Phenolic compounds from Limonium densiflorum : a multifaceted approach to antioxidant, anti-inflammatory, anticancer, and anti-influenza activities

Exploration of the hydroethanolic extracts from the halophyte Limonium densiflorum, led to the isolation of seven phenolic compounds: gallic acid, epigallocatechin gallate (EGCG), quercitrin, a mixture of myricetin 3-O-α-rhamnopyranoside + myricetin 3-O-L-arabinofuranoside, dihydrokaempferol, pinoresinol, and trans-N-ferulolyl tyramine. These compounds were assessed for anticancer, anti-influenza A virus, antioxidant, and anti-inflammatory properties. The results indicated that these compounds do not exhibit toxicity towards healthy cells (WS-1 and MDCK). Furthermore, they displayed strong antioxidant properties. Among these compounds, gallic acid, the mixture of myricetin 3-O-α-rhamnopyranoside + myricetin 3-O-L-arabinofuranoside, dihydrokaempferol, and pinoresinol, showed significant cytotoxicity against colon cancer cells (IC50: 1-39 µg/mL). EGCG, gallic acid, dihydrokaempferol, pinoresinol, and trans-N-ferulolyl tyramine demonstrated potent anti-inflammatory activity by reducing nitric oxide (NO) production and also inhibited the replication of the influenza A virus. Biological activities varied based on compound structure, with phenolic acids and flavonoid aglycones showing stronger effects than glycosylated compounds and lignans.