Antinociceptive effect of ethanolic extract of Selaginella convoluta in mice

Abstract

Background: Selaginella convoluta (Arn.) Spring (Selaginellaceae), commonly known as "jericó", is a medicinal plant found in northeastern Brazil. S. convoluta is used in folk medicine as an antidepressant, aphrodisiac, diuretic, analgesic, anti-inflammatory and it is used to combat amenorrhea, coughing and bleeding. This study was performed to evaluate the antinociceptive effects of ethanolic extract from S. convoluta in mice exposed to chemical and thermal models of nociception.

Methods: Preliminary phytochemical analysis of the ethanolic extract was performed. The ethanolic extract from Selaginella convoluta (Sc-EtOH) was examined for its intraperitoneal (i.p.) antinociceptive activity at the doses of 100, 200 and 400 mg/kg body weight. Acetic acid-induced writhing, formalin injection and hot plate tests were used to evaluate the antinociceptive activity of Sc-EtOH extract. The rota-rod test was used to evaluate motor coordination.

Results: A preliminary analysis of Sc-EtOH revealed that it contained phenols, steroids, terpenoids and flavonoids. In the acetic acid-induced writhing test, mice treated with Sc-EtOH (100, 200 and 400 mg/kg, i.p.) exhibited reduced writhing (58.46, 75.63 and 82.23%, respectively). Secondly, Sc-EtOH treatment (100, 200 and 400 mg/kg, i.p.) decreased the paw licking time in mice during the first phase of the formalin test (by 44.90, 33.33 and 34.16%, respectively), as well as during the second phase of the test (by 86.44, 56.20 and 94.95%, respectively). Additionally, Sc-EtOH treatment at doses of 200 and 400 mg/kg increased the latency time in the hot plate test after 60 and 90 minutes, respectively. In addition, Sc-EtOH did not impair motor coordination.

Conclusion: Overall, these results indicate that Sc-EtOH is effective as an analgesic agent in various pain models. The activity of Sc-EtOH is most likely mediated via the inhibition of peripheral mediators and central inhibitory mechanisms. This study supports previous claims of traditional uses for S. convoluta.

Figure 1

HPLC-DAD phenolic profile for the Sc-EtOH recorded at 320 nm.

Figure 2

Effect of ethanolic extract of the Selaginella convoluta (Sc-EtOH), acetylsalicylic acid (ASA 150 mg/kg) and morphine (Morph 10 mg/kg) on acetic acid induced writhing test. Values are mean ± S.E.M. **p < 0.01, significantly different from control; ANOVA followed Dunnett’s test (n = 6, per group).

Figure 3

Effect of ethanolic extract of Selaginella convoluta (Sc-EtOH), acetylsalicylic acid (ASA 150 mg/kg) and morphine (Morph 10 mg/kg) on formalin test (first phase). Values are mean ± S.E.M.; **p < 0.01, significantly different from control; ANOVA followed Dunnett’s test (n = 6, per group)

Figure 4

Effect of ethanolic extract of Selaginella convoluta (Sc-EtOH), acetylsalicylic acid (ASA 150 mg/kg) and morphine (Morph 10 mg/kg) on formalin test (second phase). Values are mean ± S.E.M.; *p < 0.05, **p < 0.01, significantly different from control; ANOVA followed Dunnett’s test (n = 6, per group).

Figure 5

Effect of ethanolic extract of Selaginella convoluta (Sc-EtOH) and morphine on hot plate test. Values are mean ± S.E.M.; *p < 0.05, **p < 0.01, significantly different from control; ANOVA followed Dunnett’s test (n = 6, per group).

Figure 6

Effect of ethanolic extract of Selaginella convoluta (Sc-EtOH) and diazepam (DZP) on rota-rod test. Values are mean ± S.E.M.; **p < 0.01, significantly different from control; ANOVA followed Dunnett’s test (n = 6, per group).