Plant derived anticancer agents: A green approach towards skin cancers

Plants have been used as medicinal agents since the origin of mankind. High cost and severe side effects associated with conventional chemotherapy has limited their general acceptability and fuel up the search for alternate options. The alternative treatment options like phytochemicals have come up with ease of availability and cost effectiveness. Owing to their general acceptance, safety, low side effects and multistep targeting in signal transduction pathways, plant derived phyto-constituents have promising anti-carcinogenic potential for skin related cancers. This leads to the surge in research of new phytochemicals for the prevention and cure of a variety of skin cancers which are major cause of morbidity and mortality in present world. Although very limited clinical data involving humans is available in literature to demonstrate favorable effects of phyto-constituents on various types of skin carcinomas yet the topical treatment with these plant derived anticancer phytochemicals is very promising. There are various mechanisms and pathways responsible for antitumor activity of plant derived medicinal compounds such as loss of mitochondrial membrane potential, release of cytochrome-c, Down regulation of Anti-apoptotic proteins and Up regulation of pro-apoptotic proteins, Activation of Caspase, Fas, FADD, p53 and c-Jun signaling pathway, Inhibition of Akt signaling pathway, phosphorylation of ERK, P13K, Raf, survivin gene, STAT 3 and NF-kappa B. In-vitro testing of skin cancer cell lines models offers the opportunity for identifying mechanisms of action of compounds from plant origin against variety of skin related cancers. This review thus aims at providing an overview of plant derived anti-cancer compounds which have been reported to show promising anti-carcinogenic effects against various skin cancer cell lines and on animal models. Phytochemicals that are discussed in this review include steroids, coumarines, trepenes, essential oils, alkaloids, esters, ethers, resins, phenols and flavonoids. This review also provides information about marketed formulations developed so far from plant derived compounds for skin cancer prevention and treatment.