U.S. Pacific Basin Agricultural Research Center, Agricultural Research Service, United States Department of Agricultural, 64 Nowelo St., Hilo, HI 96720, USA.
J Chem Ecol. 2011 Jun;37(6):553-64. doi: 10.1007/s10886-011-9963-y. Epub 2011 May 26.
Oriental fruit fly, Bactrocera dorsalis (Hendel), males are attracted to the natural phenylpropanoid methyl eugenol (ME). They feed compulsively on ME and metabolize it to ring and side-chain hydroxylated compounds that have both pheromonal and allomonal properties. Previously, we demonstrated that mono-fluorination at the terminal carbon of the ME side-chain significantly reduced metabolic side-chain hydroxylation, while mono-fluorination of ME at position 4 of the aromatic ring blocked ring-hydroxylation but surprisingly enhanced side-chain hydroxylation. Here, we demonstrated that the introduction of fluorine atoms on both the ring and side-chain of ME blocks both positions that undergo enzymatic hydroxylation and, in particular, completely inhibits oxidative biotransformation of the allyl group. In laboratory experiments, B. dorsalis males initially were more attracted to both 1-fluoro-4,5-dimethoxy-2-(3,3-difluoro-2-propenyl)benzene (I) and 1-fluoro-4,5-dimethoxy-2-(3-fluoro-2-propenyl)benzene (II) than to ME. However, both I and II were taken up by flies at rates significantly less than that of ME. Flies fed with difluoroanalog II partially metabolized it to 5-fluoro-4-(3-fluoroprop-2-en-1-yl)-2-methoxyphenol (III), and flies fed with trifluoroanalog I produced 4-(3,3-difluoroprop-2-en-1-yl)-5-fluoro-2-methoxyphenol (V), but the rates of metabolism relative to rates of intakes were much lower compared to those of ME. Flies that consumed either the tri- or difluorinated analog showed higher post-feeding mortality than those that fed on methyl eugenol. In field trials, trifluoroanalog I was ∼90% less attractive to male B. dorsalis than ME, while difluoroanalog II was ∼50% less attractive. These results suggest that increasing fluorination can contribute to fly mortality, but the trade off with attractancy makes it unlikely that either a di or trifluorinated ME would be an improvement over ME for detection and/or eradication of this species.
东方果实蝇雄性对天然苯丙素甲基丁香酚（ME）具有吸引力。它们会强迫性地以 ME 为食，并将其代谢为具有信息素和他感作用的环状和侧链羟化化合物。此前，我们证明了 ME 侧链末端碳的单氟化显著降低了代谢侧链羟化，而 ME 芳环上 4 位的单氟化则阻断了环羟化，但令人惊讶的是增强了侧链羟化。在这里，我们证明了 ME 环和侧链上引入氟原子会阻止两个发生酶促羟化的位置，特别是完全抑制了烯丙基的氧化生物转化。在实验室实验中，B. dorsalis 雄蝇最初对 1-氟-4,5-二甲氧基-2-(3,3-二氟-2-丙烯基)苯（I）和 1-氟-4,5-二甲氧基-2-(3-氟-2-丙烯基)苯（II）的吸引力比对 ME 的吸引力更大。然而，苍蝇摄取 I 和 II 的速度明显低于 ME。用二氟类似物 II 喂养的苍蝇部分代谢为 5-氟-4-(3-氟丙烯-2-基)-2-甲氧基苯酚（III），而用三氟类似物 I 喂养的苍蝇产生 4-(3,3-二氟丙烯-2-基)-5-氟-2-甲氧基苯酚（V），但与摄取速度相比，代谢速度要低得多。与食用 ME 的苍蝇相比，消耗三氟或二氟类似物的苍蝇在进食后死亡率更高。在田间试验中，三氟类似物 I 对雄性 B. dorsalis 的吸引力比 ME 低约 90%，而二氟类似物 II 的吸引力比 ME 低约 50%。这些结果表明，增加氟化程度可能会导致苍蝇死亡，但在吸引力方面的权衡使得二氟或三氟 ME 都不太可能比 ME 更适合检测和/或根除该物种。
