The present study explores the UVB-induced oxidative stress protective efficacy of the pigmented fungal metabolite (identified as DHICA: 5,6-dihydroxyindole-2-carboxylic acid - a melanin precursor) using human dermal fibroblast (HDF) cells. DHICA is a water soluble pigment of the marine Aspergillus nidulans strain SG 28. Preliminary compatibility studies revealed 95% HDF cell viability with 600 μM concentration of DHICA. HDF cells were exposed to UVB irradiation with and without DHICA pre-treatment and the morphological, physiological and molecular level changes were observed accordingly. The results suggested that UVB exposure increases reactive oxygen species (ROS) generation and subsequent DNA damage in HDF cells, whereas DHICA pre-treatment appreciably reduces ROS generation and DNA damage. DHICA pre-treatment upregulates the antioxidant enzyme expressions and reduces the number of cells in the sub-Go/G1 phase. Gene expression analysis of TNF-α, IL-6, COX-2, NF-κB, Bax and Caspase 3 suggested that pre-treatment with DHICA downregulates the above-mentioned genes and simultaneously upregulates Bcl2 expression. In vivo experiments with BALB/c mice suggested that the topical application of DHICA protected mice skin from UVB-induced oxidative stress (which increases the epidermal thickness as evidenced in the skin sectioning). Thus, DHICA application protects the cells from UVB induced oxidative stress and may find applications in sunscreen cosmetic preparations.
The current study explores the photo‐protective effect of asperyellone (AY) (a fungal secondary metabolite), assessed under in vitro condition using human dermal fibroblast cell line. AY was isolated from Aspergillus sp. during the resting phase and purified. The initial cytocompatibility assessment on concentrations of AY and the duration of exposure of UVB irradiations were studied respectively. N‐acetyl‐L‐cysteine (NAC) was used as positive control. Cells were then pretreated with optimized concentration of AY (2.0 μM) and NAC (1 mM) for 1 hour and then UVB irradiated (30 mJ/cm
2) for the period of 10 minutes. Results revealed that reactive oxygen species generated upon UVB irradiation found scavenged by the AY pretreatment at a significant level. Furthermore, an appreciable reduction in apoptotic cell count and DNA damages support the scavenging effect of AY. Assessments on the expression of enzymatic and nonenzymatic antioxidants evidently prove the protective role of AY. The reduced expression levels of inflammatory markers (TNF‐α and COX‐2), collagen degraders (MMP 2 and MMP 9), apoptotic protein expressions (Bax and Bcl‐2), and cell‐cycle arrest analyses substantiate the photo‐protective effect of AY similar to NAC (positive control). Thus, the observations made in the current study indicate the possible role of AY as a photo‐protective agent.
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