Chemical analysis, antifungal and antimycotoxigenic activity of tetradenia riparia essential oil and crude extract

Abstract Tetradenia riparia is known for its richness in essential oil which has been widely investigated due to its biological activities such as antimicrobial, insecticidal, trypanocidal, antimalarial and antioxidant. The objective of this work was to chemically analyze and evaluate the antifungal and antimycotoxigenic activity of the essential oil and the crude extract of leaves, flower buds and stems of T. riparia from the northwest region of the state of Paraná. The essential oil was obtained by hydrodistillation using a Clevenger-type apparatus. To obtain the crude extract, the leaves, flower buds and stems were pulverized and subjected to a dynamic maceration process using 70% v v−1 ethyl alcohol. Chemical analysis of the essential oil was performed by GC/MS, and chemical identification of the crude extract by UHPLC-ESI/qTOF. Antifungal activity (Rhizopus oryzae, Aspergillus flavus, Aspergillus ochraceus, Penicillium verrucosum and Fusarium graminearum) was performed by broth microdilution and the antimycotoxigenic assay was performed with A. ochraceus and P. verrucosum. Ochratoxin A was extracted by partition with chloroform and quantified by HPLC-FL. The oil yield was 0.29% for leaves, 0.34% for stems and 0.38% for flower buds, and the major compounds were fenchone, β-caryophyllene, α-cadinol, 14-hydroxy-9- epi-caryophyllene, 9β,13β-epoxy-7-abietene, α-cadinol and 6–7-dehydroroyleanone. The main chemical compounds identified in the crude extract were terpenes, anthocyanins, flavonoids, tannins and phenolic acids. The minimum inhibitory concentration (MIC) of oils from leaves, flower buds and stems for the strains tested ranged from 0.87 mg mL−1 to 33.3 mg mL−1, while the minimum fungicidal concentration (MFC) ranged from 6.94 mg mL−1 and 33.3 mg mL−1. The MIC and MFC for ketoconazole, tebuconazole, sorbate and nitrite ranged from 0.05 to 33.3 mg mL−1. The oil and crude extract of leaves, stems and flower buds showed an inhibition of ochratoxin A production for P. verrucosum of approximately 100%.