Determination of Azole Fungicide Residues in Fresh Juice by Magnetic Solid Phase Extraction Based on Fe3O4@ZnAl-LDH@MIL-53(Al) Sorbent in Combination with High-Performance Liquid Chromatograph.

In this work, a magnetic adsorption material based on metal-organic framework (Fe3O4@ZnAl-LDH@MIL-53(Al)) was synthesized and used as an adsorbent in the process of magnetic solid phase extraction. Then, a high-performance liquid chromatograph was used to quantitatively detect triazole fungicides in samples. In order to verify the successful preparation of the material, a series of characterization analyses were carried out. Besides, the key parameters that may affect the extraction efficiency have been optimized, and under optimal conditions the three triazole fungicides showed good linearity in the range of 10-1000 µg/L (R2 ≥ 0.9796); Limit of detections were ranged from 0.013 to 0.030 µg/mL. Finally, the established method was applied to the detection of triazole fungicides in four fresh juice samples. The results showed that the target analyte was not detected in all the test samples. By detecting the recoveries (73.3-104.3%) and coefficient variation (RSD ≤ 6.8%) of triazole fungicides in fortified samples, it proved that this established method meets the requirements of pesticide residue analysis and showed excellent application potential.

Control of pathogenic fungi on Panax notoginseng by volatile oils from the food ingredients Allium sativum and Foeniculum vulgare.

To screen natural drugs with strong inhibitory effects against pathogenic fungi related to P. notoginseng, the antifungal activities of garlic and fennel EOs were studied by targeting P. notoginseng disease-associated fungi, and the possible action mechanisms of garlic and fennel EOs as plant fungicides were preliminarily discussed. At present, the antifungal mechanism of EOs has not been fully established. Therefore, understanding the antifungal mechanism of plant EOs is helpful to address P. notoginseng diseases continuous cropping disease-related obstacles and other agricultural cultivation problems. First, the Oxford cup method and chessboard were used to confirm that the EOs and oxamyl had a significant inhibitory effect on the growth of Fusarium oxysporum. F. oxysporum is the main pathogen causing root rot of P. notoginseng and the preliminary study on the antifungal mechanisms of the EOs against F. oxysporum showed that the inhibition of EOs mainly affects cell membrane permeability and cell processes and affects the enzyme activities of micro-organism, to achieve antifungal effects. Finally, an in vivo model verified that both two EOs could significantly inhibit the occurrence of root rot caused by F. oxysporum.

Biological Activities of Two Essential Oils from Pogostemon cablin and Eupatorium fortunei and Their Major Components against Fungi Isolated from Panax notoginseng.

Panax notoginseng (Burkill) F.H.Chen (Araliaceae), of which the dry root and rhizome are precious traditional Chinese medicine, suffers severely from diseases during planting. Essential oils (EOs) with antimicrobial activity are a possibility for the development of green pesticides. We extracted EOs from Pogostemon cablin (Blanco) Benth. and Eupatorium fortunei Turcz., respectively and tested their inhibitory rates on fungi isolated from diseased P. notoginseng by the Oxford cup method. The compounds of the EO were identified by GC/MS and the minimum inhibitory concentrations (MICs) of the EOs and their main components were evaluated by the 96-well plate method. We also mixed P. cablin EO, E. fortunei EO and hymexazol in pairs to explore whether their combinations produce stronger antifungal effects than individual components. Finally, we evaluated the effects of the EOs against Fusarium oxysporum in vivo. P. cablin EO and E. fortunei EO exhibited different antifungal activities against fungi, with the inhibitory rates of 21.02 %-100 % and 54.84 %-100 % and MICs of 0.07-0.88 mg/mL and 0.20-1.17 mg/mL, respectively. Pogostone (24.96 %) and thymol (15.64 %) were the major compounds of P. cablin EO and E. fortunei EO, respectively, and they exhibited stronger antifungal activities than EOs, with MICs of 0.008-0.078 mg/mL and 0.12-0.31 mg/mL, respectively. Moreover, hymexazol was mixed with E. fortunei EO, and the inhibitory effect against Cylindrocarpon destructans was enhanced with a synergistic effect. The disease incidence and disease index of EO treatments decreased significantly in vivo. Based on our study, P. cablin EO and E. fortunei EO have great potential to be developed into green fungicides for use in agriculture to control diseases of P. notoginseng.