Exploring antifungal activity of selected medicinal plant extracts: Enhancing their efficacy through microencapsulation

This research investigates antifungal potential of ethanolic extracts from Allium sativum (AS), Alpinia galangal (AG), and the hexane extract of Costus speciosus (CS), with a primary emphasis on preserving their stability through encapsulation. A comprehensive evaluation of three extraction methods was conducted, namely, column extraction, Soxhlet extraction, and maceration for 24 hours. Qualitative tests, such as sodium nitroprusside and lead sulfide tests, were employed to identify sulfur compounds associated with antifungal activity. Quantitative assessments included total polyphenolic content and analyses utilizing X-ray photoelectron spectroscopy (XPS). Encapsulation was applied to extracts demonstrating antifungal activity against Aspergillus niger. The subsequent characterization of encapsulated beads involved assessing particle size, zeta potential, and encapsulation efficiency. The choice of extraction methods was guided by their efficiency, with column extraction selected for AS (4%) due to its capacity to preserve heat-sensitive compounds. Soxhlet extraction (100 ℃, 4 h) was deemed effective for AG (26%) and CS (11%) owing to higher yields. Accurate sulfur detection methods, including the lead sulfide test and XPS analysis, revealed exclusive sulfur compounds in AS. The phenolic content of AS, AG, and CS was quantified at 59.0 ± 0.3, 60.7 ± 0.0, and 65.1 ± 1.0 mg GAE/g, respectively. Notably, only AS (500000 mg/L) exhibited significant antifungal activity against Aspergillus niger, with a mean inhibition zone of 23.7 ± 7.3 mm after 48 hours of incubation at 35℃. To enhance the antifungal efficacy of AS, microencapsulation was employed, and the encapsulated AS beads displayed an average size of 2.38 ± 2.00 μm, a zeta potential of 2.09 ± 0.81 mV, and an encapsulation efficiency of 23%. The presence of phenolics and sulfur compounds in AS suggests promising applications in pharmaceutical and nutraceutical antifungal products.