Screening of Undaria pinnatifida (Laminariales, Phaeophyceae) Lipidic Extract as a New Potential Source of Antibacterial and Antioxidant Compounds

The lipidic extract of Undaria pinnatifida, one of the worst invasive species, was investigated for its potential exploitation in biotechnological applications. The antimicrobial activity of the lipidic extract in three different portions (blade, sporophyll, and holdfast) was assessed by using the Kirby-Bauer method, while the antioxidant activity was evaluated by the TEAC, ORAC, and Folin-Ciocalteu assays. NMR spectroscopy and thin-layer chromatography were employed for the chemical characterization. The extracts showed antibacterial activity against several of the tested Vibrio species: V. aestuarinus, V. fischeri, V. furnisii, V. inusitatus, V. litoralis, and V. mediterranei, including some pathogens for farmed fish. Intriguing antioxidant activity was recorded, with the highest value in the blade (126.907 +/- 28.993 mmol Trolox equivalent/g TEAC). Free, saturated, unsaturated, and polyunsaturated fatty acids were highlighted by 1D and 2D NMR spectroscopy. The presence of omega-3 and omega-6 PUFAs indicates the importance of this algal species in the food industry. We suggest the employment of U. pinnatifida as source of new and safer therapeutic agents to control fish and shellfish diseases due to vibriosis, as well as a source of natural antioxidants that are useful for human health, considering the growing interest in the development of strategies for invasive seaweed control.

Automated summary

The lipidic extract from Undaria pinnatifida, a highly invasive species, was found to possess antibacterial and antioxidant activity, with the highest efficacy in the blade portion. The chemical characterization revealed the presence of various fatty acids, particularly omega-3 and omega-6 polyunsaturated fatty acids, highlighting its potential in the food industry. This extract could be used as a source of therapeutic agents for fish and shellfish diseases caused by Vibrio species, as well as natural antioxidants for human health.