$re = '/(?\'foo\'\w*)@(?\'Todos_Atrib_Val\'(?\'Atrib_Val\'\w*\|\w*#{0,1})(?\'Atrib_Val_Recursivo\'\g\'Atrib_Val\')*)/';
$str = 'foo01@chave1|valor1#chave2|valor2#chave3|valor3#chaveN|valorN';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php