Phytochemicals in Cancer Treatment: From Preclinical Studies to Clinical Practice

Abstract

Cancer is a severe health problem that continues to be a leading cause of death worldwide. Increasing knowledge of the molecular mechanisms underlying cancer progression has led to the development of a vast number of anticancer drugs. However, the use of chemically synthesized drugs has not significantly improved the overall survival rate over the past few decades. As a result, new strategies and novel chemoprevention agents are needed to complement current cancer therapies to improve efficiency. Naturally occurring compounds from plants known as phytochemicals, serve as vital resources for novel drugs and are also sources for cancer therapy. Some typical examples include taxol analogs, vinca alkaloids such as vincristine, vinblastine, and podophyllotoxin analogs. These phytochemicals often act via regulating molecular pathways which are implicated in growth and progression of cancer. The specific mechanisms include increasing antioxidant status, carcinogen inactivation, inhibiting proliferation, induction of cell cycle arrest and apoptosis; and regulation of the immune system. The primary objective of this review is to describe what we know to date of the active compounds in the natural products, along with their pharmacologic action and molecular or specific targets. Recent trends and gaps in phytochemical based anticancer drug discovery are also explored. The authors wish to expand the phytochemical research area not only for their scientific soundness but also for their potential druggability. Hence, the emphasis is given to information about anticancer phytochemicals which are evaluated at preclinical and clinical level.

Chemopreventive Potential of Caryophyllane Sesquiterpenes: An Overview of Preliminary Evidence

“…In the last few years, there has been a growing interest in the identification of suitable chemopreventive (or cancer risk-reducing) agents not only to protect healthy people, but also as adjuvant regimens in oncologic and post-treated cancer patients. A number of drugs with off-target effects (namely repurposing drugs) along with phytochemicals have been approached as possible chemopreventive agents, but their efficacy has been found often null or controversial in clinical trials [ 10 , 11 , 12 , 13 , 14 ]. On the other hand, drugs with documented preventive efficacy that have been approved for treating precancerous lesions or reducing cancer risk have been scarcely adopted by both physicians and patients due to several issues, such as the risk of side effects, lacking cancer risk assessment in primary care, limited knowledge about the guidelines for chemoprevention, and medication costs [ 15 , 16 ].…”

Potential Treatment of Breast and Lung Cancer Using Dicoma anomala, an African Medicinal Plant

“…In an experimental model involving a nude mouse, 6-Shogaol inhibited the growth of lung cancer cells. The growth inhibition of NSCLC was significantly associated with the decreased proliferation and increased apoptosis induction [ 27 ].…”

“…Since 4500 BC, plant extracts have been used in traditional practices by Indian and Chinese people. Advances in analytical chemistry have improved in the investigation of plant-derived extracts for potential medicinal components [ 27 ]. Combined therapy is the new direction taken to fight against cancer.…”

Participation of MicroRNAs in the Treatment of Cancer with Phytochemicals

“…Well-known examples include etoposide, irinotecan, paclitaxel, and vincristine. Primary molecular targets of irinotecan and etoposide are topoisomerase I and topoisomerase II, respectively [ 9 , 10 ]. Paclitaxel and vincristine are microtubule inhibitors, displaying anti-cancer properties, such as cell cycle arrest and apoptosis [ 10 , 11 ].…”