Safety and efficacy of hyptis suaveolens extract for therapy of influenza in healthy adults.

Objective: To determine the safety and efficacy of H.suaveolens extract for therapy of influenza in healthy adults. Methods: The study was randomized double blind placebo controlled study conducted in 15 community and general hospitals from May to August 2006. The study subjects were healthy adults who had influenza-like symptoms and positive preliminary diagnostic test for influenza A or B from respiratory secretions. They were randomized to receive H.suaveolens extract 500 mg 3 times daily or the placebo 3 times daily for 7 days. The subjects were evaluated for the severity of symptoms related to influenza, adverse effects of the medications and the presence of influenza viruses from respiratory secretions at entry, day 4 and day 7 after treatment. Results: There were 39 subjects in the placebo group and 46 in the H.suaveolens group. There was a significant improvement in symptoms of the patients in both groups on day 4 and day 7 when compared with that at entry. However, the average duration of fever of the patients in both groups was not significantly different (3.1 days in the placebo group vs. 3 days in the H.suaveolens group, p=0.749). The recovery rates of influenza A and influenza B viruses from respiratory secretions of the subjects on day 4 and day 7 after treatment in both groups were not significantly different. A trend of less positive culture for influenza A virus in the patients receiving H.suaveolens extract (32.5%) compared with those receiving a placebo (47.1%) was observed. The compliance to medications was satisfactory. No serious adverse effects due to study medications were observed. Conclusion: H.suaveolens extract 1.5 grams per day for 7 days is safe but it is not effective in relieving influenza-related symptoms in adults with influenza. The lack of efficacy of H.suaveolens extract might be due to an insufficient dosage of the extract.

Repellent activity of essential oils against cockroaches (Dictyoptera: Blattidae, Blattellidae, and Blaberidae) in Thailand.

Seven commercial essential oils extracted from the plant species Boesenbergia rotunda (L.) Mansf., Citrus hystrix DC., Curcuma longa L., Litsea cubeba (Lour.) Pers., Piper nigrum L., Psidium guajava L. and Zingiber officinale Roscoe, and naphthalene as a control, were evaluated for repellent activity against the three cockroach species Periplaneta americana (L.), Blattella germanica (L.) and Neostylopyga rhombifolia (Stoll) under laboratory conditions. The essential oil derived from Citrus hystrix showed the best repellency over other candidate essential oils and naphthalene. The essential oil of Citrus hystrix exhibited complete repellency (100%) against P. americana and B. germanica, and also showed the highest repellency (among the essential oils tested) of about 87.5% against N. rhombifolia under laboratory conditions. In the field, Citrus hystrix essential oil formulated as a 20% active ingredient in ethanol and some additives provided satisfactory repellency of up to 86% reduction in cockroaches, mostly P. americana and N. rhombifolia with a residual effect lasting a week after treatment. Citrus hystrix essential oil has good potential for being used as a cockroach repellent. Further improvements in efficacy and residual activity may be realized with appropriate formulations.

Repellency of essential oils extracted from plants in Thailand against four mosquito vectors (Diptera: Culicidae) and oviposition deterrent effects against Aedes aegypti (Diptera: Culicidae).

In this study we evaluated and reported repellent effects of essential oils from Thai plants against 4 mosquito vectors: Aedes aegypti, Ae. albopictus, Anopheles. dirus and Culex quinquefasciatus under laboratory conditions using human volunteers. The essential oils were extracted from 18 plant species, belonging to 11 families, and the oils were then prepared as 10% solution in absolute ethanol with additives. Two chemical repellents, deet and IR3535, were also prepared in the same formulation as the essential oil repellents and tested for repellency as controls. The essential oils were also evaluated for oviposition deterrent effects against Ae. aegypti under laboratory conditions. The results show night-biting mosquitoes (An. dirus and Cx. quinquefasciatus) and Ae. albopictus were more sensitive to all the essential oils (repellency 4.5 - 8 hours) than was Ae. aegypti (repellency 0.3 - 2.8 hours), whereas deet and IR3535 provided excellent repellency against all four mosquito species (repellency 6.7- 8 hours). All essential oils exhibited oviposition deterrent activity against Ae. aegypti with various degrees of repellency ranging from 16.6 to 94.7%, whereas deet and IR3535 had no repellency. The present study demonstrates the potential for using essential oils as mosquito repellents and oviposition deterrents. These findings may lead to new and more effective strategies for protection from and control of mosquitoes.