Breast cancer treatment with plant-derived anticancer compounds
Nature provides various medicinal plants for humans to combat different
diseases and improve public health. Since ancient times, people have
used plants and their bioactive substances as medicines. It is reported
that numerous types of medicinal plants and their phytochemicals avoid
the spread and development of cancer (39). There are over 250 000 plant
species in the plant kingdom, but only about 10% of those have been
studied for potential treatments of different diseases. Plant elements
such as the flower, flower stigmas, pericarp, sprouts, fruits, seeds,
roots, rhizomes, stem, leaf, embryo, and bark contain phytochemicals and
their derived counterparts, which have a variety of therapeutic uses.
Several primary and secondary metabolites play important roles in
hindering cancer cell activating proteins, enzymes, and signaling
systems or in activating DNA repair processes, promoting the formation
of protective enzymes, and triggering antioxidant activity, resulting in
potent anticancer effects, including Lignans, flavonoids, alkaloids,
vitamins, terpenes, taxanes, saponins, mineral substances, oily
substances, gums, glycosides, biological molecules (45, 46) . Table 2
provides detailed information on some medicinal plants on cell lines of
breast cancer. Additionally, Figure 2 shows the generalized concept of
carcinogenesis, immune responses, and the efficiency of natural
phytochemicals against cancer.
Different strategies for the development of plant-derived
anticancer substances
The potency of medicinal plants as therapeutic agents depends on the
type and quantity of their active
compounds, which vary from species
to species depending on latitude, longitude, altitude, age, climate, and
season. Different parts of the plant may have various pharmaceutical
effects, which propose them as bioactive compounds in anticancer
treatments. Several techniques are used to purify active
compounds including combinatorial
chemistry, isolation tests, and bioassay-guided fractionation. The
purification of these compounds are carried out in several steps.
Firstly, natural extracts (from dry or wet plant materials) with known
biological activities are evaluated. Appropriate matrices, such as
Superdex, Sephadex, and Silica, are then employed for the fractionation
of natural extracts. The fractionated extracts are tested for
bioactivity, and then the active fractions are separated using a variety
of analytical techniques such as thin layer chromatography (TLC), high
performance liquid chromatography (HPLC), fourier-transform infrared
spectroscopy (FTIR), mass spectroscopy (MS), and nuclear magnetic
resonance (NMR). Although these steps are flexible, it is important that
the bioactive chemicals have the highest purity, quality, and quantity.
This can be achieved by utilizing high-quality solvents and matrices as
well as careful handling. The extracted compounds must be purified
before evaluating in vitro or in vivo anticancer effects.
Furthermore, it is necessary that more studies are performed on some
characteristics of the extracted bioactive compounds such as
pharmacokinetics, pharmacodynamics, immunogenicity, metabolic fate,
biosafety and side effects, drug interactions, and dose concentration.
Figure. 3 depicts a thorough planning for the synthesis,
characterization, testing, and prospective use of a bioactive chemical
as a cancer treatment agent.
Current challenges of plant-derived anticancer compounds
Although bioactive compounds have
potent anticancer properties, they also have drawbacks that need to be
resolved before their application in clinical trials and improved for
the approved drugs. The main concerns in regard to the use of these
compounds are their poor aqueous solubility, poor penetration into
tumors, absorption by normal cells, limited therapeutic activities, and
harmful side effects (47, 48). Today, the uses of colchicine,
camptothecin, and derivatives of podophyllotoxin side are limited due to
their adverse events. In addition, some anticancer compounds like vinca
alkaloids have a limited impact and are usually employed in conjunction
with other medications (49). Further challenges in the discovery and
development of new anticancer agents are associated with their
extraction, synthesis, optimization, and characterization. New
developments in analytical technology and computational methodologies
are anticipated to facilitate the identification of new compounds,
improve their extraction, and/or decide on their chemical synthesis or
modifications.