Evaluation and Comparison of the Antimicrobial Effects of Portulaca oleracea Seed Fatty Acids and Hydroalcoholic Extracts on Oral Pathogens

Background Dental caries and periodontal disease remain prevalent oral conditions. The increasing prevalence of antimicrobial resistance due to antibiotic overuse underscores the need for alternative agents. Portulaca oleracea L. (purslane) exhibits anti-inflammatory, antioxidant, and antibacterial properties. This study compared the in vitro antimicrobial activity of hydroalcoholic extracts from purslane leaves and seeds and seed-derived fatty acids against selected oral pathogens. Materials and Methods Hydroalcoholic extracts were prepared by maceration in 95% ethanol, and fatty acids were extracted with n-hexane. Antimicrobial activity was evaluated against Streptococcus sobrinus PTCC 1601, Streptococcus sanguinis PTCC 1449, Candida albicans ATCC 10231, Streptococcus mutans ATCC 35668, and Lactobacillus acidophilus ATCC 4356 using agar well diffusion and broth microdilution assays. MIC and MBC/MFC were determined in triplicate. Chlorhexidine (CHX; 0.12%) and nystatin (100,000 units) served as positive controls, and DMSO as a negative control. Principal constituents were identified by HPLC and GC–MS. Data were analyzed using ANOVA and Games–Howell tests. Results HPLC detected caffeic acid in hydroalcoholic extracts, and GC–MS identified linolenic acid methyl ester as the predominant compound in seed fatty acids. All preparations inhibited tested pathogens, although CHX and nystatin were more effective (P < 0.05). Seed fatty acids showed the lowest MIC values (P < 0.05), with MIC/MFC of 1.4/2.8 mg/mL against C. albicans . Leaf extract demonstrated greater activity than seed extract and was most active against Streptococcus species, particularly S. mutans , and least active against L. acidophilus . Conclusion Purslane seed fatty acids exhibit stronger antimicrobial activity than hydroalcoholic extracts but remain less potent than CHX or nystatin, supporting potential adjunctive use in oral hygiene formulations.