Utilization of in vitro bioassays to assess the effectiveness of chemisorption of aflatoxin B1 by aluminosilicates

Abstract

Sufficient evidence exists to regard aflatoxin B1 (AFB1) as a potent chemical carcinogen and mutagen. Sorption of AFB1 by selected inorganic sorbent materials as a method to control contaminated foodstuffs has been proposed. This study was designed to evaluate the effectiveness of hydrated sodium calcium aluminosilicate (HSCAS) and other inorganic sorbents in preventing the genotoxic and developmental toxicities of aflatoxin using a variety of in vitro bioassay systems. These included: (i) two microbial assays (Salmonella/mammalian microsome and Bacillus subtilis Rec bioassays) and, (ii) two developmental bioassays (Hydra attenuata and postimplantation rat whole embryo cultures). Results indicated that HSCAS significantly diminished the mutagenicity, lethal damage to DNA, and developmental toxicity associated with AFB1. Further studies were performed to determine the ability of selected inorganic sorbent materials to immobilize and remove AFB1 from contaminated peanut oil using the Ames assay. The mutation response to AFB1, was significantly decreased following HSCAS treatment, but other sorbents were not as effective. These results support the conclusion that the binding of aflatoxin by inorganic sorbent materials, may represent an effective and practical approach to the detoxification/remediation of contaminated peanut oil. HSCAS and selected inorganic sorbent materials were ranked according to their calculated chemisorption indices, binding capacities for aflatoxin Bb and mutagenicity based on the Ames assay. These same materials were further evaluated in vivo (in chickens). There was a notable difference in the tightness of the aflatoxin/sorbent binding complex. The order of ligand binding strength: HSCAS > attapulgite > kaolinite > alumina. Also, HSCAS had the highest capacity for AFB, compared to attapulgite, kaolinite and alumina. The in vivo study supported these findings. HSCAS (at a level of only 0.5% w/w in the diet of chickens) significantly diminished the loss of body weight resulting from 3.5 ppm aflatoxins, i.e., 69% protection. The other test materials were very marginal to non-effective in preventing aflatoxicosis in the chicken, compared to HSCAS. In this research, the usefulness of diverse in vitro bioassays and methods of binding analysis for the aflatoxins have been addressed. Methodologies established should facilitate the characterization and rapid prioritization of potential detoxification/remediation procedures for the aflatoxins (and other important toxins).