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Showing 2 results for Oueslati
Volume 21, Issue 6 (10-2019)
Abstract
In the last decades, an increasing interest has been granted to halophytes due to their high phenolic content, which have therapeutic potential in the treatment and/or management of human health. Therefore, it is important to measure the halophyte total polyphenol content correctly and to valorize their antioxidant capacity. Ethanol extracts from thirty halophytes were analyzed to evaluate the Total Phenol Content (TPC). We employed three testing methods to prove their antioxidant potentialities, including DPPH• (1-DiPhenyl-2-PicrylHydrazyl), ABTS•+ (2,20-Azino-Bis-3-ethylbenzoThiazoline-6-Sulfonic acid) and IRP (Iron Reducing Power) assays. Results showed that plants exhibited different TPC, which varied significantly from 411.5 mg GAE g-1 DW in Cynomorium coccineum to 6.02 mg GAE g-1 DW in Ammophila arenaria. Concerning antioxidant activities, data revealed that Cynomorium coccineum (IC50= 3.82 µg ml-1 versus ABTS•+) and Euphorbia paralias had the highest antiradical capacity (IC50= 0.12 µg ml-1 against DPPH•) and exhibited the best efficient concentration with an EC50 value= 9.57 µg mL-1 for the IRP. Considering correlation between phenols and antioxidant tests, three groups were distinguished with a higher correlation coefficient between 0.78 and 0.98 for the first group. These data suggest the promising potentialities of the Mediterranean medicinal halophytes as valuable source of powerful antioxidants of industries, especially for Cynomorium coccineum, Carpobrotus edulis, Reaumuria vermiculata, Tamarix gallica, and Euphorbia paralias regarding their strong phenol content.
Volume 27, Issue 2 (2-2025)
Abstract
In this study, the antagonistic effects of 14 Plant Growth-Promoting Rhizobacteria strains (PGPRs) against the phyto-pathogenic species Alternaria terricola Woudenb. & Crous were investigated, both in vitro and in vivo. The obtained results revealed significant inhibition effects of the 14 PGPR strains against A. terricola in both direct contact and indirect bioassays with significant variation. The dual in vitro culture tests revealed substantial inhibition rates in the growth of A. terricola strain, ranging from 25±5.41% (Pseudomonas koreensis O3RR25) to 71.87±3.12% (Bacillus megaterium FR1.11). Moreover, the indirect antagonism test showed that the volatile organic compounds produced by the 14 tested PGPR strains significantly inhibited the growth of A. terricola mycelium, with variations ranging from 36.61±0.94% (P. brassicacearum O3RR24) to 67.75±0.94% (B. megaterium FR1.11). Microscopic examination of A. terricola following exposure to the volatile compounds revealed significant structural damage, including inhibition of conidial germination, deformations, thin or fissured structures, irregular lengths, and the formation of empty segments. The in vivo application of B. megaterium FR1.11 resulted in the reduction of fungal development on detached leaves and tomato seedlings. This treatment engendered a significant increase in the levels of chlorophyll a, b and total, carotenoids, polyphenols, and proline in infected tomato seedlings compared to the control. Applying this PGPR strain to infected tomato plants allowed maintaining comparable level of malondialdehyde as the control. B. megaterium FR1.11 showed considerable in vitro and in vivo antifungal activity and could serve as a promising candidate for biological control strategies targeting phytopathogenic species of the genus Alternaria.
