Background/Objectives: Annona squamosa is used in folk medicine to treat pain and arthritis. Palmatine is an alkaloid isolated from several plants, including A. squamosa leaves. The aim of the present study was to investigate the analgesic, anti-arthritic, and anti-inflammatory potential of the methanolic extract of A. squamosa (EMAS) and palmatine. Methods: The chemical profile of EMAS was evaluated by ultra high-performance liquid chromatography with electrospray ionization coupled to mass spectrometry (UHPLC-ESI/MS). EMAS and palmatine were evaluated in carrageenan-induced pleurisy, zymosan-induced joint inflammation, formalin-induced nociception, and tumor necrosis factor (TNF)-induced mechanical hyperalgesia in experimental models in mice. A cytotoxicity test of EMAS and palmatine was performed using a methylthiazolidiphenyl-tetrazolium (MTT) bromide assay. Results: The analysis of the chemical profile of the extract showed the presence of palmatine, liriodenine, and anonaine. Oral administration of EMAS and palmatine significantly reduced leukocyte migration and oxide nitric production in the carrageenan-induced pleurisy model. EMAS and palmatine reduced mechanical hyperalgesia, leukocyte migration, and edema formation in the joint inflammation induced by zymosan. In the formalin test, palmatine was effective against the second-phase nociceptive response, mechanical hyperalgesia, and cold allodynia. In addition, palmatine reduced mechanical hyperalgesia induced by TNF. EMAS and palmatine did not demonstrate cytotoxicity. Conclusions: The present study showed that A. squamosa and palmatine are analgesic and anti-inflammatory agents, and that the anti-hyperalgesic properties of palmatine may involve the TNF pathway. Palmatine may be one of the compounds responsible for the anti-hyperalgesic and/or anti-arthritic properties of this medicinal plant.

The aim of this study was to evaluate the effect of ylang-ylang (Cananga odorata) essential oil (YEO) on models of experimental arthritis, persistent inflammation, and nociception in mice. YEO treatment at doses of 100 and 200 mg/kg reduced the infiltration of leukocytes into the joint cavities of mice submitted to zymosan-induced arthritis 6 h and 7 days after arthritis induction. At these doses, YEO treatment reduced the formation of joint edema 4 and 6 h after arthritis induction, and at a dose of 200 mg/kg, YEO treatment reduced mechanical hyperalgesia 3 and 4 h after arthritis induction. At the dose of 200 mg/kg, YEO treatment reduced interleukin-6 (IL-6) levels and cartilage destruction in the zymosan-induced arthritis model, and reduced edema formation and mechanical hyperalgesia in the model of persistent inflammation (21 days) induced by complete Freund’s adjuvant (CFA) in mice. YEO treatment at a dose of 200 mg/kg reduced the nociceptive response in experimental models of nociception induced by acetic acid and formalin. The YEO treatment reduced inflammatory parameters in the experimental arthritis model, and presented antiarthritic, anti-hyperalgesic, antinociceptive, and anti-inflammatory properties.

Delta-3-carene (CAR), a monoterpene derived from plant essential oils, exhibits promising biological properties, including anti-inflammatory, antioxidative, anxiolytic, and antimicrobial activities. Therefore, this study aimed to investigate the anti-inflammatory effects of CAR by analyzing the activity of this terpene on leukocyte activation through the evaluation of cell migration in in vitro and in vivo models. Cell viability analysis demonstrated that CAR (3, 10, 30, and 90 μg/mL) exerted no cytotoxic effects and significantly reduced in vitro neutrophil chemotaxis toward N-formylmethionyl-leucyl-phenylalanine (fMLP). Furthermore, CAR decreased phagocytosis in zymosan-stimulated neutrophils in vitro. In Swiss mice, oral CAR treatment, at doses of 25, 50, and 100 mg/kg, reduced inflammatory and antinociceptive parameters in zymosan-induced peritonitis, carrageenan-induced paw edema and mechanical hyperalgesia, and nociception induced by acetic acid and formalin models. In the persistent inflammation model (for 21 days) induced by complete Freund’s adjuvant (CFA), daily CAR treatment (50 mg/kg) reduced paw edema and mechanical hyperalgesia in all evaluated times at 6, 11, 16, and 21 days after CFA-induced inflammation. In conclusion, our data demonstrated that CAR modifies acute and chronic inflammatory responses, highlighting its potential therapeutic application in managing inflammation and pain.

Handroanthus heptaphyllus (Vell.) Mattos (Bignociaceae), popularly known in Brazil as "ipê-roxo" or "lapacho", is native to the Pantanal biome (Brazil). Its bark is traditionally used to treat inflammation, yet no scientific evidence currently supports this ethnomedicinal use. This study aimed to characterize the phytochemical profile of the hydroethanolic extract of H. heptaphyllus bark (HhHE), to evaluate its anti-inflammatory potential, and investigate its toxicity. From HhHE, several compounds were annotated, including glycosylated iridoids and phenolics. This extract did not present cytotoxicity, and significantly reduced the in vitro neutrophil chemotaxis and phagocytosis activity. The HhHE treatment reduced mast cell degranulation, carrageenan-induced edema formation and hyperalgesia. In addition, it reduced leukocyte recruitment, pro-inflammatory cytokines, such as tumor necrosis factor (TNF), and interleukin-6 (IL-6), and nitric oxide (NO) levels in zymosan-induced peritonitis model. The HhHE treatment also inhibited nociceptive responses in the inflammatory phase of the formalin, and acetic acid-induced abdominal writhing test, without impairing locomotion. HhHE has demonstrated significant anti-inflammatory and antinociceptive effects, possibly through the modulation of leukocyte activity and the decrease in the levels of the inflammatory mediators, such as IL-6, TNF, and NO, corroborating its traditional use and indicating its therapeutic potential in the management of inflammation and inflammatory pain.

Indigofera truxillensis Kunth is traditionally used in Brazilian folk medicine as an oral infusion of the aerial parts, taken as one cup several times daily for at least one week, to relieve inflammatory pain and gastrointestinal complaints. To chemically characterize and evaluate the anti-arthritic and analgesic properties of the methanolic extract (MEIT) and indigo obtained from the aerial parts of I. truxillensis. The chemical analysis of MEIT and the identification of indigo were performed by electrospray ionization tandem mass spectrometry and nuclear magnetic resonance. Anti-inflammatory and anti-hyperalgesic activities were assessed in mice using carrageenan-induced pleurisy and paw inflammation, complete Freund's adjuvant (CFA), and zymosan-induced articular inflammation models. Cytotoxicity and phagocytic activity were evaluated in vitro using leukocyte viability (MTT) and neutrophil phagocytosis assays. MEIT and indigo significantly inhibited leukocyte recruitment in carrageenan-induced pleurisy. In the carrageenan paw model, both reduced mechanical hyperalgesia, cold sensitivity, and edema. In CFA-induced inflammation, MEIT and indigo decreased mechanical hyperalgesia, cold response, myeloperoxidase activity, and protein exudation. In the zymosan-induced arthritis model, both treatments reduced knee edema, mechanical hyperalgesia, leukocyte migration, protein extravasation, and nitric oxide levels in synovial fluid. MEIT and indigo did not exhibit cytotoxicity in vitro; MEIT reduced neutrophil phagocytosis at specific concentrations, whereas indigo did not alter phagocytic activity. MEIT and indigo exhibit significant anti-inflammatory, anti-hyperalgesic, and anti-arthritic activities, supporting the traditional use of I. truxillensis for painful and inflammatory conditions and identifying indigo as a key bioactive constituent.