Soluble Compounds and pH Effects On Fumonisin B1 Adsorption.

Fumonisins are toxic compounds produced by fungi (mycotoxins) that often infest corn and other crops.  Mycotoxins are toxic to animals and humans and animal feeding studies have proven that some feed additives can bind mycotoxins and prevent toxicity.  Soluble compounds in feed can interfere with mycotoxin adsorption to feed additives, hence, sorbents that effectively adsorb mycotoxins from pure water might not effectively bind mycotoxins in contaminated feed.  Proteins and phytate in feed can adsorb to feed additives and might limit mycotoxin adsorption.  Fumonisin B1 (FuB1) is the most common fumonisin.  FuB1 molecules contain four carboxyls and one amine group and are, therefore, anions at neutral /alkaline pHs and cations at acidic pHs.  Proteins similarly have a pH-dependent charge.  Phytic acid and phytate organophosphates occur in feed grains (corn ~1% phytate), but are not digestable by humans or non-ruminant animals.  Phytates are multivalent anions at pHs >2 and might compete against fumonisins for feed additive adsorption sites.  Cholestyramine is an anion exchange resin that animal feeding studies have shown can adsorb fumonisins from contaminated feed and prevent toxicity.   FuB1 adsorption to cholestyramine was ~10 µg/mg from water, but only ~1.3 µg/mg from corn meal.  Cholestyramine adsorbed ~5 µg FuB1/mg from water, but only ~2 µg FuB1/mg when sodium phytate was added.  Phytate precipitation using iron or aluminum chloride restored FuB1 adsorption to no phytate levels.  Similarly, the addition of phytase enzyme or use of low-phytate grain might reduce phytate interference and enhance fumonisin adsorption to feed additives.