Inflammatory skin disorders, such as psoriasis and atopic dermatitis, are very common in the population; however, the treatments currently available are not well tolerated and are often ineffective. Averrhoa carambola L. (Oxalidaceae) is an Asian tree that has been used in traditional folk medicine in the treatment of several skin disorders. The present study evaluates the topical anti-inflammatory effects of the crude ethanolic extract of A. carambola leaves, its hexane, ethyl acetate, and butanol fractions and two isolated flavonoids on skin inflammation. Anti-inflammatory activity was measured using a croton oil-induced ear edema model of inflammation in mice. Topically applied ethanolic extract reduced edema in a dose-dependent manner, resulting in a maximum inhibition of 73 ± 3% and an ID50 value of 0.05 (range: 0.02–0.13) mg/ear. Myeloperoxidase (MPO) activity was also inhibited by the extract, resulting in a maximum inhibition of 60 ± 6% (0.6 mg/ear). All of the fractions tested caused inhibition of edema formation and of MPO activity. Treatment with the ethyl acetate fraction was the most effective, resulting in inhibition levels of 75 ± 5 and 54 ± 8% for edema formation and MPO activity, respectively. However, treatment of mice with isolated compounds [apigenin-6-C-β-l-fucopyranoside and apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside] did not yield successful results. Apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside caused only a mild reduction in edema formation (28 ± 11%). Taken together, these preliminary results support the popular use of A. carambola as an anti-inflammatory agent and open up new possibilities for its use in skin disorders.

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Melipona marginata is an endangered species of stingless bee from Brazil that produces honey with particular physicochemical features and a remarkable exotic flavor. To the best of our knowledge, this is the first report devoted to exploring the medicinal potential of this honey. Thus, the aim of this paper was to investigate the potential anti-inflammatory activity of honey extract from M. marginata on skin inflammation. The honey sample was classified as a monofloral honey of Mimosa scabrella. The presence of 11 phenolic compounds as kaempferol and caffeic acid was detected using the high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-UV-ESI-MS) method. The anti-inflammatory activity was measured using a 12-O-tetradecanoylphorbol-13-acetate-induced ear edema model of inflammation in mice. The topical application of the M. marginata honey extract (1.0 mg/ear) was able to reduce ear edema with an inhibitory effect of 54 ± 5%. This extract decreased the myeloperoxidase activity in 75 ± 3%, which suggests a lower leucocyte infiltration that was confirmed by histological analysis. This extract also provided a reduction of 55 ± 14% in the production of reactive oxygen species. This anti-inflammatory activity could be due to a synergic effect of the phenolic compounds identified in the honey sample. Taken together, these results open up new possibilities for the use of M. marginata honey extract in skin disorders.

Malva sylvestris has been used since ancient times for its emollient, laxative and anti-inflammatory properties, being extensively used as salads, soups and teas. The preset study evaluated the topical anti-inflammatory action of M. sylvestris hydroalcoholic extract (HE) and its compounds in mice ear inflammation caused by 12-O-tetradecanoylphorbol-acetate in mice. The LC-MS analysis of the HE confirmed the presence of scopoletin, quercetin and malvidin 3-glucoside compounds in the HE of M. sylvestris. Topical application of the HE reduced ear oedema, polymorphonuclear cells influx (myeloperoxydase activity and histological analysis) and interleukin-1β levels in the tissue. The topical application of the compound present in the HE, malvidin 3-glucoside was also able to inhibit ear oedema and leukocytes migration. The other tested compounds, scopoletin, quercetin and malvidin 3,5-glucoside were able to prevent the formation of oedema and cell infiltration, but with less effectiveness when compared to HE and malvidin 3-glucoside. Therefore, these results consistently support the notion that M. sylvestris leaves possesses topical anti-inflammatory activity, the compound malvidin 3-glucoside seems to be major responsible for this effect, with the participation of other anti-inflammatory compounds in the extract. Thus, as recommended by population, M. sylvestris can be used as a future treatment to skin disorders.

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Garcinia gardneriana is popularly used in skin disorders; therefore, this article investigated the effect of G. gardneriana extracts from leaves, bark and seeds and two isolated compounds in ear oedema and leucocytes migration caused by croton oil. The topical application of the extract of G. gardneriana leaves was able to reduce (70 € 3%, and ID 50 0.33 mg ⁄ ear) ear oedema, while the seeds (51 € 5%) and the wood (60 € 12%) extracts were less effective. In a time-course evaluation, the leaf extract (1 mg ⁄ ear) was effective when applied 2 hr before and until 3 hr after the stimulation, presenting a higher effectiveness when applied right after croton oil (83 € 7% inhibition). In addition, the leaf extract was able to diminish the myeloperoxidase (MPO) activity in 64 € 13%, which suggests the inhibition of leucocyte infiltration that was confirmed by histological analysis. Also, both biflavonoids isolated from the leaves of G. gardneriana, fukugetin (or morelloflavone) and 13-naringenin-II 8-eriodictyol (GB-2a), were able to reduce ear oedema, with ID 50 values of 0.18 (0.10-0.28) and 0.22 (0.15-0.31) mg ⁄ ear, respectively, besides the inhibition of MPO activity of 52 € 6% and 64 € 5%, respectively. Using the fluorescent probe 2¢,7¢-dichlorodihydrofluorescein diacetate, the leaf extract, fukugetin and GB-2a topically applied to the ear treated with croton oil reduced 52 € 15%, 63 € 17% and 83 € 4%, respectively, the production of reactive oxygen species of the skin. Thus, these results reveal the anti-inflammatory effect of G. gardneriana leaves for topical usage, and both biflavonoids are responsible for this effect.

These results suggest that HEGG inhibition relates to its tyrosinase activity. Therefore, the hydroalcoholic extract of Garcinia gardneriana shows great potential for use as a depigmenting agent in hyperpigmentation disorders.