[Subscribe to Daily Digest] |
[Profile/Gallery]
, Tue, 29 Jul 2014 06:11:00
Members do not see ads below this line. - Help Keep This Site Online - Signup
Sounds like old wives tale to me:
Field tests were conducted using a hydrogenated form of catnip oil in Florida and Maine. First, the essential oil of catnip was catalytically hydrogenated to yield dihydronepetalactones (DHN). Strictly speaking, hydrogenated catnip oil (HCO) is not something the average person can make without a palladium catalyst, hydrogen gas and a pressure vessel. DHN was previously detected in the defensive secretions of certain insects and it had been reported that DHN had the ability to repel ants. HCO was formulated into a lotion or alcohol-based spray. All HCO formulas exhibited some degree of extended protection with the 15% by weight HCO lotion providing complete protection during the eight hour tests. The authors suggest that formulations of HCO can be effective alternative to existing repellents such as DEET.
In Australia, a commercial product containing 5% catnip essential oil was tested as repellent against four different species of mosquitoes. Significant variation was observed for protection afforded against different mosquito species ranging from no protect to four hours on average. In contrast, a 7% DEET spray provided complete protection over a six hour period. Overall, the authors concluded that catnip does provide limited protection against some mosquito species in Australia, and may be more effective than other products containing natural plant extracts, but it was not as effective as DEET.
A study from China compared catnip essential oil along with other plant essential oils and DEET. Catnip essential oil (composed of 36%, 45%, 18% isomer 1, isomer 2, and caryophyllene) provided the best protection against mosquitoes and the only oil to provide complete protection for over six hours. When testing the major ingredients of catnip oil, their tests showed that a blend containing the nepetalactone isomers at a 3:1 ratio has the highest and longest repellent activity.
The most recent study published in 2011 on the use of catnip essential oils was performed on Afro-topical mosquitoes originally cultivated from Tanzania. They compared two different batches of catnip and found that the isomeric composition of nepatalactone varied considerable (batch A: 92% isomer 1 and 8% caryophyllene, and batch B: 17% isomer 1, 70% isomer 2, and 13% caryophyllene). Upon testing, batch A was not as effective at repelling mosquitoes as compared to batch B. Purified isomers provided inferior protection to either batches of essential oils. Testing of binary mixtures confirmed the synergistic effect between the two isomers. Lower activity was seen with purified isomers and, surprisingly, with equivalent or near equivalent binary mixtures. Highest activity was afforded when the isomers were mixed in 3:1 ratios. Furthermore, a ratio mixture equivalent to batch B did not perform as well compared to either batch of essential oils. A three component blend containing caryophyllene at the levels found in batch B had the same activity as the essential oil.
Typical of plant extracts, the concentration of active ingredients various from batch to batch and the variation is dependent upon things like supply location, seasonal variations, age of the plant, and extraction procedure. Indeed, the ratio of isomers within a catnip plant was shown to vary weekly and the effectiveness of the essential oils to repel insects varied greatly.
Overall, the research on catnip essential oil has proven it to be an effective repellent of mosquitoes. Some variation on the species of mosquitoes repelled and the duration of effectiveness was found. The data suggests that catnip can be used as an effective insect repellent when used as an unfractionated essential oil due to the presence of both nepetalactone isomers and other components such as caryophyllene. However, for practical use of these plant essential oils, further studies on their safety to human health are necessary.
posted by 64.140.60...
, Mon, 28 Jul 2014 15:59:36
, Wed, 30 Jul 2014 11:56:41
, Tue, 29 Jul 2014 09:06:02
, Tue, 29 Jul 2014 07:40:53, Thu, 31 Jul 2014 11:08:12
, Tue, 29 Jul 2014 05:37:03, Mon, 28 Jul 2014 21:11:39
, Mon, 28 Jul 2014 23:10:11, Tue, 29 Jul 2014 06:11:00, Tue, 29 Jul 2014 07:41:40
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
