Total phenolic content and antioxidant activity of six wild Mentha species(Lamiaceae) from northeast of Algeria

Objective:To investigate the total phenolics,flavonoids and tannins content and the in vitro antioxidant activities of methanolic extracts of six wild Mentha species which are Mentha aquatica,Mentha arvensis,Mentha piperita,Mentha pulegium,Mentha rotundifolia and Mentha villosa.Methods:The Folin–Ciocalteu method was used to determine the total phenols content while flavonoids were estimated according to the aluminum chloride colorimetric method.To evaluate tannins content,vanillin and HCl were added to methanolic extracts.The antioxidant potential was measured by 1,1-diphenyl-2-picrylhydrazyl radical scavenging,ferrous ion chelating and the inhibition of b-carotene bleaching assays.Results:The methanol extracts of Algerian mints were rich in phenolic compounds and exhibited powerful antioxidant activity ranging from 7.5 mg/mL to 44.66 mg/mL,which varied significantly among species.Mentha aquatica stood out with efficient antioxidant ability which was correlated to the high total phenolics content,followed by Mentha arvensis and Mentha piperita with very close values,comparing to Mentha pulegium,Mentha rotundifolia and Mentha villosa with lowest values.Conclusions:These results show that methanolic extracts of Mentha species from Algeria have a great potential of polyphenols which can be used as a natural food preservative and antioxidant source.

Dynamic characteristics and improved MPPT control of PV generator

This paper presents a mathematical model of photovoltaic （PV） module and gives a strategy to calculate online the maximum power point （MPP）. The variation of series and shunt resistor are taken into account in the model and are dynamically identified using the Newton-Raphson algorithm. The effectiveness of the proposed model is verified by laboratory experiments obtained by implementing the model on the dSPACE DS1104 board.