How nettle (Urtica dioica) 'stings' Candida albicans by affecting its virulence factors

With increasing incidence of drug resistance and toxicity associated with current treatments, new alternatives are needed for Candida albicans infections. This study evaluated the potential of Urtica dioica aqueous extract and essential oil as natural phytotherapeutic agents against C. albicans, with a focus on important virulence factors that contribute to the development of infection and survival in the host. Our findings demonstrate that U. dioica essential oil effectively suppressed the growth of C. albicans and exhibited synergistic activity with amphotericin B, suggesting that it could reduce the effective dose of amphotericin B required, and possibly limit its undesirable side effects. Significant and notable inhibition of phenotypic switching was also observed, with the most pronounced effects seen when used in combination with amphotericin B. Since hyphae are critical for host invasion, this inhibition could impede the ability of C. albicans to cause disseminated infections. In addition, U. dioica essential oil also inhibited the biofilm-forming ability of C. albicans, a key factor contributing to the morbidity and mortality of hospitalized patients, due to biofilm-related resistance to antimicrobial therapy. Complete inhibition of phospholipase and hemolysin activity was also observed; as key extracellular enzymes, these contribute to the virulence of C. albicans and its persistence in the host. In conclusion, U. dioica essential oil targets multiple C. albicans virulence factors, potentially limiting infection in vivo. When used in combination with amphotericin B, it may boost antifungal efficiency, offering a promising new strategy against candidiasis.