Antimicrobial Saponins of Yucca schidigera and the Implications of Their in Vitro Properties for Their in Vivo Impact

Abstract

The benefits of supplementing livestock diets with extracts from Yucca schidigera have been attributed to inhibition of selected gut microbes. The antimicrobial constituents were identified as three butanol-extractable 5β-spirostan-3β-ol saponins using Bacillus pasteurii and Saccharomyces cerevisiae as test prokaryotic and eukaryotic organisms, respectively. Although these saponins inhibited microbial growth at low cell densities, their impact was associated with adsorption to the microbes and they had no effect on dense microbial populations. The antimicrobial saponins were also observed to adsorb to the microbiota and other solids of the porcine cecum. The implications for gut microbes differ according to their ecological niche: Those sequestered to feed particles or the gut lining may accumulate saponins, whereas those flushed out synchronously with the digesta should be protected by high population densities.

Phytoconstituent screening and antimicrobial principles of leaf extracts of two variants of Morus alba (S30 and S54)

“…Though, alkaloids, phenolic compounds and flavonoids were present in limited amount. Each of this group of compounds has been reported to possess antimicrobial activity (Ragasa et al, 2005;Cuhnie and Lamb, 2006;Soetan et al, 2006) and reportedly exert their effects by affecting the cell membrane integrity of the bacteria (Hendrich, 2006;Trombetta et al, 2005;Killeen et al, 1998).…”

Antibacterial and antifungal activities of different parts of Tribulus terrestris L. growing in Iraq

“…The toxicity of saponins to insects (insecticidal activity), parasite worms (anthelmintic activity), molluscs (molluscicidal), and fish (piscidal activity), and their antifungal, antiviral, and antibacterial activities are well documented (Lacaille-Dubois and Wagner, 1996;Milgate and Roberts, 1995). The mode of action of antibacterial effects of saponins seems to involve membranolytic properties, rather than simply altering the surface tension of the extracellular medium, thus being influenced by microbial population density (Killeen et al, 1998).…”

Use of ‘natural’ products as alternatives to antibiotic feed additives in ruminant production

“…Methanogen RNA concentration was also affected and bottomed at the saponin concentration of 4 mg/ml. Because of the strong inhibiting effect of saponins on S. cerevisiae (Killeen et al, 1998), it is strongly recommended that saponins not be used in association with yeast-based probiotics.…”

“…Some of the antimicrobial compounds have been identified as three butanol-extractable 5b-spirostan-3b-ol saponins (Killeen et al, 1998), which are thought to alter bacterial membranes by increasing their porosity (Schulman et al, 1955;Wang et al, 2000). The foaming property of saponins increases the surface tension of the bulk solution and accelerates lysis of microbial cells with weakened membranes.…”

“…They are used to reduce environmental pollution due to odoriferous manures from animal sheds by decreasing release of NH 3 to the air through the mechanism already described for the rumen (Killeen et al, 1998). Also, the antiprotozoal property of saponins could be exploited in the treatment of protozoal infections in ruminants such as Giardia ) and Plasmodium (Traore et al, 2000).…”