1.Chemical and Plant-Based Insect Repellents: Efficacy, Safety, and Toxicity.
Diaz JH1. Wilderness Environ Med. 2016 Mar;27(1):153-63. doi: 10.1016/j.wem.2015.11.007. Epub 2016 Jan 27.
Most emerging infectious diseases today are arthropod-borne and cannot be prevented by vaccinations. Because insect repellents offer important topical barriers of personal protection from arthropod-borne infectious diseases, the main objectives of this article were to describe the growing threats to public health from emerging arthropod-borne infectious diseases, to define the differences between insect repellents and insecticides, and to compare the efficacies and toxicities of chemical and plant-derived insect repellents. Internet search engines were queried with key words to identify scientific articles on the efficacy, safety, and toxicity of chemical and plant-derived topical insect repellants and insecticides to meet these objectives. Data sources reviewed included case reports; case series; observational, longitudinal, and surveillance studies; and entomological and toxicological studies. Descriptive analysis of the data sources identified the most effective application of insect repellents as a combination of topical chemical repellents, either N-diethyl-3-methylbenzamide (formerly N, N-diethyl-m-toluamide, or DEET) or picaridin, and permethrin-impregnated or other pyrethroid-impregnated clothing over topically treated skin. The insecticide-treated clothing would provide contact-level insecticidal effects and provide better, longer lasting protection against malaria-transmitting mosquitoes and ticks than topical DEET or picaridin alone. In special cases, where environmental exposures to disease-transmitting ticks, biting midges, sandflies, or blackflies are anticipated, topical insect repellents containing IR3535, picaridin, or oil of lemon eucalyptus (p-menthane-3, 8-diol or PMD) would offer better topical protection than topical DEET alone.
2.Volatile Profile of Herniaria fontanesii Growing Spontaneously in Tunisia.
Hammami S1, El Mokni R2, Faidi K3, El Aouni MH2, Mighri Z3, Joshi RK4. J Chromatogr Sci. 2016 Mar;54(3):291-4. doi: 10.1093/chromsci/bmv158. Epub 2015 Nov 3.
The essential oil extracted from Desfontaine's rupturewort, Herniaria fontanesii J. Gay subsp. fontanesii growing wildly in Tunisia, was analyzed using GC and GC-MS techniques. The free radical scavenging capacity and total phenol contents of three crude extracts having different polarities (n-hexane, ethyl acetate and methanol) were examined. Thus, a total of 35 constituents were identified in the Desfontaine's rupturewort essential oil representing 89.8% of the whole constituents. The oil was dominated by hexadecanoic acid, caryophyllene oxide, terpin-4-ol, khusimone and trans-sabinene hydrate. The total phenolic contents ranged from 16.91 to 92.27 mg of gallic acid/g of dry weight and they were found to be significantly higher in methanol than in polar ethyl acetate and hexane extracts. Correlations were observed between the phenolic contents and the antioxidant properties. Thus, the antioxidant activity of the methanol extract was superior to that of all samples tested (IC50 = 0.21 ± 0.04 mg/mL).
3.The Efficacy of Some Commercially Available Insect Repellents for Aedes aegypti (Diptera: Culicidae) and Aedes albopictus (Diptera: Culicidae).
Rodriguez SD1, Drake LL2, Price DP3, Hammond JI4, Hansen IA5. J Insect Sci. 2015 Oct;15:140. doi: 10.1093/jisesa/iev125.
Reducing the number of host-vector interactions is an effective way to reduce the spread of vector-borne diseases. Repellents are widely used to protect humans from a variety of protozoans, viruses, and nematodes. DEET (N,N-Diethyl-meta-toluamide), a safe and effective repellent, was developed during World War II. Fear of possible side effects of DEET has created a large market for "natural" DEET-free repellents with a variety of active ingredients. We present a comparative study on the efficacy of eight commercially available products, two fragrances, and a vitamin B patch. The products were tested using a human hand as attractant in a Y-tube olfactometer setup with Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse), both major human disease vectors. We found that Ae. albopictus were generally less attracted to the test subject's hand compared with Ae, aegypti. Repellents with DEET as active ingredient had a prominent repellency effect over longer times and on both species. Repellents containing p-menthane-3,8-diol produced comparable results but for shorter time periods. Some of the DEET-free products containing citronella or geraniol did not have any significant repellency effect. Interestingly, the perfume we tested had a modest repellency effect early after application, and the vitamin B patch had no effect on either species. This study shows that the different active ingredients in commercially available mosquito repellent products are not equivalent in terms of duration and strength of repellency. Our results suggest that products containing DEET or p-menthane-3,8-diol have long-lasting repellent effects and therefore provide good protection from mosquito-borne diseases.
4.Biotransformation of (-)-α-pinene and geraniol to α-terpineol and p-menthane-3,8-diol by the white rot fungus, Polyporus brumalis.
Lee SY1, Kim SH, Hong CY, Park SY, Choi IG. J Microbiol. 2015 Jul;53(7):462-7. doi: 10.1007/s12275-015-5081-9. Epub 2015 Jun 27.
In this study, the monoterpenes, α-pinene and geraniol, were biotransformed to synthesize monoterpene alcohol compounds. Polyporus brumalis which is classified as a white rot fungus was used as a biocatalyst. Consequently α-terpineol was synthesized from α-pinene by P. brumalis mycelium, after three days. Moreover, another substrate, the acyclic monoterpenoids geraniol was transformed into the cyclic compound, p-menthane-3, 8-diol (PMD). The main metabolites, i.e., α-terpineol and PMD, are known to be bioactive monoterpene alcohol compounds. This study highlights the potential of fungal biocatalysts for monoterpene transformation.