Valorization of the Red Algae Gelidium sesquipedale by Extracting a Broad Spectrum of Minor Compounds Using Green Approaches.

Natalia Castejón,Susana C M Fernandes,Ryszard Lobinski,Maroussia Parailloux,Aleksandra Izdebska

doi:10.3390/md19100574

Abstract

Until now, the red algae Gelidium sesquipedale has been primarily exploited for agar production, leaving an undervalued biomass. In this work, the use of eco-friendly approaches employing ultrasound-assisted extraction (UAE) and green solvents was investigated to valorize the algal minor compounds. The green methods used herein showed an attractive alternative to efficiently extract a broad spectrum of bioactive compounds in short extraction times (15 to 30 min vs. 8 h of the conventional method). Using the best UAE conditions, red seaweed extracts were characterized in terms of total phenolics (189.3 ± 11.7 mg GAE/100 g dw), flavonoids (310.7 ± 9.7 mg QE/100 g dw), mycosporine-like amino acids (MAAs) (Σ MAAs = 1271 mg/100 g dw), and phycobiliproteins (72.4 ± 0.5 mg/100 g dw). Additionally, produced algal extracts exhibited interesting antioxidant and anti-enzymatic activities for potential applications in medical and/or cosmetic products. Thus, this study provides the basis to reach a superior valorization of algal biomass by using alternative methods to extract biologically active compounds following eco-friendly approaches. Moreover, the strategies developed not only open new possibilities for the commercial use of Gelidium sesquipedale, but also for the valorization of different algae species since the techniques established can be easily adapted.

Highlights

Marine sources, especially seaweeds and microalgae are still an unexploited reservoir of bioactive compounds, which have significant potential to provide novel and natural ingredients for food and pharmaceutical industries [1,2].Up to now, the red algae Gelidium sesquipedale has been mainly commercially exploited for agar production [3], leaving a large undervalued algal biomass
Even though it is known that red seaweeds are not the main source of phenolic and flavonoids compounds, these metabolites are targeted compounds for the valorization of the minor compounds from Gelidium sesquipedale
Even though the ultrasound-assisted extraction (UAE) approaches proposed in this study did not achieve the maximum recovery of total phenolic (TPC) obtained by the traditional method, the application of ultrasounds could be an attractive alternative due to the shorter extraction time (15 min vs. 8 h), obtaining an extraction efficiency of 81%

Summary

Introduction

Especially seaweeds and microalgae are still an unexploited reservoir of bioactive compounds, which have significant potential to provide novel and natural ingredients for food and pharmaceutical industries [1,2]. The red algae Gelidium sesquipedale has been mainly commercially exploited for agar production [3], leaving a large undervalued algal biomass. Food processing by-products obtained from plants or algae are known as important sources of functional bioactive compounds [5,6]. EU objectives include the optimization of existing bioprocesses at the industry level, and the quest for new products and/or environmental processes that improve the overall economic feasibility of algal biomass [8]. The search for new approaches that will successfully increase the value of algal biomass using minimum energy is nowadays a primary goal

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