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Résumé :
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The aim of this study is to determine the chemical composition, phenolic content, as well as the antibacterial, antifungal and antioxidant activities of hydromethanolic extracts from R. chalepensis collected at three different periods: before flowering (BF), during flowering (DF) and after flowering (AF). Three hydromethanolic extracts were prepared: the before flowering extract (BFE), during flowering extract (DFE) and after flowering extract (AFE). Hydromethanolic extracts analysis was conducted regarding their chemical composition by HPLC-DAD-ESI/MS method, quercetin, graveolin, bergapten, isoimperatorin, chalepin, rutamarin and β-carotene were detected. Also, total phenolics and flavonoids contents were determined. The AFE displayed the maximum polyphenol and flavonoid levels; 84.54 ± 1.66 µg GAE/mg dry extract and 25.15 ± 0.88 µg QE/mg dry extract, respectively. Antibacterial activity was evaluated against seven bacterial strains using disc diffusion (DD) method and minimal inhibitory concentration (MIC). The results of the studied plant showed an important antibacterial activity against both Gram-negative and Gram-positive bacteria. The bacterial strains showed sensitivity ranging from moderate to high, either in terms of ID (08.67 to 17.67 mm) or in terms of MIC (01.95 and 31.25 mg/ml). These extracts also exhibited excellent activity against eight filamentous fungi growth when tested by incorporation of plant extracts into the culture medium method at (10%) reduced the growth from 25 % to 97% of all fungi. On the other hand, The antioxidant activity was assessed using four methods; DPPH ,with IC50 ranging between 14.18 ± 1.02 and 30.96 ± 1.80 μg/mL, β-carotene/linoleic acid, with IC50 ranging between 34,86 ± 0,78 and 49,06 ± 0,15 μg/ml and reducing power, with EC50 varied between 100,61± 1,25 and 139,99± 2,08 µg/ml and TAC, with values ranging between 125,12 ± 2,47 and 160.59 ± 5.78 µg AAE/mg extract. In conclusion, the results revealed that R. chalepensis hydromethanolic extracts have strong antibacterial and antioxidant properties, highlighting their potential as natural sources for developing novel antibacterial and antioxidant agents.
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