The potential role of plant secondary metabolites on antifungal and immunomodulatory effect

Abstract

With the widespread use of antibiotic drugs worldwide and the global increase in the number of immunodeficient patients, fungal infections have become a serious threat to global public health security. Moreover, the evolution of fungal resistance to existing antifungal drugs is on the rise. To address these issues, the development of new antifungal drugs or fungal inhibitors needs to be targeted urgently. Plant secondary metabolites are characterized by a wide variety of chemical structures, low price, high availability, high antimicrobial activity, and few side effects. Therefore, plant secondary metabolites may be important resources for the identification and development of novel antifungal drugs. However, there are few studies to summarize those contents. In this review, the antifungal modes of action of plant secondary metabolites toward different types of fungi and fungal infections are covered, as well as highlighting immunomodulatory effects on the human body. This review of the literature should lay the foundation for research into new antifungal drugs and the discovery of new targets. KEY POINTS: • Immunocompromised patients who are infected the drug-resistant fungi are increasing. • Plant secondary metabolites toward various fungal targets are covered. • Plant secondary metabolites with immunomodulatory effect are verified in vivo.

Keywords: Antifungal mechanism; Fungal infection; Immunoregulation effect; Plant secondary metabolites.

Fig. 1

Mechanism of antifungal action of existing antifungal drugs and plant secondary metabolites. A Antifungal targets had been confirmed in the existing antifungal drug. Existing antifungal agents include allylamines, azoles, polyalenes, echinocins, and flucytosine. B Antifungal targets had been confirmed in the plant secondary metabolites. The antifungal pathway of plant secondary metabolites include (1) prevention of fungal biofilm formation and destruction of the established fungal biofilm; (2) alteration of cellular DNA replication and disruption of the cell cycle; (3) inhibition of fungal mycotoxin synthesis; (4) prevention of ergosterol synthesis, disruption of cell membrane permeability, and promotion of cell wall destruction and lysis; and (5) decrease in the number of spores and the growth of hyphae

Fig. 2

Summary of plant secondary metabolites with both antifungal and immunomodulatory effect. These compounds are derived from alkaloids, phenols, terpenoids, and other plant secondary metabolites, respectively