A preclinical study in diabetic rats has shown that a water-soluble curcumin derivative (NCD) alone or in combination with sildenafil citrate can significantly increase intracavernosal pressure (ICP) and positively affect other markers of erectile dysfunction. After treatment with NCD, curcumin or NCD plus curcumin, the rats had improved erectile function, as demonstrated by increased ICP and cGMP, nitric oxide synthase and haeme oxygenase-1 activity compared with no treatment. The combination intervention showed a particularly prolonged effect.