Phytochemical Screening and Antifungal Activity of Aqueous and Ethanolic Extracts of Syzygium aromaticum and Allium sativum against Clinical Candida Isolates

Abstract

The rising incidence of fungal infections and the emergence of resistance to conventional antifungals necessitate the need for alternative therapeutic agents, particularly from medicinal plants. This study investigated the phytochemical composition and antifungal efficacy of aqueous and ethanolic extracts of Syzygium aromaticum (clove) and Allium sativum (garlic) against clinical Candida isolates. Four clinical isolates - Candida albicans (strains 1 and 2), C. krusei and C. glabrata were characterized based on their morphological, biochemical, and molecular characteristics. The plant extracts were obtained using maceration method; and were screened for the presence of phenols, flavonoids, alkaloids, tannins, saponins, terpenoids, and cardiac glycosides. The extracts’ in vitro antifungal activity was evaluated using agar well diffusion and broth dilution methods. All extracts exhibited dose-dependent inhibition. Ethanolic extracts were consistently more potent, with clove ethanolic extract showing the highest activity, producing an inhibition zone of 20.4 ± 0.62 mm against C. albicans at 200 mg/mL, while the aqueous extract had no inhibition against C. glabrata. The Minimum Inhibitory Concentration (MIC) for the most effective ethanolic extracts ranged from 12.5 mg/mL to 50 mg/mL. Notably, the plant extracts were effective against the fluconazole-resistant strain of C. krusei, highlighting their potential in managing azole-resistant infections. The findings have revealed the antifungal potentials of clove and garlic extracts against Candida species, including resistant strains. These extracts represent potential raw materials for developing safe and effective natural antifungal agents for the management of various forms of mycoses.