Sustainable synthesis of magnetic Sargassum siliquastrum activated carbon loaded with NiS nanorods for adsorption of 2,4-D herbicide

The upgrade of sustainable resource waste into a valuable and beneficial material is an urgent task. The current paper outlines the development of an economical, sustainable, and prolonged adsorbent derived from Sargassum siliquastrum biomass and its use for potent 2,4-dichlorophenoxyacetic acid (2,4-D) removal. A simple carbonization approach was applied to obtain the highly functionalized carbon structure, which was subsequently transformed into a novel magnetic nanoadsorbent. The magnetic nanoadsorbent was characterized using Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Brunauer Emmett Teller (BET)-specific surface area, and vibrating sample magnetometer (VSM). The characterization results confirm the successful formation of a high specific surface area and a uniform distribution of Fe3O4/NiS NPs grafted activated carbon. The adsorption kinetics was more accurately described via the pseudo-second order model; nevertheless, the isothermal data showed that the Langmuir model was most suitable. The monolayer adsorption capacity for 2,4-D was 208.26 ± 15.75 mg/g at 328 K. The favourability and spontaneity of the adsorption process were demonstrated by thermodynamic studies. The adsorbent displayed exceptional selectivity for 2,4-D and high stability in multi-cycle use. Electrostatic attraction, π-π stacking, and hydrogen bonding were all believed to have an impact on the sorbent's robust 2,4-D adsorption. Analyses of real tap and Nile River water samples showed little effect of the sample matrix on 2,4-D adsorption. This study presents an innovative approach for developing highly efficient adsorbent from natural biomass and offers an affordable way to recycle algal waste into beneficial materials.

The Anti-Inflammatory Effect of Low Molecular Weight Fucoidan from Sargassum siliquastrum in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages via Inhibiting NF-κB/MAPK Signaling Pathways

Brown seaweed is a rich source of fucoidan, which exhibits a variety of biological activities. The present study discloses the protective effect of low molecular weight fucoidan (FSSQ) isolated from an edible brown alga, Sargassum siliquastrum, on lipopolysaccharide (LPS)-stimulated inflammatory responses in RAW 264.7 macrophages. The findings of the study revealed that FSSQ increases cell viability while decreasing intracellular reactive oxygen species production in LPS-stimulated RAW 264.7 macrophages dose-dependently. FSSQ reduced the iNOS and COX-2 expression, inhibiting the NO and prostaglandin E2 production. Furthermore, mRNA expression of IL-1β, IL-6, and TNF-α was downregulated by FSSQ via modulating MAPK and NF-κB signaling. The NLRP3 inflammasome protein complex, including NLRP3, ASC, and caspase-1, as well as the subsequent release of pro-inflammatory cytokines, such as IL-1β and IL-18, release in LPS-stimulated RAW 264.7 macrophages was inhibited by FSSQ. The cytoprotective effect of FSSQ is indicated via Nrf2/HO-1 signaling activation, which is considerably reduced upon suppression of HO-1 activity by ZnPP. Collectively, the study revealed the therapeutic potential of FSSQ against inflammatory responses in LPS-stimulated RAW 264.7 macrophages. Moreover, the study suggests further investigations on commercially viable methods for fucoidan isolation.

Step gradient alcohol precipitation for the purification of low molecular weight fucoidan from Sargassum siliquastrum and its UVB protective effects

Ultraviolet B (UVB) can induce oxidative damage to outermost layers of skin causing suntans, sunburns, and, in severe cases, blisters leading to photoaging. Low molecular weight (MW) fucoidan is renowned for possessing enhanced antioxidant activities. The present study discloses the use of step gradient ethanol precipitation in refining fucoidan fractions (SSQC1-SSQC4) from Sargassum siliquastrum and evaluation of their UVB-protective effects in human HaCaT keratinocytes. Among the fractions, SSQC4 indicated the best bioactive effects. 1H NMR, FTIR, monosaccharide composition by HPAEC-PAD analysis, MW estimation by agarose gel electrophoresis were used to characterize the fractions. SSQC4 was comprising of fucoidan, with an estimated MW distribution of 8-25 kDa. Exposure of UVB increased intracellular ROS, DNA damage, loss of mitochondrial membrane potential, apoptotic body formation causing cell death through the mitochondria-mediated apoptosis pathway. SSQC4 treatment could dose-dependently attenuate the ROS levels and suppress mitochondria-mediated apoptosis in UVB exposed keratinocytes. SSQC4 treatment enhanced cellular antioxidant defense by increasing Nrf2 mediated HO-1 generation, which was identified as the cause of observed bioactivities. The safety and stability of SSQC4 could be further evaluated to promote its use as a bioactive natural ingredient in UV-protective cosmetics.

The complete mitochondrial genome of Sargassum siliquastrum (Phaeophyceae) and its phylogenetic analysis

The complete S. siliquastrum mitogenome length was 34,765 bp. The mitogenome contains 67 genes, including 37 protein-coding, three rRNA, 25 tRNA genes, and two conserved open reading frames (ORFs). The overall GC content of the genome is 36.59%. The complete mitogenome sequence provided herein would help understand Sargassum evolution.

Chromene suppresses the activation of inflammatory mediators in lipopolysaccharide-stimulated RAW 264.7 cells

Inflammation is complex process involving a variety of immune cells that defend the body from harmful stimuli. However, pro-inflammatory cytokines and inflammatory mediators can also exacerbate diseases such as cancer. The aim of this study was to identify a natural effective remedy for inflammation. We isolated a functional algal chromene compound from Sargassum siliquastrum, named sargachromanol D (SD). We evaluated the anti-inflammatory effect of SD on lipopolysaccharide (LPS)-exposed RAW 264.7 cells by measuring cell viability, cytotoxicity, and production of inflammatory mediators such as nitric oxide (NO), prostaglandin E2 (PGE2), inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. SD inhibited production of NO and PGE2 from LPS-induced cells by preventing the expression of inflammatory mediators such as iNOS and COX-2 in a dose-dependent manner. Concurrently, levels of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 were reduced with increasing concentrations of SD. In addition, SD inhibited the activation of NF-κB and mitogen-activated protein kinases (MAPKs) pathways in a concentration-dependent manner. These results indicate that SD inhibits LPS-stimulated inflammation by inhibition of the NF-κB and MAPKs pathways in macrophages.

Preparative isolation of sargachromanol E from Sargassum siliquastrum by centrifugal partition chromatography and its anti-inflammatory activity

Centrifugal partition chromatography (CPC) can be used to isolate various bioactive compounds from natural materials by one-step. We confirmed antioxidative compounds existed in chloroform (CHCl3) fraction of Sargassum siliquastrum using online-HPLC. Fractions (A, B, C, D and E) were separated from the CHCl3 fraction by preparative CPC (n-hexane:ethyl acetate:methanol:water, 5:5:7:3, v/v). In this study, we proved that the isolated compounds exhibit anti-inflammatory activities using lipopolysaccharide (LPS) stimulated RAW 264.7 macrophages. The fraction A which exhibited the strongest inhibitory effect on nitric oxide (NO) production level, was confirmed as sargachromanol E by LC-MS-ESI, (1)H NMR and (13)C NMR data. The sargachromanol E significantly reduced the inflammatory response in LPS induced macrophages, decreasing LPS-induced transcription factor of pro-inflammatory cyclooxygenase-2, NO synthase, phosphate P38, phosphate ERK1/2, LPS-stimulated tumor-necrosis factor alpha, interleukin-1 beta and prostaglandin E2 release. In conclusion, it was suggested that sargachromanol E inhibited inflammation in LPS induced RAW 264.7 cells via MAPK pathway.