The Mexican plant zoapatle (Montanoa tomentosa) in reproductive medicine: past present and future.

The Mexican plant zoapatle (Montanosa tomentosa) and its use as an herbal medicine is described and the research that has been conducted on the plant is reviewed. In addition possible future medical uses of the natural product or analogs derived from it are projected. The zoapatle plant a branch shrub about 1-3 meters high and with heart-or-arrow shaped leaves is still sold in the markets of Mexico City. Studies near the turn of the century trying to characterize the composition of the plant revealed the presence of potassium calcium magnesium iron and sodium salts among the inorganic portion. The organic materials included chlorophyll gum pectin neutral and acidic resins glucose a neutral substance with a bitter taste and alkaloids. There was considerable confusion about which of those substances might be responsible for the plants uterotonic or oxytocic effect. Studies conducted in the 1970s ultimately led to the isolation and identification of 2 chemically novel and biologically active oxepane diterpenoids zoapatanol and montanol. The process that led to successful isolation of these 2 diterpenes began with the centuries-old preparation of a tea by extracting zoapatle leaves with hot water for several hours. Following filtration through gauze the clear and dark tea was extracted with a series of solvents to afford the crude extract. Gas chromatographic analysis of the extract revealed that it was a multicomponent mixture. Gas chromatography of the semipurified extract indicated the presence of 3 materials (triplet) with the major component being zoapatanol. Although separation of this triplet material was difficult it was finally achieved by chromatography. In this manner small samples of both zoapatanol and montanol were obtained as oils. Except for decreased spontaneous activity no untoward side effects were observed with the various zoapatle preparations during any of the reproductive studies conducted. These observations were later confirmed when triplet material was administered orally to pregnant guinea pigs rats and mice. In early 1977 Gallegos and Cortes-Gallegos reported that the oral administration of concentrated tea made from zoapatle leaves to normal menstruating women in the luteal phase produced a luteolytic effect. More recently Landgren et al. reported that when a similar preparation was administered orally to women in the 6th to 7th week of pregnancy no luteolytic properties could be detected. The utility of zoapatanol or its analogs as a contragestational agent should be studied. Other areas of utility are its potential for uterine evacuation in cases of intrauterine death management of hydatidiform moles and control of postpartum hemorrhage resulting from uterine atrophy.