Pre-treatment of extracellular water soluble pigmented secondary metabolites of marine imperfect fungus protects HDF cells from UVB induced oxidative stress

• Published in: Photochemical & photobiological sciences 2018, Vol.17 (9), p.1229-1238
• Main Authors: Shanuja, S. K, Iswarya, S, Rajasekaran, S, Dinesh, M. G, Gnanamani, A
• Format: Article
• Language: English
• Subjects: Antioxidants; Biochemistry; Biocompatibility; Biomaterials; Carboxylic acids; Caspase; Caspase-3; Chemistry; Cyclooxygenase-2; Deoxyribonucleic acid; DNA; DNA damage; Fungi; G1 phase; Gene expression; Interleukin 6; Irradiation; Melanin; Metabolites; Mice; NF-κB protein; Oxidative stress; Physical Chemistry; Plant Sciences; Pretreatment; Reactive oxygen species; Secondary metabolites; Sectioning; Skin; Sun screens; Topical application; Tumor necrosis factor-α; Ultraviolet radiation; Water chemistry; Water treatment
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/c8pp00221e

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 melanin precursor of fungal origin was found to be an excellent UVB inhibiting agent as experimented in HDF cells and in small animals.