Caprylic acid in Vitex mollis fruit and its inhibitory activity against a thiabendazole‐resistant Colletotrichum gloeosporioides strain

Abstract

BACKGROUND: Colletotrichum gloeosporioides causes anthracnose in a large number of crops. Synthetic fungicides are employed to prevent this disease, even though their effectiveness and safety is questionable. Thus, effective and innocuous antifungal compounds are proposed as natural alternatives against anthracnose. The hexane fraction of Vitex mollis pulp (HF-VM) reduces anthracnose incidence in papaya fruit; however, the active compounds and antifungal mechanism of HF-VM are unknown. The aims of this study were to characterize the activity of HF-VM sub-fractions (sHF 1 -sHF 7 ) against a thiabendazole-resistant Colletotrichum gloeosporioides strain, identify the chemical components and investigate the mechanism of the most active sub-fraction. RESULTS: The sHF 3 showed the highest inhibitory activity against Colletotrichum gloeosporioides with a minimal inhibitory concentration (MIC) of 0.5 mg mL −1 , whereas thiabendazole (TBZ) had a MIC value higher than 2 mg mL −1 . The gas chromatography-mass spectrometry (GC-MS) analysis showed that the compounds in sHF 3 were methyl 4-decenoate, caprylic acid, and 24-methylencycloartanol. These compounds are rarely found in fruits and are reported for the first time on Vitex species. The purified 24-methylencycloartanol was inactive (MIC > 0.5 mg mL −1 ). In contrast, the commercial standard of caprylic acid presented an elevated activity (MIC = 0.125 mg mL −1 ), indicating that this compound is the main one responsible for the antifungal properties of sHF 3 . Furthermore, the sHF 3 inhibited the spore germination and induced membrane disruption in both the spore and mycelium of Colletotrichum gloeosporioides.CONCLUSION: Vitex mollis fruit is a novel source of antifungal caprylic acid that could be employed as a marker to prepare standardized extracts with antifungal properties.

Microstructural and physicochemical quality maintenance in green bell pepper infected with Botrytis cinerea and treated with thyme essential oil combined with carnauba wax

“…Electrolyte leakage from spores and mycelia was determined with a manual conductivity meter (HI98312; Hanna Instruments). Total electrolyte leakage was determined by measuring the conductivity of the unfiltered samples before (initial conductivity) and after (final conductivity) boiling the mixture for 10 min (López‐Velázquez et al., 2022). Results were expressed as the percentage of leaked electrolytes as follows: $$$$\begin{equation*}{\mathrm{Electrolyte}}\,{\mathrm{leakage}}\,(\% ) = \frac{{{\mathrm{Final}}\,{\mathrm{conductivityInitial}}\,{\mathrm{conductivity}}}}{{{\mathrm{Final}}\,{\mathrm{conductivity}}}} \times 100\end{equation*}$$$$…”

“…Total electrolyte leakage was determined by measuring the conductivity of the unfiltered samples before (initial conductivity) and after (final conductivity) boiling the mixture for 10 min (López-Velázquez et al, 2022). Results were expressed as the percentage of leaked electrolytes as follows:…”

The effect of biocontrol agents and plant extracts on postharvest quality of 'kent' mangoes.

“…This was based on the experiment of both chemicals against stem-end rot of avocado caused by L. theobromae (Shimshoni, et al, 2020). López-Velázquez, et al (2022) reported the use of other chemical against a fludioxonil-resistant strain of C. gloeosporioides, this declares fludioxonil as one of the fungicides that are not eligible to be used against some of the major fungal pathogens affecting mango production, and it needs to be attended to.…”