•This study assesses optimal criteria for considering heat generation in porous media.•Fluid flow through a cylinder filled with porous media is investigated by DBF model.•Velocity, viscous ...dissipation heating and temperature distributions are presented.•The influence of dimensionless numbers on viscous dissipation is examined.•Relevant maps can exert significant criteria for the assessment of heat generation.
A numerical study of viscous dissipation heat generation by an incompressible fluid through an adiabatic cylinder filled with a porous medium is carried using Darcy-extended Brinkman–Forchheimer model and taking into account the porosity variation. The energy transport model is based on the local non-thermal equilibrium assumption with consideration of viscous dissipation effects. Dimensionless equations of the problem are solved numerically. Velocity, viscous dissipation heating and temperature distributions are presented and analyzed. The influence of various parameters on the temperature field and viscous dissipation distribution is investigated and examined throughout this paper. It is found that viscous dissipation resulted in significant generation of heat for lower Reynolds number and Darcy number and for high Eckert number. All of the ranges are implicitly clarified within pertinent maps. The temperature difference between fluid and solid phases is also performed incorporating the effect of various parameters.
A set of measurements have been carried out in order to determine the activity-levels in some powdered milks available in Tunisia. The study has shown that the average activity is about 160 ± 19 and ...2.26 ± 0.5 Bq/kg respectively for
40
K and
137
Cs, whereas it is below the detection limit for
226
Ra and
232
Th. The mean annual ingestion dose is about 102 and 225
μ
Sv
/
y
for respectively ≤ 1 year and 1–2 years old infants. The calculation of the radiological risk show that no significant threat on the infant’s health due to consumption of these milks.
Antioxidant activity of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside, isolated from the leaves of Myrtus communis, was determined by the ability of each compound to inhibit xanthine oxidase ...activity, lipid peroxidation and to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl. Antimutagenic activity was assessed using the SOS chromotest and the Comet assay. The IC50 values of lipid peroxidation by myricetin-3-o-galactoside and myricetin-3-o-rhamnoside are respectively 160μg/ml and 220μg/ml. At a concentration of 100μg/ml, the two compounds showed the most potent inhibitory effect of xanthine oxidase activity by respectively, 57% and 59%. Myricetin-3-o-rhamnoside was a very potent radical scavenger with an IC50 value of 1.4μg/ml. Moreover, these two compounds induced an inhibitory activity against nifuroxazide, aflatoxine B1 and H2O2 induced mutagenicity. The protective effect exhibited by these molecules was also determined by analysis of gene expression as response to an oxidative stress using a cDNA micro-array. Myricetin-3-o-galactoside and myricetin-3-o-rhamnoside modulated the expression patterns of cellular genes involved in oxidative stress, respectively (GPX1, TXN, AOE372, SEPW1, SHC1) and (TXNRD1, TXN, SOD1 AOE372, SEPW1), in DNA damaging repair, respectively (XPC, LIG4, RPA3, PCNA, DDIT3, POLD1, XRCC5, MPG) and (TDG, PCNA, LIG4, XRCC5, DDIT3, MSH2, ERCC5, RPA3, POLD1), and in apoptosis (PARP).
Objective: Fractionation of ethyl acetate extract (EA) obtained from Nitraria retusa leaves was assessed using different methods of chromatography, and isorhamnetin3‐O‐rutinoside (I3‐O‐R) was ...isolated from this extract. Its structure was determined using data obtained from 1H and 13C NMR spectra, as well as by various correlation experiments (COSY, HMQC and HMBC). Both EA extract and I3‐O‐R were investigated for their ability to induce apoptosis in human chronic myelogenous erythroleukaemia cells (K562).
Materials and methods: Apoptosis of cells from the K562 line was detected by DNA fragmentation, PARP cleavage and by evaluating activities of caspases 3 and 8.
Results: Apoptosis, revealed by DNA fragmentation and PARP cleavage, was observed after 48‐h incubation of these human myelogenous erythroleukaemia cells (K562), with the tested products. Likewise, caspase 3 and caspase 8 activities were induced in the presence of the EA extract and I3‐O‐R after 48 h of incubation.
Conclusion: Our results strongly suggest the involvement of the extrinsic pathway of apoptosis in cells treated by both the original EA extract and its major component, I3‐O‐R.
The aqueous, ethyl acetate, methanolic and Total Oligomer Flavonoids (TOF) enriched extracts, obtained from the aerial parts of
Cyperus rotundus, were investigated for their contents in phenolic ...compounds. Antioxidative activity using the NBT/riboflavin assay system, antimicrobial activity against Gram positive and Gram negative bacterial reference strains as well as antigenotoxic activity tested with the SOS chromotest assay were also studied. Significant antibacterial activity against reference strains;
Staphylococcus aureus,
Enterococcus faecalis,
Salmonella enteritidis and
Salmonella typhimurium, was detected in the presence of ethyl acetate and TOF enriched extracts. In addition to their antimicrobial activity, the same extracts showed a significant ability to inhibit nitroblue tetrazolium reduction by the superoxide radical in a non enzymatic O
2
.− generating system, and were also able to reduce significantly the genotoxicity induced by nifuroxazide and Aflatoxin B1. The antioxidant, antimicrobial and antigenotoxic activities exhibited by
C. rotundus depend on the chemical composition of the tested extracts.
► We determined phenolic content of
C. rotundus aerial part extract. ► Significant antibacterial activity was detected with ethyl acetate and TOF enriched extracts. ► Same extracts showed a significant ability to inhibit superoxide radicals. ► These extracts were able to reduce significantly the genotoxicity induced by genotoxic AFB1 and NF. ► We established correlations between tested activities and chemical composition.
Objectives: Poor therapeutic results have been reported for treatment of malignant melanoma; therefore in this study we have investigated inhibitory capacity of ethyl acetate, chloroform (Chl) and ...methanol extracts from Moricandia arvensis on mouse melanoma (B16‐F0) and human keratinocyte (HaCaT) cell proliferation. Influence of Chl extract on percentage distribution in cell cycle phases and melanogenesis was also studied.
Material and methods: Cell viability was determined at various periods using the MTT assay, and flow cytometry was used to analyse effects of Chl extract on progression through the cell cycle and apoptosis. In addition, amounts of melanin and tyrosinase were measured spectrophotometrically at 475 nm.
Results: Chl extract exhibited significant anti‐proliferative activity after incubation with the two types of tumour skin cells. Morphological changes in B16‐F0 cells, accompanied by increase of tyrosinase activity, and of melanin synthesis were observed, which are markers of differentiation of malignant melanoma cells. Furthermore, cell cycle analysis revealed that B16‐F0 cells treated with Chl extract were arrested predominantly in G1 phase.
Conclusion: Chl extract had the ability to reverse malignant melanoma cells from proliferative to differentiated state, thus providing a new perspective in developing novel strategies for prevention and treatment of malignant melanoma, possibly through consumption of the extract in an appropriate cancer prevention diet. Moreover, there is scope for the extract being introduced into cosmetic products as a natural tanning agent.
Résumé: Connue pour ses propriétés médicinales, aromatiques ou culinaires, la famille des Lamiacées présente un intérêt économique majeur, notamment comme source d’huiles essentielles. Dans le cadre ...de l’étude de la biodiversité de la flore algérienne, l’analyse phytochimique et la recherche des activités biologiques des parties aériennes de Marrubium deserti de Noé ont été entreprises. L’extraction par des solvants de polarité croissante tels que le dichlorométhane, l’acétate d’éthyle et le butanol, puis la purification des extraits obtenus ont permis d’isoler et d’identifier à ce jour un diterpène original de type labdane, un flavonoïde et des phénylpropanoïdes glycosylés. Les extraits et les composés isolés ont fait l’objet d’une étude biologique comme antioxydants, antibactériens et antigénotoxiques.
Abstract: Known for its medicinal, aromatic or culinary properties, the Lamiaceae family represents a major economic interest, in particular as a source of essential oils. The purpose of this research concerns the phytochemical and the biological study of one of the Algerian flora’s medicinal plants known as Marrubium deserti de Noé. The extraction by solvents of increasing polarity: dichloromethane, ethyl acetate and butanol led to the isolation and identification of a novel labdane-type diterpene, a flavonoid and phenylpropanoid glycosides. Extracts and pure compounds were tested as antioxidant, antibacterial as well as antigenotoxic.
The effect of extracts from leaves of
Myrtus communis on the SOS reponse induced by Aflatoxin B1 (AFB1) and Nifuroxazide was investigated in a bacterial assay system, i.e. the SOS chromotest with
...Escherichia coli PQ37. Aqueous extract, the total flavonoids oligomer fraction (TOF), hexane, chloroform, ethyl acetate and methanol extracts and essential oil obtained from
M. communis significantly decreased the SOS response induced by AFB1 (10
μg/assay) and Nifuroxazide (20
μg/assay). Ethyl acetate and methanol extracts showed the strongest inhibition of the induction of the SOS response by the indirectly genotoxic AFB1. The methanol and aqueous extracts exhibited the highest level of protection towards the SOS-induced response by the directly genotoxic Nifuroxazide. In addition to anti-genotoxic activity, the aqueous extract, the TOF, and the ethyl acetate and methanol extracts showed an important free-radical scavenging activity towards the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. These results suggest the future utilization of these extracts as additives in chemoprevention studies.
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