Contribution of Miscanthus x giganteus root exudates to the biostimulation of PAH degradation: an in vitro study.

Phytoremediation is considered as a promising and cost-effective method to enhance bioremediation of polluted soils. Exudation of plant root secondary metabolites similar to organic pollutants may induce the expression of microbial degradative enzymes and favour cometabolism of xenobiotics. We investigated the contribution of Miscanthus x giganteus root exudates in the biostimulation of PAH-degradation. This perennial grass was chosen because of its capability to grow on polluted soils and its high biomass production for non-food purposes. First, the impact of cometabolism phenomena was evaluated on the selective enrichment of pyrene-degrading bacterial consortia. The identification of each isolated strains following incubation with pyrene only, "pyrene+phenanthrene", "pyrene+salycilate" or "pyrene+diesel fuel" showed a varying bacterial diversity and pyrene-degrading ability, depending on the co-substrate used. Then, a microplate assay was designed, based on the simultaneous measurement of bacterial consortia growth and degradation activity, in the presence of PAH and total root exudates. Results showed that i) the addition of root exudates was efficient for promoting bacterial growth, ii) but a selective enrichment of PAH-degraders compared to aliphatic ones could be clearly demonstrated, thereby conducing to an enhanced PAH catabolism. The identification of plant secondary metabolites showed the presence of a broad range of flavonoid-derived compounds that could play a role in cometabolic processes. Microplate assays with the two major molecules, quercetin and rutin, suggested a partial involvement of these compounds in biostimulation processes. Further investigations with the other identified secondary metabolites (apigenin, isovitexin, catechin, gallic and caffeic acid) should provide more information on the exudate-PAH cometabolic degradation phenomenon.

Chemical Composition and, Cellular Evaluation of the Antioxidant Activity of Desmodium adscendens Leaves.

Desmodium adscendens plant is widely used as juice or tea in various parts of the world against a wide range of diseases. This study determines the quality and the quantity of polyphenols, flavonoids, anthocyanins, and tannins in D. adscendens leaves by UV-spectrophotometry and RP-HPLC methods. In addition, the antioxidant capacity of these phenolic compounds is evaluated by ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic)), DPPH (2,2-diphenyl-1 picrylhydrazyl), and Cellular tests. D. adscendens leaves are mainly composite of flavonoid compounds with 12.8 mg of catechin equivalent (CE)/g dw. The amounts of total polyphenol compounds are 11.1 mg of gallic acid equivalent (GAE)/g dw. The quantity of total anthocyanin and total tannin compounds is not considerable 0.0182 mg CgE/g dw and 0.39 mg CE/g dw, respectively. A direct correlation between phenolic compounds and antioxidant activity is observed (R(2) = 0.96). The RP-HPLC analyses reveal that the main phenolic compound identified in the methanol-water extract is quercetrin dihydrat (2.11 mg/mL). According to the results, it is observed that D. adscendens leaves possess a considerable scavenging antioxidant and antiradical capacity, therefore these antioxidant properties might increase the therapeutic value of this medicinal plant.

Phytochemical composition and antioxidant capacity of three malian medicinal plant parts.

This study evaluates the levels of total polyphenolic compounds in three Malian medicinal plants and determines their antioxidant potential. Quantitative and qualitative analysis of polyphenolics contained in plants extracts were carried out by RP-C18 RP-HPLC using UV detector. The antioxidant activity was determined by three tests. They are phosphomolybdenum, DPPH (2,2-diphenyl-1 picrylhydrazyl) and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic)] tests. The total phenolic and the total flavonoid contents varied from 200 to 7600 mg 100 g(-1) dry weight (dw), expressed as gallic acid equivalents and from 680 to 12 300 mg 100 g(-1) dw expressed as catechin equivalents, respectively. The total anthocyanin concentrations expressed as cyanin-3-glycoside equivalent varied from 1670 to 28 388 mg 100 g(-1) dw. The antioxidant capacity was measured by determining concentration of a polyphenolic (in mg ml(-1)) required to quench the free radicals by 50% (IC(50)) and expressed as vitamin C equivalent antioxidant capacity. The IC(50) values were ranked between 2.68 and 8.80 µg ml(-1) of a solution of 50% (v/v) methanol in water. The uses of plants are rationalized on the basis of their antioxidant capacity.

Assessment of polyphenolic compounds, in vitro antioxidant and anti-inflammation properties of Securidaca longepedunculata root barks.

The present study was carried out to evaluate the antioxidant activities of the root bark extract of Securidaca longepedunculata. This plant material is commonly used in folk medicine in several parts in the world. The bark extracts of S. longepedunculata were evaluated for their total phenols, flavonoids, anthocyanins, tannins content and total antioxidant capacity. The compounds were identified and quantified both by RP-HPLC and UV spectrophotometer; the antioxidant capacity was assessed by ABTS and DPPH tests and expressed as IC(50). The total phenolic compounds determinate was 9.86mg gallic acid equivalents/g dw, the total flavonoid contents was 5.85mg catechin equivalents/g dw, the total anthocyanin contents was 0.032mg cyanidin-3-glycosyl equivalents/g dw and the condensed tannins content were 1.03mg catechin equivalents/g dw. The major compound identified using RP-HPLC was quercetin (0.98mg/ml). The IC(50) value reached 5.5microg/ml, revealing that the root barks of S. longepedunculata have a very high antioxidant and anti-inflammation properties.