4.1. Gastric Cancer
Preclinical studies have shown that ginger extract and its constituents possess chemopreventive and antineoplastic properties in gastric cancer.
In vitro study showed that 6-gingerol induces apoptosis of gastric cancer cells. It facilitates TNF-related apoptosis-inducing ligand- (TRAIL-) induced apoptosis by increasing caspase-3/7 activation. The induction of apoptosis by 6-gingerol was mediated through downregulation of cytosolic inhibitor of apoptosis (cIAP)-1 and inhibiting TRAIL-induced nuclear factor-kappaB (NF-
κB) activation. Besides 6-gingerol, 6-shogaol also reduced the viability of gastric cancer cells by damaging microtubules [
30]. When ginger extract was given to Sprague-Dawley rats having acetic acid-induced ulcers, it significantly reduced the gastric ulcer area.
Ginger extract also attenuated elevated activities of xanthine oxidase and myeloperoxidase, as well as malondialdehyde (MDA) level in the ulcerated mucosa. Thus, ginger extract promotes ulcer healing by acting as an antioxidant and prevents gastric mucosal damage [
46].
It is also reported to be effective in ameliorating the side effects of conventional therapeutic agents including γ-radiation, doxorubicin, and cisplatin by regulating P-glycoprotein [
67]. Thus ginger extract exhibits chemosensitizing effects in certain neoplastic cells
in vitro and
in vivo. In support of this, another study showed that ginger reverses cisplatin-induced delay in gastric emptying indicating that ginger acts as an antiemetic for cancer chemotherapy [
47]. Thus, it may be useful in improving the gastrointestinal side effects of cancer chemotherapy. Besides ginger, zerumbone (a sesquiterpene) derived from a subtropical ginger
Zingiber zerumbet Smith was also reported to have antitumor and anti-inflammatory properties in different cancers. In gastric cancer cell lines, zerumbone inhibited cell proliferation, VEGF expression, and NF-
κB activation [
28]. Thus, zerumbone acts as an antiangiogenic and antitumor drug in the treatment of gastric cancer.