Anti-inflammatory potential of monogalactosyl diacylglycerols and a monoacylglycerol from the edible brown seaweed Fucus spiralis Linnaeus

Abstract

A monoacylglycerol (1) and a 1:1 mixture of two monogalactosyl diacylglycerols (MGDGs) (2 and 3) were isolated from the brown seaweed Fucus spiralis Linnaeus. The structures were elucidated by spectroscopic means (NMR and MS) and by comparison with the literature. Compound 1 was composed of a glycerol moiety linked to oleic acid (C18:1 Ω9). Compounds 2 and 3 contained a glycerol moiety linked to a galactose unit and eicosapentaenoic acid (C20:5 Ω3) combined with octadecatetraenoic acid (C18:4 Ω3) or linolenic acid (C18:3 Ω3), respectively. The isolated compounds were tested for their cytotoxic and anti-inflammatory activity in RAW 264.7 macrophage cells. All of them inhibited NO production at non-cytotoxic concentrations. The fraction consisting of compounds 2 and 3, in a ratio of 1:1, was slightly more effective than compound 1 (IC₅₀ of 60.06 and 65.70 µg/mL, respectively). To our knowledge, this is the first report of these compounds from F. spiralis and on their anti-inflammatory capacity.

Figure 1

Structures of the monoacylglycerol (Compound 1) and the monogalactosyldiacylglycerols (MGDGs) (Compounds 2 and 3) isolated from F. spiralis.

Figure 2

Influence of lipopolysaccharide (LPS) in cell viability. RAW 264.7 macrophages were exposed to 1 µg/mL of LPS during 18 h and cell viability was assessed by lactate dehydrogenase (LDH) and thiazolyl blue tetrazolium bromide (MTT) assays. Results are expressed in percentage of control (mean ± SEM of four independent assays performed in duplicate).

Figure 3

Influence of the monoacylglycerol (A) and the MGDGs (B) on cell viability and on NO released by macrophages. After pre-exposure with the test compounds and stimulation with LPS, the viability of RAW 264.7 cells was assessed by the LDH and MTT assays, and the NO production was quantified. Results are expressed as percentage of control (mean ± SEM of four independent assays performed in duplicate). ** p < 0.01, *** p < 0.001.

Figure 4

Dexamethasone effect on NO release. Quantification of NO produced by RAW 264.7 cells exposed to dexamethasone and stimulated with 1 µg/mL of LPS for 18 h. Results are expressed in percentage of control with LPS (mean ± SEM of four independent assays performed in duplicate).