Quillaja saponins inhibit tilapia aromatase activity in vitro

Growing monosex, all-male population of fish is highly desirable in some species in aquaculture, including tilapia, due to higher growth rates of males, better coloration and as a mean of controlling reproduction. The most widespread method for producing monosex populations in fish is administration of exogenous synthetic androgens in the feed during the critical period of sexual differentiation. The present study designed to investigate the possibility of natural saponins derived from Quillaja saponaria to inhibit aromatase activity, and isolate the most promising saponins for future in vivo sex inversion trials. The in vitro aromatase activity assay was based on the tritiated water assay using microsomes isolated from ovaries of previtellogenic females. Quillaja extract was separated on a column and fractions containing saponins were visualized and stained using TLC, collected, dried and redissolved in ethanol. In accordance with the staining of TLC plates with either sulphuric acid or anisealdehyde, that showed highest concentration of saponins in the 80% ethanol eluate, saponins proved to be the active chemical identities that are most potent in inhibiting aromatase activity and thus was assumed to be most promising for masculinization treatments.