Fig. 5

Proposed inhibition of the IL-6/STAT3 signalling pathway by cryptolepine. IL-6 interacts with IL-6R forming the IL-6/IL-6R complex. This complex then dimerises with GP130, a transmembrane protein, leading to the activation of the JAKs which in turn activate STAT3 via phosphorylation. The phosphorylated STAT3 (p-STAT3) homodimerise and translocate into the nucleus where the p-STAT3 dimers bind to the promoter regions of effector genes including, but not limited to, IL-23, c-Myc, Bcl-2 and HIF-1α. This study has demonstrated that cryptolepine suppresses the levels of p-STAT3 and IL-23 (indicated by red font and straight lines crossed at one end). CRYPT: Cryptolepine