Flavidin

Antioxidant biomarkers from Vanda coerulea stems reduce irradiated HaCaT PGE-2 production as a result of COX-2 inhibition.[Pubmed:21060890]

PLoS One. 2010 Oct 28;5(10):e13713.

BACKGROUND: In our investigations towards the isolation of potentially biologically active constituents from Orchidaceae, we carried out phytochemical and biological analyses of Vanda species. A preliminary biological screening revealed that Vanda coerulea (Griff. ex. Lindl) crude hydro-alcoholic stem extract displayed the best DPPH /(*)OH radical scavenging activity and in vitro inhibition of type 2 prostaglandin (PGE-2) release from UV(B) (60 mJ/cm(2)) irradiated HaCaT keratinocytes. PRINCIPAL FINDINGS: Bio-guided fractionation and phytochemical analysis led to the isolation of five stilbenoids: imbricatin (1) methoxycoelonin (2) gigantol (3) Flavidin (4) and coelonin (5). Stilbenoids (1-3) were the most concentrated in crude hydro-alcoholic stem extract and were considered as Vanda coerulea stem biomarkers. Dihydro-phenanthropyran (1) and dihydro-phenanthrene (2) displayed the best DPPH/(*)OH radical scavenging activities as well as HaCaT intracellular antioxidant properties (using DCFH-DA probe: IC(50) 8.8 microM and 9.4 microM, respectively) compared to bibenzyle (3) (IC(50) 20.6 microM). In turn, the latter showed a constant inhibition of PGE-2 production, stronger than stilbenoids (1) and (2) (IC(50) 12.2 microM and 19.3 microM, respectively). Western blot analysis revealed that stilbenoids (1-3) inhibited COX-2 expression at 23 microM. Interestingly, stilbenoids (1) and (2) but not (3) were able to inhibit human recombinant COX-2 activity. CONCLUSIONS: Major antioxidant stilbenoids (1-3) from Vanda coerulea stems displayed an inhibition of UV(B)-induced COX-2 expression. Imbricatin (1) and methoxycoelonin (2) were also able to inhibit COX-2 activity in a concentration-dependent manner thereby reducing PGE-2 production from irradiated HaCaT cells. Our studies suggest that stilbenoids (1-3) could be potentially used for skin protection against the damage caused by UV(B) exposure.

Amine Landscaping to Maximize Protein-Dye Fluorescence and Ultrastable Protein-Ligand Interaction.[Pubmed:28757182]

Cell Chem Biol. 2017 Aug 17;24(8):1040-1047.e4.

Chemical modification of proteins provides great opportunities to control and visualize living systems. The most common way to modify proteins is reaction of their abundant amines with N-hydroxysuccinimide (NHS) esters. Here we explore the impact of amine number and positioning on protein-conjugate behavior using streptavidin-biotin, a central research tool. Dye-NHS modification of streptavidin severely damaged ligand binding, necessitating development of a new streptavidin-retaining ultrastable binding after labeling. Exploring the ideal level of dye modification, we engineered a panel bearing 1-6 amines per subunit: "amine landscaping." Surprisingly, brightness increased as amine number decreased, revealing extensive quenching following conventional labeling. We ultimately selected Flavidin (fluorophore-friendly streptavidin), combining ultrastable ligand binding with increased brightness after conjugation. Flavidin enhanced fluorescent imaging, allowing more sensitive and specific cell labeling in tissues. Flavidin should have wide application in molecular detection, providing a general insight into how to optimize simultaneously the behavior of the biomolecule and the chemical probe.

Antioxidant activities of flavidin in different in vitro model systems.[Pubmed:15351397]

Bioorg Med Chem. 2004 Oct 1;12(19):5141-6.

Flavidin was isolated from Orchidaceae species and purified by silica gel column chromatography. The structure was identified using physical and spectral ((1)H, (13)C NMR, and mass) data. Antioxidant potency of Flavidin was investigated employing various established in vitro model systems viz., beta-carotene-linoleate, 1,1-diphenyl-2-picryl hydrazyl (DPPH), phosphomolybdenum method, and scavenging of hydrogen peroxide methods. Flavidin showed very good antioxidant activity (90.2%) and almost equivalent to that of BHA at 50ppm level by beta-carotene-linoleate method. Radical scavenging activity of Flavidin was compared with BHA at 5, 10, 20, and 40ppm concentration and Flavidin showed more radical scavenging activity than BHA at all the tested concentrations. Furthermore, Flavidin showed very good antioxidant capacity by the formation of phosphomolybdenum complex method. Besides this, Flavidin showed effective hydrogen peroxide scavenging activity. The data obtained in the in vitro models clearly establish the antioxidant potency of Flavidin. However, comprehensive studies need to be conducted to ascertain the in vivo safety of Flavidin in experimental animal models. This is the first report on antioxidant activity of 9,10-dihydro-5H-phenanthro-(4,5 bcd)-pyrans/Flavidin type of compounds.