Effets des extraits aqueux et méthanolique de Myrianthus arboreus P. Beauv. (Cecropiaceae) sur la fonction de reproduction chez la rate Wistar

Abstract

Infertility is a steadily growing and devastating problem worldwide touching many couples especially those in sub-Saharan Africa where procreation is considered as the bedrock for marriage. Generally, women are considered as the unique culprit and most often carry this enormous burden alone. The most common cause (25-50%) of female infertility is ovulatory dysfunctions. Due to the limits of conventional treatments, people now turn more and more to phytotherapy which is thought to be accessible and "nontoxic". In Cameroon, the extracts of Myrianthus arboreus P. Beauv (Cecropiaceae) are traditionally used to treat amenorrhea, female infertility (primary and secondary) and to improve lactation. On this basis, the present work was undertaken with the aim of evaluating the fertility effects and safety of the leaves of M. arboreus in female Wistar rat as well as identifying the compounds responsible for these effects. Accordingly, different extracts (aqueous and methanolic) were daily administered by gavage for 30 consecutive days at the doses of 20, 110 and 200 mg/kg of body weight (BW) to immature animals (sexual maturation test) and young cyclic adults (sexual behavior test), and throughout the crossing and gestation period (impact on pregnancy). The acute and subacute toxicity of the aqueous extract was done. Silica gel chromatography, thin layer chromatography and gas chromatography columns were used for fractionation of the extracts and the isolation of compounds, while gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) were used for the structure elucidation. On sexual maturation the aqueous extract increased (p < 0.01) the relative weight of the ovaries (at 20 and 110 mg/kg BW), serum levels of progesterone (at 20 and 200 mg/kg BW) and gonadotropins (200 mg/kg BW). In addition to the above-mentioned effects, the methanolic extract induced early vaginal opening at all tested doses, uterine growth (p < 0.05) at 110 mg/kg BW, and increased (p < 0.01) serum estradiol levels at 110 and 200 mg/kg BW. The fertility index was increased at doses of 20 and 110 mg/kg BW, while the dose of 200 mg/kg BW induced a decrease in this parameter. On the gestational parameters, the methanolic extract increased (p <0.05) the number of corpus luteum (110 and 200 mg/kg BW) and implantation sites (200 mg/kg BW). However, an increase in the number of resorption sites, resorption index, and fetal loss after implantation was observed at the highest dose. On the sexual behavior, the 30-day treatment with the aqueous extract induced a significant (p < 0.05) decrease in compartment change latency (110 mg/kg BW) and darting (20 and 200 mg/kg BW), and increased (p < 0.05) the frequency of darting, hopping and duration of lordosis at the dose of 200 mg/kg BW. On acute toxicity a LD50 > 5000 mg/kg BW was obtained with the aqueous extract. On subacute toxicity, no external signs of toxicity were observed during and after the 28 days of treatment. This extract also induced a decrease in the atherogenic index of plasma and creatininemia at all tested doses, and a reduction in alanine aminotransferase at a dose of 200 mg/kg BW. This dose also increased in hematocrit and mean corpuscular hemoglobin, number of red blood cells and relative weight of the ovaries in the female. The phytochemical analysis of the extracts revealed the presence of fatty acids (methyl palmitate, methyl stearate, methyl linolenate, methyl linoleate, methyl oleate, methyl eicosanoate, methyl tridecanoate, methyl (E) hexadec-2-enoate, methyl decanoate, methyl linolelaidate, methyl tetradecanoate, methyl 12-methyltetradecanoate, (Z) -Methyl hexadec-7-enoate, methyl docosanoate, methyl 8- (2-hexylcyclopropyl) octanoate, methyl tetracosanoate, methyl pentadecanoate, methyl arachidate, methyl linoleate, methyl (9E 9-dodecenoate, methyl 11,14-eicosadienoate, methyl cis-10-heptadecenoate), terpenoids (phytol, squalene, isocaryophyllene, neophytadiene, Myrcenol) and phytosterols (β-sitosterol). All these results suggest that aqueous and methanolic extracts of the leaves of M. arboreus could improve fertility in women through many effects on the reproductive system. In addition, there would be a large margin of safety for the traditional sub-acute use of the aqueous extract of M. arboreus in women.