Stereoselective Oxidation of α-Copaene, a Fire Ant Repellent Sesquiterpene from the Essential Oil of Dipterocarpus turbinatus.

IF 3.3 2区生物学 Q2 CHEMISTRY, MEDICINAL

Journal of Natural Products Pub Date : 2024-09-27 Epub Date: 2024-08-28 DOI:10.1021/acs.jnatprod.4c00758

Ginson George, Farhan Mahmood Shah, Abbas Ali, Dileep Kumar Guddeti, Noura Alowaifi, Joseph Lee, Jian Chen, Ikhlas A Khan, Xing-Cong Li

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Abstract

Imported fire ants are significant agricultural pests. Repellents can be used to prevent foraging fire ants from entering sensitive areas, including electrical equipment, nursing homes, and hospitals. Bioassay-guided fractionation of the essential oil extracted from gurjun balsam (Dipterocarpus turbinatus) resulted in the identification of (-)-α-copaene (1) as the repellent constituent with a minimum repellent effective dose (MRED) of 15.6 μg/g against both red imported fire ants (Solenopsis invicta) and hybrid imported fire ants (Solenopsis invicta × Solenopsis richteri). Stereoselective oxidation of 1 via autoxidation and chemical methods produced (-)-5R-hydroperoxy-α-copaene (2), (+)-3S-hydroperoxycopa-4-ene (3), (-)-α-copaene oxide (4), (+)-β-copaen-4α-ol (5), copaenediol (6), and copaene ketol (7). Reduction of 2 and 3 with triphenylphosphine afforded (-)-5R-hydroxy-α-copaene (2a) and (+)-3S-hydroxycopa-4-ene (3a), respectively, which led to the structural revision of copa-3-en-2α-ol and copa-2-en-4-ol as 2a and 3, respectively. The configurational assignment of compound 4 in the literature was also clarified by the detailed analysis of 2D NMR spectroscopic data. Compounds 2-7 showed repellency with MREDs ranging from 3.9 to 15.6 μg/g against hybrid and red imported fire ants, indicating that chemical modification can enhance the repellent effect of (-)-α-copaene.

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α-槐烯的立体选择性氧化，α-槐烯是一种来自双齿桉树精油的驱火蚁倍半萜。

进口火蚁是重要的农业害虫。驱虫剂可用于防止觅食火蚁进入敏感区域，包括电气设备、养老院和医院。通过生物测定法对从古尔琼香脂（Dipterocarpus turbinatus）中提取的精油进行分馏，确定了(-)-α-copaene（1）作为驱避成分，其对红进口火蚁（Solenopsis invicta）和杂交进口火蚁（Solenopsis invicta × Solenopsis richteri）的最小驱避有效剂量（MRED）为 15.6 μg/g。通过自氧化和化学方法对 1 进行立体选择性氧化，生成了 (-)-5R-hydroperoxy-α-copaene (2)、(+)-3S-hydroperoxycopa-4-ene (3)、(-)-α-copaene oxide (4)、(+)-β-copaen-4α-ol (5)、copaenediol (6) 和 copaene ketol (7)。用三苯基膦还原 2 和 3 后，分别得到了 (-)-5R-hydroxy-α-copaene (2a) 和 (+)-3S-hydroxycopa-4-ene (3a)，从而将 copa-3-en-2α-ol 和 copa-2-en-4-ol 的结构分别修正为 2a 和 3。通过对二维核磁共振光谱数据的详细分析，还澄清了文献中化合物 4 的构型分配。化合物 2-7 对杂交火蚁和进口红火蚁具有驱避作用，MRED 为 3.9 至 15.6 μg/g，表明化学修饰可增强 (-)-α-copaene 的驱避效果。

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来源期刊

Journal of Natural Products 生物-药学

CiteScore

9.10

自引率

5.90%

发文量

294

审稿时长

2.3 months

期刊介绍： The Journal of Natural Products invites and publishes papers that make substantial and scholarly contributions to the area of natural products research. Contributions may relate to the chemistry and/or biochemistry of naturally occurring compounds or the biology of living systems from which they are obtained. Specifically, there may be articles that describe secondary metabolites of microorganisms, including antibiotics and mycotoxins; physiologically active compounds from terrestrial and marine plants and animals; biochemical studies, including biosynthesis and microbiological transformations; fermentation and plant tissue culture; the isolation, structure elucidation, and chemical synthesis of novel compounds from nature; and the pharmacology of compounds of natural origin. When new compounds are reported, manuscripts describing their biological activity are much preferred. Specifically, there may be articles that describe secondary metabolites of microorganisms, including antibiotics and mycotoxins; physiologically active compounds from terrestrial and marine plants and animals; biochemical studies, including biosynthesis and microbiological transformations; fermentation and plant tissue culture; the isolation, structure elucidation, and chemical synthesis of novel compounds from nature; and the pharmacology of compounds of natural origin.