RIYADH: Oil prices edged down on Wednesday, pressured by global central bank efforts to tame inflation and ahead of expected builds in US crude inventories as product demand weakens. Brent crude prices for September fell 37 cents, or 0.3 percent, to $106.98 a barrel by 0340 GMT, while US West Texas Intermediate crude for August slipped 69 cents, or 0.7 percent, to $103.53 per