Antioxidant, antimicrobial and phytotoxic activities of Rhaponticum acaule DC essential oil

The in-vitro antioxidant activity of Rhaponticum acaule essential oil (RaEO) was evaluated using ß-carotene/linoleic acid bleaching, chelating activity, and lipid peroxidation inhibition (TBARS) assays. The antimicrobial activity of RaEO was assessed by disc diffusion and microdilution methods against 8 bacteria and 4 yeast. Finally, the allelopathic activity of RaEO on the seed germination and the shoot and root elongation of lettuce (Lactuca sativa L.) seedlings were investigated. According to our results, the RaEO exhibited significant antioxidant activity, similar to those of standards (BHT and ascorbic acid) with IC50 values of 0.042 and 0.045 mg/mL obtained by ß-carotene bleaching and TBARS assays, respectively. On the other hand, despite its interesting ferrous chelating activity, RaEO possesses moderate IC50 value (0.35 mg/mL) as compared with that of EDTA (0.015 mg/mL). RaEO exhibited a strong antimicrobial activity against all the tested microorganisms, with IZ, MIC and MBC values being in the range of 7.67 ± 0.58 to 13.33 ± 0.58 mm, 1.25 to 5.00 and 5.00 to 10.00 mg/mL, respectively. The results reveled also that RaEO inhibited the shoot and root growth of Lactuca sativa L. seedlings. Our data suggested that the RaEO had pharmaceutical benefits and could be used as a potential natural herbicide resource

Antimicrobial activities of four Tunisian Chrysanthemum species.

BACKGROUND & OBJECTIVE: Tunisian Chrysanthemum species are known to have medicinal activity and some of the species are used in traditional medicine. We have earlier shown the use of C. trifurcatum flowerheads in Tunisian traditional medicine to treat constipation. In the present study we investigated the anti microbiol activity of four Tunision Chrysanthemum species. METHODS: Different parts (flowers, leaves, stems, roots, leaves and flowers and leaves and stems) of four Tunisian Chrysanthemum species, were extracted with solvents of increasing polarity to obtain aqueous and organic extracts. These extracts were tested in vitro for their antimicrobial activity against 14 bacteria and four yeasts, using agar diffusion and microdilution methods. Activity was evaluated by measuring the zones of inhibition against the tested organisms and minimum inhibitory concentrations (MIC) were determined from the lowest concentrations of extracts to inhibit the growth of microorganisms. Cytotoxity and antiviral activities against Herpes simplex virus type 1 (HSV-1), were evaluated using the neutral red incorporation method. RESULTS: Extracts of the 4 Chrysanthemum species showed some degree of activity against one or more of the microbial strains with MIC ranging from 0.625 to 1.25 mg/ml. Most of the extracts were well tolerated by Vero cells with CC(50) > 500 microg/ml. The petroleum ether extract of C. trifurcatum stems and leaves protected infected cells with EC(50) of 100 microg/ml. INTERPRETATION & CONCLUSION: Our findings showed that some Chrysanthemum extracts exhibited antimicrobial and/or anti-HSV-1 activities. Further studies aimed to the isolation and identification of active substances from the extracts which exhibited interest activities, need to be done.