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Robert R Maronpot, Adam M Leggett, Douglas A Donahue, Shim-mo Hayashi, and William Breslin
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An embryo-fetal survival and development study was conducted to augment the toxicity database for alpha-glycosyl isoquercitrin (AGIQ), a generally recognized as safe (GRAS) additive and flavor in food and beverages. In Phase I, 24 naturally mated New Zealand white (NZW) female rabbits per group were administered AGIQ by oral gavage at 0, 250, 500, or 1000 mg/kg/day once daily during gestation days 6–28, followed by necropsy. There was no evidence of maternal or fetal toxicity except for equivocal findings of unilateral absent kidney and ureter in one and two unrelated fetuses at 500 and 1000 mg/kg/day, respectively. To more thoroughly assess fetal kidney/ureter development, in Phase II groups of time mated NZW rabbits were administered AGIQ at 0, 500, or 1000 mg/kg/day, under the same conditions as Phase I. No occurrences of absent kidney/ureter were noted in the AGIQ-treated Phase II dams or fetuses; although, one control fetus had unilateral missing kidney/ureter. Given the lack of reproducibility following treatment with AGIQ in Phase II using 48 animals per group, the missing kidney/ureter observations in Phase I were considered unrelated to treatment. Since oral gavage administration of AGIQ to pregnant female NZW rabbits at dose levels of 250, 500, or 1000 mg/kg/day was well-tolerated with no adverse treatment-related effects on the maternal animal, pregnancy, or the developing conceptus, the no-observed-adverse-effect-level (NOAEL) for maternal toxicity and embryo-fetal survival, growth, and development was 1000 mg/kg/day.

Alpha-glycosyl isoquercitrin (AGIQ) (Figure 1) is an enzymatically modified form of the natural flavonol isoquercitrin (quercetin-3-O-ß D-glucoside), derived from rutin and used in Japan as an additive or flavor ingredient in various beverages and foods. Although quercetin and its glycosides have demonstrated anti-inflammatory, pain-reducing, and cardioprotective properties1–6 and therefore have been promoted as antioxidant dietary supplements to consumers, their poor miscibility in water and limited absorption have hindered their broad application to the food and beverage industry.7 However, the enzymatic modification resulting in AGIQ has been shown to enhance the solubility and bioavailability of isoquercitrin.8,9

Figure 1. Chemical formula of alpha-glycosyl isoquercitrin.

Previous toxicity assessments have shown that AGIQ is safe, non-carcinogenic, and non-genotoxic,5,7,10–13 but some of the earlier studies used incompletely characterized AGIQ and/or did not adhere to current Good Laboratory Practice (GLP).6,10,12,13 Due to the current effort to expand the use of AGIQ in the consumer food and beverage industry, recent GLP-compliant studies of high-purity AGIQ (including comprehensive genotoxic assessment,7 10-day and 4-week studies in preweaning Göttingen minipigs,14 and a 90-day study in rats)5 were conducted to augment the older toxicity database. These studies have generally confirmed the safety profile of AGIQ.

The current study using highly purified AGIQ and New Zealand White (NZW) rabbits was conducted to assess the potential effects of the compound on embryo-fetal development, growth, and survival in a non-rodent species for registration purposes. The objective of the initial dose-response phase of the study (Phase I) was to assess the potential of AGIQ to induce prenatal developmental toxicity after maternal exposure via oral gavage during the critical period of organogenesis and fetal development. A subsequent investigational phase (Phase II) was conducted using 48 animals in each group to verify equivocal Phase I findings of unilateral absent fetal kidney/ureter in one and two (unrelated) fetuses at the mid and high dose levels, respectively. This study provides a base of non-rodent developmental toxicity data obtained in accordance with current developmental toxicity testing guidelines (Phase I)15–17 and GLP (both phases)18–21 for human risk assessment of orally administered AGIQ.