You can simply use a DateTime object:
<?php
$fulldate = 'Tue Feb 04 2014 09:30:00 GMT-0800 (Pacific Standard Time)';
//remove everything between the brackets
$dateString = preg_replace("/\([^)]+\)/","",$fulldate);
//now, get your date object
$date = new DateTime($dateString);
echo $date->format('Y-m-d H:i:s');
?>
Try the Fiddle here: http://ideone.com/odwtUH