Antiinflammatory effects of craterostigma plantagineum extracts on formalin induced inflammation and pain in male albino Rats rattus norvegicus

Abstract

Pain is a symptom of many diseases that affect humanity while inflammation is a physiological mechanism for repair of tissues after injury. Craterostigma plantagineum hoscht has been used by herbalists for treating pain. However, its efficacy and adverse effects are not scientifically validated. The broad objective of this study was to evaluate the antinociceptive and anti-inflammatory effects of qualitatively screened aqueous and organic extracts of C. plantagineum hoscht. Using modified resource formula. A total of 24 male albino rats aged 8-12 weeks and weighing 200-250 grams were used. Male rats were used to avoid data variability caused by estrous cycle. They were randomly assigned into 8 groups of 3 rats each. These included three aqueous extract treatment groups of different doses (25mg/Kgbwt, 50mg/Kgbwt and 100mg/Kgbwt), three ethanolic extract treatment groups of similar doses, 1 positive control group receiving 15mg/kg P.o. diclofenac, and a negative control group. Phytochemical analysis was carried out according to Harbone 1973 protocol. Pain and inflammation was induced by injecting 50microliter of 5% formalin into the sub plantar of hind left paw 60 minutes after administration of the herbal extract or positive control. The duration the rat spent lifting, flicking and licking the injected paw was observed in two phases and recorded. First phase was in the first 0-5 minutes while the second phase from 15th -30thminutes.Diameter of the paw was measured just before formalin injection and every 30 minutes for four hours using a digital Vernier calipers. Blood was drawn through intracardiac puncture and evaluated for AST and ALT levels at 28th day. Animals were euthanized using dose sufficient chloroform. Left hind paws were harvested and preserved in 10% formaldehyde. Fixed Tissues were stained with haematoxylin and eosin for histology examination using Leica M205C stereomicroscope. Data was entered in MS Excel spread sheet and analyzed using SPSS v26.0. Statistical analysis was done using one way ANOVA and Scheffe's post hoc test at 5% significance level (𝛼 = 0.05. Qualitatively flavonoids, sterols, Saponins, tannins, terpenoids, cardiac glycosides, phenols and anthraquinones were detected. Both aqueous and ethanolic plant extracts did not demonstrate antinociceptive effects (p>0.05). Aqueous plant extract 100 mg/kgbwt, ethanol plant extract 25 mg/kgbwt, ethanol plant extract 50 mg/kgbwt and ethanol plant extract 100mg/kgbwt had potent paw antiedema effect (p<0.05) from 30th minute of inflammation induction. Both aqueous and ethanolic plant extracts did not show hepatotoxic effect (p>0.05). Aqueous plant extract 100 mg/kgbwt, ethanol plant extract 25 mg/kgbwt, ethanol plant extract 50 mg/kgbwt and ethanol plant extract 100mg/kgbwt had potent reduction of inflammatory cells (lymphocytes) (p<0.05) observed from paw tissue histology.