Anti-diabetic activity of a sulfated galactoarabinan with unique structural characteristics from Cladophora oligoclada (Chlorophyta)

Abstract

The polysaccharide from green alga Cladophora oligoclada, OHSS2, was a sulfated galactoarabinan which was constituted by a backbone of (1 → 4)-β-l-arabinopyranose units with partial sulfate at C-3 of (1 → 4)-β-l-arabinopyranose units. The side chains containing (1 → 4)-β-l-arabinopyranose, (1 → 4)-β-d-galactopyranose and/or (1 → 4,6)-β-d-galactopyranose units were in C-2/C-3 of (1 → 4)-β-l-arabinopyranose units. OHSS2 had strong anti-diabetic activity in vitro assessed by inhibition of human islet amyloid polypeptide (hIAPP) aggregation. The mechanism analysis of anti-diabetic activity showed that OHSS2 diminished the production of intracellular reactive oxygen species and alleviated hIAPP aggregation-induced oxidative stress in NIT-1 cells. OHSS2 stabilized mitochondrial membrane potential, and enhanced the mitochondrial complex I, II or III activity and ATP level. Thus, OHSS2 effectively protected mitochondria from hIAPP aggregation-induced damage. Furthermore, OHSS2 was co-localized with mitochondria and could have a direct influence on mitochondrial function. These results revealed that OHSS2 had potential as a novel anti-diabetic agent.

Keywords: 1,1,1,3,3,3-Hexafluoro-2-propanol (PubChem CID: 13529); 2′,7′-Dichlorofluorescin diacetate (PubChem CID: 77718); 3′-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (PubChem CID: 22288011); Acetic acid (PubChem CID: 176); Adenosine triphosphate (PubChem CID:5957); Anti-diabetic activity; Cladophora oligoclada; Ethanol (PubChem CID: 702); Hexamethylene diamine (PubChem CID: 16402); Structural characterization; Sulfated polysaccharide; Thioflavine T (PubChem CID: 16953); Uranyl acetate (PubChem CID: 10915); hIAPP; l-Arabinose (PubChem CID: 439195).