Morus alba L. (mulberry) is one of the most important medicine and food crops in China and other developing countries in Asia due to its large biomass (twigs) and useful by-products. Additionally, its twigs are an excellent green resource for bioactive compounds that are resistant to ultraviolet (UV) radiation and that can whiten skin and scavenge free radicals, and are of potential interest to the cosmetics and health food industries. In this study, we evaluated the ability of Morus alba L. twig hydroethanol extract and isolated compounds to protect DNA against UV damage. Agarose gel electrophoresis showed that a hydroethanol extract and six different polyphenol monomers (oxyresveratrol, resveratrol, mulberroside A, rutin, quercetin, and morin) present in the extract protected pUC19 plasmid DNA from UV damage. The optimal concentrations of polyphenols and Morus alba L. twig extract for DNA protection were 0.500 mg/mL and 1.00 mg/mL, respectively. These compounds may have potential as skin-care products to prevent UV-induced damage to the skin. Additionally, activity contribution degree assessment revealed other Morus alba L. substances possessing significant DNA protection activity that are worthy of further investigation. [ABSTRACT FROM AUTHOR]