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


RESULTS
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 µM and 9.4 µM, respectively) compared to bibenzyle (3) (IC(50) 20.6 µM). In turn, the latter showed a constant inhibition of PGE-2 production, stronger than stilbenoids (1) and (2) (IC(50) 12.2 µM and 19.3 µM, respectively). Western blot analysis revealed that stilbenoids (1-3) inhibited COX-2 expression at 23 µM. 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.
Faculty of Pharmacy, University of Strasbourg, Illkirch, France. charlotte.simmler@pharma.u-strasbg.fr
Charlotte
C
Simmler
Cyril
C
Antheaume
Annelise
A
Lobstein
D000975:Antioxidants / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D009682:Magnetic Resonance Spectroscopy; D029595:Orchidaceae / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet
D000975:Antioxidants; D015415:Biomarkers; D052246:Cyclooxygenase 2 Inhibitors; D017382:Reactive Oxygen Species; D015232:Dinoprostone