The antioxidative effects of bioactive products from Sargassum polycystum C. Agardh and Sargassum duplicatum J. Agardh against inflammation and other pathological issues

Ultrasound-assisted extraction of phenolics from Sargassum carpophyllum - A kinetics study

The species of the brown macroalgal genus Sargassum are distributed globally and contain many bioactive compounds. In this study, ultrasound-assisted extraction (UAE) was applied to obtain phenolic compounds with strong antioxidant activity from Sargassum carpophyllum collected along the coastline of Weizhou Island in the South China Sea. The influence of different variables such as the solid-liquid ratio (1:5-1:30 g · mL-1), ultrasonic power (160-280 W), duty circle ratio (DCR, 1/3-1/1), and ethanol concentration (30% to ~90%) were studied using a single factor design. The extraction kinetics were investigated using the Peleg model and second-order kinetics model, and the second-order model described the extraction procedure better than the Peleg model. Total phenol content (TPC) values of 3.316, 2.964, 2.741, and 3.665 mg phloroglucinol (PHG) · g-1 algae were achieved at a higher solid-liquid ratio (1:30 g · mL-1), higher ultrasonic power (280 W), a higher DCR (1/1), and a moderate ethanol concentration (50%), respectively. However, a slightly different result was observed in the extract obtained, with total phenol contents (TPCextract) of 52.99, 65.00, 46.22, and 55.10 mg PHG · g-1 extract and DPPH radical scavenging activity (IC50) of 0.096, 0.066, 0.131, and 0.136 mg extract · mL-1 observed at 50% ethanol, 1:5 g m· mL-1, 2/3 DCR, and 200 W respectively. All variables studied influenced the extraction kinetics by altering the extraction rate and the TPC at equilibrium. As for the bioactivities in the extract, a larger solid-liquid ratio and greater ultrasonic power may not contribute because of their ability to extract non-phenolic components simultaneously, leading to reduced overall bioactivities. The results of the present study provide essential information for future UAE process design and optimization for extracting phenolics from S. carpophyllum through mathematical modeling and could be regarded as important reference for obtaining value-added products from other macroalgae species.

Biological Activities of Sargassum Algae Mediated ZnO and Co Doped ZnO Nanoparticles as Enhanced Antioxidant and Anti-Diabetic Agents

Brown macroalgae (BMG) were used as carriers for ZnO (ZnO/BMG) and cobalt-doped ZnO (Co-ZnO/BMG) via facile microwave-assisted hydrothermal synthesis. The multifunctional structures of synthesized composites were evaluated as enhanced antioxidant and anti-diabetic agents based on the synergistic effects of ZnO, Co-ZnO, and BMG. BMG substrate incorporation and cobalt doping notably enhanced the bioactivity of the synthesized ZnO nanoparticles. As an antioxidant, the Co-ZnO/BMG composite exhibited highly effective scavenging properties for the common free reactive oxygen radicals (DPPH [89.6 ± 1.5%], nitric oxide [90.2 ± 1.3%], ABTS [87.7 ± 1.8%], and O2●- [46.7 ± 1.9%]) as compared to ascorbic acid. Additionally, its anti-diabetic activity was enhanced significantly and strongly inhibited essential oxidative enzymes (porcine α-amylase (90.6 ± 1.5%), crude α-amylase (84.3 ± 1.8%), pancreatic α-glucosidase (95.7 ± 1.4%), crude intestinal α-glucosidase (93.4 ± 1.8%), and amyloglucosidase (96.2 ± 1.4%)). Co-ZnO/BMG inhibitory activity was higher than that of miglitol, and in some cases, higher than or close to that of acarbose. Therefore, the synthetic Co-ZnO/BMG composite can be used as a commercial anti-diabetic and antioxidant agent, considering the cost and adverse side effects of current drugs. The results also demonstrate the impact of cobalt doping and BMG integration on the biological activity of ZnO.

Effects of different extraction methods on contents, profiles, and antioxidant abilities of free and bound phenolics of Sargassum polycystum from the South China Sea

Total phenolic content (TPC), phenolic profiles, and antioxidant activity of free and bound extracts of Sargassum polycystum, obtained by different extraction solvents and hydrolysis methods, were investigated. Aqueous acetone afforded the highest free TPC and antioxidant ability, followed by aqueous ethanol and aqueous methanol. Twelve free phenolic compounds were identified by ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS), including two hydroxycinnamic acids, seven flavonoids, one stilbene, and two phlorotannins. Three to nine different free phenolic compounds were extracted by these solvents with different compositions, including nine by 70% acetone and eight by 70% methanol, 70% ethanol, and 50% ethanol. The highest total content of free phenolic compounds determined by high-performance liquid chromatography-diode array detection was obtained from 70% ethanol. Alkaline hydrolysis afforded higher bound TPC (274.27 mg GAE/100 g DW) and antioxidant ability than acid hydrolysis. Five bound phenolic compounds were characterized by UHPLC-MS and five were released from alkaline hydrolysis, whereas two were released from acid hydrolysis. Total content of bound phenolic compounds released by alkaline hydrolysis was 14.68-fold higher than that by acid hydrolysis. The free and bound TPC, phenolic profiles, and antioxidant activities depended on the extraction solvent used. These results indicate that S. polycystum is a potentially useful antioxidant source and contribute to the development of seaweed-based functional foods. PRACTICAL APPLICATION: Phenolics are usually divided into free and bound forms based on their extractability and interaction with cell wall components. The nutritional effects of bound phenolics in algae have long been neglected. These topics contribute to the development of seaweed-based functional foods.

Preliminary screening of antioxidant and cytotoxic potential of green seaweed, Halimeda opuntia (Linnaeus) Lamouroux

Marine natural products have displayed numerous advantageous effects on biological activities, including antioxidants and cytotoxicity. The total lipids, carotenoids, chlorophyll a and b content, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of methanolic crude extract of the green seaweed Halimeda opuntia were all measured in this study. The TPC of the extracts was determined according to the Folin-Ciocalteu method, yielding a result of 55.04 ± 0.98 mg GAE/g of extract. As determined by the aluminium chloride colorimetric method, the TFC of the extract was 40.02 ± 0.02 mg QE/g of extract. Antioxidant activity was determined by using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay with different concentrations that ranged between 200 and 1000 µg/mL, noted H. opuntia as the highest in DPPH reduction (63.61 %) at 1000 µg/mL concentration. Total antioxidant capacity (TAC) of the extract was 57.36 ± 0.004 mg AAE/g extract at concentration of 1.0 mg/mL. The cytotoxic activity of this seaweed was pre-screened against a panel of cell lines including estrogen receptor-positive human breast adenocarcinoma (MCF-7), estrogen negative human breast adenocarcinoma (MDA-MB-231), human colorectal adenocarcinoma (HT-29), human hepatocellular carcinoma (HepG2), and mouse embryonic fibroblast (3T3) using the MTT assay. The content of total lipids in H. opuntia was 1.60 ± 0.002 %. Total carotenoids were 115.57 ± 0.98 µg/g, while chlorophyll a and b were 148.73 ± 2.60 µg/g and 290.83 ± 9.46 µg/g, respectively. In terms of cytotoxicity activity, methanolic extract of H. opuntia was found to be highly cytotoxic to MCF-7 cells, with an IC₅₀ of 25.14 ± 1.02 g/mL, and slightly less so to 3T3 cells (IC₅₀ 65.23 ± 0.25 µg/mL). This study's findings suggest that natural pigments (carotenoids and chlorophyll), phytochemicals like phenolic and flavonoid compounds found in this species may play an important role and could be used as a natural cancer treatment.

Oral administration of Sargassum polycystum extracts stimulates immune response and increases survival against Aeromonas hydrophila infection in Oncorhynchus mykiss

This study investigated the immunomodulatory effects of Sargassum polycystum extract administration in rainbow trout (Oncorhynchus mykiss). S. polycystum methanolic extract was administered orally using feeding needles to individual rainbow trout at the dose of 0 (control), 1 (S1), 3 (S3) and 5 (S5) mg/100 μl/per fish twice a day for 7 days. On 1st, 5th, 3rd and 7th day, blood and tissues were collected from the fish and changes in humoral immune responses and immune-related gene expressions were determined. The result of oxidative radical production showed no difference during early stage of the experiment and was lately decreased (P < 0.05). Lysozyme activity increased on 3rd and 7th day of the study in S5 fish group and on 5th day in S3 group compared to control (P < 0.05). Myeloperoxidase activity had an increased level on the 1st and 3rd day in S1, S5 and S5 fish groups, respectively. IL-1β gene was significantly up-regulated in kidney and intestine in all experimental groups (except on the 1st day, in the intestine of S5 fish group) compared to control (P < 0.05). IL-8 gene expression was elevated on 1st and 3rd day in kidney of all experimental fish groups. IL-6 transcript enhanced in a dose-dependent manner on 3rd and 7th day. IL-10 and IL-12 genes were also up-regulated. Survival in all treated fish groups challenged with Aeromonas hydrophila was significantly increased compared to that of control. The highest survival rate was recorded in S5 fish group (83.65%) followed by S3 fish group (82.62%). Our results suggest that S. polycystum aqueous methanolic extract is an effective immunostimulant and provide protection against A. hydrophila infection in rainbow trout at a dose of 3-10 mg/20 g body weight/day.

Effect of solvents on bioactive compounds and antioxidant activity of Padina tetrastromatica and Gracilaria tenuistipitata seaweeds collected from Bangladesh

Seaweeds are now recognized as a treasure of bioactive compounds. However, the bioactivity of seaweed originating in Bangladesh is still unexplored. So, this study was designed to explore the secondary metabolites and antioxidant activities of solvent extracts of Padina tetrastromatica and Gracilaria tenuistipitata. Phytochemical screening and FTIR spectra confirm the diverse type of bioactive compounds. Antioxidant activity of extracts were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2, 2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), reducing power (RP), phosphomolybdenum, hydrogen peroxide and nitric oxide (NO) scavenging assays. Here, methanolic extract of P. tetrastromatica showed highest amount of total phenolic content (85.61 mg of GA/g), total flavonoid content (41.77 mg of quercetin/g), DPPH (77.07%), ABTS (77.65%), RP (53.24 mg AAE/g), phosphomolybdenum (31.58 mg AAE/g), hydrogen peroxide (67.89%) and NO (70.64%) assays compared to its methanolic extracts of G. tenuistipitata. This study concluded that methanol as a solvent extract of brown seaweed (P. tetrastromatica) exhibited bioactivity and antioxidant potentiality which will be useful for pharmacological as well as in functional food application.

Phytochemical screening and anti-oxidant activity of Sargassum wightii enhances the anti-bacterial activity against Pseudomonas aeruginosa

In this study, the phytochemical, phenolic, flavonoid and bioactive compounds were successfully screened from crude extract of Sargassum wightii by LC-MS analysis after NIST interpretation. Bacterial growth inhibition study result was shown with 24 mm zone inhibition at 200 µg/mL concentration against P. aeruginosa. The increased phenolic content was much closed to gallic acid and the range was observed at 250 μg/mL concentration. In addition, flavonoid contents of the algae extract was indicated more significant with rutin at 200 μg/mL. In result, both the phenolic and flavonoid contents of the extract were more correlated with gallic acid and rutin. Further, the total anti-oxidant and DPPH radical scavenging activities were shown increased activity at 200 μg/mL concentrations. Furthermore, the excellent anti-bacterial alteration result was observed at 200 μg/mL concentration by minimum inhibition concentration. Therefore, the result was revealed that the marine algae Sargassum wightii has excellent phytochemical and anti-oxidant activities, and it has improved anti-bacterial activity against P. aeruginosa.