Topically Applied Diterpenoids from Egletes viscosa (Asteraceae) Attenuate the Dermal Inflammation in Mouse Ear Induced by Tetradecanoylphorbol 13-Acetate- and Oxazolone

Abstract

Over the past three decades, the prevalence of atopic dermatitis and allergic or irritant contact dermatitis has been increasing significantly in the general population, causing considerable economic costs and decreased quality of life. [1][2][3] Topical corticosteroids have been the first-choice therapy for treatment of these inflammatory skin diseases such as eczema, atopic and seborrheic dermatitis, and psoriasis. While effective in many patients, this form of therapy carry the concern of local and systemic adverse effects and may induce skin atrophy, especially after long-term use. 4,5) In contrast to topical corticosteroids, the more recently introduced calcineurin inhibitors like tacrolimus and pimecrolimus do not induce skin atrophy, even after long-term use but may induce adverse effects such as burning, erythema and pruritus and are contraindicated in patients younger than two years or in those who are immunosuppressed.6,7) Thus, the available drugs, although have efficacy they are associated with adverse effects and therefore the development of new and safe anti-inflammatory topical agents for the treatment of dermatitis is needed.Studies reveal that a large percentage of patients use some form of complementary and alternative medicine for the treatment of atopic and contact dermatitis, which include herbal remedies. [8][9][10] In the recent past, several diterpene compounds of plant origin such as abietic acid from Pimenta racemosa var. grissea, hypoestoxide from Hypoestes rosea and marrubiin from Marrubium vulgare were shown to be effective in the mouse model of ear edema induced by several phlogestogens like histamine, bradykinin, capsaicin, prostaglandin E 2 , Croton oil, TPA (12-O-tetradecanoylphorbol 13-acetate) or oxazolone.11-13) Centipedic acid (CA) and 12-acetoxy-hawtriwaic acid lactone (AHAL, Tanabalin) are the naturally occurring diterpenes isolated from the aerial parts of Egletes viscosa L. (Asteraceae), a traditional medicinal plant.14) Previously we reported on the gastroprotective and antinociceptive properties of these diterpenes as well as an anti-edematogenic activity of tanabolin against ear edema induced by capsaicin. 15,16) However, the anti-inflammatory efficacy of these two diterpene compounds was not tested in the models of ear edema induced by either TPA or oxazolone, the most commonly used ones for analysing the agents effective against contact or atopic dermatitis.17,18) Thus as a part of our continuation study, we describe here for the first time the anti-dermatitis effects of these two natural diterpenes from Egletes viscosa using the experimental models of acute and chronic dermatitis induced by TPA and oxazolone, respectively, in the mouse ear. MATERIALS AND METHODS Plant Material and Isolation of DiterpenoidsThe aerial parts (2.5 kg) of Egletes viscosa LESS. (Asteraceae) were collected from the experimental plantation pertaining to the Department of Agronomy of this University, after its authentication and the voucher specimen (#16327) was retained in Prisco Bezerra He...

Luteolin-phospholipid complex: preparation, characterization and biological evaluation

“…Histopathological evaluation of ear after TPA treatment showed substantial increase in infiltration of mononuclear and polymorphonuclear inflammatory cells and epidermal hyperplasia compared with untreated control group (Figure ). The increase in ear weight of TPA‐treated animals can be attributed to the intense ear oedema induced by TPA [42]. Luteolin and LPC treatments markedly reduced the ear thickness and associated pathological indicators.…”

Extracts ofFicus exasperataleaf inhibit topical and systemic inflammation in rodents and suppress LPS-induced expression of mediators of inflammation in macrophages

“…Although the study has not associated any of these constituents with the activities recorded, some of these bioactive constituents have been reported in previous studies to inhibit inflammation and suppress the production and release of pro-inflammatory mediators by monocytic cells. For examples, plant terpenoids have been reported to possess anti-inflammatory activities (Calou et al, 2008;Salinas-Sánchez et al, 2012;Zhang et al, 2012). Plant alkaloids have also been reported, in previous studies, to suppress inflammatory responses in rodents (Chakraborty and Brantner, 2001).…”

Anti-Inflammatory Potential of Hecogenin in Experimental Animals: Possible Involvement of Inflammatory Cytokines and Myeloperoxidase

“…A large number of plant derived natural products have established anti-inflammatory activity such as; flavonoids, steroids, tannins and triterpenes, that interferes with the steps of inflammatory cascade [43]. Most of the above compounds act by non-specific mechanism (e. g., antioxidants), but may also act via specific mechanisms such as the inhibition of inflammatory mediators [44]. Hecogenin (Steroidal sapogenin) is the most ubiquitous glycoside isolated from leaves of various Agave genus species, has anti-inflammatory effects.…”