Solidagenone from Solidago chilensis Meyen inhibits skin inflammation in experimental models

Investigation of inflammatory mechanisms induced by croton oil in mouse ear

Croton oil is liquid at room temperature, with a pale-yellow color and spicy odor. It is commonly used in combination with phenol as a chemical peeling agent in dermatology, which reveals its caustic exfoliating effects. Topical use of croton oil at a high dose produces skin irritation, inflammation, swelling, pain, and even tumors. Therefore, croton oil has been widely used for inflammation, pain, and tumor related research, with different animal models having been established. However, mechanistic studies through which croton oil induces skin swelling, injury and activates tissue repair/regeneration are limited. The present study used croton oil to induce mouse ear edema and examined tissue responses 4 h after exposure. To this end, croton oil was applied to the ventral side of mouse ears, followed by tissue collection. Samples were analyzed by hematoxylin and eosin (H&E) staining, toluidine blue staining, and immunohistochemistry staining for myeloperoxidase (MPO) and matrix metalloproteinase-9 (MMP-9). Western blotting and ELISA were also carried out for MMP-9 together with unbiased proteomic analysis using mass-spectrometry. Results from our study demonstrated that as soon as 4 h of exposure to 2.5 % croton oil, the expression levels of MPO and MMP-9 in the dermis significantly increased compared to acetone-treated (vehicle) control ears, as did other inflammatory reactions such as swelling and neutrophil aggregation and infiltration. Subsequently, proteomic analysis confirmed that croton oil treatment resulted in significant upregulation of proteins such as myeloperoxidase (MPO), matrix metalloproteinase-9 (MMP-9), and matrix metalloproteinase-8 (MMP-8) in the ear skin. Interestingly, mouse ears treated with acetone vehicle showed differential expression of 2,478 proteins relative to naïve tissues; among those differentially expressed in acetone-treated samples were members of the phosphatidylinositol-glycan biosynthesis class N, T and U proteins (PIGN, PIGT, and PIGU). Overall, this work confirms the presence of neutrophil-derived MPO and MMP-9 and extends the body of knowledge to show that MMP-8 is also present during croton oil-mediated skin inflammation in the mouse ear; moreover, we find that acetone vehicle is not inert and has effects on the skin that should be considered moving forward.

Phytochemical analysis of Brugmansia suaveolens Bercht. & J. Presl and its therapeutic potential for topical use

Brugmansia suaveolens Bercht. & J. Presl represents a promising source of new active molecules. Therefore, the aim of the study is to outline the profile of secondary metabolites and their therapeutic potential and in vitro safety properties. The identification of substances was carried out through the chromatographic profile, while the evaluation of therapeutic use was conducted through in vitro biological assays of antioxidant and antimicrobial activity and quantification of the total phenolic content. The safety of the extracts was evaluated using a cytotoxicity assay. The results found revealed the presence of different secondary metabolites, such as flavonoids and alkaloids. Biological assays showed promising antimicrobial activity in gram-negative strains. Regarding safety, greater cytotoxicity is observed in macrophage cells. The study demonstrated that the extracts are potent for therapeutic use, aiming at the development of a phytoproduct for topical use, providing an innovative, relevant and significant character for future research.

Anti-Inflammatory Activity and Chemical Analysis of Different Fractions from Solidago chilensis Inflorescence

Solidago chilensis Meyen (Compositae) is a species native to South America (Brazil) popularly known as arnica. In Brazilian popular medicine, inflorescences and rhizomes of this plant have been used since the end of the 19th century to replace the exogenous and hepatotoxic Arnica montana L. in the treatment of edema and inflammatory pathologies. Although the anti-inflammatory activity of S. chilensis is evidenced in the literature, there is a lack of studies with enriched fractions or compounds isolated from it. The objective of the current study was to characterize phytochemically and to evaluate the pharmacological action in vivo and in vitro of the crude extract and the different fractions (hexane, dichloromethane, acetal, butanolic, and aqueous) isolated from the inflorescence of S. chilensis. The inflorescence crude extract (ScIE) and fractions were administered by intraperitoneal route to mice at different doses. In an LPS-induced pleurisy model, inhibition of leukocyte influx was observed for the ScIE and all fractions tested, as compared to controls. Dichloromethane (ScDicF), butanolic (ScButF), and aqueous (ScAquF) were selected for further analysis as they showed the best inhibitory effects in leukocyte migration and inflammatory cytokine and chemokine production: TNF-α, CXCL1/KC, CXCL2/MIP-2, and CCL11/eotaxin-1. In LPS-stimulated J774A.1 cell line, ScIE and the ScDicF exhibited an inhibitory effect on nitric oxide (NO) production and downmodulated the COX-2 expression; ScAquF failed to modulate NO production and COX-2 expression. In phytochemical analysis, HPLC-UV-DAD chromatograms of ScDicF and ScAquF showed the main peaks with UV spectrum characteristics of flavonoids; chlorogenic acid and isoquercetin were the most present phytochemicals identified in the ScAquF, and a high number of n-alkanes was found in ScHexF. Our study was the first to address biological effects and correlate them to phytochemically characterized fractions from inflorescences of S. chilensis.

The protective effect of solidagenone from Solidago chilensis Meyen in a mouse model of airway inflammation

Solidagenone is the main active constituent present in Solidago chilensis Meyen which is used in folk medicine to treat pain and inflammatory diseases. This study aimed to evaluate the anti-inflammatory activity of solidagenone in vitro and in a model of allergic airway inflammation. In vitro studies were performed in activated macrophages and lymphocytes. BALB/c mice were sensitized and challenged with ovalbumin and treated with solidagenone orally (30 or 90 mg/kg body weight) or dexamethasone, as a positive control in our in vivo analysis. Supernatant concentrations of nitrite, TNF and IL-1β, as well as gene expression of pro-inflammatory mediators in macrophages cultures, were reduced after solidagenone treatment, without affecting macrophages viability. Besides, solidagenone significantly decreased T cell proliferation and secretion of IFNγ and IL-2. Th2 cytokine concentrations and inflammatory cell counts, especially eosinophils, in bronchoalveolar lavage fluid were reduced in mice treated with solidagenone. Histopathological evaluation of lung tissue was performed, and morphometrical analyses demonstrated reduction of cellular infiltration and mucus hypersecretion. Altogether, solidagenone presented anti-inflammatory activity in vitro and in vivo in the OVA-induced airway inflammation model, suggesting its promising pharmacological use as an anti-inflammatory agent for allergic hypersensitivity.

Solidagenone acts on promastigotes of L. amazonensis by inducing apoptosis-like processes on intracellular amastigotes by IL-12p70/ROS/NO pathway activation

BACKGROUND

Leishmaniasis is a neglected tropical disease caused by protozoan parasites of the Leishmania genus. Currently, the treatment has limited effectiveness and high toxicity, is expensive, requires long-term treatment, induces significant side effects, and promotes drug resistance. Thus, new therapeutic strategies must be developed to find alternative compounds with high efficiency and low cost. Solidagenone (SOL), one of the main constituents of Solidago chilensis, has shown gastroprotective, anti-inflammatory and immunomodulatory effects.

PURPOSE

This study assessed the in vitro effect of SOL on promastigotes and Leishmania amazonensis-infected macrophages, as well its microbicide and immunomodulatory mechanisms.

METHODS

SOL was isolated from the roots of S. chilensis, 98% purity, and identified by chromatographic methods, and the effect of SOL on leishmanicidal activity against promastigotes in vitro, SOL-induced cytotoxicity in THP-1, J774 cells, sheep erythrocytes, and L. amazonensis-infected J774 macrophages, and the mechanisms of death involved in this action were evaluated.

RESULTS

In silico predictions showed good drug-likeness potential for SOL with high oral bioavailability and intestinal absorption. SOL treatment (10-160 μM) inhibited promastigote proliferation 24, 48, and 72 h after treatment. After 24 h of treatment, SOL at the IC₅₀ (34.5 μM) and 2 × the IC₅₀ (69 μM) induced several morphological and ultrastructural changes in promastigotes, altered the cell cycle and cellular volume, increased phosphatidylserine exposure on the cell surface, induced the loss of plasma membrane integrity, increased the reactive oxygen species (ROS) level, induced loss of mitochondrial integrity (characterized by an apoptosis-like process), and increased the number of lipid droplets and autophagic vacuoles. Additionally, SOL induced low cytotoxicity in J774 murine macrophages (CC₅₀ of 1587 μM), THP-1 human monocytes (CC₅₀ of 1321 μM), and sheep erythrocytes. SOL treatment reduced the percentage of L. amazonensis-infected macrophages and the number of amastigotes per macrophage (IC₅₀ 9.5 μM), reduced TNF-α production and increased IL-12p70, ROS and nitric oxide (NO) levels.

CONCLUSION

SOL showed in vitro leishmanicidal effects against the promastigotes by apoptosis-like mechanism and amastigotes by reducing TNF-α and increasing IL-12p70, ROS, and NO levels, suggesting their potential as a candidate for use in further studies on the design of antileishmanial drugs.