Extraction and purification of ustiloxin A from rice false smut balls by a combination of macroporous resin and high-speed countercurrent chromatography

Gang Wang,Junqiang Hu,Dan He,Jianhong Xu,Jianrong Shi,Fengchun Zhao,Yin-Won Lee

doi:10.1186/s43014-020-00043-9

Abstract

Rice false smut is an emerging plant disease worldwide. Ustiloxin A (UstA) is the major mycotoxin found in rice false smut balls, which are fungal colonies in rice florets. In this study, a new method consisting of macroporous resin column chromatography and high-speed countercurrent chromatography (HSCCC) was developed for UstA separation. UstA was extracted by a 3.81% HCOOH solution and adsorbed by XAD-4 resin. UstA was then eluted by a 40% methanol solution supplemented with 0.1% trifluoroacetic acid (TFA). Further purification was achieved by HSCCC using a two-phase solvent system consisting of n-butanol/TFA/H2O (1/0.05/1, v/v/v). Under the optimized conditions, 225 mg of UstA was obtained with a purity of 97.39% in a single run, with a final recovery of 65.2%. An inhibitory effect on seed germination of wheat and maize caused by UstA was observed in a preliminary phytotoxicity assay.Graphical abstract

Highlights

Rice false smut is a plant disease caused by the fungal pathogen Ustilaginoidea virens Takahashi, which is rapidly emerging in rice cultivation worldwide (Qiu et al 2019)
Optimized conditions for Ustiloxin A (UstA) extraction from rice false smut balls Six kinds of solvents were tested in this study for the extraction of UstA from rice false smut balls, namely, deionized water, 1% HCOOH, 1% NaOH, 1% methanol, 1% ethanol and 1% EtOAc aqueous solution
To avoid adverse effects on the subsequent isolation caused by the excessive acidity, the HCOOH concentration was set at 1% for UstA extraction

Summary

Introduction

Rice false smut is a plant disease caused by the fungal pathogen Ustilaginoidea virens Takahashi, which is rapidly emerging in rice cultivation worldwide (Qiu et al 2019). There are two main types of mycotoxins in rice false smut balls, Ustiloxins were found in almost every rice crop infected by U. virens and some high ustilotoxin-producing strains were separated from the false smut ball (Lin et al 2018). Wang et al Food Production, Processing and Nutrition (2020) 2:29 contamination an emerging threat to food safety. Both the toxicological study and the risk assessment of UstA require a significant amount of the purified substrate. No purification methods of pure UstA from rice false smut balls have been previously reported. The direct extraction and purification of UstA from rice false smut balls are worthy of further investigation

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Discussion

Conclusion