Repellency Assessment of Nepeta cataria Essential Oils and Isolated Nepetalactones on Aedes aegypti.

There is an increased need for improved and affordable insect repellents to reduce transmission of rapidly spreading diseases with high mortality rates. Natural products are often used when DEET cannot be afforded or accessed and when consumers choose not to use a synthetic repellent. The essential oils from two newly bred Nepeta cataria (catnip) plants representing two different chemotypes and their respective isolated nepetalactone isomers were evaluated as mosquito repellents against Aedes aegypti mosquitoes that transmit the Zika and Dengue virus in a one choice landing rate inhibition assay. A dose response curve was generated for each treatment and a time course analysis of repellency was performed over 24 hours with a N. cataria essential oil sample. The results indicate that all essential oil samples and their respective purified nepetalactone isomers were able to achieve greater than 95% repellency. Between two and four hours, the ability to repel more than 95% of the mosquitoes diminished. At the lowest concentrations tested, the nepetalactones and crude essential oil samples were more effective than DEET at reducing the number of mosquito landings.

[Eudesmane sesquiterpenes from twigs of Manglietia hookeri].

Chemical constituents from the acetone extract of twigs of Manglietia hookeri were isolated and purified by various column chromatographic methods over silica gel and sephadex LH-20, and preparative TLC. The structures of these compounds were identified on the basis of physicochemical properties and spectral analysis, including NMR and MS spectra. Six eudesmane sesquiterpenes were obtained and their structures were identified as trans-eudesmane-4, 11-diol(1), ß-eudesmol(2), (-) -10-epi-5ß-hydroxy-ß-eudesmol (3), epi-carrisone (4), 6-hydroxy-eudesm-4(14) -ene(5) and gynurenol(6). All the compounds were isolated from this plant for the first time. Furthermore, the 13C-NMR data of compound 3 were reported for the first time.

A new illicinolide from leaves of Illicium micranthum Dunn.

The ethyl acetate extract from leaves of Illicium micranthum Dunn exhibited radical scavenging ability on DPPH radical-scavenging assay. Further phytochemical investigation led to the isolation of a new sesquiterpenoid, illicinolide C (1), and eight known compounds (2-9). The structural elucidations of the compounds were based on spectroscopic methods and by comparison of their spectroscopic data with those reported in the references. Except compound 9, all the other compounds were isolated from I. micranthum Dunn for the first time, while compounds 1 and 2 were new to the Illiciaceae family.