Ethanol extract of propolis (EEP) inhibits nitric oxide synthase gene expression and enzyme activity
I long hoped there would be anything else but MBlue + Red Light to inhibit NO. And voilà: it's the caffeic acid phenethyl ester (CAPE), which is "identified as a major peak in the chromatogram of EEP".
From the abstract:
"EEP inhibited the iNOS promoter activity induced by LPS plus IFN-g through the NF-kB sites of the iNOS promoter. In addition, EEP directly interfered with the catalytic activity of murine recombinant iNOS enzyme. These results suggest that EEP may exert its anti-inflammatory effect by inhibiting the iNOS gene expression via action on the NF-kB sites in the iNOS promoter AND by directly inhibiting the catalytic activity of iNOS."
[emphasis mine.]
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Preparation of extract from the paper:Coarsely powdered propolis (100 g) was extracted with 10 volumes of 95% ethanol for 2 weeks. The ethanol extract was filtered, evaporated, and lyophilized to give the dry ethanol extract (33.3 g).
In Anti-inflammatory Effect of Propolis through Inhibition of Nitric Oxide Production on Carrageenin-Induced Mouse Paw Edema, even smaller amounts of extract were successfully used:
Because lyophilized ethanol extract of propolis used in the present study is equivalent to 18.5 mg propolis per 100 ml, 16) 1: 1000 and 1: 100 dilutions of propolis correspond to 1.85 and 18.5 mg/kg, respectively. Therefore, the propolis used in the present study was 5.4—54 times more potent than that reported by Borrelli et al. ... though there was a difference between mouse and rat.