Effect of amino acids on inhibition of lactate dehydrogenase-X by gossypol. (1/126)

Gossypol acetic acid (GAA) has been shown to have male antifertility effects, but there are pronounced differences among animal species. In the search of endogenous effector molecules, which interfere with the functions of GAA, we have studied the in vitro effect of various amino acids on the inhibition of the purified LDH-X by GAA. Histidine, cysteine and glycine were shown to block the effect of GAA. The effects of these amino acids were concentration dependent. Histidine and glycine protection was found to be complex type in which both the Km and Vmax were decreased compared to control. Arginine, glutamic acid, phenylalanine and valine were found to be ineffective against the inhibitory action of GAA.  (+info)

Novel derivatives of phenethyl-5-bromopyridylthiourea and dihydroalkoxybenzyloxopyrimidine are dual-function spermicides with potent anti-human immunodeficiency virus activity. (2/126)

Sexually active women represent the fastest growing HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) risk group. In an effort to develop a vaginal microbicidal contraceptive potentially capable of preventing HIV transmission as well as providing fertility control, we have synthesized novel non-nucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase (RT) and examined them for dual-function anti-HIV and spermicidal activity. Structure-based drug design by use of a computer docking procedure for the NNI binding pocket generated from nine RT-NNI crystal structures led to the synthesis of three novel NNIs: N-[2-(2, 5-dimethoxyphenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (D-PBT); N-[2-(2-fluorophenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (F-PBT); and 5-isopropyl-2-[(methylthiomethyl)thio]-6-(benzyl)-pyrimidin-4-(1H)-on e (S-DABO). The anti-HIV activity of these NNIs was compared with that of trovirdine and virucidal/spermicide, nonoxynol-9 (N-9), by measuring viral RT activity and p24 antigen production as markers of viral replication using HTLVIIIB-infected human peripheral blood mononuclear cells (PBMCs). The effects on sperm motion kinematics and sperm membrane integrity were examined by computer-assisted sperm analysis and by confocal laser scanning microscopy (CLSM), respectively. The growth-inhibitory effects of NNI versus N-9 against normal human ectocervical and endocervical epithelial cells were tested using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay. All three NNIs were potent inhibitors of purified recombinant HIV RT and abrogated HIV replication in PBMCs at nanomolar concentrations (IC50 < 1 nM) when compared with N-9 or trovirdine (IC50 values of 2.2 microM and 0.007 microM, respectively). Two NNIs, F-PBT and S-DABO, also exhibited concentration- and time-dependent spermicidal activity. The drug concentration required to inhibit sperm motility by 50% (EC50 values) for the lead compound F-PBT versus N-9 was 147 microM and 81 microM, respectively. Sperm-immobilizing activity induced by F-PBT and S-DABO was rapid (t1/2 = 7-13 min) and irreversible. Unlike that of N-9, spermicidal activity of F-PBT and S-DABO was not accompanied by loss of acrosomal membrane as detected by fluorescent-lectin binding assay and CLSM. Whereas N-9 was cytotoxic to normal human ectocervical and endocervical cells at spermicidal doses, both F-PBT and S-DABO were selectively spermicidal. We conclude that as potent anti-HIV agents with spermicidal activity and reduced cytotoxicity, F-PBT and S-DABO show unique clinical potential to become the active ingredients of a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission.  (+info)

Synthesis, characterization and preclinical formulation of a dual-action phenyl phosphate derivative of bromo-methoxy zidovudine (compound WHI-07) with potent anti-HIV and spermicidal activities. (3/126)

In a systematic effort to develop a microbicide contraceptive capable of preventing transmission of human immunodeficiency virus (HIV), as well as providing fertility control, we have previously identified novel phenyl phosphate derivatives of zidovudine (ZDV) with 5-halo 6-alkoxy substitutions in the thymine ring and halo substitution in the phenyl moiety respectively. Here, we describe the synthesis, characterization, and successful preclinical formulation of our lead compound, 5-bromo-6-methoxy-3'-azidothymidine-5'-(p-bromophenyl) methoxyalaninyl phosphate (WHI-07), which exhibits potent anti-HIV and sperm immobilizing activities. The anti-HIV activity of WHI-07 was tested by measuring viral p24 antigen production and reverse transcriptase activity as markers of viral replication in HIV-1 infected human peripheral blood mononuclear cells (PBMC). WHI-07 inhibited replication of HIV in a concentration-dependent fashion with nanomolar IC50 values. The effects of WHI-07 on human sperm motion kinematics were analysed by computer-assisted sperm analysis (CASA), and its effects on sperm membrane integrity were examined by confocal laser scanning microscopy (CLSM), and high-resolution low-voltage scanning electron microscopy (HR-LVSEM). WHI-07 caused cessation of sperm motility in a concentration- and time-dependent fashion. The in-vitro cytotoxicities of WHI-07 and nonoxynol-9 (N-9) were compared using normal human ectocervical and endocervical epithelial cells by the MTT cell viability assay. Unlike N-9, WHI-07 had no effect upon sperm plasma and acrosomal membrane integrity. N-9 was cytotoxic to normal human ectocervical and endocervical cells at spermicidal doses, whereas WHI-07 was selectively spermicidal. The in-vivo vaginal absorption and vaginal toxicity of 2% gel-microemulsion of WHI-07 was studied in the rabbit model. The sperm immobilizing activity of WHI-07 was 18-fold more potent than that of N-9. Over a 10 day period, there was no irritation or local toxicity to the vaginal epithelia or systemic absorption of WHI-07. Therefore, as a potent anti-HIV agent with spermicidal activity, and lack of mucosal toxicity, WHI-07 may have the clinical potential to become the active ingredient of a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission.  (+info)

The effects of three nonoxynol-9 preparations on vaginal flora and epithelium. (4/126)

To evaluate the effects of nonoxynol-9 (N-9) on the vaginal flora and epithelium, 48 women (16 in each group) were evaluated by use of quantitative vaginal cultures and colposcopy. at baseline and at 0.5, 4, 24, 48, and 72 h after insertion of one of three N-9 preparations (4% gel [Conceptrol], 3.5% gel [Advantage-24], or a 28% vaginal contraceptive film). The proportion positive for H2O2+ or H2O2- lactobacilli did not change significantly with any of the preparations, but lactobacilli concentrations decreased transiently. Both the proportion of women with Gardnerella vaginalis and the concentration of G. vaginalis decreased transiently. The proportion of women with Escherichia coli increased with the 4% gel, and the concentration increased with all preparations. The number with anaerobic gram-negative rods increased, although the concentrations decreased. Symptoms and colposcopic abnormalities were rare. Changes in levels of vaginal bacteria were transient after single applications of N-9, but adverse effects may be enhanced with frequent, chronic use.  (+info)

Contraceptive characteristics: the perceptions and priorities of men and women. (5/126)

CONTEXT: Despite the fact that choosing a contraceptive method is often a decision made by couples, little is known about how men and women differ in their perceptions of the characteristics of various method types, and in the importance that they attach to those characteristics when choosing a contraceptive method. METHODS: The data analyzed here are subsets from two companion surveys conducted in 1991--1,189 men aged 20-27 who were surveyed in the National Survey of Men and 740 women aged 20-27 who were surveyed in the National Survey of Women. Multivariate ordered logit analysis is used to examine how gender is related to both the importance that individuals assign to seven specific contraceptive characteristics when choosing a method, and to perceptions about the extent to which five common method types possess each of these characteristics. RESULTS: Women rank pregnancy prevention as the single most important contraceptive characteristic when choosing a method, with 90% citing it as "very important." The health risks associated with particular methods and protection from sexually transmitted diseases (STDs) are rated as the second most important characteristics by women (each mentioned as "very important" by 77%). In contrast, men consider STD prevention for themselves and their partner to be just as important as pregnancy protection (each mentioned as "very important" by 84-86%), and they rank STD prevention as more important than other health risks (by 72%). Women, but not men, rank both ease of use and the need to plan ahead as being more important characteristics than a method's interference with sexual pleasure. Both men and women have an accurate understanding of the strengths and weaknesses of particular methods, but differ enough in their perceptions to alter the relative attractiveness of each method. In particular, women have more favorable perceptions than men about the pill, being somewhat more likely than men to believe that the pill is "very good" at preventing pregnancy (75% vs. 67%) and to say that it is very good at not interfering with sexual pleasure (82% vs. 76%). In contrast, women have generally less favorable perceptions than men about other reversible methods, including the condom: Women were less likely than men to consider the condom very good at pregnancy prevention (29% vs. 46%) or at having no need for advance planning (22% vs. 38%). Gender differences in perceptions about the specific characteristics of contraceptive methods often vary by marital status. CONCLUSIONS: Men and women have somewhat different priorities when choosing a contraceptive method. Despite many similarities between women and men in their perceptions about the characteristics of each method type, numerous differences between them may have an important influence on how couples make their method choices.  (+info)

Prophylactic contraceptives for HIV/AIDS. (6/126)

The current pandemic of sexually transmitted human immunodeficiency virus (HIV) infection--the causative agent of acquired immunodeficiency syndrome (AIDS), has created an urgent need for a new type of contraceptive: one that is both a spermicide and a microbicide. Because most women at risk for HIV infection are of reproductive age (15-44 years), effective use of dual-function contraceptives is important to prevent HIV transmission and unintended pregnancies. In the absence of an effective prophylactic anti-HIV therapy or vaccine, new emphasis has been placed on the development of intravaginal microbicidal agents capable of reducing the transmission of HIV. Topical microbicidal spermicides would ideally provide a female-controlled method of self-protection against HIV as well as preventing pregnancy. However, several microbicides that are undergoing preclinical and human clinical trials contain detergent-type ingredients. The detergent-type spermicide, nonoxynol-9, the only recommended microbicide for protection against sexual transmission of HIV has been shown to cause lesions in vaginal and cervical epithelia leaving women more vulnerable to HIV infection. Therefore, a major challenge in microbicide research has been to design mechanism-based microbicides that are highly effective against pregnancy and HIV transmission while lacking detergent-type effects on epithelial cells and normal vaginal flora. We present an overview of current microbicide research and report on the identification and preclinical development of novel non-detergent spermicidal nucleoside and non-nucleoside inhibitors aimed at decreasing pregnancy and preventing sexual transmission of HIV.  (+info)

Structural requirements for potent human spermicidal activity of dual-function aryl phosphate derivative of bromo-methoxy zidovudine (compound WHI-07). (7/126)

WHI-07, a novel bromo-methoxy-substituted aryl phosphate derivative of zidovudine (ZDV), is a potent dual-function contraceptive agent. Although the bromo-methoxy functional groups in the thymine ring of its ZDV are very important for its sperm-immobilizing activity (SIA), the importance of the esterification of the phosphate group with an amino acid side chain and the identity of the para substituent in the aryl moiety remain unclear. In the present study, we have synthesized 23 new analogues of WHI-07 by replacing the alanine (Ala) side chain with different amino acids containing nonpolar side chains, namely tryptophan (Trp), proline (Pro), phenylalanine (Phe), leucine (Leu), methionine (Met), valine (Val), or glycine (Gly). The para substituents on the aryl moiety included bromo, chloro, fluoro, nitro, or methoxy groups. The SIA of each of the 23 WHI-07 analogues was evaluated by computer-assisted sperm analysis. The potential cytotoxicity of these compounds against normal human ectocervical and endocervical epithelial cells was evaluated using MTT (3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) cell viability assays. The replacement of the Ala side chain of WHI-07 with Val, Leu, or Phe led to a complete loss of SIA (EC(50) values > 500 microM), whereas replacement with Trp reduced the SIA by 4-fold. The presence of para substituents on the phenyl moiety led to significant alterations in SIA. The anti-human immunodeficiency virus (HIV) activity of Trp-containing WHI-07 analogues was also diminished. Our finding highlights the necessity of Ala side chain and the presence of electron-withdrawing para-bromo substituent on the phenyl moiety in addition to bromo-methoxy functionalization groups on the thymine ring in order for the phosphoramidate derivatives of ZDV to be effective dual-function spermicidal agents. Unlike the detergent-type microbicide, nonoxynol-9, which was cytotoxic to normal human ectocervical and endocervical epithelial cells (IC(50) values of 22 microM and 16 microM, respectively) at spermicidal concentrations (EC(50) = 81 microM), WHI-07 and its active analogues were selectively spermicidal without cytotoxicity against female genital tract epithelial cells. WHI-07 and its Trp analogues hold particular clinical promise for the development of novel, nondetergent-type prophylactic contraceptives for the prevention of heterosexual HIV/acquired immunodeficiency syndrome transmission.  (+info)

Studies in humans on the mechanism of potent spermicidal and apoptosis-inducing activities of vanadocene complexes. (8/126)

We previously demonstrated that bis-cyclopentadienyl (Cp) complexes of vanadium(IV) (vanadocenes) are potent spermicidal and apoptosis-inducing agents. To gain further insight into the structure-function relationships controlling these two properties of vanadocenes, we have synthesized analogues in which the bis-Cp rings were substituted with one or five electron-donating methyl groups. The three complexes included vanadocene dichloride (VDC), bis(methylcyclopentadienyl) vanadium dichloride (VMDC), and bis(pentamethylcyclopentadienyl) vanadium dichloride (VPMDC). The concentration-dependent effect of these vanadocenes on sperm-immobilizing activity (SIA), mitochondrial membrane potential (DeltaPsim), axonemal dynein ATPase activity, and tyrosine phosphorylation of global and axoneme-specific sperm proteins was assessed by computer-assisted sperm analysis, flow cytometry, colorimetry, and immunoblotting, respectively. Apoptosis-inducing ability was quantitated by the two-color flow cytometric terminal dideoxynucleotidyl transferase-based assay that labels 3'-hydroxyl ends of fragmented DNA. All three vanadocenes induced rapid sperm immobilization (T(1/2) < 15 sec). Substitution of the bis-Cp rings by five methyl groups augmented the SIA of VDC by 10-fold. The EC(50) values (50% inhibitory concentration) for VDC, VMDC, and VPMDC were 7.5 microM, 4.3 microM, and 0.7 microM, respectively. Whereas SIA of vanadocenes was apparent at low micromolar concentrations, the apoptosis-inducing property was evident only at higher micromolar concentrations. The concentrations of VDC, VMDC, and VPMDC required for 50% apoptosis were 49 microM, 67 microM, and 153 microM, and for 50% reduction in sperm DeltaPsim were 435 microM, 173 microM, and 124 microM, respectively. Spermicidal activity of vanadocenes was not dependent on the inhibition of ATPase or tyrosine phosphorylation of global and sperm axonemal proteins. Due to the ability of these vanadocene complexes to rapidly generate hydroxyl radicals in the presence of oxidant, our findings provide unprecedented evidence for a novel mechanism of action for spermicidal vanadocenes. The differential concentration-dependent spermicidal and apoptosis-inducing properties of vanadocenes gives them particular utility as a new class of vaginal contraceptives.  (+info)

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