Polyphenols, antioxidant activity and mode of action of antimicrobial compounds of Dittrichia viscosa extracts

In order to promote the spontaneous plant Dittrichia viscosa known by its use in traditional medicine, the content of phenolic compound in the aqueous and ethanolic extracts was determined according to the colorimetric method based on the Folin-Ciocalteu reagent, and the antioxidant activity which was evaluated by two methods: DPPH and FRAP. For antimicrobial activity, the microtiter microplate method was applied to the yeast Candida albicans and to two bacteria Staphylococcus aureus and Escherichia coli. Regarding the mode of action of the extracts of tested germs, an evaluation of the nucleic acids released during the lysis of the treated cells was carried by the spectrophotometric assay at wave length 260 nm. The results revealed that the extracts have an interesting content of polyphenols, which is higher in the ethanolic extract. Antioxidant and antimicrobial activities are higher for the alcoholic extract than the decoction. The MIC for E. coli is 0.28 ± 0.05 mg / ml, 2.290 ± 0.20 mg / ml for Staphylococcus aureus and 33.33 ± 0.33 mg / ml for C. albicans. The alcoholic extract  and decocted of  D. viscosa act  respectively by damaging the bacterial and yeast wall

Acinos alpinus and Ziziphora hispanica: Phenolic Profile, Antioxidant and Antibacterial Properties of Hydromethanolic Extracts from Aerial Parts

Acinos alpinus and Ziziphora hispanica belonging to the Lamiaceae family are well-known for their biological properties. The phenolic composition was characterized using HPLC coupled to photodiode array and electrospray ionization mass spectrometry. The antioxidant capacity was assessed by 2,2′-diphenyl-1-picrylhydrazyl radical and ferric reducing antioxidant power assays. The antibacterial activity was evaluated by disc-diffusion and broth micro-dilution methods. A total of 53 phenolic compounds were identified in both extracts, with the predominance of caffeoylquinic acid isomers with a content of 2.09 mg/g in A. alpinus extract, while coumarylquinic acid isomers with a content of 17.33 mg/g was determined in Z. hispanica extract. The Acinos alpinus extract displayed the highest radical scavenging activity (IC50 DPPH = 3.226±0.035 mg/mL) and reducing power (EC50 FRAP = 3.792±0.001 mg/mL), followed by Z. hispanica extract with IC50 DPPH value of 7.265±0.209 mg/mL, and EC50 FRAP value of 24.689± 0.106 mg/mL. Furthermore, both A. alpinus and Z. hispanica extracts exhibited a bactericidal effect against six pathogenic bacteria with a MIC value from 4.16 to 33.33 mg/mL. On the basis of the results achieved, the aerial parts of Moroccan Acinos alpinus and Ziziphora hispanica might be used as natural agents in the food and pharmaceutical field