Potencial antifúngico de Mitracarpus frigidus frente a isolados clínicos de Candida albicans: investigação do mecanismo de ação e desenvolvimento de sistemas poliméricos para o tratamento da candidíase mucosal

Abstract

Candidiasis represents a significant public health concern due to its high prevalence, clinical recurrence, and increasing tolerance to conventional antifungal agents. In this context, the prospecting of bioactive natural products and the development of technological formulations constitute promising therapeutic strategies. Therefore, this thesis aimed to investigate the antifungal potential of the methanolic extract of Mitracarpus frigidus (MFM) against clinical isolates and reference strains of Candida albicans, elucidate its possible antifungal mechanisms of action, and develop chitosanbased mucoadhesive polymeric systems for the treatment of vulvovaginal and oral candidiasis. Initially, the antifungal activity of MFM was evaluated against 52 C. albicans strains, including isolates obtained from vulvovaginal candidiasis, oral candidiasis, COVID-19-associated coinfections, and ATCC strains. The extract exhibited antifungal activity against all clinical profiles evaluated, demonstrating broadspectrum antifungal applicability (MIC = 62.5–100 µg/mL). Subsequently, studies were conducted to investigate its mechanism of action. The results indicated that MFM acts through a multifactorial mechanism, promoting cellular disorganization and impairing important virulence factors of C. albicans. Ultrastructural analyses by electron microscopy revealed alterations consistent with cell wall and membrane damage, cytoplasmic disorganization, vacuolization, and mitochondrial impairment. Phytochemical characterization by LC–MS/MS revealed a profile predominantly composed of glycosylated flavonoids and phenolic acid derivatives, with quercetin-3- O-galactoside, peltatoside, rutin, kaempferol, kaempferol-3-O-glycoside, quercetin, and chlorogenic acid identified as major compounds. Based on the observed biological potential, chitosan-based mucoadhesive films containing MFM were developed for vaginal and oral applications. The systems were characterized regarding their physicochemical, morphological, thermal, and mechanical properties using FTIR, TGA, DSC, SEM, thickness, mechanical strength, swelling degree, mucoadhesion, surface pH, and in vitro release profile analyses, demonstrating adequate uniformity, physicochemical stability, swelling capacity, and sustained extract release. Additionally, the systems showed in vitro biocompatibility, maintaining cell viability above 70%. Finally, the therapeutic efficacy of the vaginal films was evaluated in an in vivo experimental model of vulvovaginal candidiasis, in which MFM-loaded systems reduced the vaginal fungal burden by 70.1% (QMFM 1%) and 100% (QMFM 2.5%), in addition to improving inflammatory parameters. Collectively, the results demonstrate that the methanolic extract of Mitracarpus frigidus exhibits significant antifungal and antibiofilm activity against C. albicans, while the developed polymeric systems represent promising platforms for the treatment of mucosal candidiasis. This research is aligned with Sustainable Development Goal 3 (Good Health and Well-Being) of the United Nations 2030 Agenda.