Abstract
Infections by multiresistant microorganisms have led to a continuous investigation of substances acting as modifiers of this resistance. By following this approach, the chemical composition of the essential oil from Piper caldense leaf and its antimicrobial potential were investigated. The antimicrobial activity was determined by broth microdilution method providing values for minimum inhibitory concentration (MIC), IC50, and minimum fungicidal concentration (MFC). The essential oil was tested as a modulator for several antibiotics, and its effect on the morphology of Candida albicans (CA) strains was also investigated. The chemical characterization revealed an oil composed mainly of sesquiterpenes. Among them are caryophyllene oxide (13.9%), spathulenol (9.1%), δ-cadinene (7.6%) and bicyclogermacrene (6.7%) with the highest concentrations. The essential oil showed very low activity against the strains of CA with the lowest values for IC50 and MFC of 1790 μg/mL and 8192 μg/mL, respectively. The essential oil modulated the activity of fluconazole against CA URM 4387 strain, which was demonstrated by the lower IC50 obtained, 2.7 μg/mL, whereas fluconazole itself presented an IC50 of 7.76 μg/mL. No modulating effect was observed in the MFC bioassays. The effect on fungal morphology was observed for both CA INCQS 40006 and URM 4387 strains. The hyphae projection was completely inhibited at 4096 μg/mL and 2048 μg/mL, respectively. Thus, the oil has potential as an adjuvant in antimicrobial formulations.
Highlights
Infections caused by fungi, are the major problem of hospital infections, mainly due to the emergence of new infections and the generalized resistance to antibiotics [1]
In view of the above problem, this study aimed to evaluate the antibiotic and modulator potential of volatile terpenes of P. caldense against Candida albicans, as well as to determine if the natural product is capable of reducing pleomorphism
All the identified phytochemicals are secondary metabolites, with caryophyllene oxide (13.9%), spathulenol (9.1%), δ-cadinene (7.6%), and bicyclogermacrene (6.7%) as constituents with the highest concentrations (Table 1)
Summary
Infections caused by fungi, are the major problem of hospital infections, mainly due to the emergence of new infections and the generalized resistance to antibiotics [1]. Sci. 2020, 10, 631 been constant in recent years and drugs derived from plants have contributed largely to human health, historically representing a source for the creation of new drugs [2]. Yeasts of the genus Candida are found as commensals in the human organism, because of factors that disturb the dynamics of the host can favor the growth of these fungi, from superficial infections to systemic infections [5]. Among the yeasts of this genus, Candida albicans stands out as the main cause of infections, being a species with great ability to change its morphology, a necessary factor for its virulence and pathogenicity [6,7]
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