6. Conclusion and Future perspectives
Since cancer is a fatal disease affecting millions of people over
worldwide, there is a great necessity of different treatment options to
overcome the drug resistance or recurrence conditions in cancer
patients. Medicinal plants and their bioactive compounds have been a
very good and easily accessible source for the development of novel
therapeutics for different diseases. Even though hundreds of plants have
been tested for cancer, a very few of them have been studied in
vitro and in vivo , and only few of them are under clinical
trials. In view of that, information on recent preclinical and clinical
studies of medicinal plants, their bioactive compounds and herbal
edibles used against CSCs, is compiled in the present study.
Phytomedicines targeting Hedgehog, Wnt and Notch signaling pathways as
well as those targeting CSC resistance mechanisms have been listed.
Treatment of cancer cells with phytocompounds has proven to reduce the
resistance to chemotherapy. Further investigations are necessary to find
the combinatorial effects of chemotherapeutic agents and plant
extracts/compounds. Also, whether combination of two different isolated
phytocompounds shows synergism, antagonism or additive effect needs to
be explored.
In most of the studies, the main phytoconstituent is purified and then
tested. However, in case the whole plant or the extract of a particular
plant part is used, the bioactive compound present in it needs to be
characterized and its mode of action against CSC should be determined.
This is because, there might be presence of more than one bioactive
compound, each showing different mechanism; which needs to be
investigated. High throughput screening can prove to be useful in
selecting phytocompounds for targeting CSCs of a particular type of
cancer.
Throughout research is required to ascertain preclinical and clinical
safety as well as efficacy of the plant-derived bioactive compounds.
Studies based on pharmacodynamic and pharmacokinetic properties of the
phytochemicals will provide a better understanding. Poor solubility,
decreased stability and shorter circulation time in the blood are the
common problems faced in drug treatment and hence nanoparticles-based
delivery, liposomes and hydrogel formulations for these phytocompounds
can be designed. pH, temperature or tumor microenvironment responsive
intelligent nanodrug carriers, specifically targeting CSCs, might be
used and needs further exploration.