[6]-Shogaol is an aromatic constituent of ginger and the chain-dehydroxylated analog of [6]-Gingerol. [6]-Shogaol has activity very similar to [6]-Gingerol and produced an inhibition of spontaneous motor activity, antipyretic and analgesic effects, and prolonged hexobarbital-induced sleeping time. [6]-Shogaol also has potent antitussive activity and affected the cortical EEG.
6-Shogaol is the dehydrated product of 6-gingerol, extracted from the rhizome ofginger. Treatment of HCC cell line with 6-shogaol resulted in cells with apoptoticphenotypes, which showed signs of cell and nuclear shrinkage as well as substantialchromatin condensation. De-phosphorylation of PERK and activation of theexpression of CHOP initiate caspase cascade reaction inducing apoptosis inHCC. Two-dimensional gel electrophoretic analysis of proteome revealed that in response to the treatment with 6-shogaol, a significant stimulation was observed inproteins related to the ER stress, signifying that apoptosis induced by 6-shogoal didinvolve ER stress. Cells showed marked rise in the UPR target expression, HSP70,Grp94, Grp78/Bip and the other ER chaperones on exposure to 6-shogoal in a time-dependentmanner, which elicited activation of caspase-3 and degradation of polyADP ribose polymerase (PARP). Various ER chaperone proteins improve adaptationof cancer cells to hypoxic environment and aid in developing resistance againstanticancer therapy (Zorzi and Bonvini 2011; Urra et al. 2016). Screening of specificinhibitors of Grp78 as antitumour agents (Hu et al. 2012; Liu et al. 2013; Venkatesanet al. 2015) implies that inhibition of Grp78/Bip is a very promising anticancerstrategy. HCC cells are selectively killed by 6-shogaol in the absence of anynoticeable toxic consequence on normal healthy cells and very little toxicity asstudied on SMMC7721 xenograft mice. Administration of 6-shogaol and salubrinaltogether for distinct time intervals resulted in significant increase in ER stress in thecell. It appears that 6-shogaol in combination with salubrinal has great therapeuticvalue against various malignancies including HCC (Hu et al. 2012).
