N-Methyl-(2S,4R)-trans-4-hydroxy-L-proline isolated Sideroxylon obtusifolium attenuates TPA-induced irritant contact dermatitis in mice.

Dermatitis is defined as a set of inflammatory diseases that affect the skin, with varied causes. Among the different types of dermatitis, contact dermatitis is the most prevalent. Although the current therapy is often effective, it is associated with adverse effects and the possibility of drug tolerance. N-Methyl-(2S, 4R)-trans-4-hydroxy-L-proline is a L-proline amino acid derivative found in the leaves of Sideroxylon obtusifolium, a species traditionally used to treat inflammatory diseases. The aim of this study was to investigate the topical anti-inflammatory effect of N-methyl-(2S, 4R)-trans-4-hydroxy-L-proline (NMP) in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced irritant contact dermatitis in mice. Topically administered NMP, at doses of 0.03 - 0.50 mg/ear, reduced TPA-induced ear edema and neutrophil migration, as evidenced by low tissue myeloperoxidase activity and verified by histological examination. In addition, NMP (0.06 mg/ear) reduced tissue levels of pro-inflammatory cytokines (TNF-α, IL-6, IL-1ß, INF-γ and MCP-1) and of the anti-inflammatory cytokine IL-10, and reduced gene expression of TNF-α, IL-6 and IL-1ß increased by TPA. The data suggest that N-methyl-(2S, 4R)-trans-4-hydroxy-L-proline acts as a topical anti-inflammatory agent that decreases the expression of inflammatory cytokines, making it useful for the treatment of skin inflammation. Further investigations are necessary for its development as a therapeutic agent.

ß-Cyclodextrin-complexed (-)-linalool produces antinociceptive effect superior to that of (-)-linalool in experimental pain protocols.

Many plants produce (-)-linalool, a plant-derived monoterpene alcohol, including members of the Lamiaceae (mints) and Lauraceae family (laurels, cinnamon, rosewood). The anti-inflammatory and analgesic effects of (-)-linalool have been widely suggested for various studies. Poor chemical stability and short half-life restrain the clinical applications of some essential oil and monoterpenes, including (-)-linalool. However, ß-cyclodextrin (ß-CD) has been used to increase solubility and stability of lipophilic compounds and also to improve the pharmacological effects. In this study, the antinociceptive effect of (-)-linalool and (-)-linalool/ß-CD was examined using the acetic acid writhing reflex, formalin and hotplate tests in rodents. (-)-Linalool and (-)-linalool/ß-CD demonstrated strong antinociceptive activity in all the chemical- and heat-induced mice models (p < 0.01 or p < 0.001). These findings imply the involvement of both peripheral and central antinociceptive mechanisms. In peritonitis induced by carrageenan, isolated monoterpene or ß-CD complex also reduced total leucocyte migration and TNF-α levels in peritoneal fluid. The inclusion complexes, (-)-linalool/ß-CD, revealed that the antinociceptive effect was significantly (p < 0.01) improved when compared with (-)-linalool alone. Such results were unlikely to be provoked by any motor abnormality. Together, our results suggest that ß-CD might represent an important tool for improvement of analgesic and anti-inflammatory profiles of (-)-linalool and other water-insoluble compounds, such as lipophilic monoterpenes or essential oils.

Gastroprotective activity of carvacrol on experimentally induced gastric lesions in rodents.

The present study aimed to investigate the gastroprotective activity of carvacrol, a monoterpene present in essential oils from several species of medicinal and aromatic plants, by using different models of acute gastric lesions in rodents and also evaluate possible mechanisms involved in this action. For this study, absolute ethanol-, acidified ethanol-, ischemia and reperfusion-, and nonsteroidal anti-inflammatory drug-induced models of gastric lesions in mice and rats were used. The roles of nonprotein sulfhydryl groups, catalase, nitric oxide (NO), ATP-sensitive potassium channels (K(ATP) channels), and prostaglandins in carvacrol-induced gastroprotective effect were investigated. In addition, the effects of carvacrol on gastric secretion and mucus in pylorus-ligated rats were also determined. The results of the present study demonstrated that carvacrol promoted a marked gastroprotection in all models investigated, possibly mediated by endogenous prostaglandins, increase of mucus production, K(ATP) channels opening, NO synthase activation, and antioxidant properties. These findings markedly substantiate further studies to investigate the therapeutic potential of carvacrol as an effective gastroprotective agent and its safety profile in medicinal use.