Sorry, the last substance is called apocynin, but the last letters were eliminated because they exceeded capacity in the title.
NADPH oxidase is the enzyme that the immune system uses to generate super oxide (O2-), which reacts with NO to make ONOO-, a powerful oxidant used to eliminate bacteria, etc, O2- is also transformed into hydrogen peroxide, which also kills bacteria. This is called the respiratopry burst.
Unfortunately, in some conditions (homocysteinemia, MS, etc) NADPH oxidase may be active without an infection and ONOO- inhibits many essential enzymes like MnSOD, CuZnSOD & PrP (which neutralize O2-), catalase (which neutralizes hydrogen peroxide) and the enzymes that produce uric acid, netralize toxic aldehydes, sulfites, nitrites and that synthesize glutamine (so there is low glutathione, a powerful antioxidant, low GABA, a mood stabilizer, low adiponectin, an antiinflammatory hormone, etc,).
Fortunately, NADPH oxidase can be inhibited by apocynin, a small molecule very similar to vanillone (the flavoring agent in vanilla) and which is produced by Picrorhiza kurroa a plant from the Himalayas. An extract of this plant is commercialized as picroliv in the US and is used for liver disease and other conditions with severe oxidative damage.
Apocyanin to inhibit NADPH oxidase and EPA (an omega 3 oil) to increase adiponectin, which blocks MCP-1 a substance that rallies white cells, causing inflammation, may help considerably in MS.