تاثیر نوع حلال بر میزان بازده استخراج و خواص آنتی‌اکسیدانی پلی‌فنول‌ها و آلژینات از جلبک‌های قهوه‌ای sargassum cristaefolium و nizimudinia zanardinii جمع‌آوری شده از سواحل شمالی دریای عمان

در مطالعه حاضر تاثیر نوع حلال بر میزان بازده استخراج و خواص آنتی‌اکسیدانی پلی‌فنول‌ها و آلژینات استخراجی از جلبک‌های قهوه‌ای sargassum cristaefolium و nizimudinia zanardinii جمع‌آوری شده از سواحل شمالی دریای عمان مورد بررسی قرار گرفت. جلبک‌های قهوه‌ای از سواحل چابهار جمع‌آوری، شستشو و در سایه خشک گردید. در ادامه استخراج عصاره از جلبک‌ها با استفاده از حلال‌های متانول (100، 70 و 30 درصد)، اتیل استات (100، 70 و 30 درصد ) و آب (100 درصد) انجام شده و میزان استخراج عصاره، میزان فلوروتانین، توانایی مهار رادیکال آزاد dpph و توانایی کلاته‌کنندگی مس در عصاره‌های مختلف سنجش گردید. نتایج نشان داد که نوع حلال (متانول یا اتیل استات) و نسبت ترکیب آن (70، 30 و صفر درصد) با آب تآثیر زیادی بر میزان استخراج عصاره، فلوروتانین، آلژینات و خواص آنتی‌اکسیدانی آنها دارد. در هر دو جلبک، حلال‌های آلی در شکل خالص کارایی بهتری نسبت به شکل ترکیب با آب داشتند. نتایج مقایسه دو جلبک نیز نشان داد که جلبک n. zanardinii نسبت به s. cristaefolium دارای میزان فلوروتانین، آلژینات و خواص آنتی‌اکسیدانی بالاتری بوده است. بنابراین، از جلبک n. zanardinii و عصاره حاصل از حلال متانول 100 درصد برای استخراج فلوروتانین و در ادامه آلژینات استفاده گردید. نتایج ادامه پژوهش نشان داد که در فرکشن‌های مختلف حاصله از عصاره اولیه جلبک n. zanardinii،، فرکشن اتیل‌استاتی دارای میزان فلوروتانین، مهار رادیکال آزاد و کلاته‌کنندگی یون مس بالاتری نسبت به سایر فرکشن‌‌ها بوده است. به طور کلی، نتایج حاصل از این پژوهش نشان داد که نوع حلال تاثیر معنی‌داری بر میزان استخراج ترکیبات فنولی و آلژینات از جلبک قهوه‌ای دارد و میزان این ترکیبات و خواص آنتی‌اکسیدانی آنها بسته به نوع گونه و شرایط استخراج متفاوت است.

effect of solvent type on extraction efficiency and antioxidant properties of polyphenols and alginate from brown seaweeds sargassum cristaefolium and nizimudinia zanardinii collected from the northern coasts of the oman sea

introductionamong all marine organisms, seaweeds are considered as one of the sources of bioactive compounds. the most important compounds found in brown seaweed include phenolic compounds, polysaccharides, polyunsaturated fatty acids, proteins, peptides, pigments, vitamins, terpenoids and sterols (sadeghi et al., 2023). phlorotannins are compounds containing a benzene ring with one or more hydroxyl group substitutions, which are found only in brown seaweeds. so far, more than 150 algal polyphenol structures have been reported (asaduzzaman et al., 2020). reports indicate that these compounds have several medicinal properties such as antimicrobial and antioxidant (milledge et al., 2015). phycocolloids or hydrocolloids are another group of bioactive compounds found in brown seaweeds. the most important hydrocolloids found in seaweeds include alginate, agar, and carrageenan (cmikova et al., 2022). sargassum cristaefolium and nizimudinia zanardinii are brown seaweeds species with good distribution on the southern coasts of iran that can be considered as potential options for investigating the presence of compounds with antioxidant and functional properties. therefore, the objectives of the present study included 1) extraction of bioactive compounds (including phenolic compounds and alginate) using different solvents and 2) investigation of the extraction efficiency and antioxidant properties of the extracted compounds.methodologybrown seaweeds s. cristaefolium and n. zanardinii were collected from the chabahar coast, washed and dried in the shade. extraction was performed using methanol (100%, 70%, 30%), ethyl acetate (100%, 70%, 30%) and water (100%) and the extraction yield, phlorotannins content, dpph free radical scavenging activity and copper chelating ability of different extracts were measured. to purify phenolic compounds in n. zanardinii, the methanol extract was fractionated using chloroform, dichloromethane and ethyl acetate solvents. alginate was extracted using distilled water and the residue obtained from the extraction in the previous section was used for extraction. total phenol content was measured based on the standard phloroglucinol (phg) and using the folin-ciocalteu indicator. dpph free radical scavenging activity was measured according to the method of shimada et al. (1992). cupric chelating ability of different extracts was measured according to the method mentioned by wong et al. (2006).resultsin s. cristaefolium, among the different treatments, the highest extraction yield was obtained in 70% methanol solvent (5.50 g/100 g), while in n. zanardinii the highest yield was in 100% methanol solvent and equal to 43.6 g/100 g seaweed. the extract yield in n. zanardinii was higher than s. cristaefolium in most treatments. in both seaweeds, the highest phlorotannins content was observed in 100% ethyl acetate treatment and the lowest in 100% water treatment. the highest dpph scavenging activity was obtained in 100% ethyl acetate treatment of n. zanardinii at 84.38%. the lowest dpph scavenging activity was observed in 100% water extract. among the different fractions, the highest extraction yield by weight was associated with the ethyl acetate fraction (2.54 g). the highest amount of phlorotannins, i.e. 19.14 mg phloroglucinol/g extract, was found in the ethyl acetate fraction, while the lowest amount (1.35 mg phg/g) was found in the chloroform fraction. the highest radical scavenging activity, 98.95%, was found in the ethyl acetate fraction. when comparing the fractions with the first extract, only the cupric chelation rate in the ethyl acetate fraction (73.44%) was higher than in the first extract (43.45%), and lower chelating ability was observed in the other fractions.discussion and conclusionin the present study, organic solvents in pure form were more effective than those mixed with water in both s. cristaefolium and n. zanardinii. these results are in agreement with the study of el-sheekh et al. (2023) who reported that the extraction yield and antioxidant properties varied depending on the type of solvent and seaweed species, and in most species, the highest yield and antioxidant properties were in methanol extracts. the results of purification of the first extract of n. zanardinii using different solvents showed that the ethyl acetate fraction had a higher phlorotannins content, dpph free radical scavenging activity, and cupric chelating ability than other fractions. previous studies show that ethyl acetate has a better ability to separate phenolic compounds, especially phlorotannins, from the first extract compared to other solvents (sadeghi et al., 2024). therefore, it seems that the higher antioxidant properties in this fraction were due to the accumulation of polyphenols in it (chakraborty et al., 2015). in the present study, the amount of alginate extracted from n. zanardinii was higher than in similar studies and the extracted alginate had a good ability to chelate cupric ions. this property was probably due to the high ability of alginate to form gels and subsequently increase the viscosity of the solution and trap ions (jayakody et al., 2020). in general, the results of this study showed that the type of solvent had a significant effect on the extraction yield of phenolic compounds and alginate from brown seaweed, and the amount of these compounds and their antioxidant properties varied depending on the species and extraction conditions.