Table 3.

Pros and cons of natural products compared to conventional drugs (Atanasov et al. 2021; Salminen et al. 2018; van Geffen et al. 2022; Wu et al. 2022; Zhang et al. 2022)

	Pros	Cons
Conventional therapeutics	Identification of mechanisms of action can be systematically more robust	Therapy resistance. Conventional treatments over time can select cells resistant to therapy particularly when activities diminishing MDSCs depend on cancer cells
	The previous existence of toxicity studies developed facilitated incorporation of new functions on MDSCs	High toxicity is frequent in conventional drugs
	Low interference with another pharmaceutics	Increase in oxidative stress that in the long term allows an increase in MDSCs
Natural compounds	Diverse chemical structures. Plant complex extracts due to their composition act on multiple targets. Being multi-target is advantageous in the sense of combating the complexity of the heterogeneity of cancer cells and MDSCs present in TME	Lack of standardization. Sometimes targets and molecular mechanisms have not been clearly elucidated
	Its use in traditional medicine can provide information on efficacy and safety	Limited scientific evidence. It is necessary to increase the quantity and quality of the preclinical and clinical evaluation of natural products, particularly in the search for direct activities on the MDSCs
	Reduced toxicity and side effects, partly attributed to their natural origins	Have enough biological material to isolate and characterizing bioactive compounds can be challenging
	Synergism. Natural products have been shown to have synergistic activities when combined with other molecular drugs, including conventional drugs modulating MDSCs generation and/or function	Access to intellectual property rights for bioactivities associated with natural (unmodified) products it is a big challenge
	Higher stiffness of natural products structure molecules can be useful when act on protein–protein interaction involved in MDSCs functions	The generation of structural analogs for exploring structure-biological activity relationships is complex
	Decreased oxidative stress which favors the modulation of MDSCs in the TME	Despite the growing number of investigations involving natural products, very few have clinically evaluated