the nucleus of the parasites with a very condensed chromatin and an electrodense endosome. This compound showed a high in vivo activity in parasitized Wistar rats.     

Immunomodulator Effect of Picroliv and its Potential in Treatment Against Resistant Plasmodium yoelii (MDR) Infection in Mice

PURPOSE: The present study was envisaged to evaluate potential of combination therapy comprising of immunomodulator picroliv and antimalarial chloroquine against drug resistant Plasmodium yoelii (P. yoelii) infection in BALB/c mice. METHODS: The immunomodulatory potential of picroliv was established by immunizing animals with model antigen along with picroliv. Immune response was assessed using T-cell proliferation assay and also by determining the antibody isotype-profile induced in the immunized mice. In the next set of experiment, prophylactic potential of picroliv to strengthen antimalarial properties of chloroquine against P. yoelii (MDR) infection in BALB/c mice was assessed. RESULTS: T-cell proliferation as well as antibody production study reveals that picroliv helps in evoking strong immuno-potentiating response against model antigen in the immunized mice. Co-administration of picroliv enhances efficacy of CHQ against experimental murine malaria. CONCLUSION: The activation of host immune system can increase the efficacy of chloroquine for suppression of drug resistant malaria infection in BALB/c mice.     

In vitro screening of traditional South African malaria remedies against Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum

Three hundred extracts were prepared from plants traditionally used in South Africa to treat malaria and screened in vitro for activity against Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum. For the 43 extracts which inhibited the growth of one or more parasites to more than 95?% at 9.7?μg/mL, the IC?? values against all four protozoal parasites and cytotoxic IC??s against rat myoblast L6 cells were determined. Amongst the most notable results are the activities of AGATHOSMA APICULATA (IC?? of 0.3?μg/mL) against Plasmodium falciparum, as well as Salvia repens and Maytenus undata against Leishmania donovani with IC??s of 5.4?μg/mL and 5.6?μg/mL, respectively. This screening is the starting point for a HPLC-based activity profiling project in antiprotozoal lead discovery.     

槲皮素对阿霉素致小鼠心肌损伤的保护作用及其机制

观察槲皮素对阿霉素致小鼠心肌损伤的保护作用并初步探讨其机制。腹腔注射阿霉素(20 mg·kg^-1)复制小鼠心肌损伤模型，检测心电图、心肌超微结构，血清NO含量和iNOS活性，心肌组织LDH、SOD、MDA的水平和p53蛋白表达。并观察槲皮素(50，100及200 mg·kg^-1)对上述指标的影响。阿霉素可导致小鼠心律失常和心肌超微结构损伤；使NO、iNOS、MDA和LDH的水平升高，SOD的水平降低；p53蛋白表达增强。槲皮素(50，100及200 mg·kg^-1)可拮抗阿霉素所致的上述变化。槲皮素对阿霉素性小鼠心肌损伤具有保护作用，其机制与增强SOD活力、降低iNOS活性、抑制p53蛋白表达等有关。     

Inactivation of the miltefosine transporter, LdMT, causes miltefosine resistance that is conferred to the amastigote stage of Leishmania donovani and persists in vivo

Miltefosine (hexadecylphosphocholine) is the first oral antileishmanial drug. In this study, we addressed the question whether miltefosine-resistant Leishmania donovani promastigotes transform to miltefosine-resistant amastigotes. A promastigote line, M-mutR, showed defective internalisation of miltefosine owing to mutations in LdMT, similar to previously described resistant lines. M-mutR parasites were infective to macrophages in vitro as well as in BALB/c mice in vivo. There was good correlation of in vitro resistance indices between promastigotes and intracellular amastigotes. Most importantly, M-mutR parasites retained the resistant phenotype in vivo, with no decrease of hepatic burden in BALB/c mice following miltefosine treatment up to 30 mg/kg (ca. 90% inhibition in wild-type infections). No cross-resistance to other antileishmanial drugs was observed in M-mutR amastigotes.     

Protective efficacy of catalytic bioscavenger, paraoxonase 1 against sarin and soman exposure in guinea pigs

Human paraoxonase 1 (PON1) has been portrayed as a catalytic bioscavenger which can hydrolyze large amounts of chemical warfare nerve agents (CWNAs) and organophosphate (OP) pesticides compared to the stoichiometric bioscavengers such as butyrylcholinesterase. We evaluated the protective efficacy of purified human and rabbit serum PON1 against nerve agents sarin and soman in guinea pigs. Catalytically active PON1 purified from human and rabbit serum was intravenously injected to guinea pigs, which were 30 min later exposed to 1.2 × LCt₅₀ sarin or soman using a microinstillation inhalation exposure technology. Pre-treatment with 5 units of purified human and rabbit serum PON1 showed mild to moderate increase in the activity of blood PON1, but significantly increased the survival rate with reduced symptoms of CWNA exposure. Although PON1 is expected to be catalytic, sarin and soman exposure resulted in a significant reduction in blood PON1 activity. However, the blood levels of PON1 in pre-treated animals after exposure to nerve agent were higher than that of untreated control animals. The activity of blood acetylcholinesterase and butyrylcholinesterase and brain acetylcholinesterase was significantly higher in PON1 pre-treated animals and were highly correlated with the survival rate. Blood O₂ saturation, pulse rate and respiratory dynamics were normalized in animals treated with PON1 compared to controls. These results demonstrate that purified human and rabbit serum PON1 significantly protect against sarin and soman exposure in guinea pigs and support the development of PON1 as a catalytic bioscavenger for protection against lethal exposure to CWNAs.     

Characteristics of the Protective Action of α-Tocopherol in Vascular Hypoxia

Abstract: The functioning of the guinea-pig isolated portal vein was monitored by measuring spontaneous mechanical activity, responses to electrical stimulation and administered noradrenaline in normoxic conditions. The effect of hypoxia, induced by bubbling the physiological bathing solution with a 95% N₂/5% CO₂ gas mixture, on the mechanical performance of the vein was then assessed. Spontaneous activity declined in hypoxia, with mean contraction tension reduced by 55±8.8%. The responses to electrical field stimulation (2-32 Hz, 0.7 msec. 70 V) were lowered by 14±4.6% but contractions produced by a range of noradrenaline concentrations (0.01-160 μM) were unaffected by hypoxia. Substitution of glucose in the bathing solution with sucrose, a substrate unavailable to the cells for energy generation, produced a marked enhancement of the effect of hypoxia. Spontaneous activity was reduced by 76±8.3%, electrically-induced activity by 80±14.4% and noradrenaline-induced responses by 85±6.8%. Although in normoxia the activity and responses of the portal vein were unaffected by the presence of α-tocopherol, it significantly protected the functioning of the vein in hypoxic conditions. This effect was concentration-dependent within the range 10-160 μM and was most marked when glucose was replaced by sucrose in the bathing solution.     

Bisphosphonates inhibit the growth of Trypanosoma brucei, Trypanosoma cruzi, Leishmania donovani, Toxoplasma gondii, and Plasmodium falciparum: a potential route to chemotherapy

We have investigated the effects in vitro of a series of bisphosphonates on the proliferation of Trypanosoma cruzi, Trypanosoma brucei rhodesiense, Leishmania donovani, Toxoplasma gondii, and Plasmodium falciparum. The results show that nitrogen-containing bisphosphonates of the type used in bone resorption therapy have significant activity against parasites, with the aromatic species having in some cases nanomolar or low-micromolar IC(50) activity values against parasite replication (e.g. o-risedronate, IC(50) = 220 nM for T. brucei rhodesiense; risedronate, IC(50) = 490 nM for T. gondii). In T. cruzi, the nitrogen-containing bisphosphonate risedronate is shown to inhibit sterol biosynthesis at a pre-squalene level, most likely by inhibiting farnesylpyrophosphate synthase. Bisphosphonates therefore appear to have potential in treating parasitic protozoan diseases.     

Protective activity of geranium oil and its component, geraniol, in combination with vaginal washing against vaginal candidiasis in mice

In order to evaluate an effective administration method of essential oils for vaginal candidiasis, efficacy of vaginal application of essential oils against murine experimental candidiasis was investigated. The effect on vaginal inflammation and Candida growth form was also studied. Vaginal candidiasis was established by intravaginal infection of C. albicans to estradiol-treated mice. These mice intravaginally received essential oils such as geranium and tea tree singly or in combination with vaginal washing. Vaginal administration of clotrimazole significantly decreased the number of viable C. albicans cells in the vaginal cavity by itself. In contrast, these essential oils did not lower the cell number. When application of geranium oil or geraniol was combined with vaginal washing, the cell number was decreased significantly. The myeloperoxidase activity assay exhibited the possibility that essential oils worked not only to reduce the viable cell number of C. albicans, but also to improve vaginal inflammation. The smear of vaginal washing suspension suggested that more yeast-form cells appeared in vaginal smears of these oil-treated mice than in control mice. In vitro study showed that a very low concentration (25 microg/ml) of geranium oil and geraniol inhibited mycelial growth, but not yeast growth. Based on these findings, it is estimated that vaginal application of geranium oil or its main component, geraniol, suppressed Candida cell growth in the vagina and its local inflammation when combined with vaginal washing.     

兰索拉唑对乙醇诱导大鼠胃黏膜损伤的保护作用及其机制

目的　研究兰索拉唑 (LP)对乙醇诱导大鼠胃黏膜损伤的保护作用 ,探讨胃泌素受体和环氧化酶 2 (COX 2 )表达在此过程中的作用。方法　大鼠ig给予LP 0 5、5、5 0mg·kg-1·d-1,或ig联合给予LP 5 0mg·kg-1·d-1和胃泌素受体拮抗剂AG 0 4 1R 3、10、30mg·kg-1·d-1,对照组ig给予羧甲基纤维素 (CMC) 2 5mg·kg-1·d-1,连续 14d。末次给药后 8h各组大鼠ig给予无水乙醇 1ml,观察胃损伤指数 (LI)及光镜下的胃黏膜病理学改变。酶免疫方法测定胃黏膜前列腺素E2 (PGE2 )水平 ,WesternBlot和免疫组化检测胃黏膜COX 2表达。评价特异性COX 2抑制剂NS 398对LP诱导的PGE2 合成及胃黏膜保护作用的影响。结果　在 0 5、5、5 0mg·kg-1LP组 ,LI分别为 (2 5 3± 0 33) %、(1 84±0 2 9) %和 (0 83± 0 12 ) % ,小于对照组 (3 6 5± 0 19) % (P<0 0 5 ) ;胃黏膜PGE2 含量分别为 (42 7± 32 ) ,(483± 12 1)和 (6 14± 82 ) pg·g-1wwt ,高于对照组 (2 6 6± 81) pg·g-1wwt(P <0 0 5 )。LP剂量依赖性地增加大鼠胃黏膜COX 2表达。然而 ,同时给予AG 0 4 1R阻断了LP诱导的胃黏膜保护作用、COX 2表达和PGE2 合成。NS 398抑制LP诱导的PGE2 合成及胃黏膜保护作用。结论　LP的胃黏膜保护作用与内源性胃泌素激活胃泌素受     

Protective effect of cinnamon polyphenols against STZ-diabetic mice fed high-sugar,high-fat diet and its underlying mechanism

This study was designed to investigate the potential effects of 14 days’ intragastrically given of cinnamon polyphenols (CPS) in treating diabetic mice induced by intraperitoneal injection of streptozotocin (150 mg kg⁻¹) and fed high-sugar, high-fat diet. The diabetic mice model was successfully established through determining on fasting blood-glucose (FBG) test. As revealed by glucose oxidase (GOD) and radioimmunoassay (RIA), both dimethyldiguanide (DC, 0.6 g kg⁻¹ d⁻¹) and CPS (0.3, 0.6, 1.2 g kg⁻¹ d⁻¹) treatments significantly resulted in down-regulation of blood glucose and insulin levels in serum, while the levels of oxidative stress markers were markedly lowered through ELISA assay. Meanwhile, the pathological damage in islet with pancreatic beta cells was ameliorated by treatment of CPS at different doses, as shown in HE stain. At the same time, the treatments also caused notable reduction of iNOS, NF-κB expressions showing in Western blot analysis. These findings demonstrate that cinnamon polyphenols can exert the hypoglycemic and hypolipidemic effects through the mechanisms that may be associated with repairing pancreatic beta cells in diabetic mice and improving its anti-oxidative capacity, as well as attenuating cytotoxicity via inhibition of iNOS, NF-κB activation.     

重组人谷氧还蛋白1对小鼠脑缺血/再灌注损伤的保护作用

目的探讨重组人谷氧还蛋白1(rhGrx1)对小鼠局灶性脑缺血/再灌注损伤的保护作用及机制。方法线栓法制备小鼠脑缺血/再灌注模型,病理形态学方法证实模型建立成功。小鼠尾静脉注射rhGrx1(5mg·kg-1和10mg·kg-1)后,观察脑组织中乳酸脱氢酶(LDH)、超氧化物歧化酶(SOD)及蛋白质羰基含量的变化,Western blot检测小鼠脑组织中p38MAPK表达水平的变化。结果HE染色证实模型建立成功且提示rhGrx1可改善缺血/再灌注损伤所致的小鼠脑组织病理形态学变化;rhGrx1能增加小鼠脑组织LDH、SOD活性、降低蛋白质羰基的含量。与假手术组小鼠相比,缺血和再灌注时脑组织p38MAPK蛋白表达量明显增加,注射rhGrx1后p38MAPK蛋白表达被抑制。结论rh-Grx1对局灶性脑缺血/再灌注损伤小鼠有一定保护作用,其机制可能与抑制p38MAPK蛋白表达相关。     

Protective effect of forphenicinol, a low molecular weight immunomodifier, against infection with Pseudomonas aeruginosa in mice and its mechanisms

The oral administration of forphenicinol increased the survival rate of both normal and immunodepressed mice intraperitoneally or intratracheally infected with clinically isolated strains of Pseudomonas aeruginosa. The therapeutic effect of amikacin on intraperitoneal infection with P. aeruginosa was enhanced by combined use with forphenicinol. Forphenicinol did not enhance the bactericidal activity of polymorphonuclear cells (PMN) towards P. aeruginosa in vitro, but enhanced it in vivo. In vitro study indicated that the macrophages taken from mice treated with forphenicinol or the cultured supernatant of these macrophages enhanced the bactericidal activity of PMN. The protective effect of forphenicinol against P. aeruginosa infection was thus suggested to be due to macrophage activation followed by the enhancement of the bactericidal activity of PMN.