Immunomodulatory and therapeutic role of Cinnamomum verum extracts in collagen-induced arthritic BALB/c mice

Abstract

Ethnopharmacological relevance: Cinnamomum verum (CV), also known as 'Dalchini', is the dry bark of the Cinnamomum verum (L.) plant, and has been used as a traditional Pakistani medicine to alleviate pain and inflammation in patients suffering from arthritic rheumatism. It contains alkaloids, triterpenes, Cinnamaldehyde and other volatile oils. The aim of the present study was to investigate the underlying biological effect of ethyl alcohol (EtOH) and methyl alcohol (MeOH) extracts from CV on collagen type-II induced arthritic (CIA) mice.

Materials and methods: Gas chromatography mass spectrophotometry was used to perform fingerprinting identification of the EtOH and MeOH extracts. CIA mice model was established by subdermal injections of type-II bovine collagen (CII) on the 1st, 8th and 14th day of the experiment. Ethyl alcohol extract and methyl alcohol extract (1 mg/KgBW, 2 mg/KgBW and 4 mg/KgBW), was orally administered from the 15th day onwards for 2 weeks. Progression of oedema and joint inflammation was measured in the paws using a digital Vernier calliper every 3 days from day 1 till the end of the experiment. The oxidative scavenging ability of cinnamaldehyde was evaluated using a DPPH assay. Similarly, the nitrogen free radical (NOS) production of isolated lymphocytes was evaluated using Greiss's method. The spleen index was calculated and knee joint changes were observed by histopathological sectioning. Western blot analysis was performed on peripheral blood derived serum for CII, CAPN1, TNFα and NFATc3.

Results: Extracts were shown to be enriched in trans-cinnamaldehyde and its analogues. Extracts showed good ameliorative effects (p < 0.05) after day 2 of treatment. A greater therapeutic role was observed for the 4 mg/kgBW dosage of the methanolic extract (p < 0.01). Swelling in the spleen was greatly reduced along with the generation of free radicals by lymphocytes, post treatment. There was also an inhibitory role by the extracts on NFATc3 (p < 0.05), TNF-Alpha (p < 0.05), CAII (p < 0.05) and mCalpain (p < 0.05) all proteins involved in RA.

Conclusion: In this study, it has been demonstrated that administration of CV has a therapeutic potential on CIA. The data suggest that CV could have a potential role in the treatment of RA patients.

Keywords: Arthritis; CAII; Cinnamaldehyde; Joint degradation; NFatc3; mCalpain.