Antidiabetic, hypolipidaemic and antioxidant activity of Dodonaea viscosa aerial parts in streptozotocin-induced diabetic rats

We evaluated the antidiabetic and antioxidant activity of Dodonaea viscosa in streptozotocin-induced diabetic rats. The water extract (DVW) and polar fraction of ethanol extract (DVE-4) in a single-dose one-day study showed dose-dependent reduction in glucose levels with maximum effect of 42.16% and 72.9% respectively at 6 h post drug treatment (p<0.001). DVE-4 was more active than DVW and glibenclamide. In a multi-dose fifteen-day study, lower doses of DVW (400 mg/kg) and DVE-4 (200 mg/kg) exhibited higher percentage reduction in glucose levels compared to glibenclamide treated group. Altered levels of lipids, TBARS, non-enzymatic and enzymatic antioxidants were restored by DVW (400 mg/kg) and DVE-4 (200 mg/kg) in diabetic rats. In vitro steady state and time resolved studies reveled that DVW and DVE-4 showed comparable antioxidant ability in steady state and kinetic studies suggesting its possible role in observed antidiabetic and hypolipidaemic activities.Keywords: Antidiabetic, Antioxidant enzymes, Dodonaea viscosa, Free radical scavenger, Hypolipidaemic, Streptozotoci

Phenolic compounds isolated from Pilea microphylla prevent radiation-induced cellular DNA damage

AbstractSix phenolic compounds namely, quercetin-3-O-rutinoside (1), 3-O-caffeoylquinic acid (2), luteolin-7-O-glucoside (3), apigenin-7-O-rutinoside (4), apigenin-7-O-β-d-glucopyranoside (5) and quercetin (6) were isolated from the whole plant of Pilea microphylla using conventional open-silica gel column chromatography and preparative HPLC. Further, these compounds were characterized by 1D, 2D NMR techniques and high-resolution LC–MS. Compounds 1–3 and 6 exhibited significant antioxidant potential in scavenging free radicals such as DPPH, ABTS and SOD with IC50 of 3.3–20.4μmol/L. The same compounds also prevented lipid peroxidation with IC50 of 10.4–32.2μmol/L. The compounds also significantly prevented the Fenton reagent-induced calf thymus DNA damage. Pre-treatment with compounds 1–3 and 6 in V79 cells attenuated radiation-induced formation of reactive oxygen species, lipid peroxidation, cytotoxicity and DNA damage, correlating the antioxidant activity of polyphenols with their radioprotective effects. Compounds 1, 3 and 6 significantly inhibited lipid peroxidation, presumably due to 3′,4′-catechol ortho-dihydroxy moiety in the B-ring, which has a strong affinity for phospholipid membranes. Oxidation of flavonoids, with catechol structure on B-ring, yields a fairly stable ortho-semiquinone radical by facilitating electron delocalization, which is involved in antioxidant mechanism. Hence, the flavonoid structure, number and location of hydroxyl groups together determine the antioxidant and radioprotection mechanism

Free radicals, oxidative stress and importance of antioxidants in human health

Reactive oxygen species (ROS) is a collective term used for oxygen containing free radicals, depending on their reactivity and oxidizing ability. ROS participate in a variety of chemical reactions with biomolecules leading to a pathological condition known as oxidative stress. Antioxidants are employed to protect biomolecules from the damaging effects of such ROS. In the beginning, antioxidant research was mainly aimed at understanding free radical reactions of ROS with antioxidants employing biochemical assays and kinetic methods. Later on, studies began to be directed to monitor the ability of anti-oxidants to modulate cellular signaling proteins like receptors, secondary messengers, transcription factors, etc. Of late several studies have indicated that antioxidants can also have deleterious effects on human health depending on dosage and bio-availability. It is therefore, necessary to validate the utility of antioxidants in improvement of human health in order to take full advantage of their therapeutic potential