Acrosome reaction is crucial to the penetration of spermatozoa through the zona pellucida (ZP). Glycosylation of ZP glycoproteins is important in spermatozoa-ZP interaction. Human ZP glycoprotein-3 (ZP3) is believed to initiate acrosome reaction. Recently, human ZP4 was also implicated in inducing acrosome reaction. These studies were based on recombinant human ZP proteins with glycosylation different from their native counterparts. In the present study, the effects of native human ZP3 and ZP4 on acrosome reaction and spermatozoa-ZP binding were investigated. Native human ZP3 and ZP4 were immunoaffinity-purified. They induced acrosome reaction and inhibited spermatozoa-ZP binding time- and dose-dependently to different extents. These biological activities of human ZP3 and ZP4 depended partly on their glycosylation, with N-linked glycosylation contributing much more significantly than O-linked glycosylation. Studies with inhibitors showed that both human ZP3- and ZP4-induced acrosome reactions were protein kinase-C, protein tyrosine kinase, T-type Ca2+ channels, and extracellular Ca2+ dependent. G-protein also participated in human ZP3- but not in ZP4-induced acrosome reaction. On the other hand, protein kinase-A and L-type Ca2+ channels took part only in human ZP4-induced acrosome reaction. This manuscript describes for the first time the actions of purified native human ZP3 and ZP4 on acrosome reaction and spermatozoa-ZP binding.

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Objective: To evaluate the anti-diabetic potential of leaf extract from Urena lobata (U. lobata) through dipeptidyl peptidase IV (DPP-IV) inhibitory activity. Methods: U. lobata leaf was extracted in hot water and ethanol. The activity of DPP-IV inhibitor was tested by in vitro study using gly-pro-p-nitroanilide as substrat of DPP-IV and vildagliptin, as standard reference. A product of the reactions between gly-pro-pnitroanilide and DPP-IV, was observed by microplate readers with l = 405 nm. All data were expressed as mean ± SD and the IC 50 value was determined by non linear regression curve fit. Active substances in leaf extract of U. lobata was analyzed by liquid chromatography-mass spectrometry. DPP-IV inhibitory activity of active compounds was evaluated in silico using docking server. Results: The ethanolic extract of U. lobata showed stronger DPP-IV inhibitor activity than water extract with the IC 50 values of 1 654.64 and 6 489.88 mg/mL, respectively.Vildagliptin, based on standard reference for DPP-IV inhibitor activity, has IC 50 value of 57.44 mg/mL. Based on in silico analysis, mangiferin, stigmasterol and b-sitosterol in U. lobata extract have a strong inhibitory activity on DPP-IV. Conclusions: The results showed that DPP-IV inhibitory activity of U. lobata is related to its active compounds such as mangiferin, stigmasterol and b-sitosterol.

This manuscript describes the biological activities of purified hZP glycoproteins from the native source for the first time.