Unsaturated long-chain N-acyl-vanillyl-amides (N-AVAMs): Vanilloid receptor ligands that inhibit anandamide-facilitated transport and bind to CB1 cannabinoid receptors

We investigated the effect of changing the length and degree of unsaturation of the fatty acyl chain of N-(3-methoxy-4-hydroxy)-benzyl-cis-9-octadecenoamide (olvanil), a ligand of vanilloid receptors, on its capability to: (i) inhibit anandamide-facilitated transport into cells and enzymatic hydrolysis, (ii) bind to CB1 and CB2 cannabinoid receptors, and (iii) activate the VR1 vanilloid receptor. Potent inhibition of [C-14]anandamide accumulation into cells was achieved with C20:4 n-6, C18:3 n-6 and n-3, and C18:2 n-6 N-acyl-vanillyl-amides (N-AVAMs). The saturated analogues and Delta(9)-trans-olvanil were inactive. Activity in CB1 binding assays increased when increasing the number of cis-double bonds in a n-6 fatty acyl chain and, in saturated N-AVAMs, was not greatly sensitive to decreasing the chain length, The C20:4 n-6 analogue (arvanil) was a potent inhibitor of anandamide accumulation (IC50 = 3.6 mu M) and was 4-fold more potent than anandamide on CB1 receptors (Ki = 0.25-0.52 mu M), whereas the C18:3 n-3 N-AVAM was more selective than arvanil for the uptake (IC50 = 8.0 mu M) vs CB1 receptors (Ki = 3.4 mu M). None of the compounds efficiently inhibited [C-14]anandamide hydrolysis or bound to CB2 receptors, All N-AVAMs activated the cation currents coupled to VR1 receptors overexpressed in Xenopus oocytes, In a simple, intact cell model of both vanilloid- and anandamide-like activity, i.e., the inhibition of human breast cancer cell (HBCC) proliferation, arvanil was shown to behave as a "hybrid" activator of cannabinoid and vanilloid receptors.