Citrus limon from Tunisia: Phytochemical and Physicochemical Properties and Biological Activities

Abstract

Natural plant extracts contain a variety of phenolic compounds which are assigned various biological activities. Our work aims to make a quantitative and qualitative characterization of the Zest (ZL) and the Flesh (FL) of lemon (Citrus limon), to valorize the pharmacological uses of lemon, by evaluating in vitro activities (DPPH, free radical scavenging and reducing power). The antibacterial, antifungal, and antiproliferative activities were sought in the ability of Citrus limon extracts to protect DNA and protein. We found that the ZL contains high amounts of phenolics responsible for the important antioxidant properties of the extract. However, the FL is richer in flavonoids than the ZL. The FL extract was also found to be more effective than the ZL in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals. We also concluded that the FL extract exhibited potent antibacterial activity unlike ZL. Analysis by LC/MS-MS identified 6 compounds (Caffeoyl N-Tryptophan, Hydroxycinnamoyl-Oglucoside acid, Vicenin 2, Eriocitrin, Kaempferol-3-O- rutinoside, and Quercetin-3-rutinoside). These preliminary results showed that Citrus limon has antibacterial and antioxidant activity in vitro. It would be interesting to conduct further studies to evaluate the in vivo potential in an animal model.

Figure 1

Radical scavenging effect (%) on DPPH (2,2-diphenyl-1- picrylhydrazyl) radicals of ZL and FL extracts of Citrus limon. The values are the mean of three determinations ± SD.

Figure 2

Reducing power of ZL and FL extracts of Citrus limon, as measured by changes in DO at 700 nm. The values are the mean of three determinations ± SD.

Figure 3

Effect of ZL and FL extracts of Citrus limon on proliferative activity of B95-8 cell line.

Figure 4

Effect of the ZL and FL Citrus limon extracts on protein damage.

Figure 5

Inhibitory effect of the ZL and FL Citrus limon extracts on the oxidative DNA damage caused by H₂O₂. Line 1: untreated plasmid; Line 2: plasmid treated with 5 mg/ml ZL extract; Line 3: plasmid treated with 5 mg/ml of FL extract; Line 4: positive control (quercetin (10 mg/ml) + Rf Fenton); Line 5: negative control (plasmid + Rf Fenton).