Nanosized delivery systems for plant-derived therapeutic compounds and their synthetic derivative for cancer therapy

Abstract Cancer, a multifactorial disease, is recognized as one of the primary reasons of mortality around the globe. In 2019 1,762,450 cancer cases with death rates of 606,880 were reported only in the United States. Despite the various advancements in the field of modern medicine, cancer treatment remains a challenging task. Treatment of cancer usually involves chemotherapy, radiotherapy, or surgery, out of which the most common method is chemotherapy. Cancer chemoprevention by definition means making use of bioactive or chemically synthesized compounds for inhibition and prevention of the cancer relapse. The synthetic drugs used as cancer therapeutics have number of side effects and are costly, which increase the socioeconomic burden. The traditional system of medicines involves the use of compounds of natural origin. The rationale for the use of phytometabolites over synthetic drugs is their safety profile, ease of availability, and nontoxic nature. These metabolites are also known as “phytochemicals,” which has got its origin from the Greek word “phyto,” which refers to plant. Thus these are the active plant constituents found usually in fruits, cereals, herbs, and legumes. These are usually secondary metabolites produced by an organism as defense against predators or as an adaptive measure to various stressful conditions. These are not generally essential for the survival of the plant. On the basis of the chemical nature, phytometabolites are divided into polyphenolic compounds, terpenes, and thiols. The polyphenol group consists of flavonoids, phenolic acids, and other nonflavonoid polyphenols such as tannin, curcumin, and lignans. Among these the phenolic compounds have proved their worth as potent antioxidant, antineoplastic, antimicrobic, hypoglycemic, and neuroprotective agent. Phytochemicals inhibit carcinogenesis by various underlying mechanisms such as disruption in the cancer signaling pathways, antiproliferative effect, prevention of angiogenesis, and additive effect with various chemotherapeutics. These bioactive constituents have played a vital role in the treatment of infections and various cancer types. With the advancements in high-throughput screening and combinatorial chemistry, there was an increase in the screening of natural compounds as molecular leads for drug developmental processes and in the synthesis of new chemical entities. The use of the natural products and their semisynthetic derivatives as cancer chemotherapeutics started from the late 1930s to early 1940s. In the recent era, about 7000 medicinal plants are used in the modern medicine based on the use in the folklore medicine. These are used as such or provide templates for development of analogues and prodrugs. Taxol, an anticancer drug originally isolated from Taxus brevifolia (western yew) that was approved for clinical use by FDA in the year 1992, has gained utmost importance in breast cancer treatment.