Characterization and immunomodulatory activities of polysaccharides from Spirogyra neglecta (Hassall) Kützing

Abstract

Sulfated polysaccharides (SP) isolated from freshwater green algae, Spirogyra neglecta (Hassall) Kützing, and fractionated SPs were examined to investigate their molecular characteristics and immunomodulatory activity. The crude and fractionated SPs (F1, F2, and F3) consisted mostly of carbohydrates (68.5–85.3%), uronic acids (3.2–4.9%), and sulfates (2.2–12.2%) with various amounts of proteins (2.6–17.1%). d-galactose (23.5–27.3%), d-glucose (11.5–24.8%), l-fucose (19.0–26.7%), and l-rhamnose (16.4–18.3%) were the major monosaccharide units of these SPs with different levels of l-arabinose (3.0–9.4%), d-xylose (4.6–9.8%), and d-mannose (0.4–2.3%). The SPs contained two sub-fractions with molecular weights (Mw) ranging from 164 × 103 to 1460 × 103 g/mol. The crude and fractionated SPs strongly stimulated murine macrophages, producing considerable amounts of nitric oxide and various cytokines via up-regulation of their mRNA expression by activation of nuclear factor-kappa B and mitogen-activated protein kinases pathways. The main backbone of the most immunoenhancing SP was (1→3)-l-Fucopyranoside, (1→4,6)-d-Glucopyranoside, and (1→4)-d-Galactopyranoside.

Spirogyra neglecta inhibits the absorption and synthesis of cholesterol in vitro

“…Besides polyphenolic compounds, SN was also known to possess polysaccharides 26 . Taken altogether, we postulated that the activities exhibited by SN extract could be possibly linked to the presence of polyphenols and polysaccharides.…”

Antioxidant and immunomodulatory activities of sulphated polysaccharides from purple glutinous rice bran (Oryza sativa L.)

“…The range of 0.46–0.78 of DS had the greatest ability to stimulate macrophages (Sun et al ., ; Bao et al ., ). Moreover, macrophage cell NO production is affected by various factors such as molecular weight, chemical composition and polysaccharide structure (Schepetkin et al ., ; Surayot et al ., ). Regarding the size of polysaccharide, low molecular weight polysaccharides strongly induced immunomodulatory activity.…”

“…Nitric oxide (NO) production in the macrophage culture supernatant was determined following the method of Surayot et al . (). A polysaccharide solution (100 μL) at a concentration of 12.5–50 μg mL −1 or 100 μL of a lipopolysaccharide solution (LPS, 10 μg mL −1 , positive control) was added to the cultured cells (RAW 264.7 cells; 1 × 10 6 cells mL −1 ), and the cells were kept at 37 °C for 24 h. The absorbance was measured at 540 nm using an EL‐800 microplate reader (BioTek Instruments, Winooski, VT, USA).…”

“…The reverse transcription polymerase chain reaction (RT‐PCR) was carried out using the method of Surayot et al . (). Total RNA of RAW 264.7 cells (1 × 10 6 cells well −1 ) treated with LPS and polysaccharide solution was extracted using the TRIzol reagent (Invitrogen, Carlsbad, CA, USA) following the manufacturer's protocol.…”

“…The weight‐average molecular weight (Mw) and radius of gyration (Rg) were assessed using the method of Surayot et al . () with modifications. The polysaccharides (3 mg) were dissolved in distilled water (1 mL).…”