SPERMICIDAL ACTIVITY OF NONOXYNOL-9 AND ANALOGS - QUANTITATIVE ASSESSMENTS BY FLOW-CYTOMETRY

A flow cytometer-based method was developed for the quantitative asses sment of spermicidal action of nonoxynol-9 (N-9) against human sperm. Two fluorescent dyes were chosen: carboxyfluorescein diacetate (CFDA) was employed as an indicator for viable sperm, while propidium iodide (PI) identified the sperm membrane integrity disrupted by spermicidal agents. Living, motile sperm were identified by the green fluorescence of CFDA, while the red fluorescence of PI reflected the ability of th e spermicide to kill sperm. Both living and dead sperm were effectivel y resolved from the acellular components of seminal fluid. N-9 was use d as a model spermicidal agent to study the feasibility as well as est ablish the various technical aspects of this method. Further studies w ith a series of structurally-related nonoxynol analogs, using the meth od established, demonstrated that N-9 is the most effective spermicida l agent. The spermicidal activity of N-9 and analogs was also determin ed by a a computer-assisted semen analysis (CASA) method for compariso n. This conventional CASA method is designed to detect sperm motility, in contrast to the flow cytometry method which is capable of identify ing the loss of membrane integrity. A discrepancy in the concentration needed for comparable spermicidal action between these assay methods was observed, which could imply that there is a concentration dependen cy on the disruption of membrane integrity and the complete loss of mo tility.