The Mechanism of Ochratoxin Contamination of Artificially Inoculated Licorice Roots

Mechanism of Mycotoxin Contamination of Medicinal Herbs

Mycotoxin contamination in medicinal plants can lead to toxicity, reduced therapeutic efficacy, and economic losses. This contamination has emerged as a significant issue, drawing attention from researchers and research centers worldwide. Over recent decades, numerous analytical studies have addressed mycotoxin contamination in these herbs, evaluating various methods to determine their presence quantitatively and qualitatively. While several reviews have summarized these studies, they often overlook a comprehensive exploration of the mechanisms and influencing factors of mycotoxin contamination in medicinal herbs. Therefore, this review aims to delve into the mechanisms of aflatoxin and ochratoxin contamination in some of the most widespread medicinal herbs, including jujube fruits, lotus seeds, and licorice roots. The factors influencing these mechanisms were also examined, including the physical composition and maturity stages of the herbs. This review concluded that aflatoxin and ochratoxin A contamination of medicinal herbs involves complex interactions between the herbs' natural defenses, fungal pathogenicity, chemical composition, physical characteristics, and individual plant differences at various maturity stages. Understanding these mechanisms of contamination, and their association with maturity, nutrient profile, and physical development, advances our comprehension of mycotoxin contamination in medicinal herbs.

Susceptibility and Mechanism of Aflatoxin Contamination of Ziziphus jujuba var. spinosa

The susceptibility and mechanism of aflatoxin (AF) contamination in Ziziphus jujuba var. spinosa, whose seeds are important for medicinal use, were evaluated in this study. First, the susceptibility of intact fruits, classified into four maturity groups, to AF accumulation was assessed through artificial contamination with an aflatoxigenic Aspergillus flavus strain. AF analysis revealed that mid-mature fruits were highly susceptible to AF contamination. Next, AF accumulation in seed parts was examined by artificially inoculating A. flavus on intact fruits, showing AF presence in seeds after 30 days of incubation. The susceptibility of jujube kernels to AF accumulation in seed parts was then studied. The artificial inoculation of A. flavus on kernels, classified into three groups based on the pedicel condition, showed no correlation between AF contamination and the pedicel condition, with large fluctuations within each group. Finally, the effect of the hilar region morphology on AF contamination in seeds was investigated. The microscopic investigation of artificially contaminated seeds and AF quantification revealed that variations in AF concentration were linked to differences in the hilar region morphology.

Evaluation of the Susceptibility of Lotus Seeds (Nelumbo nucifera Gaertn.) to Aspergillus flavus Infection and Aflatoxin Contamination

The seeds of lotus (Nelumbo nucifera Gaertn.) have been used as significant medicinal and nutritional ingredients worldwide. The abundant proteins and polysaccharides in lotus seeds make them susceptible to contamination by aflatoxin (AF), a fungal toxic metabolite. This study was conducted to investigate the susceptibility of lotus seeds at different stages of ripening to AF contamination, as well as the mechanism of the contamination. Seven groups of lotus receptacles with seeds at different ripening stages (A-G, from immature to mature) were used for the experiment. Spores of Aspergillus flavus, an AF producer, were inoculated on the water-gap area of the seeds in each receptacle. Then, each receptacle was covered with a sterilized bag, and its stalk part was soaked in water containing a life-prolonging agent, after which it was kept at room temperature for 14 days. The AF content of each whole inoculated seed from the A-G groups and that of each seed part (pericarp, cotyledon, and embryo) from the D and E groups were determined using high-performance liquid chromatography. Microtome sections were prepared from the samples and observed under a light microscope and scanning electron microscope. The seeds from the A and D groups had higher AF contents than the seeds from the B, C, E, F, and G groups, indicating that the condition of the water-gap area and the development of the embryo and cotyledon parts of the seeds are associated with AF contamination.