Peroxynitrite　is　known　as　a　strong　deleterious　species　that　may　readily　trigger　several　geriatric　diseases　via　injuring　cellular　constituents.　Proanthocyanidins,　a　biological　flavonoids　constituent　of　Pinus　sylvestris　L.　bark,　has　been　attributed　a　large　variety　of　phaimacological　functions　to　its　antioxidant　potential.　The　results　revealed　that　peroxynitrite　could　cause　the　generation　of　hydroxyl　radical,　the　breakage　of　phi　X-174　plasmid　DNA　brand　as　well　as　the　nitration　of　L-tyrosine.　However,　pine　(Pinus　sylvestris　L.)　bark　proanthocyanidins　extracts　at　low　concentration　range　markedly　inhibited　the　peroxynitrite　-induced　the　formation　of　open　circular　DNA　form　(IC50　=　5.03　+/-　0.39　mg/mL).　The　3-Nitro-L-tyrosine　generated　by　the　reaction　of　peroxynitrite　with　L　-tyrosine　was　reduced　by　PBP　(IC50　=　1.01　+/-　0.01　mg/mL).　Besides,　electron　spin　resonance　spectroscopy　data　indicates　that　the　intensive　signal　of　dimethyl　pyridine　N-oxide　hydroxyl　radical　adduct　from　peroxynitrite　was　reversed　by　pine　bark　proanthocyanidins　extracts　(IC50　=1.02　+/-　0.04　mg/mL).　Moreover,　the　obtained　data　shows　that　PBP　provides　more　efficient　protection　against　peroxynitrite　than　that　of　ascorbic　acid.　Together,　the　present　study　suggests　that　pine　bark　proanthocyanidins　could　exert　potent　preventive　activity　against　peroxynitrite　-elicited　cytotoxicity　on　the　biomacromolecules,　a　study-worthy　finding　with　pharmacological　importance.