Plant products impairing fertility of animals.

Fertility is possibly the most important capability contained within living cells or species. Therefore, finding the most efficacious way to enhance or promote fertility is the main goal of all living things. To best manage nature's strong predisposition for fertility, plant-based traditional medicines for birth control have long been incorporated into medical practices throughout the world, including those in the rural populations of North-East India, China, and Africa. In this issue of the Journal of the Chinese Medical Association, Muhammad and Muhammad published a very interesting review article entitled “Anti-fertility activity of medicinal plants,” introducing >60 species of plants that might possess antifertility activity. This article divided these antifertility plants into five categories, namely, plants exhibiting antiovulation activity, anti-implantation activity, antispermatogenic activity, antifertility activity by interfering with the action of hormones, and finally abortifacient activity. The authors claimed to have provided a comprehensive summary of medicinal plants from the literature, including results from Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and PubMed searches using terms such as antifertility, anti-implantation, antiovulation, and antispermatogenic activity of plants. We applaud the authors on the success of this article, because their research and information-gathering task were not easy. However, given the size of the project that they undertook, it goes without saying that their review ultimately will omit certain important data. For example, information about the extract of Drynaria quercifolia (L.) J. Smith rhizome was missed in their review. This extract was proven to possess significant antifertility activity, not only showing a high efficacy for both abortifacient and anti-implantation activities, but also affecting sexhormone release. In addition, the presence of an “adjuvant reagent,” including that in solutions or solvents, could influence the final effect of antifertility activity of these medicinal plants. As noted earlier, the methanol extract of D. quercifolia (L.) J. Smith rhizome has shown higher efficacy for both abortifacient ( p < 0.01) and anti-implantation performance ( p < 0.01) than its aqueous extract dose. Furthermore, the effect of plant-derived products on antifertility may be dose dependent, reversible, and sex dependent. For example, Shaik and colleagues demonstrated the antifertility potential of methanolic leaf extract of Artemisia vulgaris, which showed a strong and significant decrease in implant formation