Preface

Aflatoxin B1, a class-chemical carcinogen mainly produced by *Aspergillus flavus*, has noticeable toxicity because of its organophilism, mutagenic features, and carcinogenicity. Progression in understanding aflatoxin B1 has greatly improved with new techniques in genome sequencing and the development of molecular methods and tools that enable rapid molecular and genetic analyses for individual genomes. Especially, the genetics of aflatoxin B1 biosynthesis is regarded as a model to gain insight into fungal metabolism. This book reviews a number of important topics related to aflatoxin B1.

This book consists of 11 chapters, divided into four parts. The chapters are written by experts in the field of aflatoxins. Select topics are presented here to provide a snapshot of current understanding of the occurrence and metabolism of aflatoxin B1, the contamination, exposure, and detection of aflatoxin B1, and the toxicological effects and detoxification of aflatoxin.

The first part, Chapters 1–4, is devoted to the occurrence of aflatoxin B1, focusing on its chemistry, biological metabolism, and food exposure and control. In the first chapter, Joseph Owuor Lalah et al. review the chemistry, synthesis, analysis, and identification techniques, production conditions, and exposure information of aflatoxin B1 in Kenya. The second chapter by Nancy Nleya et al. illuminates aflatoxin occurrence in dairy feeds on the basis of analyses from a case in Bulawayo, Zimbabwe. Adekunle Odunayo Adejuwon et al. in the third chapter describe the potential value of aflatoxin B1-producing toxigenic strains of *Aspergillus flavus*, *Aspergillus parasiticus*, *Penicillium citrinum*, and *Penicillium rubrun*. Interestingly, their findings provide an important method for the industrial production of α-amylases. In the fourth chapter, Yamina Ben Miri et al. systematically review prevention by essential oils of the occurrence and growth of *A. flavus* and aflatoxin B1 production in food systems.

The second part of the book consists of Chapters 5 and 6 and deals with an updated view of aflatoxin B1 detection. In the fifth chapter, Xing-Zhizi Wang summarizes and evaluates the detection methods for aflatoxin B1, including enzyme-linked immunosorbent assay, high-performance liquid chromatography, and thin-layer chromatography. The sixth chapter by Qin-Qin Long et al. displays the effects of the aflatoxin B1-DNA adduct in the nucleus from peripheral blood white cells on the risk and prognosis of hepatocellular carcinoma investigated via a hospitalbased case–control study. In their study, they collected relatively large samples without hepatitis virus B or C infection, including 380 patients with pathologically diagnosed hepatocellular carcinoma and 588 controls without any evidence of hepatic diseases. Their results show that the increasing amount of blood aflatoxin B1-DNA adducts significantly increase the risk and poor outcome of hepatocellular carcinoma. This is indicative of the serum aflatoxin B1-DNA adducts acting as a potential valuable detection method for aflatoxin B1.

The third part, consisting of Chapters 7–10, discusses the toxifications of aflatoxin B1 and particularly focuses on genic toxification, cytotoxicity, carcinogenicity, and

**II**

**Section 3**

*by Yuhua Shan*

**Section 4**

*by Qian Yang*

in Human: An Update *by Qun-Ying Su*

The Toxic Effects of Aflatoxin B1: An Update

The Carcinogenicity of Aflatoxin B1

*by Jie Li and Mengxi Liu*

in Hepatocellular Carcinoma

Decontamination of Aflatoxin B1

The Toxification Effects of Aflatoxin B1 **117**

**Chapter 7 119**

**Chapter 8 141**

**Chapter 9 153**

The Detoxification of Aflatoxin B1 **175**

**Chapter 10 177**

**Chapter 11 191**

X-Ray Repair Cross Complementing 4 (XRCC4) Genetic Single Nucleotide Polymorphisms and the Liver Toxicity of AFB1

The Toxification and Detoxification Mechanisms of Aflatoxin B1

*by Yan Deng, Xue-Min Wu, Xiao-Ying Huang and Xi-Dai Long*

liver injury. The seventh chapter by Yuhua Shan summarizes the toxicity and toxic mechanisms of aflatoxin B1 as well as detoxification of aflatoxin B1. The eighth chapter by Jie Li et al. summarizes recent literature involving aflatoxin B1's carcinogenicity, including the metabolism of aflatoxin B1 and DNA damage such as adduct formation, oxygenic damage, genic mutations, and genetic alteration. They also discuss how aflatoxin B1 results in abnormal DNA repair and reactive oxygen species depression, and explore all known biomarkers for predicting aflatoxin B1's carcinogenicity. The following chapter by Yan Deng et al. shows an important molecular mechanism: the different modificative effects of genetic singlenucleotide polymorphisms (GSNPs) in DNA repair gene XRCC4, using hospitalbased clinical sample analysis. In their study, they screened a total of 143 GSNPs in the coding regions of XRCC4 and ultimately five SNPs (rs1237462915, rs28383151, rs762419679, rs766287987, and rs3734091) were confirmed to significantly alter the hepatoxic effects of aflatoxin B1. Particularly, they also found that some XRCC4 GSNPs (rs28383151, rs766287987, and rs3734091) modified the prognosis of patients with hepatocellular carcinoma.

The last part includes Chapters 10 and 11 and covers detoxification methods and corresponding mechanisms. In the eleventh chapter, Qian Yan reviews all known methods for aflatoxin B1 decontamination, including physical methods (e.g. cleaning and segregation, heating, microwave heat treatment, irradiation, electrolyzed water treatment, and pulsed light technology), chemical methods (e.g. ammonia decontamination treatment, hydrochloric acid treatment, lactic acid and citric acid treatment, and ozonation), biological methods (e.g. soil bacteria, fungi, yeasts and lactic acid bacteria, enzymes, and cold plasma technology), the sorbent additives method, and so on. In the twelfth chapter, Qun-Ying Su summarizes all significant detoxification mechanisms of aflatoxin B1 in the human body.

Together, the chapters in this book are a collection of contemporary works on aflatoxin B1 occurrence, detection, and toxification. Although not every topic in aflatoxin B1 could be reviewed or discussed in this book, I do believe that the authors have done an outstanding job and that it is helpful for readers who wish to become more familiar with the corresponding fields.

The editor wishes to acknowledge Ms. Kristina Kardum for her tireless efforts in collecting and organizing all of the manuscripts from our illustrious contributors.

> **Xi-Dai Long, PhD** Professor, Diagnostic and Research Center of Clinic-Pathology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Bose, China

> > **1**

Section 1

Aflatoxin B1 Occurrence

Section 1
