Oxyresveratrol Attenuates Inflammation in Human Keratinocyte via Regulating NF-kB Signaling and Ameliorates Eczematous Lesion in DNCB-Induced Dermatitis Mice.

Oxyresveratrol (ORV) is one of the novel antioxidants having been extensively studied in recent years. One of the main sources of ORV is Artocarpus lakoocha, which has been used in traditional medicine in Thailand for decades. However, the role of ORV in skin inflammation has not been clearly demonstrated. Therefore, we investigated the anti-inflammatory effects of ORV on dermatitis model. The effect of ORV was examined on human immortalized and primary skin cells exposed to bacterial components including peptidoglycan (PGN) and lipopolysaccharide (LPS) and 2,4-Dinitrochlorobenzene (DNCB)-induced dermatitis mouse model. PGN and LPS were used to induce inflammation on immortalized keratinocytes (HaCaT) and human epidermal keratinocytes (HEKa). We then performed MTT assay, Annexin V and PI assay, cell cycle analysis, real-time PCR, ELISA and Western blot in these in vitro models. H&E staining, immunohistochemistry (IHC) staining with CD3, CD4 and CD8 markers were used to evaluate the effects of ORV in in vivo model of skin inflammation using BALB/c mice. Pretreatment of HaCaT and HEKa cells with ORV inhibited pro-inflammatory cytokine production through inhibition of NF-κB pathway. In DNCB-induced dermatitis mouse model, ORV treatment reduced lesion severity, and skin thickness and numbers of CD3, CD4 and CD8 T cells in the sensitized skin of mice. In conclusion, it has been demonstrated that ORV treatment can ameliorate inflammation in the in vitro models of skin inflammation and in vivo models of dermatitis, suggesting a therapeutic potential of ORV for treatment of skin diseases particularly eczema.

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.

Field evaluation of deet, Repel Care, and three plant based essential oil repellents against mosquitoes, black flies (Diptera: Simuliidae) and land leeches (Arhynchobdellida: Haemadipsidae) in Thailand.

Diethyl methyl benzamide, or deet, a commercial plant-based repellent (Repel Care), and essential ils from 3 species of plants (finger root rhizomes, guava leaves, and turmeric rhizomes), steam distillated and formulated as insect repellents, were evaluated in the field on human volunteers against hematophagous mosquitoes, black flies, and land leeches in Thailand. Field trials were conducted against wild mosquitoes in Bang Bua Thong District, Nonthaburi Province, and in the Thap Lan National Park Headquarters, Nadee District, Pranchinburi Province; anthroophilic black flies (Diptera: Simuliidae) at the Forestry Fire Control Station in Doi Inthanon National Park, Chomthong district, Chiang Mai Province; and land leeches (Arhynchobdellida: Haemadipsidae) in the Khao Yai National Park, Pak Chong District, Nakhon Ratchasima Province. The 3 experimental plant-based essential oil formulations as well as Repel Care and deet provided complete protection from mosquito landing and biting for up to 9 h (duration of the experiment). Similar results were obtained with the 5 products against black flies, providing 100% protection for 9 h but 96-82% protection after 10 and 11 h posttreatment. The 5 repellent products also provided 100% protection against land leeches for at least 8 h. Thi is the 1st report of repellency of plant-based repellents against black flies and land leeches in Thailand. The identification and availability of inexpensive sources of plant-based oils, i.e., finger root rhizomes, guava leaves, and turmeric rhizomes providing long-lasting repellency against blood-sucking organisms are promising leads into commercial production of relatively safe and effective repellents.

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.

Acaricidal daphnane diterpenoids from Trigonostemon reidioides (KURZ) CRAIB roots.

A new daphnane diterpenoid, rediocide F (1), was isolated together with three known compounds, rediocides A (2), C (3) and E (4), from the hexane extract of Trigonostemon reidioides roots by bioassay-guided fractionation for acaricidal activity on Dermatophagoides pteronyssinus, Thai common house dust mite. The structure of rediocide F (1) was established as the demethyl analog of rediocide C (3) on the basis of spectral analysis. Compounds 1-4 exhibited potent activity against D. pteronyssinus with respective LC50 values of 2.53, 0.78, 5.59 and 0.92 microg/cm2.

Antitumor agents. Part 209: Pheophorbide-a derivatives as photo-Independent cytotoxic agents.

A methanolic crude extract of the plant Garuga pinnata Roxb. (Burseraceae) showed promising cytotoxic activity against a panel of human tumor cell lines in vitro, including KB and its drug-resistant sublines (Ferguson et al. Cancer Res. 1988, 48, 5956). Pheophorbide-a and-b methyl esters (3,4) were isolated as active principles with broad photo-dependent cytotoxic activities in the micromolar range. These findings prompted SAR studies of known and novel pheophorbide-a derivatives as photo-dependent and photo-independent cytotoxic agents. The results showed that zinc-protoporphyrin IX (10), zinc 13(R)-hydroxypheophorbide-a methyl ester (22), and zinc chlorin-e6 trimethyl ester (13) possessed photo-independent cytotoxic activity. Compounds 13 and 22 were the most active cytotoxic agents of the series (mean ED(50) 4.6 +/- 1.0 microM and 5.7 +/- 0.7 microM, respectively) against KB cells incubated in the dark.