Allium vegetables for possible future of cancer treatment

Natural resources such as plants are an upright curing option in treating cancers and reducing the side effects of current therapeutic modalities. Allium genus vegetables are of the most interesting herbs in restricting cancers that includes garlic, onions, leeks, chives, and shallots. These plants have been exploited in folk medicine because of their beneficial health effects in improving numerous diseases. The phytochemical analysis of various Allium genus members showed that, to date, 16 species have proved potential anticancer properties due to the accumulation of various sulfur and organic compounds like S-allyl mercaptocysteine, quercetin, flavonoids, and ajoene. These compounds with various mechanisms such as hindering cell cycle, inhibiting signaling pathways, inducing apoptosis, and antioxidant activity interfere with diverse stages of formation, growth, differentiation, and metastasis of cancer cells. Similar to garlic and onion, other species have exhibited anticancer activities, so that active natural molecules extracted from them might serve as possible anticancer agents. Therefore, evaluating the main ingredients and studying their anticancer mechanisms are of great importance. In this review, we aim to summarize the available data on anticancer mechanisms of 16 species of Allium genus and their major compounds to assist further researches on the treatment and prevention of cancers.