Oct 16 (Reuters) - Ruby Tuesday Inc said on Monday it would be acquired by private equity firm NRD Capital for an enterprise value of about $335 million.

The cash offer of $2.40 per share represents a premium of about 21 percent over Friday's closing price.

The restaurant operator's shares were trading up 19 percent at $2.37 before the bell, still a far cry from the $33 high it hit in 2004.

Excluding debt, the equity value of the deal is about $145 million.

Ruby Tuesday, which has suffered losses and declining sales for the last five years as fewer diners visited its restaurants, said in March it was exploring strategic alternatives.

(Reporting by Sruthi Ramakrishnan in Bengaluru; Editing by Martina D'Couto)