Candida species are the most common cause of fungal infections that range from
non-life-threatening mucocutaneous illness to life-threatening invasive processes that may
involve virtually any organ. Such a broad range of infections requires an equally broad range
of therapeutic approach. Persian shallot (Allium stipitatum Regel.) is a medicinal plant that
has been widely used in tradition Persian medicine for various ailments. Allium stipitatum is
also used in modern medicine and has been reported to have a range of health benefits
including antibiotic (antifungal) properties. The present study assessed the in vitro
anticandidal and antibiofilm potential of hexane (ASHE) and dichloromethane (ASDE) extracts
of Allium stipitatum (Persian shallot) against planktonic and biofilm forms of 5 medically
important Candida spp. Antifungal activity was assessed by disk diffusion, minimum inhibitory
concentration (MIC), minimum fungicidal concentration (MFC) and time-kill assay. The
antibiofilm activity of ASHE and ASDE against reference strain C. albicans ATCC 14053 was
determined by XTT [2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide]
reduction assay. The zone of inhibition ranged from 22 to 40 mm, while the MICs ranged from
8 to 32 µg mL-1. The MFCs of ASHE and ASDE were in the range of 16 to 32 µg mL-1 each
respectively. Time-kill kinetics showed that both extracts were strongly fungicidal against
planktonic cultures of C. albicans with ~ 1.45 log reduction in CFU at 4 h post-treatment
(hpt). In addition, both ASHE and ASDE were shown to inhibit preformed C. albicans biofilms
in a concentration-dependent manner. The results demonstrated that ASHE and ASDE were
broad-spectrum in action, and could be developed as a promising alternative to synthetic
antifungals in controlling infections due to Candida spp. of clinical significance.