Slamet Pujianto, Boy Arief Fachri, Istiqomah Rahmawati, Erna Subroto

Effect of Ethanol Solvents in the Extraction Process of Bioactive Compounds from Brown Seaweed (Sargassum sp.) with the Ultrasound Assisted Extraction Method

Introduction

Effect of ethanol solvents in the extraction process of bioactive compounds from brown seaweed (sargassum sp.) with the ultrasound assisted extraction method. Optimize ultrasound assisted extraction with ethanol to extract natural antioxidant phenolic compounds from brown seaweed (Sargassum sp.). Maximize phenol yields & antioxidant activity.

Abstract

Sargassum sp., part of brown algae, is traditionally used as animal feed. Nonetheless, Sargassum contains phenolic compounds that promise to be the raw material of natural antioxidants. The work is to extract phenolic compounds from Sargassum sp. in ethanol and to investigate the effect of the process on phenol yields. Several dried Sargassum sp. are milled in a certain size and extraction using ultrasound assisted extraction with ethanol solvent. Process variables are the extraction time (30-50 minutes) and the Ratio of Sargassum sp. to ethanol which is 5:100-15:100 (b/v), and power of 170-190 watts. Phenol compounds are quantified using the error acid method. The DPPH method is performed to check the antioxidant activity. To investigate the influence of the process, surface response methods based on central composite designs are applied in this work. 153.334 mgGAE/g in 30-minute extraction conditions, 170 watts of power, and a ratio between masses and solvents of 0.05. The antioxidant activity (IC50) of Sargassum sp. extract is 87.57 ppm.

Review

This manuscript presents a timely investigation into the valorization of *Sargassum sp.* brown seaweed, traditionally considered animal feed, as a source of natural antioxidants. By focusing on ultrasound-assisted extraction (UAE) with ethanol as the solvent, the authors aim to optimize the recovery of phenolic compounds and assess their antioxidant potential. The approach utilizing Response Surface Methodology (RSM) based on Central Composite Design (CCD) is appropriate for systematically exploring the effects of extraction time, solid-to-solvent ratio, and ultrasound power on phenol yield. The work demonstrates the promising potential of *Sargassum sp.* extracts, reporting a notable phenolic yield of 153.334 mgGAE/g and an impressive antioxidant activity with an IC50 value of 87.57 ppm, thereby contributing to the growing interest in marine bioresources for functional ingredients. While the study's overall objective and application of RSM are commendable, a few aspects require clarification and precision for full reproducibility and impact. The "error acid method" for quantifying phenolic compounds is ambiguous and should be clarified to a standard protocol such as the Folin-Ciocalteu method, which typically uses gallic acid equivalents (GAE). Furthermore, while the optimal conditions for maximum yield are stated (30 minutes, 170 watts, 0.05 mass/solvent ratio), a more detailed discussion of how each variable influenced the yield and antioxidant activity based on the RSM model would strengthen the findings. Clarity on the specific particle size range after milling the dried *Sargassum sp.* would also be beneficial, as this can significantly impact extraction efficiency. Overall, this research successfully highlights the potential of *Sargassum sp.* as a rich source of phenolic compounds with significant antioxidant activity, extracted efficiently using a green technology like UAE with ethanol. The findings lay a solid foundation for the development of natural antioxidants from underutilized marine biomass. Future work could build upon these results by identifying the specific phenolic compounds present in the optimized extract, conducting stability studies, exploring different bioactivities beyond DPPH, and potentially scaling up the process to industrial applications. This study is a valuable contribution to the field of marine bioprospecting and sustainable resource utilization.

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