Chemical Profile and Antimicrobial Activity of the Marine Diatom Chaetoceros muelleri

Microalgae, due to its rapid growth, low nutritional requirements, and versatility of adaptation to different environmental conditions, has aroused the biotechnological interest, synthesizing novel molecules with antioxidant, anticoagulant, anti-inflammatory, antitumor, and antimicrobial activities. In this sense, we carried out the bioprospection of Chaetoceros muelleri, a marine diatom employed in aquaculture, as a candidate to the development of new drugs for the treatment of bacterial infections. The chemical profile of extracts in different solvents (hexane, chloroform, methylene chloride, ethyl acetate, methanol, and acetone) were analyzed by ¹ H-NMR. The hexane extract was the most active against all bacteria species tested, including Mycobacterium tuberculosis, with a minimum inhibitory concentration of 100 μg/ml. Contrarily, the methanol extract was inactive against all tested microorganisms and, in addition, was the only one with IC₅₀ >800 μg/mL, showing no cytotoxicity in VERO cell lines. All other extracts showed antibacterial potential and IC₅₀ values varying between 267.58 and 142.47 μg/ml. The fact that C. muelleri is a microalga easily grown on bioreactors on a large scale may promote its biotechnological use, especially as scaffolds for the development of new compounds against bacterial species of clinical and public health interest.