title: Hippophae leaf extract concentration regulates antioxidant and prooxidant effects on DNA.
abstract: Extracts from Hippophae leaves constitute some commonly consumed beverages such as tea and wine. We had developed an extract of Hippophae leaves (SBL-1), which was rich in quercetin, had antimutagenic effects, radioprotective effects, and countered radiation-induced gene conversion in Saccharomyces cerevisiae. This study was designed to investigate the action of SBL-1 on guanine cytosine (GC)-rich nascent and mouse genomic DNA in vitro. The human and mouse liver DNA have about 43% GC content. Our results showed that at small concentration SBL-1 protected nascent as well as genomic DNA, while at large concentration SBL-1 damaged both types of DNA. The concentration of SBL-1 that protected DNA also demonstrated higher free radical scavenging activity. The reducing power of SBL-1 was greater than its free radical scavenging activity. The greater reducing power may have reduced the trace metals present in the SBL-1, leading to generation of hydroxyl radicals via Fenton reaction. The increased proportion of unscavenged hydroxyl radicals with increase in SBL-1 concentration may have been responsible for DNA damage or prooxidant effect of SBL-1 in vitro. This study suggests that the dietary supplements prepared from Hippophae should have low metal content.
authors.affiliation: Division of Radiation Biology, Institute of Nuclear Medicine and Allied Sciences, New Delhi, India.
authors.forename: Manu
authors.initials: M
authors.lastname: Saini
authors.forename: Sandhya
authors.initials: S
authors.lastname: Tiwari
authors.forename: Jagdish
authors.initials: J
authors.lastname: Prasad
authors.forename: Surender
authors.initials: S
authors.lastname: Singh
authors.forename: M S Yogendra
authors.initials: MS
authors.lastname: Kumar
authors.forename: Madhu
authors.initials: M
authors.lastname: Bala
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001482:Base Composition; D004247:DNA / Q000187:drug effects*; D004249:DNA Damage; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000494:pharmacology; D016678:Genome / Q000187:drug effects*; D031281:Hippophae / Q000737:chemistry*; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D008099:Liver; D051379:Mice; D016877:Oxidants / Q000009:adverse effects*; D010936:Plant Extracts / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves; D011794:Quercetin / Q000494:pharmacology; D011837:Radiation-Protective Agents; D014131:Trace Elements
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D016877:Oxidants; D010936:Plant Extracts; D011837:Radiation-Protective Agents; D014131:Trace Elements; D017665:Hydroxyl Radical; D004247:DNA; D011794:Quercetin