Polyphenols content, antioxidant and antimicrobial activities of leaf extracts of Marrubium deserti de Noé ex Coss | Polyphénols totaux, activités antioxydante et antimicrobienne des extraits des feuilles de Marrubium deserti de Noé
2015
Ghedadba, N. | Hambaba, L. | Ayachi, A. | Aberkane, M. C. | Bousselsela, H. | Oueld-Mokhtar, S. M.
In the present study, in vitro, antimicrobial activities and the antioxidant capacity of the various extracts prepared starting from the leaves of Marrubium deserti de Noé were studied. The antimicrobial activity was evaluated by the method of diffusion against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Klebsiella pneumoniae, Candida albicans, Aspergillus niger and Penicillium digitatum. The antioxidant effect was determined by ß-carotene bleaching method, the DPPH test and FRAP assay. Qualitative analysis of the methanolic extract by Thin Layer Chromatography (TLC) revealed the presence of Gallic acid, Quercetin, Rutin and the Kaempferol. Moreover, three new metabolites were investigated for the first time: trans-Cinnamic acid, 4-hydroxybenzoïc acid and 4-methyl-Catechol. Quantification of total phenols by Folin-Ciocalteu colorimetric method and flavonoïds by AlCl3 method gave higher values with the MeOHE, where the highest value estimated by: 184 ± 0.78 mg GAE/100g of extract; 28.48 ± 0.40 mg QE/100 g of extract. However, the proportioning of the tanins condensed by the method of vanillin revealed that the AQE gives the highest value: 15.68 ± 0.08 mg EC/100g of extract. The evaluation of the antimicrobial activity showed that the methanolic and dichloromethanic extracts are most active on the whole of the bacteria tested and revealed a significant antibacterial activity against S. aureus (ATCC 25923) resistant to the methicillin and Escherichia coli (ATCC 25922). With regards to IC50 values (50% inhibitory concentration) of scavenging abilities of the DPPH radical, methanol extract exhibited important antioxidant activities with IC₅₀ of 15.1 µg/ml. Beside, The methanol extract showed the highest antioxidant activity using the linoleic acid emulsion system (76.92%). Method FRAP shows also that MeOHE is most active: 3.25 ± 0.06 EAA/g of extract. In conclusion, these results can be considered very promising and justify further research, amongst others on the identification of antioxidant and antimicrobial components in the active extracts.
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