Isoflavaspidic Acid PB Extracted from Dryopteris fragrans (L.) Schott Inhibits Trichophyton rubrum Growth via Membrane Permeability Alternation and Ergosterol Biosynthesis Disruption

Figure 4

Transmission electron micrographs of T. rubrum (CMCC(F)T1d) exposed to isoflavaspidic acid PB and terbinafine. (a) Cross-section of T. rubrum hyphae in the control group (drug free) indicated bilateral cell wall with intact edges, the outer cell wall (OCW) and the inner cell wall (ICW), uniform cytoplasm, nucleus (N), and clearly visible mitochondria (M); (b) cross-section of hyphae exposed to terbinafine (: 0.0625 μg/mL) showed disorganization and degradation of cytoplasmic content (1); (c) cross-section of hyphae exposed to isoflavaspidic acid PB (: 10 μg/mL) exhibited abnormal distributions of polysaccharides in the cytoplasm (2) and demolition of the endomembrane system (3); (d) cross-section of hyphae exposed to isoflavaspidic acid PB (: 20 μg/mL) displayed cell membrane damage and cytoplasm shrinkage away from the cell wall (4). The medullary bodies and protein coagulators (5) were conspicuous in the cytoplasm (manifestations of apoptosis); (e) cross-section of hyphae exposed to isoflavaspidic acid PB (: 40 μg/mL) had intact cell wall, uneven cytoplasmic density, blurred organelles, and excessive vacuolization (6). MIC: minimum inhibitory concentration. Bar represents 500 nm. Images were shown as 12000x magnification.

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