A modulatory effect of Psidium guajava L., (known as goiaba) an important
medicinal plant found in tropical regions, was assayed against Candida albicans,
Candida tropicalis and Candida krusei in association with fluconazole. The synergistic effect varied from 925.56 to 1.57 lg/mL. The flavonoid and tannic fractions, rich in phenolic compounds, potentiated the action of Fluconazole, reducing
its concentration and impeding morphological transition, one of the virulence
factors of the genus (Bezerra et al. 2018).
7.8 Fungal Resistance and Modulatory Potential
of Extracts, Fractions and Essential Oil from Tropical
Medicinal Species
The involvement of fungal infections in humans has gained prominence in recent
years, and among the most common fungi infections, those of the genus Candida
stand out, being among the species causing opportunistic infections. This is justified
by the fact that they are very well adapted to the human body, being able to
colonize it without producing signs of disease under conditions of physiological
normality. However, they can become pathogenic in immunosuppressed patients,
generating infections that are difficult to diagnose and are associated with high
mortality and morbidity. As for clinical manifestations, we can divide them into
cutaneous, systemic, and allergic. The treatment of these pathologies is performed
with synthetic drugs with systemic action such as amphotericin B, fluconazole,
itraconazole, voriconazole and echinocandins, azoles being the most used, due to
their low cost and low toxicity.
The availability of antifungal agents for the treatment of systemic infections is
somewhat reduced, becoming a problem with multi-drug resistant yeasts. In addition, one of the stalemates today is resistance to antifungals and difficulties in
effective treatment. As a way to ease this resistance and difficulty in treatment,
medicinal plants are strongly used by the population for the treatment of infections,
and this fact has aroused interest from several research centers for the study of this
activity, with the aim of isolating new molecules with antimicrobial activity.
Natural plant products have been evaluated not only for their direct antimicrobial
activity, but as a modification agent of resistance to antifungals, which can be a
synergistic or antagonistic effect. Thus, the associated use of medicinal plants or
their derived compounds may interfere, inhibiting or intensifying the therapeutic
effect of conventional antimicrobials. In this context, the synergistic effect of Piper
mikanianum essential oil species rich in safrole was investigated against Candida
strains. An interesting result was observed where the oil was combined with gentamicin against the multi-drug resistant E. coli strain and also associated with
fluconazole against fungal strains. The oil presented a fungistatic effect. The
P. mikanianum essential oil has shown an inhibitory effect of one of the main
virulence factors of the Candida genus, morphological transition, which has been
278
L. E. da Silva et al.
medicinal plant found in tropical regions, was assayed against Candida albicans,
Candida tropicalis and Candida krusei in association with fluconazole. The synergistic effect varied from 925.56 to 1.57 lg/mL. The flavonoid and tannic fractions, rich in phenolic compounds, potentiated the action of Fluconazole, reducing
its concentration and impeding morphological transition, one of the virulence
factors of the genus (Bezerra et al. 2018).
7.8 Fungal Resistance and Modulatory Potential
of Extracts, Fractions and Essential Oil from Tropical
Medicinal Species
The involvement of fungal infections in humans has gained prominence in recent
years, and among the most common fungi infections, those of the genus Candida
stand out, being among the species causing opportunistic infections. This is justified
by the fact that they are very well adapted to the human body, being able to
colonize it without producing signs of disease under conditions of physiological
normality. However, they can become pathogenic in immunosuppressed patients,
generating infections that are difficult to diagnose and are associated with high
mortality and morbidity. As for clinical manifestations, we can divide them into
cutaneous, systemic, and allergic. The treatment of these pathologies is performed
with synthetic drugs with systemic action such as amphotericin B, fluconazole,
itraconazole, voriconazole and echinocandins, azoles being the most used, due to
their low cost and low toxicity.
The availability of antifungal agents for the treatment of systemic infections is
somewhat reduced, becoming a problem with multi-drug resistant yeasts. In addition, one of the stalemates today is resistance to antifungals and difficulties in
effective treatment. As a way to ease this resistance and difficulty in treatment,
medicinal plants are strongly used by the population for the treatment of infections,
and this fact has aroused interest from several research centers for the study of this
activity, with the aim of isolating new molecules with antimicrobial activity.
Natural plant products have been evaluated not only for their direct antimicrobial
activity, but as a modification agent of resistance to antifungals, which can be a
synergistic or antagonistic effect. Thus, the associated use of medicinal plants or
their derived compounds may interfere, inhibiting or intensifying the therapeutic
effect of conventional antimicrobials. In this context, the synergistic effect of Piper
mikanianum essential oil species rich in safrole was investigated against Candida
strains. An interesting result was observed where the oil was combined with gentamicin against the multi-drug resistant E. coli strain and also associated with
fluconazole against fungal strains. The oil presented a fungistatic effect. The
P. mikanianum essential oil has shown an inhibitory effect of one of the main
virulence factors of the Candida genus, morphological transition, which has been
278
L. E. da Silva et al.