Project 2
Isolation, Identification, and Activity Study of Secondary Metabolites from Zostera marina L. L¶
Jul. 2021
Zostera marina L.L is the most widely distributed perennial seagrass along the coast of the Northern Hemisphere. In this study, we investigated the secondary metabolites of Zostera marina L.L and their associated activities. Ethanol extraction was employed with ethyl acetate to yield an extract. This extract was then further processed using ether extraction, resulting in a smaller polar fraction that underwent GC-MS analysis. Subsequently, the larger polar fraction within the extract underwent repeated separation and purification through silica gel column chromatography and thin-layer chromatography. Ultimately, this process yielded two compounds: 3', 4', 5,5', 6,7-hexamethoxyflavone and β-sitosterol. The compounds' structures were confirmed through MS, NMR, and other spectroscopic techniques. Antioxidant activity was determined via the DPPH method, revealing an EC50 value of 78.54 μg/ml for the crude extract and an EC50 value of 0.778 mg/ml for 3', 4', 5,5', 6,7-hexamethoxyflavonoid. It can be seen that the crude extract of Zostera marina L. L has good antioxidant activity, and the DPPH clearance rate can reach 90% at a concentration of 150 μg/ml.
This investigation significantly broadens the scope of natural metabolites derived from marine sources. Notably, we conducted the first-ever analysis of the small polar fraction of Zostera marina L.L, identifying a total of 33 compounds and analyzing their relative content. Of particular interest is the polymethoxyflavonoid 3', 4', 5,5', 6,7-hexamethoxyflavonoid, which exhibits rapid and reversible activation of CFTR Cl- channels in a dose-dependent manner. This activation is achieved by increasing cAMP levels and directly binding to the cystic fibrosis transmembrane conductance regulator (CFTR). Crucially, among flavonoid compounds, it exhibits the highest affinity as a CFTR Cl- channel activator (EC50 = 2 μmol/L). Given the vital role of CFTR in fluid transport, water and electrolyte balance, and its close association with conditions like habitual constipation and bronchiectasis, 3', 4', 5,5', 6,7-hexamethoxyflavonoid presents promising potential as a lead compound for CFTR-related disease treatment.