Influence of Echeveria gibbiflora DC aqueous crude extract on mouse sperm energy metabolism and calcium-dependent channels.

In traditional Mexican medicine Echeveria gibbiflora DC has been used as a vaginal post coital rinse to prevent pregnancy. The aqueous crude extract (OBACE) induced sperm immobilization/agglutination and a hypotonic-like effect, likely attributed to the high concentrations of calcium bis-(hydrogen-1-malate) hexahydrate [Ca²⁺ (C₄H₅O₅)₂•6H₂O]. Further studies showed that OBACE impedes the increase of [Ca²⁺]i during capacitation.

This study aims to show the antifertility effect of OBACE, as well as its possible mechanism of action.

In vitro, we have quantified the mouse sperm immobilization effect and the antifertility potential of OBACE. Also, we have evaluated the energetic metabolism status, assessing the ATP levels, general mitochondrial activity, and the enzymatic activity of three key enzymes of energy metabolism. Furthermore, we evaluate the ion efflux of Cl^- and K⁺, as well as the pHi in order to elucidate which channel is suitable to perform an in silico study.

Total and progressive motility notably decreased after 60 min of incubation and also the fertility rates. ATP levels and mitochondrial activity suffered a drastic decrease. Furthermore, the three enzymes decreased their activities. Neither Cl^- or K⁺ channel activities were affected at low concentrations of OBACE, nevertheless, pHi did not alkalinize. Finally, we performed an in silico analysis between Catsper channel and calcium bis-(hydrogen-1-malate) hexahydrate, which showed a possible blockade of this sperm cation channel.

All these results are useful to elucidating the effect of OBACE and to propose it as a future male contraceptive.