Alpha-mannan

Alpha-mannan is a linear or branched polysaccharide polymer, composed mainly of α-1,6-linked mannose residues with side chains attached via α-1,2 or α-1,3 linkages, abundant in the outer layer of fungal cell walls[2][6][7]. In many pathogenic fungi, such as *Aspergillus fumigatus* and *Candida albicans*, alpha-mannan is covalently or non-covalently linked to core cell wall components like β-glucans and chitin, often decorating glycoproteins (mannoproteins) exposed on the fungal cell surface[2][6]. Alpha-mannan plays a key role in maintaining cell wall architecture, rigidity, and shape, and helps fungi evade immune detection by masking immunogenic β-glucan from host immune receptors[2]. Shedding of mannan polysaccharide during invasive disease supports its use as a diagnostic marker in blood and urine[7]. Enzymes essential to its biosynthesis, principally mannosyltransferases such as α-(1→6)-mannosyltransferase (AnpA) and α-(1→2)-mannosyltransferase (CmsA/Ktr4), are under investigation as potential antifungal drug targets, given both the necessity of α-mannan for fungal viability and its absence in mammalian cells[5][4]. Disruption of alpha-mannan synthesis impairs fungal growth, conidia formation, and virulence[5][4].

Other names

α-mannanalpha-1,6-mannanfungal mannancell wall mannan

Candidate drugs inhibit enzymes in α-mannan biosynthesis, such as α-(1→6)-mannosyltransferases (e.g., AnpA) and α-(1→2)-mannosyltransferases (e.g., CmsA/Ktr4), which impairs cell wall integrity, fungal growth, and virulence[4][5]. - Exposure or unmasking of β-glucan following alpha-mannan disruption can enhance host immune recognition and response[2].