Study of the potential adverse effects caused by the dermal application of Dillenia indica L. fruit extract standardized to betulinic acid in rodents.

This study aimed to evaluate the potential adverse effects of the dermal administration of Dillenia indica Linnaeus (D. indica) fruit extract in healthy rodents; the extract was standardized to betulinic acid. In the initial phase, the acute effects were evaluated on the skin application site of a single extract dose. A skin irritation test was performed in male Wistar rats (n = 8/group) receiving the extract (50-150 mg/mL) with betulinic acid (0.5-1.5%, respectively). A photosensitivity test was performed in male BALB/c mice (n = 6/group) receiving the extract (150 mg/mL). Afterwards, other BALB/c mice (n = 20, male:female, 1:1) were used to assess the systemic alterations caused by 14 daily repeated doses (150 mg/mL) by monitoring the effects on mortality, body morphology, behavior, nutrition status, neuromotor reactions, organ morphology and weight, and blood tests. At this time, 0.5 mg/mL clobetasol was used as the positive control. The skin irritation index suggested that negligible skin irritation had occurred, even when the extract was applied to the rat skin at 150 mg/mL. However, the extract acted as a photosensitizer on mouse skin, showing a photosensitizing activity close to that of 10 mg/mL 5-methoxypsoralen. Repeated doses caused no mouse mortality, aggressiveness, piloerection, diarrhea, convulsions, neuromotor alterations or nutrition status changes. The mouse organ weights did not change, and the mice did not have alterations in their blood compositions. Clobetasol caused a reduction in the mononuclear leukocyte numbers. In general, the data suggest that the extract was safe in healthy rodents but indicate that caution should be taken with the photosensitizing activity; in addition, this activity should be further explored as it may be useful for phototherapeutic drug development.

Healing effect of Dillenia indica fruit extracts standardized to betulinic acid on ultraviolet radiation-induced psoriasis-like wounds in rats.

CONTEXT: Dillenia indica Linn. (Dilleniaceae) is traditionally used to treat skin inflammation. OBJECTIVE: This study evaluated the healing effect of Dillenia indica fruit extracts on induced psoriasis-like wounds in Wistar rats. MATERIALS AND METHODS: Extracts were standardized to betulinic acid, including an aqueous ethanolic extract (AEE), ethyl acetate extract (EAE) and petroleum ether extract. Effects against lipid peroxidation were assessed in vitro. Wounds were created at rat tails (n = 12). Topical treatments were applied once daily for 7 days (1 mL of AEE or EAE at 5 or 50 mg/mL). Maximal dose was defined by the extract solubility. A 10-fold lower dose was also tested. Positive and negative controls were treated with clobetasol (0.5 mg/mL) or excipient. Half of each group was euthanized for histology. The remaining animals were observed for 20 days for wound measurements. RESULTS: Yields of AEE and EAE were 4.3 and 0.7%, respectively. Betulinic acid concentrations in AEE and EAE were 4.6 and 107.6 mg/g. Extracts neutralized lipid peroxidation in vitro at 0.02 µg/mL, accelerating healing at 50 mg/mL. Complete healing in mice treated with AEE occurred 16 days after wound induction. This time was 14 and 12 days in mice treated with EAE and clobetasol. Compared to orthokeratosis, parakeratosis was reduced by AEE (25%), EAE (45%) and clobetasol (55%). EAE caused superior protection against biomolecules oxidation of skin compared to AEE. DISCUSSION AND CONCLUSION: EAE exhibited activity closer to that of clobetasol. Betulinic acid may be an active constituent, which should be assessed in future studies.

In Vivo Assessment of Clobetasol Propionate-Loaded Lecithin-Chitosan Nanoparticles for Skin Delivery.

The aim of this work was to assess in vivo the anti-inflammatory efficacy and tolerability of clobetasol propionate (CP) loaded lecithin/chitosan nanoparticles incorporated into chitosan gel for topical application (CP 0.005%). As a comparison, a commercial cream (CP 0.05% w/w), and a sodium deoxycholate gel (CP 0.05% w/w) were also evaluated. Lecithin/chitosan nanoparticles were prepared by self-assembling of the components obtained by direct injection of soybean lecithin alcoholic solution containing CP into chitosan aqueous solution. Nanoparticles obtained had a particle size around 250 nm, narrow distribution (polydispersity index below 0.2) and positive surface charge, provided by a superficial layer of the cationic polymer. The nanoparticle suspension was then loaded into a chitosan gel, to obtain a final CP concentration of 0.005%. The anti-inflammatory activity was evaluated using carrageenan-induced hind paw edema test on Wistar rats, the effect of formulations on the barrier property of the stratum corneum were determined using transepidermal water loss measurements (TEWL) and histological analysis was performed to evaluate the possible presence of morphological changes. The results obtained indicate that nanoparticle-in-gel formulation produced significantly higher edema inhibition compared to other formulations tested, although it contained ten times less CP. TEWL measurements also revealed that all formulations have no significant disturbance on the barrier function of skin. Furthermore, histological analysis of rat abdominal skin did not show morphological tissue changes nor cell infiltration signs after application of the formulations. Taken together, the present data show that the use of lecithin/chitosan nanoparticles in chitosan gel as a drug carrier significantly improves the risk-benefit ratio as compared with sodium-deoxycholate gel and commercial cream formulations of CP.

Clobetasol promotes remyelination in a mouse model of neuromyelitis optica.

Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system that can produce marked neurological deficit. Current NMO therapies include immunosuppressants, plasma exchange and B-cell depletion. Here, we evaluated 14 potential remyelinating drugs emerging from prior small molecule screens done to identify drugs for repurposing in multiple sclerosis and other demyelinating neurological diseases. Compounds were initially evaluated in oligodendrocyte precursor cell (OPC) and cerebellar slice cultures, and then in a mouse model of NMO produced by intracerebral injection of anti-AQP4 autoantibody (AQP4-IgG) and human complement characterized by demyelination with minimal axonal damage. The FDA-approved drug clobetasol promoted differentiation in OPC cultures and remyelination in cerebellar slice cultures and in mice. Intraperitoneal administration of 2 mg/kg/day clobetasol reduced myelin loss by ~60 %, even when clobetasol was administered after demyelination occurred. Clobetasol increased the number of mature oligodendrocytes within lesions without significantly altering initial astrocyte damage or inflammation. These results provide proof-of-concept for the potential utility of a remyelinating approach in the treatment of NMO.

A comparison of the effects of topical treatment of calcipotriol, camptothecin, clobetasol and tazarotene on an imiquimod-induced psoriasis-like mouse model.

The interleukin-23/interleukin 17A (IL-23/IL-17A) cytokine axis plays a critical role in the pathogenesis of psoriasis. In this study, we report the effects of topical calcipotriol, camptothecin, clobetasol and tazarotene on the treatment of imiquimod (IMQ)-induced psoriasis-like inflammation, the development of which is dependent on the IL-23/IL-17A axis. IMQ-induced epidermal hyperplasia and inflammation in the BALB/c mouse ear were significantly inhibited following clobetasol treatment but not calcipotriol, camptothecin or tazarotene treatments. Real-time polymerase chain reaction showed that the mRNA levels of IL-17A, IL-17F, IL-22, IL-1ß, IL-6 and TNF-α in ear skin were significantly decreased by clobetasol. In addition, we observed that calcipotriol, camptothecin and tazarotene failed to show any inhibitory effects on the IL-23/IL-17A/IL-22 axis. We also found that clobetasol treatment inhibited the proliferation of γδ T cells and C-C chemokine receptor type 6 (CCR6) expression induced by IMQ. Calcipotriol, camptothecin and tazarotene not only failed to inhibit this proliferation but also enhanced retinoic acid-related orphan receptor γ (RORγ) expression in IMQ-induced psoriasis-like inflammation. In conclusion, we suggest that clobetasol induces the relief of IMQ-induced psoriasis-like inflammation in a mouse model but that calcipotriol, camptothecin and tazarotene cannot. Therefore, we suggest that more in-depth studies on pharmacological effects of tazarotene, camptothecin and calcipotriol should be carried out.

Tea tree oil attenuates experimental contact dermatitis.

Herbs and minerals have been used in clinical dermatology for hundreds of years and herbal ingredients are becoming increasingly popular with the public in treatment of various dermatological conditions characterised by inflammation and pruritus. The aim of this study was to compare the efficacy of traditional topical therapeutic agents with a moderate potency topical glucocorticoid on experimental contact dermatitis and contact urticaria. The effects of ichthammol 10% pet, zinc oxide 20% pet, camphor 20% pet, levomenthol 10% pet, tea tree oil 20 or 50% and clobetason butyrate 0.05% ointment were studied in the following experimental models: elicitation of allergic contact dermatitis to nickel, irritant contact dermatitis to benzalkonium chloride, and in immediate reactions to histamine and benzoic acid (non-immunological contact utricaria) respectively. Delayed reactions were evaluated using a clinical scoring system and immediate reactions were estimated by planimetry. Histamine-induced pruritus was evaluated using VAS. Tea tree oil reduced allergic contact dermatitis by 40.5% (p = 0.003), zinc oxide by 17.4% (p = 0.04) and clobetason butyrate by 23.5% (p = 0.01). Zinc oxide reduced histamine induced flare by 18.5% (p = 0.01), ichthammol by 19.2% (p = 0.02) and clobetason butyrate by 44.1% (p = 0.02). Irritant contact dermatitis and non-immunological contact urticaria were not influenced by the pre-treatments. Pruritus induced by histamine also remained unchanged. In conclusion, tea tree oil seems to be a more effective anti-eczematic agent than zinc oxide and clobetasone butyrate, while clobetasone butyrate is superior to both ichthammol and zinc oxide in topical treatment of urticarial reactions.

Tachyphylaxis to histamine-induced wheal suppression by topical 0.05% clobetasol propionate in normal versus croton oil-induced dermatitic skin.

BACKGROUND: Patients often tell about reduced effectiveness of topical steroids on repeated use. Tachyphylaxis to these agents has been demonstrated in humans for vasoconstriction and histamine-induced wheal suppression in normal skin, but not in diseased skin. Relevance of these data to diseased skin is not clear. Further, the clinical impression does not appear to match tachyphylaxis shown in normal skin with regard to the time course. OBJECTIVES: To examine whether tachyphylaxis to histamine-induced wheal suppression by a topical steroid occurs in dermatitic skin and to determine its time course vis-à-vis normal skin. METHODS: Pharmacodynamic response to 0.05% clobetasol propionate applied daily under occlusion was measured by histamine-induced wheal suppression assay in 10 individuals. This test was performed on a steroid-treated normal site, on a steroid-treated site where dermatitis was induced by occlusive application of 40% croton oil, and on a vehicle-treated site in each individual at different intervals up to 14 days. RESULTS: Suppression of wheal volume started from second day in steroid-treated sites. There was significant difference in the wheal volume in steroid treated normal vs. dermatitic sites from day 2 to day 10. Maximum wheal suppression occurred earlier in dermatitic skin (day 4 vs. day 6). After this, the volume of wheal started increasing and became equal to control (complete tolerance) on 12th day in dermatitic skin and on 14th day in normal skin. CONCLUSIONS: Time courses of tachyphylaxis to the action of 0.05% clobetasol propionate were significantly different in normal skin and dermatitic skin. Complete tolerance occurred earlier in dermatitic skin compared to normal skin.

Effect of RU 486 on the atrophogenic and antiinflammatory effects of glucocorticoids in skin.

Clobetasol-17-propionate (CP), a synthetic glucocorticoid (GC), reduced skin thickness in rats. Both the subcutaneous injection and topical applications of RU 486 counteracted CP-induced reduction in skin thickness. Topical application of the CP cream completely inhibited the ear edema produced by croton oil. A less potent GC, hydrocortisone-17-butyrate, also inhibited ear edema. This antiinflammatory effect was not abolished by the subcutaneous injection or topical application of RU 486. These observations suggest that GC-induced skin atrophy is mediated by glucocorticoid receptors (GRs), while the inhibition of croton oil-induced inflammation by GC is primarily related to the direct effects of GC, which are not mediated by GRs. Our findings suggest that RU 486 inhibits the atrophogenic effect of GCs without interfering with their antiinflammatory effect. Dissociation of antiinflammatory and atrophogenic activity of GC seems favorable in treating inflammatory skin diseases lacking epidermal proliferation.

New experimental model for the primary evaluation of topical contra-inflammatory agents.

Assays of steroidal and non-steroidal drugs in an experimental model of dermatitis induced in the ear of the rabbit by the application of a solution of croton oil revealed clearly differentiable inhibitory effects on the rise in skin temperature, the oedema and the increase in tissue mass due to the inflammatory process. The results obtained in this test system fairly accurately reflect the relative therapeutic potencies of known dermatocorticoids and, in conjunction with those found by other methods, afford a more exact characterization of the activity profiles of non-steroidal contra-inflammatory agents.