Antigestagenic activity of Ixora finlaysoniana in rat

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.

Toxicological screening of Euphorbia tirucalli L.: developmental toxicity studies in rats

Euphorbia tirucalli (Euphorbiaceae family), an environmental risk factor for Burkitt's lymphoma, also presents pharmacological activities. In the northeast region of Brazil its latex is used as an antimicrobial, antiparasitic in the treatment of coughs, rheumatism, cancer and other maladies as folk remedy. The present work concerns its developmental toxicity in rats. Wistar rats on the first day post-coitum (dpc) were grouped as control (distilled water) and treated (latex aqueous solution) groups. Animals were treated by oral gavage from the 1st to the 4th (Experiment I) and from the 5th to 7th dpc (Experiment II) and killed on the 5th or 14th dpc, respectively. Maternal variables were: clinical signs of toxicity, body weight, ovaries, liver and kidneys weight and number of corpora lutea. The uterine tubes and cornua were washed for counting and identification of embryos. The embryos and placenta were weighed. Apart from the leucopenia and the higher placental weight observed in treated rats from Experiment II, there were no significant differences between the groups. It is possible to conclude that the latex aqueous solution of Euphorbia tirucalli did not interfere with tubaric embryo development or with implantation, but it seems to alter the placenta morphology.

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.

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.

A review on potentiality of medicinal plants as the source of new contraceptive principles

Recently, a review has already been made on the synthetic contraceptive agents whereas this review embraces the natural contraceptives upto year 2001 with 355 references. It also includes the isolation of their active principles, methods of analysis of active ingredients through TLC, HPLC, their side effects and pharmacological action.

Absence of interceptive effect in rats treated with Solanum lycocarpum (St. Hil)

The interceptive effect of the powder of Solanum lycocarpum (St. Hil) (Solanaceae) fruit, used as a hypoglycemic agent by diabetic patients in Minas Gerais state (Brazil), was evaluated to observe possible effects upon zygote and pre-embryo transport in rats, since it contains solamargine and solasonine from which a 3beta-acetoxipregna-5,16-dien-20-one is obtained as well as an alkaloid with stereospecific configuration to the synthesis of steroid hormones. Inseminated rats received an aqueous suspension of 100 mg of the lobeira powder/kg of body weight, by oral gavage, from the 1st to the 4th day of pregnancy. A control group received 5 mL of distilled water in the same schedule. The pregnant rats were weighed at the beginning of treatment and on sacrifice day. Animals were killed on the 5th day of pregnancy. The oviducts and uterine horns were removed and flushed with saline solution to count expanded blastocysts. It was concluded that administration of lobeira did not cause maternal toxicity, alteration of the pre-embryo transport or reduction of the number of expanded blastocysts.