Gracilaria gracilis (Gracilariales, Rhodophyta) from Dakhla (Southern Moroccan Atlantic Coast) as Source of Agar: Content, Chemical Characteristics, and Gelling Properties

Abstract

Agar is a sulfated polysaccharide extracted from certain marine red algae, and its gel properties depend on the seaweed source and extraction conditions. In the present study, the seaweed Gracilaria gracilis (Gracilariales, Rhodophyta) from Dakhla (Moroccan Atlantic Coast) was investigated for its agar content, structure, and gel properties. The agar yields of G. gracilis were 20.5% and 15.6% from alkaline pretreatment and native extraction, respectively. Agar with alkaline pretreatment showed a better gelling property supported by higher gel strength (377 g·cm−2), gelling (35.4 °C), and melting (82.1 °C) temperatures with a notable increase in 3,6-anhydro-galactose (11.85%) and decrease in sulphate (0.32%) contents. The sulfate falling subsequent to alkaline pretreatment was verified through FT-IR spectroscopy. The 13C NMR spectroscopy showed that alkaline-pretreated agar has a typical unsubstituted agar pattern. However, native agar had a partially methylated agarose structure. Overall, this study suggested the possibility of the exploitation of G. gracilis to produce a fine-quality agar. Yet, further investigation may need to determine the seasonal variability of this biopolymer according to the life cycle of G. gracilis.

An agar–polyvinyl alcohol hydrogel loaded with tannic acid with efficient hemostatic and antibacterial capacity for wound dressing

“…It consists of linear chains of β (1 → 3) linked galactose and (1 → 4) linked 3,6-anhydroα-galactopyranose repeat units, forming a double helix structure. 21 The ability of agar to form cross-linked structures without adding any chemicals leads to its wide use in food and medical applications. [22][23][24] Tannic acid (TA), a natural polyphenol found in plants and fruits, is widely used as a cross-linking agent due to its abundant hydroxyl groups.…”

“…It consists of linear chains of β (1 → 3) linked galactose and (1 → 4) linked 3,6-anhydro-α-galactopyranose repeat units, forming a double helix structure. 21 The ability of agar to form cross-linked structures without adding any chemicals leads to its wide use in food and medical applications. 22–24…”

Precise healing of oral and maxillofacial wounds: tissue engineering strategies and their associated mechanisms

“…Furthermore, SA adheres to tissues via the oxidation of functional groups of the molecular chain, which results in the formation of imines ( Han et al, 2017 ; Reakasame and Boccaccini, 2018 ; Gao et al, 2019 ). Moreover, Agar polysaccharides (AGAR), which are extracted from seaweed ( Belattmania et al, 2021 ), have been infused with fumaric acid (FA) to modify and synthesize silver nanoparticles (Ag NPs) resulting in the development of AA-Ag-FA hydrogels ( Basha et al, 2020 ). FA promotes the angiogenic pathway to stimulate neovascularization, increase granulation tissue formation, and remodel collagen, thus accelerating wound healing.…”

The Controlled Semi-Solid Fermentation of Seaweeds as a Strategy for Their Stabilization and New Food Applications

“…It was applied to G. gracilis , which is already established in several lagoons of the Mediterranean Basin [ 99 , 100 , 101 , 102 , 103 ]. Very recent studies addressed the possible exploitation of the red alga G. gracilis [ 34 , 104 , 105 ].…”