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

Isoflavaspidic acid PB (PB), a phloroglucinol derivative extracted from aerial parts of Dryopteris fragrans (L.) Schott, had antifungal activity against several dermatophytes. This study was aimed at exploring the antifungal mechanism of PB against Trichophyton rubrum (T. rubrum). The effectiveness of PB in inhibiting T. rubrum growth was detected by time-kill kinetics study and fungal biomass determination. Studies on the mechanism of action were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), sorbitol and ergosterol assay, nucleotide leakage measurement, and UPLC-based test and enzyme-linked immunosorbent assay. Fungicidal activity of PB was concentration- and time-dependent at 2 × MIC (MIC: 20 µg/mL) after 36 h. The total biomass of T. rubrum was reduced by 64.17%, 77.65%, and 84.71% in the presence of PB at 0.5 × MIC, 1 × MIC, and 2 × MIC, respectively. SEM analysis showed that PB changed mycelial morphology, such as shrinking, twisting, collapsing, and even flattening. TEM images of treated cells exhibited abnormal distributions of polysaccharide particles, plasmolysis, and cytoplasmic content degradation accompanied by plasmalemma disruption. There were no changes in the MIC of PB in the presence of sorbitol. However, the MIC values of PB were increased by 4-fold with exogenous ergosterol. At 4 h and 8 h, PB increased nucleotide leakage. Besides, ergosterol content in T. rubrum membrane treated with PB at 0.5 × MIC, 1 × MIC, and 2 × MIC was decreased by 9.58%, 15.31%, and 76.24%, respectively. There was a dose-dependent decrease in the squalene epoxidase (SE) activity. And the reduction in the sterol 14α-demethylase P450 (CYP51) activity was achieved after PB treatments at 1 × MIC and 2 × MIC. These results suggest that PB displays nonspecific action on the cell wall. The membrane damaging effects of PB were attributed to binding with ergosterol to increase membrane permeability and interfering ergosterol biosynthesis involved with the reduction of SE and CYP51 activities. Further study is needed to develop PB as a natural antifungal candidate for clinical use.

Anoectochilus roxburghii flavonoids extract ameliorated the memory decline and reduced neuron apoptosis via modulating SIRT1 signaling pathway in senescent mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Anoectochilus roxburghii (A. roxburghii) is a precious herb and folk medicine in many Asian countries. It has been used traditionally to treat diabetes, etc., and also used as a dietary therapy to delay senescence. AIM OF THE STUDY: This study was to evaluate the neuroprotective effects of A. roxburghii flavonoids extract (ARF) and whether its effects were due to the regulation of SIRT1 signaling pathway in senescent mice and in D-galactose (D-gal) induced aging in SH-SY5Y cells. MATERIALS AND METHODS: 18-month-old mice were randomly divided into senescent model, low-dose ARF, high-dose ARF and vitamin E group. 2-Month-old mice were as a control group. After 8 weeks treatment, Morris water maze (MWM) was performed. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), monoamine oxidase (MAO) and acetylcholinesterase (ACh-E) in the cortex were determined. Hippocampus morphologic changes were observed with haematoxylin and eosin (H&E), Nissl, senescence-associated-galactosidase (SA-ß-gal) and terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) staining. Apoptosis-related molecular expressions in the hippocampus were performed by western blotting. Furthermore, after stimulated by EX527 (a SIRT1 inhibitor), the SIRT1-dependent neuroprotective effects of ARF were determined by measuring SRIT1 and p53 expression in SH-SY5Y aging cells induced by D-gal. RESULTS: ARF could significantly ameliorate memory decline in senescent mice and reduce the generations of ROS, MDA and the activities of MAO and ACh-E, while increasing SOD activities in the cortex of aging mice. ARF obviously improved hippocampus pathological alterations, increased the number of Nissl bodies, while reducing senescent and apoptotic cells in senescent mice hippocampus. Further, ARF positively regulated SIRT1 expression, and reduced apoptosis-related molecules p53, p21 and Caspase-3 expression, while increasing the ratio of Bcl-2/Bax. In D-gal-induced SH-SY5Y cells, the effects of ARF on SIRT1 and p53, and the ability of scavenging ROS were mostly abolished after incubation with the EX527. CONCLUSIONS: ARF, in a SIRT1-dependent manner, exerted neuroprotection via modulating SIRT1/p53 signaling pathway against memory decline and apoptosis due to age-induced oxidative stress damage in senescent mice.