Postcoital interceptive activity of Wrightia tinctoria in Sprague-Dawley rats: a preliminary study.

BACKGROUND: This study was aimed to investigate the pregnancy-interceptive activity of the stem bark of Wrightia tinctoria R.Br. (Family Apocynaceae) administered during the preimplantation, peri-implantation and early postimplantation periods by oral route in adult female Sprague-Dawley rats. STUDY DESIGN: The ethanolic extract of the stem bark and its serial fractions were administered to female rats on Days 1-7 or 1-5 postcoitum (Day 1: day of sperm-positive vaginal smear) by the oral route. At autopsy on Day 10 postcoitum, the number and status of corpora lutea and implantations were recorded. For estrogen-agonistic activity, immature rats ovariectomized 7 days earlier received the test extract or the vehicle once daily for 3 days and, at autopsy on Day 4, uterine weight, status of vaginal opening and extent of vaginal cornification were recorded. RESULTS: The ethanolic extract of the stem bark of W. tinctoria R.Br. inhibited pregnancy in 100% of rats when administered orally at a 250-mg/kg dose on Days 1-7 or 1-5 postcoitum. On fractionation, the hexane-soluble, chloroform-soluble, water-soluble and water-insoluble fractions showed 100% anti-implantation effect, while n-butanol-soluble fraction intercepted pregnancy in 75% of animals when administered in the Days 1-5 postcoitum schedule. In immature rat bioassay, the active ethanolic extract and its fractions exhibited moderate to potent estrogen-agonistic activity, which might be responsible for their contraceptive action in this species. CONCLUSIONS: Findings demonstrate the antifertility activity of the ethanolic extract of the stem bark of W. tinctoria and its hexane-soluble, chloroform-soluble, water-soluble and water-insoluble fractions. Studies that pursue promising natural products (to identify contraceptive agents from natural sources lacking potent estrogenic activity) towards a fruitful conclusion for development/lead generation should continue.

Synthesis and structure guided evaluation of estrogen agonist and antagonist activities of some new tetrazolyl indole derivatives.

Several regioisomeric tetrazolyl indole derivatives with structurally modified alkyl substituents at the tetracyclic indole nitrogen containing N-ethyl amino tetrazole moiety have been synthesized and screened for their ER binding affinity, agonist (estrogenic), antagonist (antiestrogenic) and anti-implantation activities. N-2 regioisomers were found to be moderately antagonists and one compound showed 100% contraceptive efficacy at 10 mg/kg dose. Molecular docking studies carried out in comparison to estradiol and raloxifene showed different binding modes of the two regioisomers to the binding site.

Contraceptive and hormonal properties of the stem bark of Dysoxylum binectariferum in rat and docking analysis of rohitukine, the alkaloid isolated from active chloroform soluble fraction.

BACKGROUND: This study was aimed to investigate the pregnancy interceptive activity of the stem bark of Dysoxylum binectariferum Hook. f. administered during the pre- and peri-implantation periods and immediately after implantation by oral route in adult female Sprague-Dawley rats. STUDY DESIGN: Ethanolic extract and its fractions were administered to female rats on Days 1-10, Days 1-7, Days 1-5 or Day 1 postcoitum by oral route. At autopsy on Day 12, the number and status of corpora lutea and implantations were recorded. For estrogenic activity, ovariectomized immature rats received the test extract or the vehicle once daily for 3 days and at autopsy on Day 4, uterine weight and status of vaginal opening and extent of vaginal cornification were recorded. For antiestrogenic activity, the extract was administered along with ethinyl estradiol. Docking analysis of rohitukine, the alkaloid isolated from active chloroform soluble fraction, to estrogen receptor (ERalpha) was conducted using AutoDock 3.0.5 on a Linux workstation. RESULTS: The ethanolic extract intercepted pregnancy in rats at a daily dose of 500 mg/kg on Days 1-7 postcoitum. On fractionation, the activity was localized in the chloroform fraction, which inhibited pregnancy in all females at the 35-mg/kg dose on Days 1-7, at the 50-mg/kg dose on Days 1-5 or at the single 300-mg/kg dose on Day 1 postcoitum. Chromatography of this fraction yielded an alkaloid, rohitukine, which prevented pregnancy at the 10-mg/kg dose administered on Days 1-7 but was partially (45%) effective at this dose when administered during the entire preimplantation period and ineffective even at 10 times this dose when administered only on Day 1 postcoitum, except that there was a significant reduction in implantation number in pregnant females. While the active chloroform soluble fraction was devoid of any estrogen agonistic or antagonistic properties, a mild uterotropic effect without induction of premature opening of vagina or cornification of vaginal epithelium was observed in rohitukine at the 10-mg/kg dose. Rohitukine, with an almost similar molecular size (mol. wt. 305) as 17beta-estradiol, fits ideally into the hydrophobic pocket of ER. While it does not appear to simultaneously interact with GLU353, ARG394 and HIS524 as estradiol to elicit frank estrogenic response, different conformations of the ligand or its metabolite(s) might acquire geometry with phenolic groups at C-3', C-5 and C-7 positions disposed in a fashion to interact with active site(s) of ER, which might be responsible for its contraceptive and/or weak uterotropic effects. The absence of a basic side chain directed toward the antiestrogen binding site (ASP351) on the receptor appears to be responsible for the lack of any estrogen antagonistic activity. CONCLUSIONS: Findings demonstrate the antifertility activity of the ethanolic extract of D. binectariferum, its chloroform soluble fraction and rohitukine. Efforts are being made to enhance the anti-implantation activity of rohitukine by structural modifications.

Synthesis of 3-phenyl-4-phenylvinyl benzopyranones and the corresponding 2,2-dimethyl-benzopyrans with structural similarity to estradiol, as estrogen receptor ligands.

7-Methoxy-3-phenyl-4-phenylvinyl benzopyran-2-ones and the corresponding 2,2-dimethyl-benzopyrans, substituted with different alkylamino residues were synthesized. Except compound 13e, all compounds showed high level of estrogen agonistic activity (>81 %) whereas, compounds 13 b-e and 15a showed significant estrogen antagonistic activity (>20 %). X-Ray analysis of a 7-methoxy-3-phenyl-4-phenylvinyl benzopyran-2-one derivative 13d showed its structural resemblance to endogenous estrogen, 17beta-estradiol. Estrogenic and antiestrogenic activities of these derivatives demonstrate their estrogen receptor (ER) binding ability. The lack of hydroxyl groups at appropriate positions resulted in poor Relative Binding Affinity (RBA).

Amide derivatives of 2,3-diarylacrylophenone as estrogen receptor binding ligands.

Substituted amidoalkyl derivatives of 2,3-diarylacrylophenones carrying the amide chain on the 3-aryl residue have been prepared by reacting corresponding phenolic 2,3-diarylacrylophenones with haloalkyl carboxylic acid esters, their hydrolysis and subsequent treatment with different alkyl amines. Compounds thus prepared were evaluated for their relative binding affinity (RBA) towards estrogen receptors (ER), estrogen agonistic and antagonistic activities. Out of eleven amide derivatives thus prepared, compounds 7, 13, 15-19, 23, 24 showed significant estrogen antagonistic activity. Interestingly the phenolic compound 7 and the acid ester 18 also exhibited estrogen inhibiting property. Majority of the dimethoxy derivatives (R = OCH(3)) showed significantly high estrogenic activity. In order to throw light on their SAR, In silico docking of the acrylophenone derivatives in the ligand binding site of the ERalpha and their comparison with pure steroidal estrogen antagonist ICI-164,384 and the non-steroidal antiestrogen raloxifene, was carried out. Crystal structure of compound 6 revealed relative trans-geometry of the 2(B) and 3(C) phenyl rings.

Pregnancy interceptive activity of the roots of Calotropis gigantea Linn. in rats.

OBJECTIVE: We conducted this study to evaluate the pregnancy interceptive activity of the roots of Calotropis gigantea Linn. in colony-bred adult Sprague-Dawley rats when administered during the preimplantation and/or peri-implantation periods. METHODS: The ethanolic extract of the roots of C. gigantea Linn. and its hexane, chloroform, n-butanol-soluble and n-butanol-insoluble fractions were administered to rats on Day 1, Days 1-5, Days 1-7 or Days 5-7 postcoitum. Rats from the control group received an equal volume of the vehicle (Tween 80 in glass distilled water) only. At autopsy on Day 10 postcoitum, the final body weight and number as well as status of the corpora lutea and implantations in each animal were recorded. For estrogen agonistic and antagonistic activities, 21-day-old immature rats ovariectomized 7 days earlier were treated orally with the test agent or the vehicle for 3 days. In the case of estrogen antagonistic activity, the rats also received 0.05 mg/kg of 17alpha-ethinyl estradiol for 3 days. At autopsy 24 h after the last treatment, uterine fresh weight was taken and premature opening of the vagina as well as the extent of vaginal cornification, if any, were recorded. RESULTS: The ethanolic extract of the roots of C. gigantea Linn. exhibited 100% pregnancy interceptive activity in rats when administered as a single oral dose of 100 mg/kg on Day 1 postcoitum. The extract also exhibited 100% efficacy at the dose of 12.5 mg/kg when administered in the Days 1-5 and 1-7 postcoitum schedules. When administered during the peri-cum-early postimplantation period (i.e., Days 5-7 postcoitum at 250 mg/kg), most of the implantations showed signs of resorption. On fractionation, the chloroform fraction showed 100% activity at 100 mg/kg in the single-day (Day 1 postcoitum) schedule, whereas the hexane, n-butanol-soluble and n-butanol-insoluble fractions were found to be inactive at this dose. At autopsy on Day 10 postcoitum, 7-25% loss in body weight was recorded at the minimum effective contraceptive dose (MED) in rats treated with the ethanolic extract as well as its chloroform-soluble fraction on Days 1-7, 1-5 and 1 postcoitum, in comparison with the 6-7% increase in body weight observed in vehicle control rats. There was however no mortality in any of the treatment groups. The active ethanolic extract and its chloroform fraction were devoid of any estrogen agonistic or antagonistic activity at their respective MEDs in the ovariectomized immature rat bioassay. Efforts are being made to isolate the active principles devoid of effect on body weight. CONCLUSIONS: The findings suggest the potential for developing products of this plant as contraceptives for human use and welfare. In addition, characterization of the agents responsible for body weight decrease and evaluation of their mechanism of action and safety profile, with or without contraceptive efficacy, might have added advantage for the management of obesity.

Rapid synthesis of 4-benzylidene and 4-[bis-(4-methoxyphenyl)-methylene-2-substituted phenyl-benzopyrans as potential selective estrogen receptor modulators (SERMs) using McMurry coupling reaction.

7-Methoxy-4-(4-methoxybenzylidene)-2-substituted phenyl-benzopyrans I and 4-[bis-(4-methoxyphenyl)-methylene-2-substituted phenyl-benzopyrans II carrying different alkylamino residues, designed as estrogen receptor (ER) binding ligands, were successfully synthesized through the McMurry coupling reaction of substituted benzaldehyde/substituted benzophenones and 2-hydroxyphenyl-7-methoxy-chroman-4-one in presence of lithium aluminum hydride and titanium (IV) chloride (LAH-TiCl(4)). Self-coupling of carbonyl reactants led to the formation of several side products. The prototypes were evaluated for their relative binding affinity (RBA), as well as their estrogenic and antiestrogenic activities. High order of estrogenic activity (>50% gain) observed with compounds 3, 7a, 7b, 7c, 8, and 10a and also their partial estrogen antagonistic activity (> or =15%) at the uterine level points toward successful designing of the compounds. Compounds 4, 7a, 7b, 7c, and 10a also possessed significant anticancer activity against human adenocarcinoma cell line (MCF-7 cell line) that may be related to their estrogen-dependent action.

Evaluation of contraceptive activity of a mineralo-herbal preparation in Sprague-Dawley rats.

OBJECTIVE: This study was aimed to evaluate a marketed mineralo-herbal preparation containing plants known to have potent contraceptive activity, or contraindicated for use during pregnancy in folklore/ancient Indian literature and recommended for use as an appetizer and headache, hyperacidity and chronic constipation reliever for effect on spermatogenesis and implantation-cum-early postimplantation events in adult Sprague-Dawley rats. METHODS: The preparation, suspended in distilled water with the addition of sterile gum acacia, was administered at 1 g/kg daily dose (extrapolated from human dose on surface area basis) to male rats covering one spermatogenic cycle and to female rats during the entire preimplantation and early postimplantation period by oral route. Fertility performance of male rats was tested following mating with untreated fertile females. RESULTS: Findings of this study indicate that the mineralo-herbal preparation at this dose and schedule produced no discernible effect on weight of testis, epididymis and accessory glands, spermatogenesis, vasal sperm picture or mating rate in male rats when administered during the period covering one spermatogenic cycle, but caused significant reduction in number of implantations in females mated with these male rats as well as in female rats treated during the postcoital period. CONCLUSIONS: Any adverse effect on fertility/reproductive health following administration over longer periods/at higher doses in humans habituated to continuous use of this preparation cannot be completely ruled out from this limited study. Findings also suggest caution in indiscriminate use of this and other such preparations containing varying amounts of plants/plant products reported to possess contraceptive property and available for other pharmacological indications over-the-counter in most countries.

Role of energy metabolism in the pregnancy interceptive action of Ferula assafoetida and Melia azedarach extracts in rat.

Ethanolic extract of Ferula assafoetida and chloroform fraction of Melia azedarach, both devoid of estrogenic activity, were examined for their pregnancy interceptive property. Treatment of rats from days 1 to 7 of pregnancy with either of the plant extracts resulted in pregnancy failure in about 65-85% of the animals. The possible role of energy metabolism in the antifertility action was investigated by measuring changes in activities of the key enzymes of carbohydrate metabolism in uterus on day 7 of pregnancy. It was observed that on the day 7 of pregnancy, one key enzyme of glycolytic pathway (phosphofructokinase) was significantly reduced in the uteri of treated rats as compared to controls. Hexosemonophosphate pathway also appeared to be sensitive to treatment with the plant extracts and showed an inhibitory effect on the enzyme activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Oxidative energy metabolism through tricarboxylic acid cycle, which is considered to be the main source of energy to the uterus at this stage, was maximally affected by the treatment with several enzymes showing significant inhibition. The two plant materials appeared to interrupt the latter metabolic pathway more significantly. It is thus concluded that plants lacking phytoestrogens may intercept pregnancy by their ability to disrupt energy metabolism in rat uterus during implantation, especially the oxidative pathway.