Antioxidant and antibacterial activities of Artemisia absinthium and Citrus paradisi extracts repress viability of aggressive liver cancer cell line.

BACKGROUND: Numerous reports show that herbal medicines can be utilized in the treatment of different liver disorders. In this study, antioxidant, antibacterial, and anticancer activities of individual as well as combined 80% ethanolic extracts of Artemisia absinthium leaves and Citrus paradisi peels were investigated. METHODS AND RESULTS: Values of total phenolic contents (TPC), total flavonoid contents (TFC), DPPH-radical scavenging activity, and ferric reducing antioxidant power (FRAP) were measured to explore the antioxidant capacity. To assess antibacterial activity, four bacterial strains (Escherichia coli, Staphylococcus aureus, Salmonella enterica, and Klebsiella pneumoniae) were used. Anticancer activity was assessed on Huh-7 (liver cancer) and Vero (non-cancerous) cell lines. FRAP activity of combined plants extract was higher as compared to their individual effect; the trend did not hold in the case of DPPH-radical scavenging activity. Antibacterial activity of combined extracts by disk diffusion method was observed only against E.coli. MTT results indicated that both plants had a cytotoxic effect on Huh-7 cell line but did not show any effect on Vero cell line. Our data showed a strong negative correlation between the amount of TPC, TFC, & DPPH radicals-scavenging activity and viability of Huh-7 cell line.However, no effect was shown on the non-cancerous cell line. CONCLUSION: The ethanolic extracts of Artemisia absinthium leaves and Citrus paradisi peels can be used against liver cancer because of their antioxidant, antibacterial, and anticancer activities.

Variation in Key Flavonoid Biosynthetic Enzymes and Phytochemicals in 'Rio Red' Grapefruit (Citrus paradisi Macf.) during Fruit Development.

In the current study, the phytochemical contents and expression of genes involved in flavonoid biosynthesis in Rio Red grapefruit were studied at different developmental and maturity stages for the first time. Grapefruit were harvested in June, August, November, January, and April and analyzed for the levels of carotenoids, vitamin C, limonoids, flavonoids, and furocoumarins by HPLC. In addition, genes encoding for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), and 1,2-rhamnosyltransferase (2RT) were isolated, and their expression in grapefruit juice vesicles was studied. Fruit maturity had significant influence on the expression of the genes, with PAL, CHS, and CHI having higher expression in immature fruits (June), whereas 2RT expression was higher in mature fruits (November and January). The levels of flavonoids (except naringin and poncirin), vitamin C, and furocoumarins gradually decreased from June to April. Furthermore, limonin levels sharply decreased in January. Lycopene decreased whereas ß-carotene gradually increased with fruit maturity. Naringin did not exactly follow the pattern of 2RT or of PAL, CHS, and CHI expression, indicating that the four genes may have complementary effects on the level of naringin. Nevertheless, of the marketable fruit stages, early-season grapefruits harvested in November contained more beneficial phytochemicals as compared to mid- and late-season fruits harvested in January and April, respectively.

Identification, recombinant expression, and biochemical characterization of a flavonol 3-O-glucosyltransferase clone from Citrus paradisi.

Glucosylation is a predominant flavonoid modification reaction affecting the solubility, stability, and subsequent bioavailability of these metabolites. Flavonoid glycosides affect taste characteristics in citrus making the associated glucosyltransferases particularly interesting targets for biotechnology applications in these species. In this work, a Citrus paradisi glucosyltransferase gene was identified, cloned, and introduced into the pET recombinant protein expression system utilizing primers designed against a predicted flavonoid glucosyltransferase gene (AY519364) from Citrus sinensis. The encoded C. paradisi protein is 51.2 kDa with a predicted pI of 6.27 and is 96% identical to the C. sinensis homologue. A number of compounds from various flavonoid subclasses were tested, and the enzyme glucosylated only the flavonol aglycones quercetin (K(m)(app)=67 microM; V(max)=20.45 pKat/microg), kaempferol (K(m)(app)=12 microM; V(max)=11.63 pKat/microg), and myricetin (K(m)(app)=33 microM; V(max)=12.21 pKat/microg) but did not glucosylate the anthocyanidin, cyanidin. Glucosylation occurred at the 3 hydroxyl position as confirmed by HPLC and TLC analyses with certified reference compounds. The optimum pH was 7.5 with a pronounced buffer effect noted for reactions performed in Tris-HCl buffer. The enzyme was inhibited by Cu(2+), Fe(2+), and Zn(2+) as well as UDP (K(i)(app)=69.5 microM), which is a product of the reaction. Treatment of the enzyme with a variety of amino acid modifying compounds suggests that cysteine, histidine, arginine, tryptophan, and tyrosine residues are important for activity. The thorough characterization of this C. paradisi flavonol 3-O-glucosyltransferase adds to the growing base of glucosyltransferase knowledge, and will be used to further investigate structure-function relationships.

Potentiation of the antiinflammatory effect of Anacardium occidentale (Linn.) stem-bark aqueous extract by grapefruit juice.

In an attempt to scientifically appraise some of the ethnomedical uses of Anacardium occidentale Linn. (family: Anacardiaceae), the present study was undertaken to examine the antiinflammatory effect of the plant's stem-bark aqueous extract in rats. Young adult male Wistar rats weighing 250-300 g were used. The antiinflammatory effect of A. occidentale stem-bark aqueous extract alone and in combination with grapefruit (Citrus paradisi Macf.) juice was investigated on fresh egg albumin-induced rat paw edema. Like diclofenac (100 mg/kg p.o.), aqueous extract of A. occidentale stem-bark (800 mg/kg p.o.) produced time-related, sustained and significant reduction (p < 0.05-0.001) of the fresh egg albumin-induced acute inflammation of the rat hind paw. However, the antiinflammatory effect of the plant extract was found to be approximately 8-15 times less than that of diclofenac. Coadministration of grapefruit juice (5 ml/kg p.o.) with A. occidentale stem-bark aqueous extract (800 mg/kg p.o.) or diclofenac (100 mg/kg p.o.) significantly potentiated (p < 0.05-0.001) the antiinflammatory effects of the crude plant extract and diclofenac on fresh egg albumin-induced rat paw edema. Although A. occidentale stem-bark aqueous extract is less potent than diclofenac as an antiinflammatory agent, the results of this experimental animal study indicate that the plant extract possesses antiinflammatory activity, and thus lend pharmacological support to the folkloric use of the plant in the management and/or control of arthritis and other inflammatory conditions among the Yoruba-speaking people of western Nigeria.