Orientin: A C-Glycosyl Flavonoid that Mitigates Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequent malignancies, causing human deaths in large numbers around the world. It can be prevented by using chemotherapeutic drugs; however, the available drugs have shown systemic toxicity and drug resistance, which makes the treatment a challenging issue. The use of flavonoid-rich sources may effectively reduce the risk of colorectal cancer. Orientin, a C-glycosyl flavonoid exists in diverse medicinal flora, such as Aspalathus linearis, Ocimum tenuiflorum, Passiflora, and Phyllostachys species, and it has been shown to have beneficiary effects in treating cancers, cardiovascular diseases, and neurodegenerative disorders. Recent preclinical validation studies on orientin have evidently shown its anti-carcinogenic effect against human colorectal adenocarcinoma cells and carcinogen-induced CRC albino Wistar rat models. Orientin reinstates the antioxidants to put forth their scavenging mechanism and limits the activation of phase 1 enzymes. Orientin induces mitochondrial intrinsic apoptosis in CRC cells, and thereby actively interrupt cell proliferation and inflammatory signaling pathways without disturbing the normal tissue. Research reports have reported the attenuating effects of orientin on aberrant crypt foci progression in cancer-bearing animal, and it results in a significant suppression of pre-neoplasia to malignant neoplasia transformation. Orientin also suppresses NF-κB and the associated inflammatory cytokines, and thereby ameliorates inducible nitric oxide synthase and cyclooxygenase-2 expression in 1,2-dimethylhydrazine rat models. Thus, this chapter emphasizes the therapeutic effects of flavonoids with a special focus on orientin against CRC. Also, it summarizes our understandings about the molecular mechanisms behind orientin-mediated cancer prevention.