Stimulation of LH Release from Cultured Pituitary Cells by Saponins ofPetersianthus macrocarpus: A Permeabilizing Effect

Abstract

Aqueous extracts from stem bark of Petersianthus macrocarpus contain substances exhibiting both estrogenic and antiestrogenic potency. Triterpenic saponins were identified and extracted as a bulk. Their action on the in vitro LH released by cultured rat pituitary cells was investigated. P. macrocarpus saponins stimulated the LH release in a dose-dependent manner (from 10 micrograms/ml to 300 micrograms/ml). When added simultaneously, saponins and LHRH exerted initial additive effects on LH release, demonstrating independent mechanisms of stimulation. If cells were pre-treated with saponins for 15 min, the amount of LH released under a subsequent LHRH stimulation was lowered, presumably due to a partial depletion of the cells in hormone (data not presented). However, the action of saponins on LH release did not appear specific since a general permeabilizing effect of the cell membrane was evidenced both by trypan blue exclusion and by analysis of the total protein output. When using low concentrations of saponins (10 micrograms/ml), scanning electron microscopy did not reveal any significant alteration of the cell structure, which explains why the cells remain responsive to LHRH after withdrawal of saponins. With higher concentrations (greater than 30 micrograms/ml), the same analytical studies evidenced numerous perforations of the cell membrane, with subsequent cell death. Two highly purified saponin species were tested on LH release by cultured cells; one of them (petersaponin I) appeared responsible for the observed biological effects in vitro. But as cells were shown to be efficiently protected from saponin effects by the presence of serum, it may be concluded that saponins of P. macrocarpus extracts are probably not candidate molecules promoting the in vivo estrogenic and antiestrogenic effects.

The biological action of saponins in animal systems: a review

“…Saponins were found to be extremely strong stimulators of luteinising hormone release from cultured hypophysial cells (El Izzi et al 1989;Benie et al 1990) but their action was neutralised in the presence of serum indicating a passive membrane-permeabilising effect (El Izzi et al 1992) in this case. However, saponin-rich extracts from Combretodendron africanum injected into female rats stimulated uterine growth, lowered luteinizing hormone release, and blocked the oestrous cycle (Benie et al 1990).…”

“…A large number of the biological effects of saponins have been ascribed to their action on membranes. In fact, their specific ability to form pores in membranes has contributed to their common use in physiological research (El Izzi et al 1992;Authi et al 1988;Choi et al 2001;Menin et al 2001;Plock et al 2001). Saponins have long been known to have a lytic action on erythrocyte membranes and this property has been used for their detection.…”

Study of the action of α‐hederin on the ultrastructure of Candida albicans

“…With a higher concentration (12.5 pgml-') we noted an activity on the cell envelope involving the integration of polysaccharidic material. Saponins are known to interact with phospholipids [13] and sterols [14,15], some promoted perforations in the plasma membrane with a massive loss of proteins [ 16). Therefore saponins may have acted on Candida albicans plasmalemma and consequently on the cell wall.…”

Effects of Quillaja Saponin (Quillaja saponaria) on Early Embryonic Zebrafish (Danio rerio) Development

“…The observed toxic effects of quillaja saponin on zebrafish embryos at concentrations of more than 5 μ g/ml might be due to physicochemical (surfactant) properties (Güçlü-Ustündag and Mazza 2007) and/or membranolytic effects (Price, Johnson, and Fenwick 1987) on the chorion, which is a semipermeable protective membrane that surrounds the developing embryo until hatching at 48 to 72 hpf. Many studies have reported that quillaja saponin affects animal cell membrane permeability by forming pores in membranes (Authi et al 1988; El Izzi et al 1992; Choi et al 2001; Menin et al 2001; Plock, Sokolowska-Kohler, and Presber 2001) or by creating pores of 40 to 50 Å diameter in cell membranes of human erythrocytes (Seeman, Cheng, and Iles 1973). It is possible that the zebrafish chorion or the embryo proper is not significantly affected by exposure to low concentrations (1 or 5 μ g/ml) of quillaja saponin, because no alterations in morphology were observed in embryos exposed to these concentrations of quillaja saponin.…”