Extraction, purification and antioxidant activity of polysaccharides from different parts of Hibiscus manihot L.

The goal of this study was to elucidate the characteristics and properties of polysaccharides from different parts of cultivated Hibiscus manihot L. (HM). Polysaccharides were extracted with hot-water from the flowers, leaves, roots, stems and epidermis of HM. Two purified fractions having high content, HMPS-F2 and HMPS-F4, were isolated from floral polysaccharides. The results showed that HMPS-F2 was a homopolysaccharide composed of glucose residues with an average molecular weight of 8.59 × 104 Da, which might have a backbone structure of →1)-α-d-Glcp (4→. HMPS-F4 was a natural acetylated heteropolysaccharide with a complex structure and an average molecular weight of 1.63 × 105 Da. It was mainly composed of Rha(rhamnose), GalA(galacturonic acid), and Gal(galactose) with a molar ratio of 3.06:1.00:1.62. The results of antioxidant experiments showed that HM polysaccharides (0.125–4.0 mg/L) had certain inhibitory effects on DPPH radicals, hydroxyl radicals and lipid peroxidation, among which the scavenging effect on hydroxyl radicals was the best. These results suggest that HM polysaccharide is a potent active ingredient that may play an active role in the medicinal activity of HM.