Therapeutic potential of Polyalthia cerasoides stem bark extracts against oxidative stress and nociception

Abstract

Background: Polyalthia cerasoides is a medicinal plant known for its ethnopharmacological importance. Despite this, investigation related to its therapeutic benefit is still unexplored.

Aim: To evaluate the stem bark extracts of Polyalthia cerasoides for pharmacological activities relating to inflammation, nociception and oxidative stress using in vivo and in vitro models.

Materials and methods: Pet ether, ethyl acetate and chloroform fractions of the stem bark were evaluated for anti-inflammatory activity by carrageenan-induced hind paw edema in rats. Anti-nociceptive activity in mice was assessed using thermally and chemically induced analgesic models. The free radical quenching potential of the extracts was initially analyzed using the in vitro DPPH photometric assay, Hydroxyl radical scavenging and Lipid Peroxidation assays. Then modulatory effect of the extracts on in vivo antioxidant system was evaluated by carbon tetrachloride induced hepatotoxicity and subsequent measurements of antioxidant enzymes such as Superoxide dismutase, Catalase and Peroxidase from the liver homogenate.

Results: Among the tested fractions, ethyl acetate extract had substantially inhibited the inflammation by 68.5% that was induced by subcutaneous carrageenan injection whereas pet ether and chloroform extract showed only minimal inhibitory effect. Investigation of the anti-nociceptive activity revealed that the ethyl acetate fractions had significantly repressed the algesia in both the analgesic experimental models. In vitro and in vivo individual antioxidant assays demonstrated that the ethyl acetate fraction has strong free radical quenching potential which also restores the endogenous hepatic enzymes.

Conclusion: The ethyl acetate fraction enriched with flavinoids and steroids from Polyalthia cerasoides stem bark has potent bioactivity to combat inflammation, ROS and pain. This needs further characterization for potential therapeutic applications.

Keywords: Analgesia; anti-inflamatory; carageenan; catalase; lipid peroxidation; nociception; reactive oxygen species.

Figure 1

Anti-nociceptive activity of P. cerasoides stem bark extracts in acetic acid induced writhing in Swiss albino mice. (a) P. cerasoides stem bark fractions (100 and 200 mg/kg, p.o.). Control distilled water (10 ml/kg, p.o.), standard drug diclofenac sodium (5 mg/kg. i.p.). (b) Percentage reduction of writhing in groups treated with the extracts and standard drug. One way ANOVA followed by multiple Tukey's comparison test. Values are presented as the mean ± SEM (standard error); n = 6 for all groups (Statistically significant values are *P < 0.05; **P < 0.01)

Figure 2

Anti-nociceptive activity of P. cerasoides stem bark determined on Eddy's hot plate test in Swiss albino mice. P. cerasoides stem bark fractions (PEPCF, CFPCF, EAPCF, 100 and 200 mg/kg, p.o.). Control distilled water (10 ml/kg, p.o.), standard drug pentazocine (5 mg/kg, i.p.). One way ANOVA followed by multiple Tukey's comparison test. Values are the mean ± SEM, n = 6 in each group, (statistically significant values are *P < 0.05; **P < 0.01)

Figure 3

Inhibitory effect of P. cerasoides stem bark on carageenan induced paw edema model in rats. (a) P. cerasoides stem bark fractions (PEPCF, CFPCF, EAPCF, 100 and 200 mg/kg p.o.). Control distilled water (10 ml/kg, p.o.), standard drug diclofenac sodium (5 mg/kg. i.p.). (b) Percentage reduction of paw volume (ml) in treated groups. PEPCF and EAPCF at 200 mg/kg had exhibited 36.06% and 68.85% inhibition respectively. One way ANOVA followed by multiple Tukey's comparison test. Values are presented as the mean ± SEM (standard error); n = 6 for all groups, (statistically significant values are *P < 0.05; **P < 0.01)

Figure 4

Free radical scavenging ability of P. cerasoides stem bark (EAPCF) by DPPH radical, Hydroxyl radical and Lipid Peroxidation by in-vitro assays. IC₅₀ value of EAPCF on ROS scavenging potential is compared to the respective standards. Values are mean ± SEM, n = 6, one way ANOVA followed by Tukey's multiple comparison test. Significant values are *P < 0.05; **P < 0.01)

Figure 5

Schematic representation of the pharmacological activities of P. cerasoides stem bark extracts