Involved in the detoxification of reactive carbonyls (PubMed:10848984, PubMed:12514241, PubMed:16299173). Acts on lipid peroxide-derived reactive aldehydes (PubMed:12514241). Specific to a double bond activated by an adjacent carbonyl group (PubMed:12514241). Can use both quinones and diamide as substrates, but not menadione, ferricyanide or phylloquinone (PubMed:10848984). Can use 4-hydroxy-(2E)-nonenal (HNE), 4-hydroxy-(2E)-hexenal (HHE), (2E)-nonenal, (2E)-hexenal, (2E)-pentenal, propenal (acrolein), 3-buten-2-one and 3-penten-2-one, but not (R)-(-)-carvone, n-nonanal, n-hexanal, (3Z)-hexanal, cyclohex-2-en-1-one or 12-oxo phytodienoic acid (OPDA) as electron acceptors (PubMed:12514241). Catalyzes the reduction of the alpha,beta-unsaturated bond of 2-alkenals, of lipid peroxide-derived oxenes 9-oxo-10(E),12(Z)-octadecadienoic acid (9-KODE) and 13-oxo-9(Z),11(E)-octadecadienoic acid (13-KODE), as well as 4-oxo-(2E)-nonenal and 4-hydroxynonenal (PubMed:16299173). Can use 12-oxo-10(E) dodecanoate (traumatin), trans-1,3 diphenyl-2-propenone, trans-1,4-diphenyl-2-butene-1,4-dione, 9-oxo-12,13-epoxy-(10E)-octadecenoic acid (trans-EKODE-1b) and 9,13-dihydroxy-10-oxo-11-octadecenoic acid as substrates (PubMed:26678323). Catalyzes the reduction of the 7-8 double bond of phenylpropanal substrates, such as p-coumaryl aldehyde and coniferyl aldehyde (in vitro) (PubMed:17028190). Has activity towards toxic substrates, such as 4-hydroxy-(2E)-nonenal (in vitro) (PubMed:17028190). May play a distinct role in plant antioxidant defense and is possibly involved in NAD(P)/NAD(P)H homeostasis (PubMed:17028190). an n-alkanal + NAD(+) = an alk-2-enal + H(+) + NADH an n-alkanal + NADP(+) = an alk-2-enal + H(+) + NADPH Inhibited by N-ethylmaleimide and p-chloromercuribenzoic acid. kcat is 3.8 sec(-1) for trans-1,3 diphenyl-2-propenone. kcat is 4.9 sec(-1) for trans-1,4-diphenyl-2-butene-1,4-dione. kcat is 10 sec(-1) for traumatin (PubMed:26678323). kcat is 98 sec(-1) for 9,10-phenanthrenequinone. kcat is 1.9 sec(-1) for 5-Hydroxy-1,4-naphtoquinone. kcat is 12 sec(-1) for 1,4-Benzoquinone. kcat is 0.10 sec(-1) for decyl-plastoquinone. kcat is 0.03 sec(-1) for ferricytochrome c. kcat is 95 sec(-1) for azodicarboxylic acid bis[dimethylamide]. kcat is 42 sec(-1) for 1,10-(azocarbonyl)-dipeperidine. kcat is 31 sec(-1) for azocarbonamide (PubMed:10848984). kcat is 88 sec(-1) for 4-hydroxy-(2E)-nonenal. kcat is 42 sec(-1) for 4-hydroxy-(2E)-hexenal. kcat is 51 sec(-1) for (2E)-nonenal. kcat is 63 sec(-1) for (2E)-hexenal. kcat is 35 sec(-1) for (2E)-pentenal. kcat is 40 sec(-1) for propenal. kcat is 83 sec(-1) for 3-buten-2-one. kcat is 103 sec(-1) for 3-penten-2-one (PubMed:12514241). kcat is 33.9 sec(-1) for (2E),(6Z)-nonadienal. kcat is 20.1 sec(-1) for 4-oxo-(2E)-nonenal. kcat is 0.94 sec(-1) for 9-oxo-10(E),12(Z)-octadecadienoic acid. kcat is 1.10 sec(-1) for 13-oxo-9(Z),11(E)-octadecadienoic acid. kcat is 18.9 sec(-1) for 3-nonen-2-one (PubMed:16299173). Optimum pH is 8.0 for 9,10-phenanthrenequinone-reduction. Optimum pH is 6.5-7.0 for azodicarboxylic acid bis[dimethylamide]-reduction (PubMed:10848984). Optimum pH is 6.0 with (2E)-hexenal or 4-hydroxy-(2E)-nonenal as substrate (PubMed:12514241). Homodimer. Expressed in leaves. Up-regulated upon treatment with paraquat, t-butylhydroperoxide, diamide, and menadione. Belongs to the NADP-dependent oxidoreductase L4BD family.