Mark A. Scialdone

Repellency of Hydrogenated Catmint Oil Formulations to Black Flies and Mosquitoes in the Field

Abstract The essential oil of catmint, Nepeta cataria L., was hydrogenated to yield an oil enriched in dihydronepetalactone (DHN) diastereomers, termed. This material was used for the preparation of liquid alcohol–based and lotion formulations. The efficacy of these formulations as repellents was tested after application to human test subjects at two locations in the United States: Maine and Florida. In Maine, data on repellency of the hydrogenated catmint oil formulations toward black flies (Simulium decorum Walker) and mosquitoes (primarily Aedes intrudens Dyar) were obtained. In these tests, protection from black flies was conferred for 6 h or more with all formulations, and both liquid and lotion formulations at 15 wt% active ingredient gave complete protection for 7.5 h. All formulations conferred protection from mosquitoes for >4 h, with the best (15 wt% lotion) giving >8 h of complete protection. In Florida, data on repellency toward a mixed population of mosquitoes indicated that all formulations conferred protection for >4 h, with the 15 wt% lotion giving >6 h complete protection from bites.

Dihydronepetalactones deter feeding activity by mosquitoes, stable flies, and deer ticks.

ABSTRACT The essential oil of catmint, Nepeta cataria L., contains nepetalactones, that, on hydrogenation, yield the corresponding dihydronepetalactone (DHN) diastereomers. The DHN diastereomer (4R,4aR,7S,7aS)-4,7-dimethylhexahydrocyclopenta[c]pyran-l(3H)-one, DHN 1) was evaluated as mosquito repellent, as was the mixture of diastereomers {mostly (4S,4aR,7S,7aR)-4,7-dimethylhexahydrocyclopenta[c]pyran-1(3H)-one, DHN 2} present after hydrogenation of catmint oil itself. The repellency of these materials to Aedes aegypti L. and Anopheles albimanus Wiedemann mosquitoes was tested in vitro and found to be comparable to that obtained with the well-known insect repellent active ingredient N,N-diethyl-3-methylbenzamide (DEET). DHN 1 and DHN 2 also repelled the stable fly, Stomoxys calcitrans L., in this study. DHN 1, DHN 2, and p-menthane-3,8-diol (PMD), another natural monoterpenoid repellent, gave comparable levels of repellency against An. albimanus and S. calcitrans. Laboratory testing of DHN 1 and DHN 2 using human subjects with An. albimanus mosquitoes was carried out. Both DHN 1 and DHN 2 at 10% (wt:vol) conferred complete protection from bites for significant periods of time (3.5 and 5 h, respectively), with DHN2 conferring protection statistically equivalent to DEET. The DHN 1 and DHN 2 diastereomers were also efficaceous against black-legged tick (Ixodes scapularis Say) nymphs.

Lysinol: a renewably resourced alternative to petrochemical polyamines and aminoalcohols

This paper reports the preparation of lysinol (2,6-diamino-1-hexanol) by the hydrogenation of lysine and an example of its use as a replacement for petrochemical-derived amines. Lysine is presently manufactured by fermentation of sugars and other carbon sources at scale exceeding 109 kg per year. Therefore, lysinol is potentially a renewable, platform aminoalcohol of previously unrecognized potential. Lysine hydrogenation proceeds under relatively modest conditions with Ru/C catalyst in water (100–150 °C, 48–70 bar, pH 1.5–2) to give lysinol in good yield (100% conversion, >90% selectivity; 50–70% isolated yield after purification by distillation). The impact of the various reaction parameters on conversion and selectivity are presented and discussed. Lysine hydrogenation at higher temperatures provides a pathway to piperidines and other products via further reduction and elimination of lysinol. The feasibility of lysinol synthesis from commodity, animal feed-grade lysine sources is presented as well. An example of the potential utility of lysinol is demonstrated by its use as a diamine curing agent with a standard epoxy resin. The properties of the resulting thermoset are contrasted with that obtained with a typical petrochemical amine used in this application (diethylenetriamine, DETA).