An anti-neoplastic glycan isolated from Mycobacterium bovis (BCG vaccine)

Abstract

Tice substrain BCG is used clinically as an immunotherapeutic agent against superficial bladder cancer. A boiling-water extract of this BCG showed anti-tumour activity against a murine S180 sarcoma model and was fractionated into three fractions, A, B and C, by the use of Sephadex LH-20 chromatography. An anti-tumour glucan, PS1A1, was isolated from fraction PS1A with Sephadex G-75. The molecular mass of PS1A1 was between 65 and 87 kDa by Sephadex G-100 chromatography. The structure of PSIA1 was investigated by one- and two-dimensional NMR spectroscopy and methylation analysis and was demonstrated to be primarily 1 → 6-α-linked glucose units. We postulate that the repeating unit is: →6)-α-D-Glcp(1→6)-α-D-Glcp(1→4)-α-D-Glcp(1→6)-α-D-Glcp(1→6)-α-D-Glcp (1→ 6 ↑ 1 α-d-Glcp