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In vitro immunomodulating properties of selected Sudanese medicinal plants

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In vitro immunomodulating properties of selected Sudanese medicinal plants
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   Journal of Ethnopharmacology 118 (2008) 26–34 Contents lists available at ScienceDirect  Journal of Ethnopharmacology  journal homepage: www.elsevier.com/locate/jethpharm In vitro  immunomodulating properties of selected Sudanese medicinal plants W.S. Koko a , ∗ , M. Ahmed Mesaik b , S. Yousaf  c , M. Galal a , M. Iqbal Choudhary b , c a Medicinal and Aromatic Plants Research Institute, National Center for Research, P.O. Box 2404, Khartoum, Sudan b Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences,University of Karachi, Karachi - 75270, Pakistan c H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi - 75270, Pakistan a r t i c l e i n f o  Article history: Received 25 August 2006Received in revised form 4 February 2008Accepted 3 March 2008Available online 18 March 2008 Keywords: Sudanese medicinal plantsImmunomodulationChemiluminescenceOxidative burst a b s t r a c t Ethanolic extracts of 23 medicinal plants, commonly used in Sudanese folk medicines against infectiousdiseases, were investigated for their immunomodulating activity using luminol/lucigenin-based chemi-luminescence assay. Preliminary screenings on whole blood oxidative burst activity showed inhibitoryactivities of 14 plant extracts, while only one plant,  Balanites aegyptiaca  fruits exhibited a proinflam-matory activity. Further investigation was conducted by monitoring their effects on oxidative burst of isolated polymorphonuclear cells (PMNs) and mononuclear cells (MNCs) by using two different phago-cytosis activators (serum opsonizing zymosan-A and PMA). Results obtained showed that the fruits andbarks of   Acacia nilotica , and leaves and barks of   Khaya senegalensis , possess average inhibitory effects inthe range of 70.7, 67.1, 69.5 and 67.4% on both types of phagocytes (PMNs and MNCs), respectively, at a6.25  g/mL concentration. Moderate inhibitory activity (52.2%) was exerted by the aerial parts of   Xan-thium brasilicum , while the rest of the plants showed only a weak inhibitory activity. The inhibition of oxidative burst activity was found to be irreversible in most of the extracts, except for  Peganum harmala , Tephrosia apollinea ,  Tinospora bakis , and  Vernonia amygdalina . Interestingly, the fruits of   Balanites aegyp-tiaca  exhibited a moderate proinflammatory effect (37–40.4% increases in ROS level compared to thecontrol) at 25–100  g/mL concentration in the case of whole blood along with PMNs phagocyte activity.The Tinosporabakis extractshowedproinflammatoryresponseatalowconcentration(6.25  g/mL)duringactivationwithPMA.NoneoftheseextractsaffectedPMNsviability(90–98%)upon2hincubation,exceptof the ethanolic extracts of   Acacia nilotica  fruits and  Balanites aegyptiaca  barks.© 2008 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Manyclinicaldisordersareassociatedwiththeimmunesystem.Suppressionoftheimmunesystemisrequiredinthemanagementandtreatmentofinflammationandallergicdiseases,whilestimula-tionishighlydesirableforthetreatmentofHIV,immunodeficiencyand infectious diseases (Mesaik et al., 2004). Previously, Atal et al.  Abbreviations:  DMSO, dimethylsulfoxide; HBSS, Hanks Balance Salts Solution;HCV, hepatitis C virus; HIV, human immunodeficiency virus; IC 50 , inhibitory con-centration 50%; ICCS, International Center for Chemical Sciences, University of Karachi, Pakistan; LSM, Lymphocytes Separation Medium; MAPRI, Medicinal andAromatic Plants Research Institute, Khartoum, Sudan; MNCs, mononuclear cells;NADPH, reduced form of nicotinamide adenine dinucleotide phosphate; P, prob-ability (statistical evaluation); PKC, protein kinase C; PMA, phorbol 12-myristate13-acetate; PMNs, polymorphonuclear cells; RAW 264.7, mouse leukaemic mono-cytemacrophagecellline;RBCs,redbloodcells;RLU,readingperluminometerunit;ROS, reactive oxygen species; SOZ, serum opsonizing zymosan-A; TB, trypan blue;TNF-  , tumor necrosis factor alpha. ∗ Corresponding author. E-mail address:  wasyko2002@yahoo.com (W.S. Koko). (1986)andVanderNatetal.(1987)suggestedthatmanytherapeu- tic effects of plant extracts are mainly due to their influence on theimmune system of the human body.Only a few studies have been conducted to evaluate the medic-inal flora of Sudan for its potential immunomodulating properties.Mostofthepreviousstudieswerefocusedmainlyoninfectiousdis-eases.Severalbroad-basedscreeningsofmanySudanesemedicinalplants were conducted for their antibacterial, antifungal, antiviral,antimalarial, and anthelmintic properties (Khalid et al., 1986; ElTahir et al., 1999a,b; Hussein et al., 1999, 2000; Koko et al., 2000,2005; Elegami et al., 2001; Ali et al., 2002).In the present study, we have investigated the immunomod-ulating activities of 23 ethanolic extracts obtained from 20 plantspecies (Table 1). The main phytochemical classes of secondary metabolites, previously obtained from these plants, are also pre-sentedinTable1.Duringthisstudy,theseplantswerescreenedfor the inhibition of oxidative burst using luminol/lucigenin-inducedchemiluminescence technique. Comparison of PMA and SOZ acti-vators on immunodulation properties of these plants extract wasalso conducted. 0378-8741/$ – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved.doi:10.1016/j.jep.2008.03.007  W . S  .K  o k   o e  t   a l    . /   J   o ur  n a l    o f  E  t   h  n o p h  ar  m a c  o l    o g  y 1 1  8  (  2  0  0  8  )  2  6 – 3 4  2  7    Table 1 Sudanese medicinal plants screened for their potential immunomodulating properties, their major classes of secondary metabolites previously isolated and some of reported bioactivitiesScientific names Family Secondary metabolites Bioactivity Reference Part used % Yield S. no.Alk Anth Coum flav Lig Phe Sap Terp Tan Oth  Acacia nilotica  L.  Mimosaceae – – – 6 – 10 5 4 2 – Antiinflammatory,antimicrobialanthelminticChuabal et al., 2003 Fruits 35.56  1 Barks 21.30  2  Albizzia anthelmintica  Broongn. Mimoscasea – – – – – – 4 6 – – Anthelmintic Koko et al., 2000 Barks 07.87  3  Argemone mexicana  L. Nyctaginaceae 15 – – 8 – 4 4 7 – 5 – Whole plant 15.33  4  Aristolochia braceolata  Lam. Aristolochiaceae – – – – – – – – – – Antiinflammatory,estrogenicRoots 03.95  5  Balanites aegyptiaca  L.  Balanitaceae – – 2 5 – 5 11 17 – 3 Antiinflammatory,antimicrobialSperoni et al., 2004 Fruits 17.50  6 Barks 10.10  7 Cassia nigricans  Vahl. Caesalpinaceae – – – – – – – – – – – Whole plant 13.46  8 Citrullus colocynthis  L.  Cucurbitaceae – – – 5 – 4 2 13 – 3 Laxative, antitoxic Agrawal et al., 1994 Fruits 02.39  9 Geigeria alata  D.C.  Asteraceae – – – – – – – 2 – – – Whole plant 08.43  10 Hydnora abyssinica  A. Braun. Hydnoraceae – – – – – – – – – – – Whole plant 14.52  11 Hyphaene thebaica  L. Mart. Arecaceae – – – – – – – – – – – Fruits 34.06  12  Khaya senegalensis  Desr A.  Meliaceae – – – 2 – 11 6 25 – 4 Antimicrobial,antiprotozoalKayser and Abreu, 2001 Barks 07.56  13 Leaves 18.74  14 Nigella sativa  L. Ranunculaceae 18 – – – 3 7 4 14 – 9 Antimicrobial,antihistaminic,antiinflammatoryAhmed and Mahmud, 2006 Seeds 14.84  15 Ocimum basilicum  L  . Lamiaceae – – – – – 2 – 4 – 2 Insecticidal Chokechaijaroenporn et al., 1994 Arial part 07.19  16  Peganum harmala  L.  Zygophyllaceae 33 4 2 12 – 16 9 19 – 8 Antimicrobial, CNSstimulantShahverdi et al., 2005 Seeds 05.22  17  Sonchus oleraceus  L  . Asteraceae – – – – – – 1 4 – – – Whole plant 10.77  18 Tephrosia apollinea  D. C.  Papilionaceae – – – 7 – 4 – 5 – 2 – Whole plant 08.25  19 Tinospora bakis  A. Rich. Miers  Menispermaceae – – – – – – – – – – – Roots 05.48  20 Vernonia amygdalina  Del.  Asteraceae – – – – – 4 1 12 – 3 Antimicrobial Newbold et al., 1997 Leaves 06.70  21  Xanthium brasilicum  Waller.  Asteraceae – – – 6 – 10 5 4 2 – Antioxidant Kim et al., 2005 Leaves 21.73  22  Ximenia americana  L. Olacaceae – – – – – – 4 6 – – – Leaves 05.93  23 Source : Dictionary of Natural Products (2005) Chapman and Hall CRC FL 33487 USA.Table key (secondary metabolite classes): Alk=alkaloids, Anth=Anthraquinones, Coum=Coumarins, flav=flavonoids, Lig=Lignins, Phe=Phenols, Sap=Saponins, Terp=Terpenes, Tan=Tannins, Oth=Others.The active plants were written in bold.The S. no. used as code for the above mentioned plant ethanolic extract in all coming tables and figures.  28  W.S. Koko et al. / Journal of Ethnopharmacology 118 (2008) 26–34 2. Material and methods  2.1. Reagents, chemicals, and equipments Luminol (3-aminophthalhydrazide) was purchased fromResearch Organics, while lucigenin (bis- N  -methylacridiniumnitrate) and Hanks Balance Salts Solution (HBSS) were purchasedfromSigma,Germany.LymphocytesSeparationMedium(LSM)waspurchased from MP Biomedicals, Inc., Germany. Zymosan-A ( Sac-charomyces cerevisiae  srcin) and phorbol 12-myristate 13-acetate(PMA) were purchased from Fluka (BioChemika). Dimethylsulfox-ide (DMSO), ethanol and ammonium chloride of analytical gradeswere purchased from Merck Chemicals, Darmstadt, Germany. TheLuminometer used was Luminoskan RS.  2.2. Plant material Theselectedplantspecies(seeTable1)werecollectedbetween  January and April 2005 from their natural habitats in the centralpartofSudan.ThevoucherspecimenswereidentifiedbyDr.Wai’lS.Abdalla and Mr. Haidar Elsidig of Herbarium of Medicinal and Aro-matic Plants Research Institute (MAPRI), Khartoum, Sudan, wherethe specimens were also deposited.  2.3. Preparation of the crude extract  Hundred grams of each plant material were air-dried under theshed, grounded, and extracted by triple soaking in 80% ethanol atroom temperature for 3 days. Extracts were obtained by remov-ing the organic solvent under reduced pressures, followed by thecalculation of the % yield obtained (Table 1).  2.4. Bioassay techniques 2.4.1. Isolation of human polymorphoneutrophils (PMNs) andmononuclear cells (MNCs) Heparinized blood was obtained by vein puncture asepticallyfrom healthy volunteers (25–38 years age). The buffy coat con-taining PMNs and MNCs was collected by dextran sedimentationandthecellswereisolatedaftertheLSMdensitygradientcentrifu-gation. MNCs were separated gently by collecting them from theplasma–ficollinterfaceusingpasteurpipette,whilePMNSwerecol-lectedfromthetubebase.Cellswerewashedtwiceandsuspendedin Hank’s Balance Salt Solution [Ca and Mg free] (HBSS −− ), pH 7.4.Neutrophils were purified from RBCs contamination using hypo-tonic solution. Cells were adjusted to their required concentrationusing Hank’s Balance Salt Solution containing Ca and Mg (HBSS ++ ).  2.4.2. Chemiluminescence assay Luminolorlucigenin-enhancedchemiluminescenceassaywereperformed as described by Helfand et al. (1982) and Haklar et al. (2001). Briefly, 25  L diluted whole blood (1:50 dilution in sterileHBSS ++ ) or 25  L of PMNCs (1 × 10 6 ) or MNCs (5 × 10 6 ) cells wereincubated with 25  L of serially diluted plant extract with concen-trationrangesbetween6.25and100  g/mL.ControlwellsreceivedHBSS ++ and cells but no extract. Tests were performed in white96 wells plates, which were incubated at 37 ◦ C for 30min in thethermostatedchamberoftheluminometer.Opsonizedzymosan-Aor PMA 25  L, followed by 25  L luminol (7 × 10 5 M) or lucigenin(0.5mM) along with HBSS ++ was added to each well to obtain a200  L volume/well. The luminometer results were monitored aschemiluminescence RLU with peak and total integral values setwithrepeatedscansat30sintervalsand1spointsmeasuringtime.  2.4.3. Effect of extracts on cell response Cellswerewashedafter30minincubationwiththetestedplantextracts HBSS ++ . Cells were activated using SOZ and then scannedfor oxidative burst, as described in Section 2.4.2.  2.4.4. Cells viability Cellsviabilitywasdeterminedbyusingthestandardtrypanblue(TB) exclusion method. PMNs (1 × 10 6 ) were incubated for 60 and120min with 100 or 50  g/mL of plant extracts, each in triplicateatroomtemperature.Asthebluedyeuptakeisanindicationofcelldeath, the percentage viability was calculated from the total cellcounts.  2.5. Statistical analysis Student’s  t  -test was performed to compare the significancemean differences between the control and tested extracts for var-ious chemiluminescence results. The differences were consideredto be significant at levels of   P  ≤ 0.05. 3. Results The preliminary screening results of the whole blood showedthat out of the 23 ethanolic extracts, only 14 exhibited signifi-cant inhibitory activity at the initial screening doses (25, 50 and100  g/mL). These were, namely the fruits of   Acacia nilotica , and Citrullus colocynthis , barks of   Acacia nilotica ,  Balanites aegyptiaca ,and  Khaya senegalensis , leaves of   Khaya senegalensis , and  Ver-nonia amygdalina , seeds of   Peganum harmala , roots of   Tinosporabakis , aerial part of   Ocimum basilicum ,  Sonchus oleraceus , and  Xan-thium brasilicum , and whole plants of   Geigeria alata , and  Tephrosiaapollinea ,whilethefruitsof  Balanites aegyptiaca showedaremark-able increase in cell oxidative burst response (proinflammatory)(Table 2).All of these 15 extracts were further investigated for theireffects on zymosan-A activated neutrophils (PMNs). All theextracts showed a dose-dependant effect with >90% inhibition atthe highest concentration (100  g/mL), except for  Peganum har-mala  (62%). Moderate inhibitory activities of   Tephrosia apollinea , Peganum harmala , leaves of   Khaya senegalensis  and  Tinosporabakis  (61.2, 59.2, 57.9 and 54.8%, respectively) were recorded at6.25  g/mL concentrations. The rest of the extracts were observedto possess less than 50% inhibition activity at this concentration(Fig. 1).A similar experiment was performed after the removal of theplant extracts by washing, in order to check if this reduction incells activities is reversible or not. Some of the plants were foundto be less active such as  Peganum harmala  (25–3.5% inhibition), Tephrosia apollinea  (61–32% inhibition),  Tinospora bakis  (54–13%inhibition)and Vernoniaamygdalina (50–29%inhibition).However,the remaining extracts were found to have no effect on the cellresponse (Fig. 2).With the use of PMA, a protein kinase C (PKC) activator, thepotent inhibitory activity was observed with the fruits and barksextractsof   Acacianilotica andbarksandleavesof  Khayasenegalensis (84.0, 75.6, 81.6, and 81.1%, respectively) at 6.25  g/mL concentra-tion.Amoderateactivitywasalsoobservedinthecaseof   Xanthiumbrasilicum  (55.7%) and  Geigeria alata  (52.6%) at similar concentra-tion. However, the rest of the extracts showed a weak inhibitoryactivity (Fig. 3).In another set of experiments, luminol was substituted withlucigenin. The highest inhibitory activity was exhibited by thefruits and barks of   Acacia nilotica , barks and leaves of   Khaya sene- galensis , and  Xanthium brasilicum  (95.9, 90.7, 90.9, 81.2, and 85.7%,respectively), while a moderate activity was observed in the case  W.S. Koko et al. / Journal of Ethnopharmacology 118 (2008) 26–34  29  Table 2 Screening of the selected Sudanese medicinal plant extracts using whole blood for their immunomodulating inhibitory propertiesS. no. Con. RLU mean ± S.D. Inh. % S. no. Con. RLU mean ± S.D. Inh. % 1 100 61.3  ±  11.8 93.0 * 13 100 79.8  ±  7.1 90.8 * 50 156.3  ±  15.1 82.1 * 50 300.0  ±  2.8 65.6 * 25 225.0  ±  35.4 74.2 * 25 331.0  ±  26.9 62.1 * 2 100 104.5  ±  44.6 88.0 * 14 100 180.6  ±  3.5 79.3 * 50 250.5  ±  71.4 71.3 * 50 232.6  ±  12.6 73.3 * 25 330.5  ±  27.6 62.1 * 25 255.8  ±  3.6 70.7 * 3 100 576.4  ±  68.7 33.9 15 100 885.6  ±  34.7  − 1.550 717.0  ±  23.5 17.8 50 1030.4  ±  62.5  − 18.125 857.0  ±  39.0 1.7 25 870.3  ±  63.5 0.2 4 100 580.1  ±  12.2 33.5 16 100 204.2  ±  0.6 76.6 * 50 863.3  ±  25.9 1.0 50 227.5  ±  5.2 73.9 * 25 971.0  ±  8.9  − 11.3 25 256.2  ±  16.2 70.6 * 5 100 860.5  ±  25.0 1.4 17 100 163.3  ±  13.6 81.3 * 50 887.6  ±  26.9  − 1.8 50 205.3  ±  6.8 76.5 * 25 1037.6  ±  273.5  − 18.9 25 270.5  ±  3.9 69.0 * 6 100 1201.5  ±  173.2  − 37.7 * 18 100 135.3  ±  9.7 84.5 * 50 1152.5  ±  10.6  − 32.1 * 50 187.9  ±  20.1 78.5 * 25 1224.5  ±  12.0  − 40.4 * 25 279.0  ±  30.1 68.0 * 7 100 206.0  ±  12.7 76.4 * 19 100 159.9  ±  15.5 81.7 * 50 312.5  ±  3.5 64.2 * 50 195.0  ±  16.5 77.6 * 25 375.0  ±  7.1 57.0 * 25 265.0  ±  24.6 69.6 * 8 100 376.9  ±  12.9 56.8 20 100 163.6  ±  26.2 81.2 * 50 672.4  ±  15.8 22.9 50 192.9  ±  14.6 77.9 * 25 918.3  ±  72.8  − 5.3 25 216.9  ±  5.5 75.1 * 9 100 78.3  ±  10.4 91.0 * 21 100 117.5  ±  1.9 86.5 * 50 119.1  ±  1.2 86.4 * 50 189.2  ±  7.8 78.3 * 25 392.8  ±  4.0 55.0 * 25 233.6  ±  8.4 73.2 * 10 100 96.8  ±  11.4 88.9 * 22 100 92.9  ±  5.7 89.4 * 50 287.5  ±  3.5 67.0 * 50 104.9  ±  3.6 88.0 * 25 313.5  ±  2.1 64.1 * 25 179.9  ±  34.0 79.4 * 11 100 87.5  ±  32.7 90.0 23 100 777.4  ±  5.8 10.950 347.9  ±  308.2 60.1 50 837.1  ±  23.6 4.025 675.9  ±  482.4 22.5 25 900.7  ±  41.8  − 3.2 12 100 739.9  ±  71.8 15.2Control 872.3 ±  83.650 904.8  ±  68.8  − 3.725 899.5  ±  69.7  − 3.1Con.=concentration. Inh.%=inhibition%. * Extracts selected for further investigation due to their significant activity at all concentrations tested.Control: the cells incubated with activator (SOZ) with no extract. ** Keyforthebotanicalname(S.no.):1=  Acacianilotica (fruits),2=  Acacianilotica (barks),3=  Albizziaanthelmintica 4=  Argemonemexicana 5=  Aristolochiabraceolata 6= Balanitesaegyptiaca  (fruits), 7= Balanites aegyptiaca  (bark), 8= Cassia nigricans  9= Citrullus colocynthis  10= Geigeria alata  11= Hydnora abyssinica  12= Hyphaena thebaica  13= Khayasenegalensis (bark),14= Khayasenegalensis (leaves),15= Nigellasativa 16= Ocimumbasilicum 17= Peganumharmala 18= Sonchusoleraceus 19= Tephrosiaapollinea 20= Tinosporabakis  21= Vernonia amygdalina  22=  Xanthium brasilicum  23=  Ximenia americana . Note : this key is also used in Figs. 1–6. of   Ocimum basilicum ,  Citrullus colocynthis , and  Tephrosia apollinea extracts (62.1, 61.8, and 61.0%, respectively) at 6.25  g/mL concen-tration. All the tested plant extracts at the highest concentration(100  g/mL) exerted more than 90% inhibitory activity, except for Peganum harmala  (75%),  Tinospora bakis  (47%), and  Vernonia amyg-dalina  (88%) with the use of lucigenin (Fig. 4).Furthermore, all these 15 extracts were also tested for theireffects on mononuclear cells (Fig. 5) by using serum opsonized zymosan-A (SOZ) and the luminol-based chemiluminescenceassays.  Acacia nilotica  fruits extract was found to have the high-est inhibitory activity (81.9%), while moderate inhibitory activitieswereexhibitedby  Acacianilotica barks(66.9%),leavesof  Khayasene- galensis  (64.4%), and  Xanthium brasilicum  (62%) at a 6.25  g/mL concentration. Whereas, the remaining extracts showed no sig-nificant effect at the same concentration. However, at 100  g/mL concentration, majority of the extracts showed >90% inhibitoryactivity, except for  Ocimum basilicum ,  Peganum harmala ,  Sonchusoleraceus ,  Tephrosia apollinea ,  Tinospora bakis , and  Vernonia amyg-dalina , which showed 56, 64, 39, 53, 73 and 59% inhibition,respectively.Interestingly, the extract of   Balanites aegyptiaca  was found topossess a stimulatory activity with the use of PMA (50–24%cell activation). However, this stimulation was less whenzymosan-A (31–1% cell activation) was used with PMNs(Figs. 1, 3 and 4).All plants ethanolic extracts (only those which posses cellinhibitoryactivity)wereincubatedfor2hwithneutrophils(Fig.6).Cells were found viable (>90%) after 2h of incubation, while  Oci-mum basilicum , and  Tephrosia apollinea  showed less cytotoxicityupon increase in the incubation time ( ∼ 60–70% cell viability) at50 and 100  g/mL concentrations. However, fruits of   Acacia nilot-ica , and barks of   Balanites aegyptiaca  were found to be cytotoxic toneutrophils after the second hour of incubation, as they showed 1and 31% cell viability, respectively.  30  W.S. Koko et al. / Journal of Ethnopharmacology 118 (2008) 26–34 Fig. 1.  Inhibitory properties of the tested plant ethanolic extracts. PMNs cells were activated by SOZ (luminol-based). Each bar represents a mean triplicate reading.  Note :For all botanical names refer to the key in Table 2. 4. Discussion Plants remain one of the main sources of natural products fornewtherapies(Fransworth,1990).Inthecurrentstudy,23ethanolic extracts of 20 different Sudanese plants with ethnomedici-nal uses, were tested for their immunomodulatory properties in vitro .In this study we employed two probes (luminal and lucigenin)that were capable of detecting the level of reactive oxygen species(ROS)tostudyeffectoftheseplantextractonoxidativeburst.Lumi-nol is characterized by its ability to enter the cell and reacts withintracellularROS(DahlgrenandBriheim,1985;Allen,1986).Onthe other hand, the second probe, lucigenin does not exhibit the abil-ity to enter the phagocytic cells due to its high molecular weight,and therefore, can react only with the extracellular ROS, which ismainly superoxide radicals (Dahlgren and Briheim, 1985; Meneseset al., 2005) (Fig. 7). The extracts of   Tinospora bakis  showed inhibitory activitiesbetween 55 and 91% (IC 50 <6.25  g/mL) with zymosan-A and10–68%(IC 50 =42 ± 3.6  g/mL)whenPMAwasused.Thisinhibitoryactivitycouldbeduetotheabilityoftheextractstoblockthecom-plement receptors, consequently inhibiting NADPH oxidase, a cellmembraneassociatedenzyme.Aszymosan-Aactivatesphagocytesbybindingtocomplementreceptortype3onthecellsurface.This, Fig.2.  Inhibitorypropertiesofthetestedplantethanolicextracts,followedbywashingoftheextracts.PMNscellswereactivatedbySOZ(luminol-based).Eachbarrepresentsa mean triplicate reading.  Note : For all botanical names refer to the key in Table 2.
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