Rational design and synthesis of l-carvone-derived 4-methyl-1,2,4-triazole-thioether/nanochitosan complexes as potent nanopesticides for sustainable and efficient herbicidal application

Abstract

Natural product-based nanopesticide is an effective and sustainable approach for solving the environmental issues caused by the application of current commercial herbicides. In this work, 21 novel L-carvone-derived 4-methyl-1,2,4-triazole-thioether derivatives...

An Effective and Promising Strategy for Plant Protection: Synthesis of L-Carvone-Based Thiazolinone–Hydrazone/Nanochitosan Complexes with Antifungal Activity and Sustained Releasing Performance

“…For designing a carrier for the sustained release of the antifungal compound, L-carvone and 1,3,4-thiadiazole-amide moieties were both introduced into the skeleton of chitosan. In our previous work [8], the original skeleton of the L-carvone moiety has been proven to be effective for improving the dispersibility and hydrophobicity of chitosan. Furthermore, both of the 1,3,4-thiadiazole-amide and thiazolinone-hydrazone groups possessed a five-membered heterocycle containing N and S atoms, along with amido linkage, and thus we envisioned that the 1,3,4-thiadiazole-amide group could further increase the dispersibility of the carrier and its interaction with compound 4h because of the similarity of the 1,3,4-thiadiazole-amide and thiazolinone-hydrazone groups.…”

“…As illustrated in Scheme 2, an L-carvone-based nanochitosan carrier 7 bearing the 1,3,4thiadiazole-amide group was synthesized through the chemical modification of chitosan. Firstly, L-carvone chloride 5 was obtained by the method described in previously published papers [8,25]…”

“…For exploring novel nano-pesticides with sustained releasing properties, L-carvonebased thiazolinone-hydrazone/nanochitosan complexes were fabricated by the reported method [8]. Compound 4h with antifungal activity was loaded on L-carvone-based nanochitosan carrier 7 bearing the 1,3,4-thiadiazole-amide group in three different mass ratios of 7/4h to obtain three complexes: 7/4h-1, 7/4h-2, and 7/4h-3, respectively.…”

“…The inhibitory rates of the tested compounds were calculated by comparing the expanded mycelium diameters in every treatment group and control check. L-Carvone chloride 5 was prepared according to the literature [8,25]. To a mixture of 5-amino-1,3,4-thiadiazole-2-thiol (2.00 g, 15.0 mmol) and potassium hydroxide (0.89 g, 15.9 mmol) in ethanol (20 mL) and water (5 mL), a solution of L-carvone chloride 5 (2.59 g, 14.0 mmol) in ethanol (10 mL) was added dropwise, and then the reaction mixture was stirred at room temperature for 12 h. After the reaction was completed, the mixture was extracted with ethyl acetate (30 mL × 3), and the combined organic layer was washed with a saturated sodium chloride solution (30 mL).…”

“…Nevertheless, the long-term employment of the current commercial fungicides has caused the development of fungi resistance and the running-off of bioactive components into the surrounding environment (e.g., soil and air), which would further result in the low efficiency of the fungicides in protecting plants and irreversible environmental pollution [1,2]. The development of nano-pesticide systems with high loading capacity for bioactive compounds and desirable sustained releasing performance is considered an effective, emerging, and promising strategy for improving the utilization efficiency of fungicides [3][4][5], and the construction of a complex containing a natural product-based bioactive compound and a corresponding polysaccharide carrier has also proven to be an ingenious design strategy for novel nano-pesticide systems [6][7][8].…”