Analgesic and anti-inflammatory activities of NPK 500 capsules, a Cassia sieberiana DC. - Based herbal analgesic medicine used to treat dysmenorrhea and peptic ulcer, is mediated through the inhibition of PGE2 and iNOS.

Ethnopharmacological Relevance: Pain and inflammation are the most frequent reasons for which people seek medical care. Currently available analgesics against these conditions produce fatal adverse effects. NPK 500 capsules is an alternative herbal analgesic employed to treat dysmenorrhea, peptic ulcer and pain. NPK 500 is produced from Cassia sieberiana. A plant used in traditional medicine to treat pain and inflammation.

Aim Of The Study: This study reports the analysis, phytochemical characterization and mechanism of analgesic and anti-inflammatory activities of two NPK 500 capsules, called old and new NPK500 capsules (ONPK500 and NNPK500) respectively.

Materials And Methods: Physicochemical, organoleptic, GC-MS and LC-MS methods were employed to analyze the NPK 500 capsules. Analgesic activity was evaluated using tail immersion, Randall-Selitto and acetic acid induced writing tests. Anti-inflammatory activity was evaluated using carrageenan-induced rat paw inflammation. Additionally, pro-inflammatory mediators such as prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase 1 and 2 (COX-2 and COX-1) were quantified in the sera of the rats using Enzyme Linked Immunosorbent Assay (ELISA) kits.

Results: Thirteen major compounds were characterized in the NNPK 500 capsules via the GC-MS and LC-MS spectroscopies. Kaempferol was the major compound characterized in addition to physcion, β-sitosterol 3-O-β-D-glucopyranoside, betulinic acid and nine others. Physicochemical and organoleptic indices of the capsules were also derived for its authentication and quality control. Furthermore, NNPK 500 0.5-1.5 mg/kg p.o. produce significant (P < 0.5) analgesic activity (160-197%) higher than that of ONPK500 (109.8%) and Morphine (101%) in the tail immersion test. The analgesic activity of NNPK 500 0.5-1.5 mg/kg p.o. (171.0-258.3%) and ONPK 500 (179.5%) were also significant (P < 0.01) and higher than that of Aspirin (103.00%) in the Randall-Selitto test. Both capsules also demonstrated significant (P < 0.5) analgesic and anti-inflammatory activities in the acetic acid-induced writhing and carrageenan-indued paw edema tests respectively. The two NPK500 capsules also, significantly (P < 0.5) inhibited PGE2 and iNOS but not COX-2 and COX-1 in the carrageenan-indued paw edema test.

Conclusion: These results show that NNPK 500 and ONPK 500 capsules possessed potent analgesic and anti-inflammatory activities via inhibition of PGE2 and iNOS as a result of their chemical constituents. NPK500 capsules thus, relief acute pain and inflammation without causing gastrointestinal, renal or hepatic injuries, since they did not inhibit COX-1.