In this study, LC–MS/MS-based structural characterisation of phlorotannins from Padina tetrastromatica, a marine brown macroalga collected from South-West coastal region of Kerala, and its bioactivities are presented. The tandem mass spectrometric data revealed a series of phlorotannins with degree of polymerisation ranging from 2 to 18. The characteristic neutral loss of tandem mass spectra further confirmed that these molecules belong to fucophlorethol class of phlorotannins. DPPH assay of the HPLC-purified, phlorotannin-enriched fraction possesses significant free radical-scavenging activity. Cell viability assay indicated that phlorotannin concentration ranging from 1.5 to 50.0 μg mL−1 is non-toxic to THP-1 cell lines. Anti-inflammatory assay performed through gelatin zymography confirmed that phlorotannins ameliorated high-glucose-induced pro-MMP-9 expression in a dose-dependent manner whereas the level of pro-MMP-2 remains unaltered. The antimicrobial assays carried out using both the crude and HPLC-purified phlorotannin fraction showed its anti-MRSA potential.
Divya Nair, Muralidharan Vanuopadath, Balasubramanian, A., Iyer, A., Ganesh, S., Anil, A. Nair, Vikraman, V., Pillai, P., Chinchu Bose, Dr. Bipin G. Nair, Pai, J. Gopalakris, and Nair, S. Sadasivan, “Phlorotannins from Padina tetrastromatica: structural characterisation and functional studies”, Journal of Applied Phycology, pp. 1–11, 2019.