Natural Anticancer Agents: Their Therapeutic Potential, Challenges and Promising Outcomes

Cancer, the second leading cause of death worldwide, is a major health problem. Chemotherapy, radiation therapy and surgery are current treatments for cancer. Most anticancer drugs have severe toxic effects and are required to be administered in cycles to reduce toxicity and prevent resistance. Plant-based drugs have shown a potential for treatment of cancer, and various plant secondary metabolites have shown promising antitumor activity against several cancer cell lines, such as leukemia, colon cancer, prostate cancer, breast cancer and lung cancer. Vincristine, etoposide, topotecan and paclitaxel, which are of natural origin, are successfully used in clinical practice, and this has generated interest in natural compounds as anticancer agents. Some phytoconstituents like curcumin, piperine, allicin, quercetin and resveratrol have been extensively researched and reviewed. In the current study, we have reviewed several plants like Athyrium hohenackerianum, Aristolochia baetica, Boswellia serrata, Panax ginseng, Berberis vulgaris, Tanacetum parthenium, Glycine max, Combretum fragrans, Persea americana, Raphanus sativus, Camellia sinensis, and Nigella sativa for their source, key phytoconstituents, and anticancer activity along with their toxicity profile. Few phytoconstituents like boswellic acid, sulforaphane and ginsenoside showed excellent anticancer activity compared to standard drugs and are potential clinical candidates.