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 hydroalcoholicstem extract and were considered as Vanda coerulea stem biomarkers. Dihydro-phenanthropyran (1) and dihydrophenanthrene (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) (IC50 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. © 2010 Simmler et al.
Simmler, C., Antheaume, C., & Lobstein, A. (2010). Antioxidant biomarkers from vanda coerulea stems reduce irradiated HaCaT PGE-2 production as a result of COX-2 inhibition. PLoS ONE, 5(10). https://doi.org/10.1371/journal.pone.0013713