Russell Brand’s ex Katy Perry says she’s troubled by the “dark” side of show business and in news that may rock the world of pop and teen film franchises, she also says she has given up trying to save troubled celebrities.

Speaking about her friendship with Rihanna, the 29-year-old California girl told Elle magazine: “I love her and every time I see her I’m reminded of the light that she has. There’s a lot of dark in this business.

“I know a lot of people with the most detrimental entourages – they are the root of their demise. It’s really unfortunate but you can’t save these people. My days of celebrity saving are over.”

Perry has an on-off relationship with singer John Mayer and she says she was so embarrassed by rumours that she was dating Twilight star Robert Pattinson that she contacted his ex-girlfriend Kristen Stewart to explain the situation.

“I sent her a text message saying, ‘I know you’ve seen all this stuff but you know I would never disrespect you. I’m not that person. I’m just trying to be a friend to him’.”

Perry also told Elle that she’s attracted to “challenging” men but she says she doesn’t feel the need to get them to settle down: “I’m not interested in taming anyone, I’m pretty wild myself.”