Comparison of in vitro Antioxidant and Anti-inflammatory Activity of Two Cinnamomum zeylanicum Blume Varieties

Abstract

Background: Cinnamomum zeylanicum Blume known as Ceylon cinnamon has been widely used in traditional medicines since ancient times. Sri Gemunu (SG) and Sri Wijaya (SW) are the most cultivating cinnamon varieties in Sri Lanka. Objective: To compare in vitro antioxidant and anti-inflammatory activities of barks and leaves of SG and SW varieties of C. zeylanicum Methods: Aqueous extracts of SG barks (SGB), SW barks (SWB), SG leaves (SGL), and SW leaves (SWL) were subjected to in vitro DPPH radicals scavenging assay and ferric reducing antioxidant power (FRAP) assay using ascorbic acid (AA) as the standard. Inhibition of egg albumin denaturation (EA) and heat-induced human red blood cell membrane stabilization (HRBC) assays were used to assess the in vitro anti-inflammatory activity, using diclofenac sodium as the standard. Tests were done in triplicates. Results: Half-maximal inhibitory concentrations (IC50) of SGB, SWB, SGL, SWL and AA for DPPH assay were 2.86±1.03, 6.58±2.63, 31.83±12.05, 26.14±12.06 and 1.78±0.37 in µg/mL, respectively. FRAP assay showed antioxidant capacities as 90.44±10.95, 253.61±4.46, 31.22±3.94, and 65.17±4.85 in mg AA equivalent/g for SGB, SWB, SGL, and SWL, respectively. The IC50 values obtained in EA assay for SGB, SWB, SGL, SWL and the standard were 1.78±0.10, 1.06±0.19, 2.06±0.22, 1.16±0.09, and 0.74±0.01 in mg/mL while IC50 values obtained in HRBC assay were 1.79±0.17, 1.74±0.11, 3.44±0.15, 1.96±0.09, and 0.95±0.03 in mg/mL, respectively. Results showed barks have significantly higher antioxidant capacity than leaves of the same variety (p<0.05) in FRAP assay. SW variety showed the highest antioxidant capacity among barks and among leaves of both varieties (p<0.05) in FRAP assay while comparable activity was shown (p>0.05) in DPPH assay. When consider the anti-inflammatory potency, barks and leaves of the same variety and barks of the two varieties showed comparable potency (p>0.05) in EA and HRBC assays, while SWL showed the highest activity among leaves of the two varieties (p<0.05) in HRBC assay. Conclusion: Both barks and leaves of C. zeylanicum varieties have comparable antioxidant and anti-inflammatory activities.