Abstract
Citrillus colocynthis peel aqueous extract (CCPAE) is widely used to treat disorders such as inflammation, ulcers and infections, but its pharmacological target is not known. The objectives of this work were to study the effect of C. colocynthis peel aqueous extract, on human neutrophil reactive oxygen species (ROS) production in vitro, and to evaluate its protective effect on lipopolysaccharide (LPS)-induced lung inflammation in vivo in mice. Neutrophils were isolated from blood of healthy volunteers. ROS generation was measured by luminol-amplified chemiluminescence. Superoxide anion generation was detected by the cytochrome c reduction assay. H2O2 was detected by horseradish peroxidase (HRP)-amplified chemiluminescence assay. Myeloperoxidase (MPO) activity was measured by the tetramethylbenzidine oxidation method. Lung inflammation was induced in mice by LPS instillation. CCPAE inhibited luminol-amplified chemiluminescence of resting neutrophils and N-formyl-methionyl-leucyl-phenylalanine (fMLF)- or phorbolmyristate acetate (PMA)-stimulated neutrophils, in a concentration-dependent manner. CCPAE also inhibited superoxide anion generation; and did not scavenge H2O2 and superoxide anions nor inhibited MPO activity in vitro suggesting that it inhibits nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. In vivo studies showed that CCPAE attenuated LPS-induced lung inflammation in mice. This study shows that CCPAE inhibits neutrophil ROS production and attenuates LPS-induced lung inflammation in mice. Inhibition of NADPH oxidase activation by CCPAE could explain its anti-inflammatory action. Key words: Citrullus colocynthis, colocynth, inflammation, neutrophils, reactive oxygen species (ROS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase.
Highlights
Citrullus colocynthis (L.) Schrad. (Cucurbitaceae), commonly known as “bitter apple” is a plant that grows abundantly in Tunisia (Pottier-Alapetite, 1981), and widely in other parts of the world (Abbes el al., 2006)
Production, human neutrophils were incubated with different colocynthis peel aqueous extract (CCPAE) concentrations and reactive oxygen species (ROS) were detected by luminol-amplified chemiluminescence
As fMLF and phorbolmyristate acetate (PMA) activate neutrophils through different transduction pathways, these results suggested that CCPAE decreases neutrophil ROS production by either inhibiting a final common target, such as the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase or MPO, or by scavenging ROS
Summary
Citrullus colocynthis (L.) Schrad. (Cucurbitaceae), commonly known as “bitter apple” is a plant that grows abundantly in Tunisia (Pottier-Alapetite, 1981), and widely in other parts of the world (Abbes el al., 2006). Med. Plants Res. oedema bacterial infections, cancer and diabetes, and as an abortifacient (Abbes el al., 2006). The ethnobotanical uses of this plant include its use as cathartic, purgative and vermifuge, and for the treatment of fever, cancer, amenorrhea, jaundice, leukemia, rheumatism and tumour (Abbes el al., 2006). The ethnobotanical use efficiency of this plant was consolidated by a number of studies which demonstrated that C. colocynthis Schrad has a potent anti-tumour (Tannin-Spitz et al, 2007), anti-microbial (Marzouk et al, 2009, 2010a) and antioxidant activity (Marzouk et al, 2010b). Many secondary metabolites from C. colocynthis, including cucurbitacins, flavonoids, caffeic acid derivatives and terpenoids, have been previously reported (Yankov and Hussein, 1975; Hatam et al, 1989; Maatooq et al, 1997) and could explain the biological activity of this plant
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