Evaluation of the in vitro and in vivo antioxidant potential of whole plant extracts of Hedyotis puberula (G. Don) R. Br. ex Arn.

The total phenolic content and in vitro and in vivo antioxidant activities of the whole plants of Hedyotis puberula (G. Don) R.Br. ex Arn. were appraised. The methanol extract of the plant contained higher levels of total phenolics, tannins and flavonoids content than other solvent extracts. Extracts were screened for antioxidant and free radical scavenging activities using various in vitro model systems. The methanol extract manifested strongest antioxidant and free radical scavenging activity. The treatment of paracetamol intoxicated wistar rats with methanol extract at the dose of 400 mg/kg, b.wt. attenuated the elevated enzyme level such as glutathione, glutathione S-transferase, glutathione peroxidase, superoxide dismutase and catalase to normal level and significantly reduced the levels of lipid peroxidation. These results showed that the methanol extract of H. puberula has significant antioxidant activity both under in vitro and in vivo conditions.Colegio de Farmacéuticos de la Provincia de Buenos Aire

In vitro antioxidant potential of different solvent extracts of Naregamia alata

Total phenolics, tannins, flavonoids and the antioxidative properties of the traditionally used medicinal plant Naregamia alata Wight. & Arn. were assessed. The hot water extract contained higher levels of total phenolics, tannins and flavonoids. The extracts were subjected to assess their potential antioxidant activities using various in vitro systems such as DPPH•, ABTS•+, FRAP, β-carotene linoleic acid bleaching system, phosphomolybdenum reduction and Fe2+ chelation. It is concluded that N. alata may serve as a potential source of natural antioxidants capable of offering protection against free-radical mediated damages.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Characterization of tannic acid- and gallic acid-functionalized single- and multiwalled carbon nanotubes and an in vitro evaluation of their antioxidant properties

AbstractObjectivesCarbon nanotubes (CNTs) have powerful oxidative properties that influence their biomedical applications. This study addresses the oxidative potential of both single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) by functionalizing them with tannic acid (TA) and gallic acid (GA), and an in vitro evaluation of their antioxidant properties is presented. Their effective role as antioxidants is influenced by their dual functions of reducing toxicity and inducing antioxidant effects.MethodsFunctionalization was confirmed by Fourier transform infrared spectroscopy (FTIR), and the total phenolic content was assessed. The antioxidant properties were analyzed by scavenging di(phenyl)-(2,4,6-trinitrophenyl) iminoazanium, lipid peroxidation, reactive oxygen species (ROS) quantification and quenching externally generated hydroxyl and superoxide radicals.ResultsThe functionalization of nanotubes with antioxidants was conformed via FTIR and measurement of total phenolic compounds. Higher radical scavenging was observed for TA-functionalized SWCNTs than for other functionalizations and MWCNTs. The lipid peroxidation results revealed that the functionalization of nanotubes with the antioxidant TA significantly decreased lipid peroxidation (36%) compared with naked nanotubes (85%) and the positive control (94%). Furthermore, antioxidant-functionalized nanotubes showed negligible production of ROS after being irradiated under different conditions, and externally generated hydroxyl and superoxide radicals were quenched.ConclusionThis study showed, using in vitro models, that effective functionalization of CNTs with TA and GA leads to remarkable antioxidant properties. Antioxidant-functionalized nanotubes showed a reduction in cell lethality correlated with negligible ROS production under different irradiation conditions and quenching of externally generated hydroxyl and superoxide radicals. Further, antioxidant-functionalized nanotubes were more compatible with the cell membrane

In Vitro Bacterial Cytotoxicity of CNTs: Reactive Oxygen Species Mediate Cell Damage Edges over Direct Physical Puncturing

Understanding the bacterial cytotoxicity of CNTs is important for a wide variety of applications in the biomedical, environmental, and health sectors. A majority of the earlier reports attributed the bactericidal cytotoxicity of CNTs to bacterial cell membrane damage by direct physical puncturing. Our results reveal that bacterial cell death via bacterial cell membrane damage is induced by reactive oxygen species (ROS) produced from CNTs and is not due to direct physical puncturing by CNTs. To understand the actual mechanism of bacterial killing, we elucidated the bacterial cytotoxicity of SWCNTs and MWCNTs against Gram-negative human pathogenic bacterial species <i>Escherichia coli, Shigella sonnei</i>,<i> Klebsiella pneumoniae</i>, and <i>Pseudomonas aeruginosa</i> and its amelioration upon functionalizing the CNTs with antioxidant tannic acid (TA). Interestingly, the bacterial cells treated with CNTs exhibited severe cell damage under laboratory (ambient) and sunlight irradiation conditions. However, CNTs showed no cytotoxicity to the bacterial cells when incubated in the dark. The quantitative assessments carried out by us made it explicit that CNTs are effective generators of ROS such as ¹O₂, O₂^•–, and ^•OH in an aqueous medium under both ambient and sunlight-irradiated conditions. Both naked and TA-functionalized CNTs showed negligible ROS production in the dark. Furthermore, strong correlations were obtained between ROS produced by CNTs and the bacterial cell mortality (with the correlation coefficient varying between 0.7618 and 0.9891) for all four tested pathogens. The absence of bactericidal cytotoxicity in both naked and functionalized CNTs in the dark reveals that the presence of ROS is the major factor responsible for the bactericidal action compared to direct physical puncturing. This understanding of the bactericidal activity of the irradiated CNTs, mediated through the generation of ROS, could be interesting for novel applications such as regulated ROS delivery in cancer therapy and the sanitation of potable water supplies