Intracellular production of reactive oxygen species and a DAF-FM-related compound in Aspergillus fumigatus in response to antifungal agent exposure

Abstract

Fungi are ubiquitously present in our living environment and are responsible for crop and infectious diseases. Developing new antifungal agents is constantly needed for their effective control. Here, we investigated fungal cellular responses to an array of antifungal compounds, including plant- and bacteria-derived antifungal compounds. The pathogenic fungus Aspergillus fumigatus generated reactive oxygen species in its hyphae after exposure to the antifungal compounds thymol, farnesol, citral, nerol, salicylic acid, phenazine-1-carbonic acid, and pyocyanin, as well as under oxidative and high-temperature stress conditions. The production of nitric oxide (NO) was determined using diaminofluorescein-FM diacetate (DAF-FM DA) and occurred in response to antifungal compounds and stress conditions. The application of reactive oxygen species or NO scavengers partly suppressed the inhibitory effects of farnesol on germination. However, NO production was not detected in the hyphae using the Greiss method. An LC/MS analysis also failed to detect DAF-FM-T, a theoretical product derived from DAF-FM DA and NO, in the hyphae after antifungal treatments. Thus, the cellular state after exposure to antifungal agents may be more complex than previously believed, and the role of NO in fungal cells needs to be investigated further.

Insight into novel anti-mucormycosis therapies: investigation of new anti-mucormycosis laser-induced photodynamic therapy based on a sulphone bis-compound loaded silica nanoemulsion

“…In accordance with our results, an anti-mucormycosis compound, SBDMP-loaded silica nanoemulsion, increases the induction of the ROS level, which suggests that oxidative stress intracellularly causes growth inhibition. 54 Observably, one of the compounds tested, SBDMP, triggered ROS production in the hyphae of the Mucorales strains under laser light exposure. To our knowledge, this is the first study of the significant anti-mucormycosis activity of SBDMP-loaded silica nanoemulsion under PDA.…”

AfuPmV-1-Infected Aspergillus fumigatus Is More Susceptible to Stress Than Virus-Free Fungus

“…Fungal response to high temperatures, as well as to other environmental stresses, also is regulated through the high-osmolarity glycerol mitogen-activated protein kinase (HOG-MAPK) pathway [21]. It is known that A. fumigatus, in response to oxidative and high-temperature stress, exposure to antifungal compounds like thymol, farnesol, citral, nerol, and salicylic acid, and exposure to bacterial compounds like phenazine-1-carbonic acid, and pyocyanin, generates reactive oxygen and nitric oxygen species [22]. A study in Cryphonectria parasitica, a phytopathogenic fungus that causes chestnut blight, showed that infection with the mycovirus Cryphonectria hypovirus 1 (CHV1) induces oxidative stress [23].…”

Nitric Oxide in Fungi: Production and Function

“…Effects of antifungal agent (farnesol) on germination [100] Ganoderma lucidum Heat-stress-induced ganoderic acid levels [101] Lentinula edodes and Grifola frondosa…”

“…After stimulation with 420 nm intense pulsed light (IPL), the levels of nitric oxide synthase (NOS) and NO increase, while there are decreases in the intracellular levels of asymmetric dimethylarginine (ADMA), a natural compound structurally similar to L-arginine that acts as an inhibitor of NOS, along with keratinase activity, and fungal growth in T. rubrum [43]. Upon exposure to antifungal agents, A. fumigatus responds by increasing NO production in the exposed hyphae [100]. Interestingly, the arbuscular mycorrhizal fungus R. irregularis can enhance rice NR and NOS activity, increase intracellular NO accumulation in symbionts, and improve the tolerance of rice plants to low-temperature stress by regulating proline metabolism [47].…”