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.

Clinical study of morus alba linn. on glycemic control and blood lipids in patients with type 2 diabetes: A preliminary study.

Effects of Morus alba-leaf extracts on glycemic control and blood lipids were carried out in 27 patients with newly diagnosed type 2 diabetes. Water extracts of Morus alba leaves at a dosage of 700 mg were given to the patients thrice daily for 8 weeks. The patients did not receive any concomitant medications for diabetes or hyperlipidemia. The mean fasting plasma glucose levels at baseline, week 2, week 4, week 6 and week 8 were 155.1, 179, 173.6, 183.9 and 185.8 mg/dl, respectively (p=0.04). The mean glycosylated hemoglobin levels at baseline and week 8 were 7.6% and 8.4%, respectively (p=0.002). The mean blood total cholesterol levels at baseline, week 2, week 4, week 6 and week 8 were 229.6, 211.2, 210.2, 204.5 and 199.4 mg/dl, respectively (p<0.001). The mean blood triglyceride levels at baseline, week 2, week 4, week 6 and week 8 were 235.4, 191.3, 174.5, 183.5 and 168.2 mg/dl, respectively (p=0.001). No patients experienced side effects of the treatment. Laboratory results on CBC, urine, blood electrolytes, renal function and liver function at baseline, week 2, week 4, week 6 and week 8 were not significantly different. Morus alba-leaf extracts have no hypoglycemic effect but they exert lipid lowering effects.

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.

In vitro antiviral activity of clinacanthus nutans on varicella-zoster virus.

The effect of crude extract of Clinacanthus nutans (CN) was studied to determine the antiviral activity against varicella-zoster virus (VZV) with three different treatments. Specifically the effects studied were that of CN extract on (I) cells before infection (pre-treatment); (II) virus infected cells (post-treatment); and (III) virus directly (inactivation assay). After treatment, the virus was detected by methods of DNA hybridization and plaque reduction assay. It was shown that CN had an effect on VZV depending on concentration and methods of treatment. Via DNA hybridization, the ID50 (50% inhibitory dose) of pre-treatment, post-treatment, and inactivation assay was by weight per volume dilution 1:2,000, 1:6,000 and > 1:18,000, respectively; by plaque reduction assay, they were 1:2,000, 1:4,800 and 1:9,600, respectively. From the present findings, based on the result of inactivation assay, it was recognized that the in vitro antiviral activity of CN might be a direct interaction of the extract with the virus.