Turkish marine biodiversity: chemical profile and <i>in vitro</i> biological activities

Abstract Marine organisms account for more than half of the global biodiversity and have proven to be a rich source of pharmacologically active compounds. Turkey has an extensive coastline hosting a diverse marine ecosystem. This paper describes the phytochemical prospection based on chromatographic profiles of extracts, fractions, and sub-fractions from Turkish organisms. In addition, the samples were evaluated for their antioxidant, anticholinesterasic, and antibacterial activities. According to the chromatographic profiles, terpenes were identified in most samples, with the exception of Dictyonella incisa . Alkaloids were detected in Ascidiella aspersa, Eunicella cavolini, Halocynthia papillosa, Limaria hians, Microcosmus polymorphus , and D. incisa . The phenolic carboxylic acids were detected in all the samples, and the results for polyphenols were similar. The extract of P. clavata showed antioxidant activity in both models evaluated, whereas the remaining samples were positive only in the bioautographic assay. With regard to AChE inhibition, D. incisa fraction showed potent activity (% I ˃ 90%), while the sub- fractions were moderate (% I ˃ 45%). In the antibacterial assay, the same samples from D. incisa have shown activity against both Gram-negative and Gram-positive bacteria. On the other hand, the present study opens up avenues for future research on D. incisa by aligning alkaloids and neuroprotective effects, taking into account that inhibition of AChE is a therapeutic strategy in the treatment of Alzheimer’s disease.