Homoisoflavanone inhibits UVB-induced skin inflammation through reduced cyclooxygenase-2 expression and NF-kappaB nuclear localization.

BACKGROUND: Since the generation of reactive oxygen species (ROS) and release of inflammatory mediators play a major role in UVB-induced inflammation, vigorous attempts have been made for the pharmacological management of these molecules as well as for uncovering the molecular signaling pathways. Homoisoflavanone (5,7-dihydroxy-3-(3-hydroxy-4-methoxybenzyl)-chroman-4-one, HIF) extracted from Cremastra appendiculata has anti-angiogenic activities, but its effect on inflammation was unknown. OBJECTIVE: To investigate the anti-inflammatory effects of HIF on the skin and the underlying molecular mechanisms. METHODS: HaCaT cells were irradiated by UVB (10 mJ/cm(2)) with or without HIF. Prostaglandin E(2) (PGE(2)) level was measured by enzyme immunoassay. Activation of MAPK and production of cyclooxygenase-2 (COX-2) were determined by Western blot analysis. Localization of nuclear factor kappa B (NF-kappaB) was assessed by immunofluorescence microscopy. Hairless mice were stimulated with UVB or chemical stimulants to induce inflammatory responses in skin. RESULTS: Pretreatment with HIF inhibited the production of intracellular ROS induced by UVB irradiation in HaCaT cells. Further analysis revealed a decrease in the level of MAPK activation and down-regulation of COX-2 expression. In addition, HIF attenuated the nuclear localization of NF-kappaB, resulting in the suppression of inflammatory molecules such as IL-6, IL-8, and TNF-alpha. Finally, topical treatment with HIF inhibited ear edema induced by UVB, 12-O-tetradecanoylphorbol-13-acetate (TPA), arachidonic acid (AA), or croton oil. CONCLUSION: HIF has a strong protective effect against proinflammatory responses, implying the possibility of preventive application for inflammatory skin diseases.

Cardiovascular effects of the essential oil of Croton zehntneri leaves and its main constituents, anethole and estragole, in normotensive conscious rats.

Cardiovascular effects of the essential oil of Croton zehntneri (EOCZ) were investigated in conscious rats. In these preparations, intravenous (i.v.) injections of EOCZ (1-20 mg kg(-1)) and its main constituents anethole and estragole (both at 1-10 mg kg(-1)) elicited brief and dose-dependent hypotension and bradycardia (phase I) that were followed by a significant pressor effect associated with a delayed bradycardia (phase II). The initial hypotension and bradycardia (phase I) of EOCZ were unchanged by atenolol (1.5 mg kg(-1), i.v.) or L-NAME (20 mg kg(-1), i.v.) pretreatment, but were respectively reversed into pressor and tachycardic effects by methylatropine (1 mg kg(-1), i.v.) pretreatment. The subsequent pressor effect and the delayed bradycardia (phase II) remained unaffected by atenolol, but were abolished by L-NAME and methylatropine pretreatment, respectively. In rat endothelium-containing aorta preparations, the vasoconstrictor responses to phenylephrine were enhanced and reduced, respectively, by the lower (1-30 microg mL(-1)) and higher (300-1000 microg mL(-1)) concentrations of EOCZ. Only the enhancement of phenylephrine-induced contraction was abolished by either the incubation with L-NAME (50 microM) or in the absence of the endothelium. These data show, for the first time, that i.v. administration EOCZ induces an initial hypotension followed by a pressor response, two effects that appear mainly attributed to the actions of anethole and estragole. The EOCZ-induced hypotension (phase I) is mediated by a cholinergic mechanism and seems to result mainly from the concomitant bradycardia. The pressor response of EOCZ (phase II) seems to be caused by an indirect vasoconstrictive action of EOCZ most likely through inhibition of endothelial nitric oxide production.

Antagonism of croton oil inflammation by topical emu oil in CD-1 mice.

Emu oil is derived from the emu (Dromaius novaehollandiae), which originated in Australia, and has been reported to have anti-inflammatory properties. Inflammation was induced in anesthetized CD-1 mice by applying 50 microL of 2% croton oil to the inner surface of the left ear. After 2 h, the area was treated with 5 microL of emu, fish, flaxseed, olive, or liquified chicken fat, or left untreated. Animals were euthanized at 6 h postapplication of different oils, and earplugs (EP) and plasma samples were collected. Inflammation was evaluated by change in earlobe thickness, increase in weight of EP tissue (compared to the untreated ear), and induction in cytokines interleukin (IL)-1alpha and tumor necrosis factor-alpha (TNF-alpha) in EP homogenates. Although reductions relative to control (croton oil) were noted for all treatments, auricular thickness and EP weights were significantly reduced (-72 and -71%, respectively) only in the emu oil-treated group. IL-1alpha levels in homogenates of auricular tissue were significantly reduced in the fish oil (-57%) and emu oil (-70%) groups relative to the control group. The cytokine TNF-alpha from auricular homogenates was significantly reduced in the olive oil (-52%) and emu oil (-60%) treatment groups relative to the control group. Plasma cytokine levels were not changed by croton oil treatment. Although auricular thickness and weight were significantly correlated with each other (r = 0.780, P < 0.003), auricular thickness but not weight was significantly correlated with cytokine IL-alpha (r = 0.750, P < 0.006) and TNF-alpha (r = 0.690, P < 0.02). These studies indicate that topical emu oil has anti-inflammatory properties in the CD-1 mouse that are associated with decreased auricular thickness and weight, and with the cytokines IL-1alpha and TNF-alpha.

Enhancement of the contact hypersensitivity reaction by acute morphine administration at the elicitation phase.

The present study investigated the effects of morphine on the irritant contact sensitivity (ICS) and contact hypersensitivity (CHS) reaction. ICS was induced by croton oil application on the pinnae of naïve rats. Morphine injected prior to croton oil application did not affect the ICS response when assessed by measurements of pinnae thickness. CHS was induced by applying the antigen 2,4-dinitro-1-fluorobenzene (DNFB) to the pinnae of rats sensitized to DNFB. Rats received an injection of morphine prior to either initial antigen exposure (sensitization) or antigen reexposure (challenge). Morphine prior to challenge, but not sensitization, resulted in a pronounced enhancement of the CHS response as measured by pinna thickness. Quantitative PCR also showed increased IFN-gamma mRNA levels in the inflamed tissue of morphine-treated rats. Naltrexone blocked the morphine-induced enhancement of the CHS response. The differential effects of morphine suggest that opioids have a more pronounced effect on in vivo immune responses that involve immunological memory.

Selective effects of 7 alpha-halogeno substitution on corticosteroid activity: Sch 22219 and Sch 23409.

Two 7 alpha-halogeno substituted corticosteroids, 7 alpha-chloro-16 alpha-methylprednisolone-17,21 dipropionate (Sch 22219) and 7 alpha-bromo-16 alpha-methylprednisolone-17-benzoate-21-acetate (Sch 23409) were compared to other clinically utilized topical corticosteroids for local and parenteral antiinflammatory and glucocorticosteroid activity. Both compounds were at least equivalent to the most potent comparison corticosteroids in topical antiinflammatory activity, and exhibited favorable ratios of local to systemic effects. In mice, Sch 22219 showed a greater dissociation of antiinflammatory activity from side effects than Sch 23409, although the reverse was true in rats. On the basis of the data available, both compounds possess enhanced topical antiinflammatory potency, with the potential for reduced side effects in man.

Croton oil- and benzo(a)pyrene-induced changes in cyclic adenosine 3':5'-monophosphate and cyclic guanosine 3':5'-monophosphate phosphodiesterase activities in mouse epidermis.

The topical application of croton oil, benzo(a)pyrene, acetic acid, and 12-O-tetradecanoyl-phorbol-13-acetate to mouse skin caused an increase in the activity of epidermal low-affinity cyclic adenosine 3':5'-monophosphate (cyclic AMP) phosphodiesterase. The increase was most pronounced with croton oil, began between 4 and 6 hr after application of this material, and was maintained for at least 48 hr. The activity of cyclic guanosine 3':5'-monophosphate phosphodiesterase was also increased by treatment with croton oil or 12-O-tetradecanoyl-phorbol-13-acetate, but detailed time courses were not obtained. Increased activity was observed in both the soluble fractions and the washed particulate fractions of epidermis. Fractionation of soluble extracts from acetone-treated epidermis on DEAE-cellulose columns showed the presence of enzymes with specificity for both cyclic AMP and cyclic guanosine 3':5'-monophosphate, together with a peak catalyzing the hydrolysis of both cyclic AMP and cyclic guanosine 3':5'-monophosphate. The activity of this latter nonspecific activity was selectively increased following treatment with croton oil. The increase in cyclic AMP phosphodiesterase activity was partially abolished by multiple injections of cycloheximide, suggesting that new protein synthesis was involved. Injection of the alpha-receptor antagonist phentolamine abolished a croton oil-induced rise in epidermal cyclic AMP levels and decreased the induction of cyclic AMP phosphodiesterase activity. From these results it was concluded that the increase in enzyme activity was induced by cyclic AMP.

Tumorigenesis in mouse skin: inhibition by synthetic inhibitors of proteases.

Three synthetic inhibitors of proteases (tosyl lysine chloromethyl ketone, tosyl phenylalanine chloromethyl ketone, and tosyl arginine methyl ester) inhibit the tumorigenesis initiated in mouse skin by 7,12-dimethylbenz(a)anthracene and promoted by croton oil or its active principle, phorbol ester. These protease inhibitors, when applied directly to mouse skin, inhibit some of the irritant effects of the tumor promoter and are not toxic.