NAGPUR: An anti-cancer drug extracted from cow urine and developed by an affiliate of the RSS has got a US patent for the third time for its anti-genotoxicity properties, a senior official has said.The drug developed by RSS-backed Go Vigyan Anusandhan Kendra had earlier got the US patent as a bio-enhancer with antibiotics and anti-cancer drugs.The research for the drug brand named 'Kamdhenu Ark' was carried out jointly by the Anusandhan Kendra and National Environmental Engineer Research Institute (NEERI), Acting Director of NEERI Tapan Chakraborty said.The research found that Re-distilled Cow Urine Distillate (RCUD) was useful for protecting and repairing DNA from oxidative damage, Chakraborty and Sunil Mansinghka of Kendra told reporters yesterday.Oxidative DNA damage is a leading cause of ageing, cancer and other diseases.RCUD works against genotoxicity, a harmful action on a cell's genetic material, they said, adding research has strengthened the efficacy of 'Kamdhenu Ark' as an anti-cancer drug.The research was carried out on three patients, two of them having throat and uterus cancer, Mansinghka said.