Radicals and antioxidants updating a personal view


A number of plants from the Apocynaceae family are considered to be potential sources of antioxidants which have been attributed to the high phenolic content in the phytochemical profile of some of these plants [].Antioxidants may be defined as free radical scavengers which protect living organisms from damage caused by the accumulation of free radicals.The total phenolic content was 420 ± 0.17 and 319.9 ± 0.2 mg GAE/g for the ethanol and ethyl acetate extracts, respectively.The ethanol extract, which revealed the presence of tannins, had a tannin content of 330 ± 0.2 mg TAE/g extract.Full-length recombinant HIV-1 integrase protein was then loaded onto the oligo substrate.extracts or sodium azide (standard control) was added to the reaction plates together with a double-stranded target substrate (TS) oligo containing 3′-end modifications.TTC was determined from extrapolation of a standard calibration curve (R crude extracts on HIV-1 reverse transcriptase (RT) was tested using an RT colorimetric ELISA kit from Roche Diagnostics (Mannheim, Germany).The assay was performed according to the manufacturer’s instructions.

In the final step, the ABTS substrate solution was cleaved by the peroxidase enzyme, producing a coloured reaction product.The horseradish peroxidase (HRP)-labelled antibody was directed against the TS 3′-end modification and the absorbance due to the HRP antibody– tetramethylbenzidine peroxidase substrate reaction was measured at 450 nm using a Spectra Max M2 plate reader. Due to the limited number of reactions of the kit, samples were tested at five concentrations, namely; 25, 50, 100, 200 and 400 μg/m L.Acetyl pepstatin (AP) was used as a known standard for HIV-1 PR inhibition.Plant identification was done by Silke Rugheimer at the National Herbarium of Namibia.Voucher number M1 [ Plant material (108.3 g) was macerated at room temperature in 1 L of ethanol for 48 h.The mixture was allowed to stand for 30 min and then 2 m L of 20 % sodium carbonate was added.

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