The Bombay Stock Exchange Sensex declined by nearly 45 points in opening trade today as participants booked profits recorded during the previous two sessions amid a weakening Asian trend.The 30-share barometer, which gained over 475 points during the past two sessions, declined by nearly 45 points, to around 16,439 in the first five minutes of trade.The wide-based National stock Exchange Nifty followed suit, shedding about 11 points, to 4,925.50.