Identification of Bioactive Compounds in the Extracts of Brown Algae Sargassum (Sargassum angustifulium) and Padina )Padina distromatic( and Evaluation of Antimicrobial, Antioxidant and Enzymatic Properties

Sargassum and Padina are two genera of brown algae that are widely scattered in temperate regions. Sargassum species are categorized as tropical and sub-tropical brown seaweed which are valuable sources of bioactive compounds including dietary fibers, carotenoids, vitamins, and minerals. These brown algae demonstrate diverse biological activities such as antioxidant, antimicrobial, and anti‑Alzheimer, due to the presence of flavonoids, triterpenoids, flavonoids, sterols, polyphenols, and pheophytine. The genus Padina is scattered in many environmental conditions, mainly in the tropical marine waters, and belongs to the family Dictyotaceae. Some bioactive components isolated from Padina species have been demonstrated hypoglycemic, hypolipidemic, anti-obesity, hepatoprotective, cardioprotective, immunostimulatory, and antimicrobial activities., The aim of this study was to prepare an extract from two species of algae Padina and Sargsum by massaging and ultrasound assisted-methods  as well as analyzing their compounds and investigating the antioxidant, antimicrobial and enzymatic properties of the extracts. According to the obtained results, ultrasound assisted method was a suitable method for extraction. This extract can be used as a combination of antioxidant, antimicrobial, anti-Alzheimer's and nitrate reducing agent in food additives.

Chemical materials were supplied by Sigma-Aldrich GmbH (Sternheim, Germany). The algal species utilized in the current investigation; namely, Padina distromatic and Sargassum angustifolium were collected from the coastal region of Chabahar bandar, Sistan and Baluchistan Province, Iran. To eliminate all the impurities and extraneous materials, they were washed by using distilled water and then dried at ambient temperature (24-48 h) until the constant weight. Extraction by maceration was compared with the extraction using ultrasonic assisted method. Determination of chemical compounds was parformed using GC-MS device. Investigation of antioxidant properties and total polyphenol and flavonoid content were also performed. The degree of free radical scavenging was done according to DPPH method. Evaluation of antimicrobial effect of algae extracts were the main challenges in our research. S. aureus ATCC25923, Listeria innocua ATCC 33090, E. coli ATCC 25922 and S. typhi ATCC 6539 were used for antimicrobial test. Determination of minimum growth inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were performed using wells in agar.The enzymatic activity was also determined. In this study, the activity of acetylcholinesterase was investigated using the method introduced by Ellman et al. (1961) and also the activity of nitric oxidase was determined using a kit protocol (Nvand-Iran). Factorial experiment in the form of a completely randomized design was used to analyze the data. Duncan's multiple range test was used to determine the difference between the means at the 95% confidence level, and SAS software version 2.9 will used for statistical analysis.

The current study investigated the antioxidant, antibacterial, anti-inflammatory, and anti-Alzheimer’s attributes of two brown algae namely Padina distromatic and Sargassum angustifolium which were collected from the coastal region of Chabahar Bandar, Iran. The results clearly indicated that the type of algae and extraction techniques used in this investigation highly affected phytochemical compositions, antioxidant, AChE inhibitory, scavenging, and antimicrobial activities. Considering both extraction yield and phytochemical components, extraction by ultrasound assisted method provided better results. Among all algal extracts, UPE presented the highest AChE inhibitory activity, and antibacterial activity and USE presented the highest antioxidant activities, total phenols and flavonoids, reflecting the presence of various bioactive components. The extracts of two various seaweeds utilized in the current study highlighted considerable inhibitory action against four pathogenic bacteria. According to the observations of the antibacterial assay, S. aureus was the most sensitive microorganism, while L. innocua was revealed as the most resistant bacteria to the extracts of P. distromatic and S. angustifolium. Further, the chemical components responsible for the antioxidant, AChE inhibitory, and antibacterial power were confirmed by GC-MS analysis. The findings of the current investigation confirmed the potential of the health benefits and therapeutic effect of brown marine algae. Thus, the extract of P. distromatic and S. latifolium could be an effective supplement to be incorporated into the products’ formulation in the food and pharmaceutical industries as well as in medication to alleviate several disorders such as Alzheimer.