Identification of Phytochemicals and Antibacterial Activity of South Sulawesi Propolis (Apis mellifera) Using TLC and LC-MS/MSQTOF

Introduction: Propolis from Apis mellifera exhibits antimicrobial and antioxidant activities. Despite Indonesia’s rich biodiversity, the phytochemical profile of propolis from South Sulawesi and its antibacterial potential against Pseudomonas aeruginosa remain underexplored. Objective: This study aimed to tentatively identify flavonoid and glycoside compounds in A. mellifera propolis from South Sulawesi and to evaluate its antibacterial activity. Methods: Propolis samples were collected from Masamba Subdistrict, South Sulawesi, and extracted using 70% ethanol through ultrasonic-assisted extraction. Phytochemical profiling and tentative compound identification were performed using Thin Layer Chromatography (TLC) and LC-MS/MS-QTOF. Antibacterial activity was tested by the disk diffusion method at concentrations of 0.25%, 0.5%, and 0.75%, with ciprofloxacin and distilled water as positive and negative controls. Results: The analysis revealed that flavonoids and glycosides were the main constituents of the extract. These compounds were tentatively identified along with other secondary metabolites, including alkaloids, terpenoids, and phenolic compounds, indicating a complex chemical composition. Antibacterial testing showed mean inhibition zones of 11.23 mm (0.25%), 13.65 mm (0.5%), and 16.50 mm (0.75%), whereas ciprofloxacin and the negative control produced zones of 31.95 mm and 5.70 mm, respectively. ANOVA revealed significant differences among treatments (F = 232.4, p < 0.0001), with the 0.75% extract showing the largest mean inhibition zone. Conclusions: These findings suggest that South Sulawesi propolis contains tentatively identified bioactive flavonoids and glycosides and demonstrates antibacterial activity against Pseudomonas aeruginosa, indicating its potential as a natural antibacterial source for further investigation.