The optimum conditions for the extraction of antioxidant compounds from the Persian gulf green algae (Chaetomorpha sp.) using response surface methodology

Macroalgae as a Source of Valuable Antimicrobial Compounds: Extraction and Applications

In the last few decades, attention on new natural antimicrobial compounds has arisen due to a change in consumer preferences and the increase in the number of resistant microorganisms. Macroalgae play a special role in the pursuit of new active molecules as they have been traditionally consumed and are known for their chemical and nutritional composition and their biological properties, including antimicrobial activity. Among the bioactive molecules of algae, proteins and peptides, polysaccharides, polyphenols, polyunsaturated fatty acids and pigments can be highlighted. However, for the complete obtaining and incorporation of these molecules, it is essential to achieve easy, profitable and sustainable recovery of these compounds. For this purpose, novel liquid-liquid and solid-liquid extraction techniques have been studied, such as supercritical, ultrasound, microwave, enzymatic, high pressure, accelerated solvent and intensity pulsed electric fields extraction techniques. Moreover, different applications have been proposed for these compounds, such as preservatives in the food or cosmetic industries, as antibiotics in the pharmaceutical industry, as antibiofilm, antifouling, coating in active packaging, prebiotics or in nanoparticles. This review presents the main antimicrobial potential of macroalgae, their specific bioactive compounds and novel green extraction technologies to efficiently extract them, with emphasis on the antibacterial and antifungal data and their applications.

Emerging Technologies for the Extraction of Marine Phenolics: Opportunities and Challenges

Natural phenolic compounds are important classes of plant, microorganism, and algal secondary metabolites. They have well-documented beneficial biological activities. The marine environment is less explored than other environments but have huge potential for the discovery of new unique compounds with potential applications in, e.g., food, cosmetics, and pharmaceutical industries. To survive in a very harsh and challenging environment, marine organisms like several seaweed (macroalgae) species produce and accumulate several secondary metabolites, including marine phenolics in the cells. Traditionally, these compounds were extracted from their sample matrix using organic solvents. This conventional extraction method had several drawbacks such as a long extraction time, low extraction yield, co-extraction of other compounds, and usage of a huge volume of one or more organic solvents, which consequently results in environmental pollution. To mitigate these drawbacks, newly emerging technologies, such as enzyme-assisted extraction (EAE), microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE) have received huge interest from researchers around the world. Therefore, in this review, the most recent and emerging technologies are discussed for the extraction of marine phenolic compounds of interest for their antioxidant and other bioactivity in, e.g., cosmetic and food industry. Moreover, the opportunities and the bottleneck for upscaling of these technologies are also presented.

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

The current interest of the scientific community for the exploitation of high-value compounds from macroalgae is related to the increasing knowledge of their biological activities and health benefits. Macroalgae phenolic compounds, particularly phlorotannins, have gained particular attention due to their specific bioactivities, including antioxidant, antiproliferative, or antidiabetic. Notwithstanding, the characterization of macroalgae phenolic compounds is a multi-step task, with high challenges associated with their isolation and characterization, due to the highly complex and polysaccharide-rich matrix of macroalgae. Therefore, this fraction is far from being fully explored. In fact, a critical revision of the extraction and characterization methodologies already used in the analysis of phenolic compounds from macroalgae is lacking in the literature, and it is of uttermost importance to compile validated methodologies and discourage misleading practices. The aim of this review is to discuss the state-of-the-art of phenolic compounds already identified in green, red, and brown macroalgae, reviewing their structural classification, as well as critically discussing extraction methodologies, chromatographic separation techniques, and the analytical strategies for their characterization, including information about structural identification techniques and key spectroscopic profiles. For the first time, mass spectrometry data of phlorotannins, a chemical family quite exclusive of macroalgae, is compiled and discussed.

Optimization of Surfactant-Mediated, Ultrasonic-assisted Extraction of Antioxidant Polyphenols from Rattan Tea (Ampelopsis grossedentata) Using Response Surface Methodology

BACKGROUND

Rattan tea is a medicinal plant that has been used for many years for the treatment of inflammation, fatty liver, tumor, diabetes, and hyperlipidemia.

OBJECTIVE

A green and novel approach based on surfactant-mediated, ultrasonic-assisted extraction (SM-UAE) was developed for the extraction of antioxidant polyphenols from Rattan tea. A nonionic surfactant Tween-80 was selected as extraction solvent. The antioxidant activity was measured by total phenolic content (TPC) and ferric-reducing/antioxidant capacity (FRAC) assay.

MATERIALS AND METHODS

Optimization of extraction parameters including concentration of solvent, ultrasonic time, and temperature were investigated by response surface methodology. The antioxidant activity was measured by TPC and FRAC assay.

RESULTS

The optimal extraction conditions were determined as 6.8% (v/v) of aqueous Tween-80, ultrasonic temperature of 54°C, and ultrasonic time of 28.8 min. Under these conditions, the highest TPC value of 360.4 mg gallic acid equivalent per gram of dry weight material (GAE/g DW) was recorded. Moreover, 6.8% (v/v) of aqueous Tween-80, ultrasonic temperature of 54.5°C, and ultrasonic time of 28.4 min were determined for the highest FRAC value of 478.2 μmol of Fe²⁺/g of weight material (μmol Fe²⁺/g DW). Compared with other methods, the TPC and FRAC values of 313.5 mg GAE/g DW and 389.6 μmol Fe²⁺/g DW were obtained by heat reflux extraction using ethanol as solvent, respectively, and 343.2 mg GAE/g DW and 450.1 μmol Fe²⁺/g DW were obtained by UAE using ethanol as solvent, respectively.

CONCLUSION

The application of SM-UAE markedly decreased extraction time or extraction cost and improved the extraction efficiency, compared with the other methods.

SUMMARY

Surfactant-mediated ultrasonic-assisted extraction of antioxidant polyphenols from Rattan TeaResponse surface methodology used to optimize parameters and study combined effectsOptimized surfactant-mediated ultrasonic-assisted extraction process enhances the antioxidant phenolics extraction in less time. Abbreviations used: SM-UAE: Surfactant-mediated ultrasonic-assisted extraction; TPC: total phenolic content; FRAC: Ferric reducing antioxidant capacity; RSM: Response surface methodology; BBD: Box-Behnken design.

Antioxidant screening and phenolic content of ethanol extracts of selected Baja California Peninsula macroalgae

The Baja California Peninsula in México has about 670 species of macroalgae along its coast. Species richness increases the probability of finding native macroalgae with potential as sources of bioactive compounds suitable for health, pharmacological, and cosmetic ingredients. To understand the biotechnological value of macroalgae from the peninsula, ethanol extracts from 17 macroalgae (four Chlorophyta, six Rhodophyta, seven Ochrophyta) were screened for antioxidant potential. To determine the antioxidant capacity of macroalgal extracts, 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power, and nitric oxide radical scavenging as well as total phenolic content (TPC) were measured. Extracts of the brown macroalgae were most active. Among these, Eisenia arborea, Padina concrecens, and Cystoseira osmundacea had the highest TPC and exhibited the strongest radical scavenging activities. Correlations were found between TPC macroalgal and scavenging capacity, indicating an important role of polyphenols as antioxidants. This suggests that some brown macroalgae from Baja California Peninsula may be a good source of natural bioactive compounds.