Preparation and Biological Evaluation of Novel Osthole-Derived N-Benzoylthioureas as Insecticide Candidates

Abstract

To discover novel natural-product-based insecticide candidates, herein, a variety of osthole-derived Nbenzoylthioureas were synthesized and assessed for their insecticidal activities against three insect pests. An insecticidal assay showed that most of the target osthole-derived N-benzoylthioureas displayed a more potent and broad-spectrum insecticidal effect than the parent osthole after the introduction of N-benzoylthioureas on the C-3′ position of osthole. Compound B24 displayed the most potent growth inhibitory (GI) effect on Mythimna separata Walker, with a final corrected mortality rate of 82.1% when treated with a concentration of 1 mg/mL, which was 1.64-and 1.53-fold higher in comparison to osthole and the botanical insecticide toosendanin, respectively. Compounds B22, B23, and B25 displayed a more promising aphicidal effect on Myzus persicae Sulzer, and their LD 50 values were 0.015, 0.017, and 0.019 μg/larvae, respectively, superior to the commercially available insecticide rotenone (0.024 μg/larvae). Derivatives B19, B20, B23, and B25 displayed more potent larvicidal activity against Plutella xylostella Linnaeus, with LC 50 values of 0.22, 0.26, 0.15, and 0.30 mg/mL, respectively, exceeding that of rotenone (0.37 mg/mL). Furthermore, both compounds B19 and B23 against P. xylostella were found to be more effective than rotenone in a control efficacy assay under greenhouse conditions. The structure−activity relationship (SAR) suggested that osthole-derived N-benzoylthioureas are more active in most cases when the R group is an electron-withdrawing group than when it is an electron-donating group, especially for halogenated groups. Additionally, the potent compounds B19 and B23 possessed good selectivity and were less toxic to non-target organisms. This study suggests that these osthole-derived N-benzoylthioureas could be further studied in depth as eco-friendly natural product pesticides in crop protection.

Natural Sesquiterpene Lactone as Source of Discovery of Novel Fungicidal Candidates: Structural Modification and Antifungal Activity Evaluation of Xanthatin Derived from Xanthium strumarium L

“…Moreover, compound 8 was condensed with 2-bromoacetophenone to generate compound 10 containing a phenylthiazole moiety. The C-4 carbonyl group of xanthatin was reduced with sodium borohydride to afford xanthatinol (11). Intermediate 11 reacted with carbon disulfide and methyl iodide in the presence of sodium hydride to provide carbonodithioate 12.…”

“…Among the many possible solutions, natural products (NPs) from plants usually provide an abundant source for developing new chemical entities or lead compounds in the agrochemical and pharmaceutical industries. , Meanwhile, the newly discovered pesticides based on plant secondary metabolites as templates or pharmacophores often demonstrate excellent biological performance, good environmental compatibility, relative safety for mammals, generally satisfactory development success rate, and other benefits. – Therefore, this approach has become one of the essential sources of inspiration for chemists to develop novel pesticidal candidates in recent years. , …”

“…8−10 Therefore, this approach has become one of the essential sources of inspiration for chemists to develop novel pesticidal candidates in recent years. 11 Natural sesquiterpene lactones (STLs) are a large group of small molecules with multiple biological properties, 13 mainly distributed in Asteraceae plants, many of which can be used as clinical chemotherapeutic agents (Figure 1). Among them, xanthatin (1, Figure 2) is a natural STL-bearing 5,7-fused ring system, which widely exists in the aerial parts of various species in the genus of Xanthium plants (composite family).…”

“…When the reaction was complete after 0.5 h, the solvent was concentrated in vacuo. Saturated brine (30 mL) was added to the above residue, then the mixture was extracted with EtOAc (60 mL × 3), and the combined organic phase was dried over anhydrous Na 2 SO 4 , concentrated in vacuo, and purified by PTLC to get the intermediate xanthatinol (11) in a 72% yield.…”

Recent Advances and Outlook of Benzopyran Derivatives in the Discovery of Agricultural Chemicals

“…In recent years, benzopyran active compounds have attracted more and more attention in the discovery of new agricultural chemicals, especially osthole and coumarin. − A systematic and comprehensive review of benzopyran active compounds in the discovery of new agricultural chemicals is helpful to promote the discussion and development of benzopyran active compounds. Therefore, we systematically reviewed the progress and application of benzopyran active compounds in the development of new agricultural chemicals and discussed their antiviral, herbicidal, antibacterial, fungicidal, insecticidal, nematcidal and acaricidal activities.…”