Purification, characterization and promoting effect on wound healing of an exopolysaccharide from Lachnum YM405

• A novel extracellular polysaccharide from Lachnum YM405 was isolated and purified.
• A failed experiment proved that the mannofuranosyl residues contained methoxy group.
• LEP-2b's backbone was composed of 1,4-β-Manp, 1,2-α-Rhap, 1,6-β-Glcp and 1,6-α-Galp.
• LEP-2b's branches consisted of 2,6-α/β-1-OMe-Manf, 1,6-α/β-Galp, and 1-β-Glcp.
• LEP-2b played a positive role in promoting wound healing.

An exopolysaccharide (LEP-2b) with molecular weight of 2.8 × 104 Da was isolated from Lachnum YM405 and purified by DEAE-cellulose 52, Sepharose CL-6B chromatographic column. It consisted of rhamnose (Rha), mannose (Man), glucose (Glc) and galactose (Gal) in a molar ratio of 1.0:5.0:11.5:12.5. Its backbone consisted of → 4)-β-d-Manp-(1 →, → 2)-α-d-Rhap-(1 →, → 6)-β-d-Glcp-(1 →, and → 6)-α-d-Galp-(1 →, and three types of branches were composed of → 6)-α-d-1-OMe-Manf-(2 →, → 6)-β-d-1-OMe-Manf-(2 →, → 1)-α-d-Galp-(6 →, → 1)-β-d-Galp-(6 →, and → 1)-β-d-Glcp, which were at O-3 of 1,3,6-linked α-d-Manp and O-2, O-3 of the same 1,2,3,6-linked β-d-Glcp in the backbone respectively. LEP-2b ointment significantly accelerated the decrustation of the wounded skin, shortened the healing time and increased the water and hydroxyproline contents of the healed skin. Combined with the results of macroscopic and histological observations, we deemed that LEP-2b could inhibit inflammatory reaction of scalded skin, accelerate tissue repair and re-epithelialization, thereby playing a positive role in promoting wound healing.