Phytoconstituents of leaf extracts of Ziziphus jujuba Mill. plants harvested in Tunisia

The present study aimed to determine the phytoconstituent compositions of the leaves of four Ziziphus jujuba ecotypes (Choutrana, Mahdia, Mahres and Sfax). The chromatographic peaks of 18 compounds, including nine major fatty acids, five sterols, two triterpene alcohols and two methysterols, were quantified by the capillary gaseous chromatography method. The major fatty acids identified were linolenic (42.04%) and palmitic (23.04%). Unsaturated fatty acids ranged between 53% and 60%. The predominant sterols (mg/100g) were β-sitosterol (40.36) and stigmasterol (24.18). Cycloartenol (68.55mg/100g) and citrostadienol (12.27mg/100g) were the major metylsterols. Methylene cycloartanol ranged between 1.2mg/100g (Sfax) and 1.5mg/100g (Mahdia). Total phenolic content measured by Folin-ciocalteux ranged from 3.97mg GAE/g to 6.04mg GAE/g. The predominant flavonoids identified by HPLC were apigenin (6.1mg/g) and rutin (1.91mg/g). The fatty acids and flavonoids in the Z. jujuba leaves were responsible for their therapeutic and pharmaceutical effects. This could explain why Tunisian people traditionally use it as medicine to treat several pathologies

Allelopthic Effects of Ziziphus jujuba and Z. lotus Leaf Extracts on Triticum durum and Lens culinaris

Ziziphus species were known for their widespread uses in folk medicine. This work aimed to determine the secondary metabolites (total phenols, flavonoïds, and tannins) of aqueous leaf extracts of two Ziziphus species (Z. jujuba and Z. lotus) from different origins (Mahres, Mahdia, Kairouan, or Rouhia) and their allelopathic effects on Triticum durum and Lens culinaris. The germination percentage, plumule and radicle lengths were recorded after seven days. Total phenols and flavonoïds varied from 10 to 14.03 mg EAG/g DW (total phenols) and from 4.63 to 7 mg QE/g DW (flavonoïds) for Z. jujuba and Z. lotus, respectively. Tannin contents varied from 4.4 (Z. jujuba) to 6 mg CE/g DW (Z. lotus). The radicle length was strongly inhibited by 69.38% in T. durum and by 43.29% in L. culinaris especially when treated with Ziziphus spp. leaf extracts at 100 mg/ml concentration. Root length of T. durum was more inhibited (86.75%) by Z. lotus leaf extract than that of L. culinaris. High levels of phenolic compounds detected especially in Z. lotus leaf extract could justify its inhibitory effect on germination rate and seedling length. Z. lotus leaf extract could be used as herbicide to delete undesirable weeds

Effect of salt stress on growth, chlorophyll content, lipid peroxidation and antioxidant defence systems in Phaseolus vulgaris L

[EN] Salinity is one of the major abiotic stresses which affects plant cell metabolism and reduces plant productivity. Variations in the antioxidant defence systems under salinity among two bean genotypes were investigated. Our results indicate that the difference between the genotypes in response to salinity is a quantitative trait rather than qualitative since they develop the same strategies with a significant variation in the rate of synthesis and accumulation, with the exemption of the antioxidant defence based on the synthesis of phenolic compounds. For both genotypes, salinity induced a marked reduction in dry matter gain in roots and shoots along with oxidative stress as indicated by the significant increase in malondialdehyde content. In addition, the photosynthetic pigments decreased with the increase of salinity. The only qualitative difference that we found among both genotypes was the decrease of total production of phenolic compounds in leaves that was only detectable in the low-yielding genotype under high salinity. The high-yielding genotype may have a better protection against oxidative damages by increasing the activity of antioxidant enzymes and the amounts of total flavonoids and ascorbic acid under high salinity, which allows maintaining higher yield even upon stress conditions. These results indicate that salt induced oxidative stress in bean is mainly counteracted by enzymatic defence systems, and that the metabolism of phenolic compounds is induced under very extreme conditions. The selection of genotypes for this trait will increase yield under stress conditions.Taïbi, K.; Taïbi, F.; Abderrahima, LA.; Ennajahb, A.; Belkhodja, M.; Mulet Salort, JM. (2016). Effect of salt stress on growth, chlorophyll content, lipid peroxidation and antioxidant defence systems in Phaseolus vulgaris L. South African Journal of Botany. 105:306-312. doi:10.1016/j.sajb.2016.03.011S30631210