Elicitor Activity of Low-Molecular-Weight Alginates Obtained by Oxidative Degradation of Alginates Extracted from Sargassum muticum and Cystoseira myriophylloides

Abstract

Alginates extracted from two Moroccan brown seaweeds and their derivatives were investigated for their ability to induce phenolic metabolism in the roots and leaves of tomato seedlings. Sodium alginates (ALSM and ALCM) were extracted from the brown seaweeds Sargassum muticum and Cystoseira myriophylloides, respectively. Low-molecular-weight alginates (OASM and OACM) were obtained after radical hydrolysis of the native alginates. Elicitation was carried out by foliar spraying 20 mL of aqueous solutions (1 g/L) on 45-day-old tomato seedlings. Elicitor capacities were evaluated by monitoring phenylalanine ammonia-lyase (PAL) activity, polyphenols, and lignin production in the roots and leaves after 0, 12, 24, 48, and 72 h of treatment. The molecular weights (Mw) of the different fractions were 202 kDa for ALSM, 76 kDa for ALCM, 19 kDa for OACM, and 3 kDa for OASM. FTIR analysis revealed that the structures of OACM and OASM did not change after oxidative degradation of the native alginates. These molecules showed their differential capacity to induce natural defenses in tomato seedlings by increasing PAL activity and through the accumulation of polyphenol and lignin content in the leaves and roots. The oxidative alginates (OASM and OACM) exhibited an effective induction of the key enzyme of phenolic metabolism (PAL) compared to the alginate polymers (ALSM and ALCM). These results suggest that low-molecular-weight alginates may be good candidates for stimulating the natural defenses of plants.

The Ocean’s Pharmacy: Health Discoveries in Marine Algae

“…Algal compounds have many activities that were not included in the present review, such as anti-microbial [224], anti-viral [225], anti-bacterial [226], neuroprotective [227], osteogenic potential [228], and immunomodulatory activities [229], which might also benefit human health. Additionally, some bioactive compounds act on plant and animal health (such as biological activities in aquaculture) [230,231] and were not explored in the present review either.…”

Optimization of hydrolysis conditions of alginate based on high performance liquid chromatography

“…D. I. Sánchez-Machado et al [ 22 ] used sulfuric acid to hydrolyze algal dietary fibers and established a high-performance liquid chromatography method for the determination of the M, G ratio. Although the hydrolysis effect of alginate varies under different acids [ 16 ], it is simple to operate, less costly and more stable in obtaining fragments with intrinsic structural features [ 23 ], so further studies on the hydrolysis efficiency of different acids and optimization of hydrolysis conditions are needed to improve the hydrolysis effect.…”