In vitro and in vivo safety evaluation of Nephure™

Helena Cowley,Qin Yan,Lee Koetzner,Laurie Dolan,Erik Nordwald,Aaron B Cowley

doi:10.1016/j.yrtph.2017.03.016

Abstract

Nephure™ is a proprietary oxalate decarboxylase (OxDC) enzyme being developed as a food ingredient. In this study, the safety of Nephure™ was evaluated in a bacterial mutagenicity assay and in a sub-chronic (13-week) oral toxicity study in rats. Nephure™ did not show any mutagenic properties in the mutagenicity assay. In the 13-week sub-chronic oral toxicity study in which 10 Sprague Dawley rats per sex were administered 0, 118, 235 and 475 mg/kg bw/day (8260, 16450 and 33,250 Units/kg bw/day, respectively) of Nephure™ by gavage, male and female rats did not show any test article-related clinical observations or effects on body weight, body weight gain, food consumption, food efficiency, ophthalmology, functional observational battery parameters or motor activity. Furthermore, there were no changes in coagulation, clinical chemistry, urinalysis or hematology parameters, macroscopic/microscopic findings or organ weights that could be attributed to the test article. Based on these results, Nephure™ was not mutagenic and the no-adverse-effect level (NOAEL) in the 13-week study was determined to be 475 mg/kg bw/day (33,250 Units/kg bw/day). Evaluation of the estimated consumption of Nephure™, generation of the metabolite formate, and the current safety studies resulted in a conclusion of a tolerable upper limit of 3450 Units of OxDC activity/day (57.5 Units activity/kg bw/day), when Nephure™ is added to food to decrease dietary oxalate.

Highlights

Oxalate is normally produced in plants, primarily in the leaves, nuts, fruits, and bark
NephureTM is a proprietary oxalate decarboxylase (OxDC) enzyme being developed as a food ingredient to degrade oxalic acid in food, reducing the concentration of oxalate available to cause anti-nutritional or toxicological effects
The results of the studies described in this manuscript show that NephureTM is not genotoxic and is not toxic to Sprague Dawley rats at the dose levels provided

Summary

Introduction

Oxalate is normally produced in plants, primarily in the leaves, nuts, fruits, and bark. The content of oxalate is high in many plant foods, including vegetables, cereal grains, nuts, beans and beverages. Oxalate concentrations (mg/100 g) in fresh spinach, dried soy beans, dried peanuts, and dried wheat bran are 400e900 mg, 82e214 mg, 96e705 mg and 457 mg, respectively (Massey, 2007). Oxalate intake is typically 80e120 mg/day; it can range from 44 to 350 mg/day in individuals who eat typical Western diets (Holmes and Kennedy, 2000). Oxalate content can vary widely within the same plant species due to growth seasons, soil and water conditions (Massey, 2007; Holmes and Kennedy, 2000)

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Discussion

Conclusion