Evaluation of bioactive compounds in extracts obtained from some algae and plants

Bioactive compounds are natural substances that have positive effects on human health and are widely used in areas such as dietary supplements, pharmaceuticals, and cosmetic products. Some plant and algal species, which can be found naturally, are also rich sources of bioactive compounds. In this study, bay leaves, which are known to be rich in bioactive compound content and are commonly found in our country, and the microalga Spirulina, whose cultivation is highly suitable for our country's climate, were selected. To determine the most efficient extraction conditions for bay leaves and Spirulina algae, different extraction conditions were specified using Design-Expert software, and extractions were performed separately under all conditions with an automatic solvent extraction system. The chemical compositions of extracts obtained under different extraction conditions where solid amount, solvent ratio, and extraction time varied were tested by Gas Chromatography-Mass Spectrometry (GC-MS), and the resulting chromatograms were examined. The extracts considered to be the most efficient were subjected to DPPH (2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)) and FRAP (ferric ion reducing antioxidant power) analyses. Additionally, using the disk diffusion method and minimum inhibitory concentration (MIC) determination methods, the obtained extracts were tested to determine their antimicrobial properties against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungal species (Candida albicans and Aspergillus niger). For the analysis of experimental results, analysis of variance (ANOVA) was developed using Design-Expert software, and model fit was evaluated with statistical indicators such as lack-of-fit test, coefficient of determination (R²), adjusted R², and predicted R².