In Vitro Effect of Antifungal Fractions from the Plants Baccharis glutinosa and Jacquinia macrocarpa on Chitin and β‐1,3‐Glucan Hydrolysis of Maize Phytopathogenic Fungi and on the Fungal β‐1,3‐Glucanase and Chitinase Activities

Abstract

Baccharis glutinosa and Jacquinia macrocarpa are medicinal plants whose antifungal activity has been observed on maize phytopathogenic fungi. However, the specific site where those compounds act has not been studied. The objective of this work was to evaluate the hydrolytic effect of antifungal fractions from B. glutinosa (BgF) and J. macrocarpa (JmF) on β-glucan and chitin isolated from Aspergillus flavus and Fusarium verticillioides, as well as their inhibition activity on the fungal hydrolases β-glucanase and chitinase. The antifungal fractions did not show β-1,3-glucanase activity, instead, they showed chitinase activity against polymeric extracts from fungi. None of the antifungal fractions inhibited the chitinase activity of the fungi. However, both BgF and JmF antifungal fractions inhibited fungal β-1,3-glucanase activity acting as competitive inhibitors. It is possible that the antifungal fractions inhibit the β-1,3-glucanase activity affecting β-1,3-glucan synthesis, causing the production of a defective cell wall. These defects in the cell wall may allow the antifungal fractions to hydrolyze chitin causing delay in fungal growth. PRACTICAL APPLICATIONSStudies have proved that plants are one of the major sources for drug discovery and development, because plant-derived drugs have been reported to be safe and with no side effects. B. glutinosa and J. macrocarpa are plants used in traditional medicine by native people of Mexico, and their antifungal activity has been observed against mycotoxigenic fungi commonly associated with maize and other cereal grains. Although the effect on hyphae and spores suggests the interaction between the antifungal fractions and the fungal cell walls, as far as we know, there are no studies designed to elucidate the mode of action and the specific site of the cell wall where those compounds act. The results obtained in the present study suggest the presence of chitinase activity and a β-1,3-glucanase inhibitor found together in the antifungal fractions, which makes them a potential valuable alternative to synthetic fungicides for protecting maize and other cereal grains from fungal contamination.

Postharvest biochemical characteristics and ultrastructure ofCoprinus comatus

“…Studies have shown that the content of chitin in edible fungi decreases due to the effect of chitinase in the storage process. Chitinase hydrolyzes the beta-1, 4-glycoside bond in chitinol to produce n-acetylglucosamine oligomer or monomer (Buitimea et al, 2013). Lim & Choi (2009) found that the Agaricus bisporus could produce black juice in the process of autolysis at 25 • C for 15 h. By PCR confirmed that the amount of chitinase synthesis in the process of autolysis of A. bisporus mushroom was significantly higher than that in the normal A. bisporus mushroom.…”

“…During postharvest storage of edible fungi, changes in cell wall structure and composition directly contribute to cell separation, resulting in loose organizational structure and decreased hardness of fruiting body and, finally, decreased storability of edible fungi (Zivanovic, Buescher & Kim, 2003;Qi et al, 2015). Studies have addressed that the content of chitin decreased during postharvest storage due to the effect of chitinase by hydrolyzing the β-1, 4-glycoside bond in chitin and producing n-acetylglucosamine oligomer or monomer (Buitimea et al, 2013;Jiang et al, 2010a;Jiang et al, 2010b). Lim & Choi (2009) revealed that the Agaricus bisporus could rapidly produce black juice at 25 • C for 15 h after harvest and confirmed that the amount of chitinase synthesis in the autolysis process was significantly higher than that of unpicked mushrooms.…”

In Vitro Antifungal Activity and Chemical Composition of Piper auritum Kunth Essential Oil against Fusarium oxysporum and Fusarium equiseti

“…The effect of the essential oil concentration on the antifungal activity on F. oxysporum FCHJ-T6 and FCHA-T7 and F. equiseti FCHE-T8 was determined using the previously reported poisoned food technique [28][29][30]. The essential oil was incorporated into the sterilized and cooled PDA (~50 • C) at the proportions required to reach 0.1 mg/mL, 0.2 mg/mL, 0.4 mg/mL, 3 mg/mL, 5 mg/mL, and 8.4 mg/mL of medium and was poured into sterile 50 mm diameter Petri dishes.…”

Activity of chitosan–lysozyme nanoparticles on the growth, membrane integrity, and β-1,3-glucanase production by Aspergillus parasiticus

“…b-1,3-Glucanases enzymatic assay b-1,3-Glucanase extracts were prepared in flasks containing 20 mL of Czapek broth, which were separately inoculated with 1 9 105 spores/mL of A. parasiticus and incubated for 96 h at 28 °C. The cultures were centrifuged, sonicated, and the supernatants were obtained following the procedure reported (Buitimea-Cantu ´a et al 2013).…”

“…The effect of either CS nanoparticles or CS-LZ BNCs on the b-1,3-glucanase activity of A. parasiticus was determined by the production of reducing sugars, using 12 lL of the supernatant, 125 lL of laminarin 2.5% as substrate (Sigma-Aldrich, USA), 10 lL of bovine serum albumin (BSA, Sigma-Aldrich), and 362 lL of 50 mM sodium acetate buffer, pH 5.2. The mixture was incubated for 25 min at 37 °C and reducing sugars were estimated at 610 nm following the Somogyi-Nelson method using a standard curve of glucose (Buitimea-Cantu ´a et al 2013).…”