Abstract :Reversible transition from yeast to hypha in Candida albicans represents a good model system for
studying cell differentiation. In this study, we have studied the effect of human muscarinic receptor
antagonists, dicyclomine, solifenacin and flavoxate on C. albicans morphogenesis induced by
muscarinic receptor agonists, acetylcholine and bethanechol. We show that muscarinic receptors
antagonists inhibited yeast to hyphal form transition in a concentration dependent manner.
Dicyclomine inhibited yeast to hyphal form transition induced by bethanechol and acetylcholine
more than solifenacin and flavoxate. We are reporting that solifenacin and flavoxate have good
binding with C. albicans Rrp9. Solifenacin and flavoxate formed hydrogen bond interactions with
the residues GLU509 and ILE510 respectively in the active site region of Rrp9. Acetylcholine and
bethanechol also bound with Rrp9 by forming hydrogen bond interactions. Acetylcholine formed
hydrogen bond interaction with SER314 and SER323 while bethanechol formed hydrogen bond
interaction with ASP384 and ASP506 at the active site of Rrp9. C. albicans Rrp9 may have a role in
yeast to hyphal form morphogenesis and that muscarinic acetylcholine receptor antagonists may be
repositioned as anti-virulence agents in C. albicans.