Why after changing ideal OPAMP to a real one, there appeared bounding in negative part of the sine wave(Proteus)?
With a 741 on +15 V and -15 V power rails, the output might be able to give you a voltage of +/-13 volts. That's a broad-brushed typical value. The guaranteed value is +/-12 volts.

You could try coupling the output from the 555 via a 10 uF capacitor if you don't need the DC level to be fed through the filter.