Optimization of Phlorotannins Extraction from Fucus vesiculosus and Evaluation of Their Potential to Prevent Metabolic Disorders

Abstract

Phlorotannins are phloroglucinol-based phenolic compounds, occurring particularly in brown macroalgae, that have been recognized for their promising bioactive properties. In this study, the extraction of phlorotannins from Fucus vesiculosus was evaluated with particular emphasis on the influential parameters, including the solvent concentration, solvent-solid ratio, extraction temperature and extraction time, using a single-factor design followed by a Box-Behnken design. The maximum total phlorotannin content, determined using the 2,4-dimethoxybenzaldehyde (DMBA) method, corresponded to 2.92 ± 0.05 mg of phloroglucinol equivalents/g dry seaweed (mg PGE/g DS), and was achieved for extracts carried out with acetone 67% (v/v), a solvent-solid ratio of 70 mL/g and temperature at 25 °C. This crude extract, together with a semi-purified phlorotannin fraction, were further evaluated for their anti-enzymatic capacity against α-glucosidase, α-amylase and pancreatic lipase, both showing promising inhibitory effects, particularly against α-glucosidase for which a greater inhibitory effect was observed compared to the pharmaceutical drug acarbose (IC50 = 4.5 ± 0.8 and 0.82 ± 0.3 μg/mL, respectively, against 206.6 ± 25.1 μg/mL). Additionally, the ultra-high-pressure liquid chromatography coupled to mass spectrometry (UHPLC-MS) analysis carried out on the ethyl acetate fraction revealed the presence of fucols, fucophlorethols, fuhalols and several other phlorotannin derivatives. Moreover, possible new phlorotannin compounds, including fucofurodiphlorethol, fucofurotriphlorethol and fucofuropentaphlorethol, have been tentatively identified in this extract. Overall, this study provides evidence that F. vesiculosus phlorotannin-rich extracts hold potential for the management of the activity of α-glucosidase, α-amylase and pancreatic lipase, which are well known to be linked to metabolic disorders such as diabetes and obesity.

Antidiabetic Potential of Marine Brown Algae—a Mini Review

“…Fucus vesiculosus is a brown alga with prominent antidiabetic activities. According to the ultra-high-pressure liquid chromatography coupled to mass spectrometry (UHPLC-MS) analysis, the ethyl acetate fraction of Fucus vesiculosuswas reported to have phlorotannins such as fucols, fucophlorethols, fuhalols, fucofurodiphlorethol, fucofurotriphlorethol, and fucofuropentaphlorethol which showed a promising antidiabetic activity through the inhibitory activity of α-glucosidase (IC 50 : 0:82 ± 0:05 μg/ml: acarbose IC 50 : 206:6 ± 25:1 μg/ml) and α-amylase (IC 50 : 2:8 ± 0:3 μg/ml: acarbose IC 50 : 0:7 ± 0:2 μg/ml) enzymes [36]. In addition to the phlorotannins, Fucus vesiculosus produce fucoidans and Shan et al [37] evaluated the α-glucosidase inhibitory activity of fucoidan extracted from a brown alga Fucus vesiculosus and was reported to have the highest α-glucosidase inhibitory effect with IC 50 of 67.9 μg/ml compared to the standard drug acarbose (IC 50 :1000 μg/ml).…”

The Quest for Phenolic Compounds from Macroalgae: A Review of Extraction and Identification Methodologies

“…The extraction of Fucus vesiculosus with acetone:water (70:30, v/v) obtained a higher content of soluble phlorotannins than with other solvents or mixtures [79,80]; this is one of the most frequently used extraction solvent mixtures in the studies regarding phenolic compounds from macroalgae [35,60,70]. Catarino et al optimized the acetone concentration (in a range from 30% to 70% (v/v)) in order to maximize the TPhC of Fucus vesiculosus acetone:water extracts, reaching a maximum at 67% of acetone [9]. Additionally, in a scale-up perspective, the benign character of acetone has been up and coming in the increasing demand in the last years to achieve efficient extraction methodologies with a reduction, or an absence, of unsafe organic solvents consumption.…”

“…Actually, the use of higher extraction temperatures has been described to promote the oxidation of phenolic compounds [53]. Catarino et al demonstrated that the highest TPhC of Fucus vesiculosus extracts is obtained at 25 • C, in a studied range between 15 and 50 • C [9]. Notwithstanding, other authors have verified a positive effect of the extraction temperature on the phlorotannins recovery, namely in Eisenia bicyclis [38] and Macrocystis pyrifera [69], for which the best temperatures were reported to be 80 and 55 • C, respectively.…”

“…Marine macroalgae (seaweeds) have been seen in the last years as a valuable source of bioactive components, including phenolic compounds [5], which in some cases are quite exclusive to macroalgae, e.g., phlorotannins. Despite the growing number of studies regarding the analysis of the phenolic fraction of macroalgae [6,7], including the optimization of extraction conditions [8,9] and analysis [10] of such components, a detailed and comprehensive revision of their phenolic composition as well as of the extraction and analytical methodologies applied to their detailed characterization, has not been available so far. Actually, and despite the increasing interest from the scientific community, the bioprospection of phenolic compounds from macroalgae has been a challenging issue.…”

Evaluation of the Antibacterial Material Production in the Fermentation of Bacillus amyloliquefaciens-9 from Whitespotted Bamboo Shark (Chiloscyllium plagiosum)

“…The experiments were carried out by varying one condition at a time [48]. First, the carbon source (sucrose) was set to five concentration gradients (10-50 g L −1 ), and GBacillus-9 was cultured in M9 culture media for 10 h at 37 • C. Next, the antimicrobial ability was detected using the inhibition zone method to find the optimal concentration of the carbon source.…”