No abstract

This study reports the link between larvicidal activity and the phytochemical composition of male and female leaf extracts of Mercurialis annua L. (M. annua) from four Tunisian regions: Bizerte, Jandouba, Nabeul and Beja. Their antioxidant activity was evaluated using DPPH (2, 2-diphenyl-1-picrylhydrazyl) assays. Phenolic compounds were identified and quantified using liquid chromatography coupled with a UV detector and mass spectrometry (LC-UV-ESI/MS). Higher antioxidant activity (AOA) was found in the leaves of male plant extracts than of female ones. The leaves of male and female plant extracts from Bizerte exhibited the highest AOA: 22.04 and 22.78 mg Trolox equivalent/g dry matter (mg TE/g DM), respectively. For both sexes, plant extracts from Beja had the lowest AOA with 19.71 and 19.67 mg TE/g DM for male and female plants, respectively. Some phenolic compounds such as narcissin, gallocatechin, rutin, epigallocatechin and epicatechin were identified and quantified using LC-MS, which highlighted the abundance of narcissin and rutin in the male leaves of M. annua. We noted that the interaction between the sex of plants and the provenance had a significant effect on TFC (F = 6.63; p = 0.004) and AOA (F = 6.53; p = 0.004) assays, but there was no interaction between sex and origins for TPC (F = 1.76; p = 0.19). The larvicidal activity of aqueous leaf extracts of M. annua against Tribolium confusum (Du Val) (T. confusum), an insect pest of flour and cereal seeds, showed that the mortality could reach 100% after 48 h of exposure in the Bizerte region. The LC50 values for the leaf extract were low in Bizerte, with 0.003 and 0.009 g/mL for male and female plants, respectively, succeeded by Jandouba, which displayed 0.006 and 0.024 g/mL for male and female plants, respectively. Nabeul showed 0.025 g/mL for male plants and 0.046 g/mL for female plants and Beja showed 0.037 and 0.072 g/mL for male and female plants, respectively. This is the first time that a study has revealed a negative correlation between the antioxidant activity and the larvicidal activity of the leaf extracts of M. annua with the following correlation coefficients of Perason: r = −0.975 and r = −0.760 for male and female plants, respectively.

Background and objectives: Natural products from plants and their biological potentialities have increased environmental concerns. This study aimed to evaluate the phenolic composition, along with the antioxidant, antimicrobial, and insecticidal activities of Ziziphus spina-christi leaf extracts using LC-MS. Methods:The plant materials were obtained from three Tunisian localities (Metlaoui, Degueche, and Tozeur). Results:The leaf extracts contained phenols (8.157 mg GAE/DW), flavonoids (4.42 mg Quercetin Eq/gDW), and tannins (1.62 mg Cat Eq. g −1 ). LC-MS analysis identified the rutin compound at a rate between 1.3 ± 0.005 µg/mL (Dgueche) and 2 ± 0.005 µg/mL (Metlaoui) while 3 ± 0.005 µg/mL in the extracts from the Tozeur. The extracts from the Tozeur had the highest antioxidant activity with a concentration for 50% inhibition of 0.125 mg/mL and the highest antibacterial activity against Streptococcus agalactiae specie with a superior diameter of zone inhibition of about 27.5 mm and against Staphylococcus aureus specie with a diameter of 16 mm. In contrast, the extracts from the Deguech displayed stronger activity against Escherchia coli specie with a diameter of 13.5 mm. There were only two Tozeur extracts that exhibited activity against Candida albicans and Candida Sake species. Furthermore, treatment with methanolic extracts caused 66.60% mortality in Tribolium castaneum. Conclusions:This study showed that Ziziphus spina-christi extracts contained several components that had potent antioxidant and antibacterial activities against some types of bacteria. Hence, these extracts or their components may be recommended as an eco-friendly alternative for synthetic insecticides and used as natural antioxidants in phototherapy.