Analgesic and anxiolytic properties of aqueous extract of bark from trunk of Diospyros mespiliformis (Ebenaceae) on arthritis induced in mice

Background: Arthritis is an inflammatory disease that affects the joints. Patients suffering from chronic pain are anxious, which contributes to reducing the quality of life. The development of analgesic compounds with anxiolytic properties could prove to be of great interest for the treatment of chronic pain. The objective of the present study was to evaluate the analgesic and anxiolytic properties of the aqueous extract of the bark of the trunk of Diospyros mespiliformis in arthritic mice. Methods: Arthritis was induced by injection of 1% formaline into the left hind paw of the animals. Inflammatory pain and comorbid anxiety were tested using a hotplate (55 ± 0.5 °C) and labyrinths (Dark and Light and the open arena), respectively. Results: The aqueous extract of Diospyros mespiliformis reduced the inflammatory process by inhibiting the edema of the legs of animals to a maximum percentage of 63.63 % as well as the significant increase (p < 0.001) of the threshold of nociception at the dose of 100 mg/kg. A significant increase (p < 0.001) in the time spent in the lighted compartment alongside the decrease in the time spent in the dark environment was observed with the two-compartment maze. In the open arena the time spent in the central plaza significantly (p < 0.001) increased compared to the time spent on the edge. In addition, a significant decrease (p < 0.01) in the frequency of grooming and reaning was observed. Conclusion: The aqueous extract of the bark of the trunk of Diospyros mespiliformis displayed beneficial effects on pain and anxiety, justifying it traditional use for the management of arthritis. Keywords: analgesic, anxiolytic, Diospyros mespiliformis, arthritis

Polyphenols from <i>Dichrostachys cinerea</i> Fruits Anti-Inflammatory, Analgesic, and Antioxidant Capacity in Freund’s Adjuvant-Induced Arthritic Rat Model

Dichrostachys cinerea (L.) Wigth & Arn. (DC) is widely used in traditional medicine against several inflammatory diseases, especially rheumatoid arthritis, because of its antioxidant and anti-inflammatory effects. This study aimed to characterize the polyphenol-rich DC fruit extracts and investigate the analgesic, anti-inflammatory, and antioxidant effects in a rat inflammation model induced by complete Freund’s adjuvant (CFA). Water and ethanolic extracts were characterized using liquid chromatography coupled with mass spectrometry (LC-MS), Fourier-transform infrared (FTIR) spectroscopy, and gas chromatography coupled with mass spectrometry (GC-MS). The polyphenol-rich extracts were administered in three different concentrations for 30 days. Pain threshold, thermal hyperalgesia, edema, and serum biomarkers specific to inflammatory processes or oxidative stress were evaluated. Both extracts were rich in polyphenolic compounds, mainly flavan-3-ols, proanthocyanidins, and flavone glycosides, which had important in vitro antioxidant capacity. DC fruit extracts administration had the maximum antinociceptive and anti-inflammatory effects after one day since the CFA injection and showed promising results for long-term use as well. The measurement of pro-inflammatory cytokines, cortisol, and oxidative stress parameters showed that DC extracts significantly reduced these parameters, being dose and extract-type dependent. These results showed potential anti-inflammatory, analgesic, and antioxidative properties and revealed the necessity of using a standardized polyphenolic DC extract to avoid result variability