Physical and chemical preservatives such as ultraviolet and

Physical and chemical preservatives such as ultraviolet and ɣ-rays irradiation, sulphur and aluminium phosphide fumigation, etc, have been introduced to inhibit the growth of fungi. Nevertheless, due to the potential decomposition reactions and residues, as well as their own potential toxicity, and potential undesirable biological effects on human health, these strategies have been forbidden in many official documents (da Cruz Cabral et al., 2013; Li et al., 2016; Prakash et al., 2015). Recently, some plant essential YC 1 (PEOs) and their active components with strong and broad-spectrum antifungal properties as the succedaneums to protect foods, agricultural commodities and CHMs from fungal contamination in a safe, non-residual, biodegradable and environment-friendly way have been taken into consideration in some aspects (Prakash et al., 2012a, Prakash et al., 2012b; Viuda-Martos et al., 2011). Several studies have shown the antifungal and antimicrobial properties of PEOs from Syringa Linn., Cinnamomum cassia Presl, Litsea cubeba, Cymbopogon martini, Foeniculum uulgare Mill, etc, and they were of great value in foods, cosmetics, and cigarettes (da Cruz Cabral et al., 2013; Li et al., 2016; Soylu et al., 2006; Van Haute et al., 2016; Velluti et al., 2004; Zuzarte et al., 2013). It could be concluded that most of the reported bacteria or fungi were not toxigenic and could not produce mycotoxins. The relationships of the antifungal and antimicrobial properties and the internal compositions of PEOs were not explained. In addition, the antifungal effects of PEOs from the above-listed CHMs on the toxigenic fungi such as Aspergillus flavus, Penicillium viridicatum and Aspergillus carbonarius have not been clarified from then on. Therefore, evaluation on the antifungal activities of EOs from some widely-distributed and easy-to-obtain plants on the toxigenic fungi widely-found in the foods, agricultural commodities and other CHMs matrices that are easily to be contaminated by toxigenic fungi to explore natural and highly-effective mould inhibitor is still urgently needed. As a proof of concept, this study aimed to firstly evaluate the inhibitory activities of 11 kinds of PEOs from anticipated candidates including Cinnamomum cassia Presl, Litsea cubeba, Cymbopogon martini, Thymus mongolicus Ronn, Syringa Linn., Lavendula angustifolia Mill., Foeniculum uulgare Mill, Citrus reticulata Banco, Mentha haplocalyx Briq., Allium sativum and Artemisia argyi on the toxigenic fungi of Aspergillus flavus, Aspergillus carbonarius and Penicillium viridicatum by using the modified in vitro inhibition zone assay through fumigation mode. Then, the minimal inhibitory concentrations (MIC) of the PEOs with stronger antifungal activities on the selected fungi were determined with the same method. The chemical compositions of PEOs with stronger antifungal activities were analyzed by an optimized gas chromatography-mass spectrometry (GC–MS) method. Then, the inhibitory activities of main active components in the selected PEOs were assessed and compared to elucidate the relationship between the active components and their antifungal properties. The schematic representation for this study was presented in Fig. 1. This work will provide powerful references for exploring highly-effective, safe, and economic antifungal agents including PEOs together with some active compounds with low cost and wide source for inhibiting or controlling fungal contamination and mycotoxins residue in a large number of foods, agricultural commodities and CHMs matrices with high edible or medicinal values to assure their quality and safety for clinical application.
Materials and methods
Results and discussion
Conclusions In this study, essential oils from 11 natural plants, together with their active components were evaluated regarding the antifungal activities on three toxigenic fungi including A. flavus, A. carbonarius and P. viridicatum through the determination of fungi zone diameter. The results have demonstrated that 4 PEOs of Cinnamomum cassia Presl, Litsea cubeba, Cymbopogon martini and Thymus mongolicus Ronn out of the 11 candidates expressed stronger antifungal activities and lower MICs against the three kinds of fungi, which might be related or attributed to their main active components including trans-cinnamaldehyde, citral, trans-geraniol, and carvacrol, respectively. The 4 selected PEOs and their main active components has large possibility and wide application prospect to be used as the novel natural antifungal alternatives for preventing fungal contamination and mycotoxins residues in foods, agricultural commodities and CHMs matrices. More joyfully and expectantly, the use of PEOs with highly volatile components as the natural antifungal agents is environment-friendly, easy-to-obtain, convenient and highly-effective with minimal residues in protecting a large number of matrices from fungal contamination to assure their quality and safety. Further study will focus on extending the real application of the selected PEOs in practice.