Semisynthesis and insecticidal bioactivities of benzoxazole and benzoxazolone derivatives of honokiol, a naturally occurring neolignan derived from Magnolia officinalis

• Published in: Bioorganic & medicinal chemistry letters Vol. 30; no. 9; p. 127086
• Main Authors: Zhi, Xiao-yan, Jiang, Ling-yun, Li, Ting, Song, Li-li, Wang, Yi, Cao, Hui, Yang, Chun
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 01.05.2020; Elsevier
• Subjects: Animals; Benzoxazole; Benzoxazoles - chemical synthesis; Benzoxazoles - chemistry; Benzoxazoles - pharmacology; Benzoxazolone; Biphenyl Compounds - chemistry; Chemistry; Chemistry, Medicinal; Chemistry, Organic; Honokiol; Insecticidal activity; Insecticides - chemical synthesis; Insecticides - chemistry; Insecticides - pharmacology; Larva - drug effects; Life Sciences & Biomedicine; Lignans - chemistry; Magnolia - chemistry; Models, Molecular; Molecular Structure; Moths - drug effects; Mythimna separata Walker; Neolignan; Pharmacology & Pharmacy; Physical Sciences; Plant Bark - chemistry; Plant Stems - chemistry; Plutella xylostella Linnaeus; Science & Technology; Plutella xylostella Linnaeus; Benzoxazole; Honokiol; Mythimna separata Walker; Insecticidal activity; Neolignan; Benzoxazolone; DESIGN; PRODUCTS; AGENTS; INHIBITORS; PESTICIDES
• ISSN: 0960-894X; 1464-3405
• DOI: 10.1016/j.bmcl.2020.127086

Two series of 8/8′-alkylthiolbenzoxazole (5a–s) and N-alkyl/sulfonyl-benzoxazolone (7a, c–e, h, k, l, n, o–s, and 8a–e) derivatives of honokiol have been prepared and evaluated for their insecticidal activities against Mythimna separata Walker and Plutella xylostella Linnaeus. [Display omitted] Honokiol, a natural bioactive neolignan isolated from the bark and leaf of Magnolia officinalis and Magnolia obovata, exhibits many important biological properties. In continuation of our interest in discovery of the agrochemicals derived from the natural sources, thirty-seven new 8/8′-alkylthiol-benzoxazole and N-alkyl/sulfonyl-benzoxazolone derivatives of honokiol were prepared and their insecticidal activities were evaluated against the larvae of Mythimna separata Walker and Plutella xylostella Linnaeus. The results showed that eleven derivatives exhibited potent insecticidal activity against M. separata when compared with the positive control. Particularly, compound 5h displayed the most promising insecticidal activity against M. separata with the final mortality rate (FMR) of 58.6%. Meanwhile, compounds 7n (FMR = 65.3%), 7p (FMR = 61.5%), and 8c (FMR = 65.3%) demonstrated a greater insecticidal activity against P. xylostella than toosendanin, a well-known botanical insecticide. Additionally, the preliminary structure-activity relationships (SARs) were also discussed. This study indicates that these honokiol derivatives could be used as leads for the further derivation and development of the potential pesticide candidates for crop protection.