In Vitro Evaluation and Chemical Composition of Acacia mangium Extracts Against Anthracnose Disease

Abstract

Anthracnose, caused by Colletotrichum truncatum, is a major disease of chilli that results in substantial yield and quality losses. This study evaluated the antifungal activity and chemical composition of Acacia mangium leaf and stem extracts against C. truncatum under in vitro conditions. The pathogen was isolated from symptomatic chilli fruits and identified as C. truncatum based on internal transcribed spacer (ITS) sequencing and phylogenetic analysis, showing 99.82% similarity to reference sequences deposited in GenBank. Ethanol extracts of A. mangium leaves (AMLE) and stems (AMSE) were evaluated using the poisoned food technique at concentrations ranging from 50 to 500 mg/mL. Both extracts exhibited strong concentration-dependent antifungal activity, with significant differences among treatment concentrations (p < 0.05). Complete inhibition of mycelial growth was achieved at concentrations of 200 mg/mL and above for both extracts. At lower concentrations, AMSE exhibited slightly greater antifungal activity than AMLE, producing 76.5% and 81.0% inhibition at 50 and 100 mg/mL, respectively, while AMLE inhibited fungal growth by 73.0% at 50 mg/mL. In contrast, benomyl produced only 30.0% inhibition under the experimental conditions tested. Gas chromatography-mass spectrometry (GC-MS) analysis identified 25 compounds in AMLE and 35 compounds in AMSE. AMLE was dominated by squalene, α-tocopherol and lupenone, whereas AMSE was characterized primarily by oleic acid, linoleic acid, butyl linolenate and glycidyl oleate. The distinct phytochemical profiles of the two extracts suggest that different classes of bioactive metabolites may contribute to their antifungal activity. Overall, the results demonstrate that A. mangium possesses promising potential as a source of natural antifungal compounds and provide a scientific basis for the development of plant-based biofungicides as environmentally friendly alternatives for the sustainable management of chilli anthracnose.