ANTI-INFLAMMATORY EFFECTS AND KERATINOCYTE REGENERATIVE POTENTIAL OF CASSIA ALATA (LINN) LEAF EXTRACTS AND THEIR IMPLICATIONS FOR WOUND HEALING

In this study, dried and ground plant leaves of Cassia alata were extracted with methanol and water, which were then subjected to various analyses. Morphological changes of human keratinocytes in response to plant extracts were observed with a differential interference contrast (DIC) microscope imaging system. The cell viability and proliferation effects of the plant extracts were also evaluated via colorimetric cytotoxicity assays and the CyQUANT® assay. Anti-inflammatory effects of the plant extracts were evaluated by flow cytometry with a cytometric bead array (CBA) kit and also cyclooxygenase (COX)-1, COX-2 and 5-lipoxygenase (5-LOX) enzyme inhibition assays. Results of the DIC microscopy assay indicated that Human keratinocytes treated with either the C. alata methanol (CAM) or aqueous (CAA) extracts (0.1-0.2 mg/mL) achieved 100% confluency. Cytotoxicity testing confirmed that the plant extracts were not toxic to keratinocyte cells at the concentrations used in the study. Only two cytokines i.e. interleukin (IL)-6 and IL-8 were detected by the CBA method, with the results confirming that none of the plant extracts induce a pro-inflammatory effect. Moreover, CAM and CAA extracts showed strong anti-inflammatory effects in suppressing IL-8. Both plant extracts (6.25-100 µg/mL) demonstrated strong inhibitory effects on COX-1 and 5-LOX enzymes compared to the standards i.e. indomethacin and nordihydroguaiaretic acid, respectively. However, inhibition of the COX-2 enzyme was less compared with indomethacin. The CAM extract at a concentration of 6.25 µg/mL, produced strong inhibition of COX-1 and 5-LOX enzymes, which was greater than that of the respective control treatments at the same concentration. Hence, our results indicate that the C. alata leaf extracts have a strong anti-inflammatory potential, which could be used to treat wounds and inflammation associated with the skin.