$re = '/\b[A-Z].*?(?= [a-z])/';
$str = 'wikiradio 27/09/2012 - LE QUATTRO GIORNATE DI NAPOLI raccontate da Ida Gribaudi
wikiradio 10/04/2013 - DAG HAMMARSKJOLD raccontato da Susanna Pesenti
wikiradio 11/02/2014 - L\'ABBE\' PIERRE raccontato da Giovanni Anversa
wikiradio 22/12/2015 - JEAN-MICHEL BASQUIAT raccontato da Costantino D\'Orazio';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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