Determination by isothermal microcalorimetry of the sensitivity of phytopathogenic fungi of tropical fruits against an ethanolic extract of jackfruit leaf (Artocarpus heterophyllus Lam.)

Abstract

Conventional microbiological methods to evaluate the in vitro antifungal activity of bioactive compounds usually consume a long time. It is also difficult to calculate different kinetic parameters. For this reason, this study aimed to evaluate the sensitivity of phytopathogenic fungi to an ethanolic extract of jackfruit leaf by the poison agar and isothermal microcalorimetry (IMC) tests. The kinetic parameters (maximum growth rate (μ_Max), total heat (ϕ_Max), time to peak (T¹), and lag (λ) phase) varied by fungal isolate. However, the results indicated a reduction of the total heat produced from the fungi at 5 mg/mL of the extract referred to as the control without extract (p < 0.05). Pearson coefficients were established to determine the relationship between both techniques. Correlations demonstrated that the λ phase and μ_Max are highly related (> 0.51) to the in vitro percentage inhibition. Therefore, this study contributes to the use of the IMC as an alternative to complement the classical methods of fungal inhibition, providing data in real-time.

Keywords: Antifungal activity; Ethanolic extract; Isothermal microcalorimetry; Jackfruit leaves.