Antifungal mechanism against Candida albicans and antitumor activity of phenazines produced by Pseudomonas sp. strain DH.

UNLABELLED: Candida albicans, a commensal yeast, causes severe infections especially in immunocompromised patients, and microbial secondary metabolites offer sustainable sources for novel antifungal development. This study investigated the antifungal activity against C. albicans CMCC98001 and antitumor potential of phenazines from Pseudomonas sp. strain DH. At 20 µg/mL, 1-hydroxyphenazine (2) and phenazine-1-carboxamide (3) inhibited Aurora-A kinase (a key mitotic regulator). Conversely, they showed no inhibitory effect on JAK2, a distinct tyrosine kinase involved in cytokine signaling. This selectivity suggests that the anti-proliferative effects of these compounds are likely mediated through the induction of mitotic disruption rather than through broad off-target kinase inhibition, highlighting their potential as specific leads for anti-cancer therapy. Phenazine-1-carboxylic acid (1) displayed potent antifungal activity, showing a zone of inhibition of 25.33 ± 0.38 mm at 25 µg/mL, with an MIC of 4 µg/mL and an MFC of 8 µg/mL. It reduced dehydrogenase activity (72.05–69.51%), increased leakage of water-soluble proteins (11.18–14.18%), DNA (6.18–7.51%), and rapid K⁺efflux (5.51% within 30 min). TEM revealed severe cellular damage at 6.25 µg/mL, including membrane disruption, thinned cell walls, cytoplasmic dispersion, and cavitation. Metabolomics identified 43 differential metabolites (e.g., ergosterol) and 8 perturbed pathways (notably terpenoid backbone and steroid biosynthesis) relative to the untreated control, suggesting that treatment disrupts fungal cell membrane integrity while simultaneously impairing energy metabolism (glycolysis/gluconeogenesis, pyruvate, and methane metabolism) and nucleotide biosynthesis, including a significant reduction in ergosterol, which correlates with the observed disruption of the terpenoid backbone and steroid biosynthesis pathways. RT-PCR confirmed downregulation of ERG24 (sterol synthesis), APM1, CHS8 (cell wall), and YPT72 (vesicular transport). These findings elucidate phenazine-1-carboxylic acid’s multifaceted antifungal mechanism—disrupting membrane integrity, inducing component leakage, perturbing metabolic pathways, and downregulating key genes—and support its potential as a sustainable antifungal agent.

SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10123-026-00830-3.