scholarly journals Alkyl Length Effects on the DNA Transport Properties of Cu (II) and Zn(II) Metallovesicles: An In Vitro and In Vivo Study

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Itizia Z. Arroyo ◽  
Clarissa Gomez ◽  
Hugo Alarcon ◽  
Araceli Jimenez ◽  
Andrew Pardo ◽  
...  

Cationic liposomes with DNA-transportation properties have attracted considerable attention for their ability to deliver medicinal oligonucleotides to mammalian cells. Amongst these are metalloliposomes that use transition metal ions to confer the lipid molecules cationic charge and unique advantages such as redox- and ligand-exchange triggered DNA-release properties. In this study, lipophilic copper (II) and zinc (II) complexes of 1-alkyl-1,4,7-triazacyclononane were prepared to investigate their ability to bind and transfect double stranded DNA with mammalian cells in vitro and in vivo. The copper(II)-surfactant complexes Cu(TACN-C8)2 (1), Cu(TACN-C10)2 (2), Cu(TACN-C12)2 (3), Cu(TACN-C14)2 (4), Cu(TACN-C16)2 (5), and Cu(TACN-C18)2 (6) that comprise ligands that vary in the length of the alkyl group and the zinc (II)-surfactant complex of Zn(TACN-C12)2 (7) were synthesized. The critical micelle concentration (CMC) for 1-7 was measured using fluorescence spectroscopy and an evaluation of the transfection efficiency of the complexes was assessed using the pEGFP-N1 plasmid and HEK 293-T cells. An inverse relationship between DNA transfection efficiency and CMC of the Cu(II) metallosurfactants was observed. The highest transfection efficiency of 38% was observed for Cu(TACN-C12)2 corresponding to the surfactant with dodecyl alkyl chain having a CMC of 50 μM. Further, an in vivo experiment using mice models was conducted to test the Cu(TACN-C12)2 (3) and Zn(TACN-C12)2 (7) metallosurfactants delivering a DNA vaccine designed for protection against leishmaniasis disease and the study revealed that the Cu-lipoplex elicited the production of significantly more T cells than the Zn-lipoplex and the control group in vivo.

Blood ◽  
1999 ◽  
Vol 93 (9) ◽  
pp. 3140-3147 ◽  
Author(s):  
Joshua A. Grass ◽  
Tamim Wafa ◽  
Aaron Reames ◽  
David Wages ◽  
Laurence Corash ◽  
...  

Abstract Photochemical treatment (PCT) with the psoralen S-59 and long wavelength ultraviolet light (UVA) inactivates high titers of contaminating viruses, bacteria, and leukocytes in human platelet concentrates. The present study evaluated the efficacy of PCT to prevent transfusion-associated graft-versus-host disease (TA-GVHD) in vivo using a well-characterized parent to F1 murine transfusion model. Recipient mice in four treatment groups were transfused with 108 splenic leukocytes. (1) Control group mice received syngeneic splenic leukocyte transfusions; (2) GVHD group mice received untreated allogeneic splenic leukocytes; (3) gamma radiation group mice received gamma irradiated (2,500 cGy) allogeneic splenic leukocytes; and (4) PCT group mice received allogeneic splenic leukocytes treated with 150 μmol/L S-59 and 2.1 J/cm2UVA. Multiple biological and clinical parameters were used to monitor the development of TA-GVHD in recipient mice over a 10-week posttransfusion observation period: peripheral blood cell levels, spleen size, engraftment by donor T cells, thymic cellularity, clinical signs of TA-GVHD (weight loss, activity, posture, fur texture, skin integrity), and histologic lesions of liver, spleen, bone marrow, and skin. Mice in the control group remained healthy and free of detectable disease. Mice in the GVHD group developed clinical and histological lesions of TA-GVHD, including pancytopenia, marked splenomegaly, wasting, engraftment with donor derived T cells, and thymic hypoplasia. In contrast, mice transfused with splenic leukocytes treated with (2,500 cGy) gamma radiation or 150 μmol/L S-59 and 2.1 J/cm2 UVA remained healthy and did not develop detectable TA-GVHD. Using an in vitro T-cell proliferation assay, greater than 105.1 murine T cells were inactivated by PCT. Therefore, in addition to inactivating high levels of pathogenic viruses and bacteria in PC, these data indicate that PCT is an effective alternative to gamma irradiation for prevention of TA-GVHD.


Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 318-318 ◽  
Author(s):  
Lequn Li ◽  
Hui Wang ◽  
Vassiliki A. Boussiotis

Abstract Cell cycle re-entry of quiescent T lymphocytes is required for generation of productive T cell responses. Cyclin-dependent kinases (cdk), particularly cdk2, have an essential role in cell cycle re-entry. Cdk2 promotes phosphorylation of Rb and related pocket proteins thereby reversing their ability to sequester E2F transcription factors. Besides Rb, cdk2 phosphorylates Smad2 and Smad3. Smad3 inhibits cell cycle progression from G1 to S phase, and impaired phosphorylation on the cdk-mediated sites renders it more effective in executing this function. In contrast, cdk-mediated phosphorylation of Smad3 reduces Smad3 transcriptional activity and antiproliferative function. Recently, we determined that induction of T cell tolerance resulted in impaired cdk2 activity, leading to reduced levels of Smad3 phosphorylation on cdk-specific sites and increased Smad3 antiproliferative function due to upregulation of p15. We hypothesized that pharmacologic inhibition of cdk2 during antigen-mediated T cell stimulation might provide an effective strategy to control T cell expansion and induce tolerance. (R)-roscovitine (CYC202) is a potent inhibitor of cdk2-cyclin E, which in higher concentrations also inhibits other cdk-cyclin complexes including cdk7, cdk9 and cdk5. It is currently in clinical trials as anticancer drug and recently was shown to induce long-lasting arrest of murine polycystic kidney disease. We examined the effect of roscovitine on T cell responses in vitro and in vivo. We stimulated C57BL/6 T cells with anti-CD3-plus-anti-CD28 mAbs, DO11.10 TCR-transgenic T cells with OVA peptide or C57BL/6 T cells with MHC disparate Balb/c splenocytes. Addition of roscovitine in these cultures resulted in blockade of cell proliferation without induction of apoptosis. Biochemical analysis revealed that roscovitine prevented phosphorylation of cdk2, downregulation of p27, phosphorylation of Rb and synthesis of cyclin A, suggesting an effective G1/S cell cycle block. To determine whether roscovitine could also inhibit clonal expansion of activated T cells in vivo, we employed a mouse model of GvHD. Recipient (C57BL/6 x DBA/2) F1 mice were lethally irradiated and were subsequently infused with bone marrow cells and splenocytes, as source of allogeneic T cells, from parental C57BL/6 donors. Roscovitine or vehicle-control was given at the time of allogeneic BMT and on a trice-weekly basis thereafter for a total of three weeks. Administration of roscovitine protected against acute GvHD resulting in a median survival of 49 days in the roscovitine-treated group compared to 24 days in the control group (p=0.005), and significantly less weight loss. Importantly, roscovitine treatment had no adverse effects on engraftment, resulting in full donor chimerism in the treated mice. To examine whether tolerance had been induced by in vivo treatment with roscovitine, we examined in vitro rechallenge responses. While control C57BL/6 T cells exhibited robust responses when stimulated with (C57BL/6 x DBA/2) F1 splenocytes, responses of T cells isolated from roscovitine-treated recipients against (C57BL/6 x DBA/2) F1 splenocytes were abrogated. These results indicate that roscovitine has direct effects on preventing TCR-mediated clonal expansion in vitro and in vivo and may provide a novel therapeutic approach for control of GvHD.


2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Yinan Zhao ◽  
Tianyi Zhao ◽  
Yanyan Du ◽  
Yingnan Cao ◽  
Yang Xuan ◽  
...  

Abstract Background During the course of gene transfection, the interaction kinetics between liposomes and DNA is speculated to play very important role for blood stability, cellular uptake, DNA release and finally transfection efficiency. Results As cationic peptide liposomes exhibited great gene transfer activities both in vitro and in vivo, two peptide lipids, containing a tri-ornithine head (LOrn3) and a mono-ornithine head (LOrn1), were chosen to further clarify the process of liposome-mediated gene delivery in this study. The results show that the electrostatically-driven binding between DNA and liposomes reached nearly 100% at equilibrium, and high affinity of LOrn3 to DNA led to fast binding rate between them. The binding process between LOrn3 and DNA conformed to the kinetics equation: y = 1.663631 × exp (− 0.003427x) + 6.278163. Compared to liposome LOrn1, the liposome LOrn3/DNA lipoplex exhibited a faster and more uniform uptake in HeLa cells, as LOrn3 with a tri-ornithine peptide headgroup had a stronger interaction with the negatively charged cell membrane than LOrn1. The efficient endosomal escape of DNA from LOrn3 lipoplex was facilitated by the acidity in late endosomes, resulting in broken carbamate bonds, as well as the “proton sponge effect” of the lipid. Conclusions The interaction kinetics is a key factor for DNA transfection efficiency. This work provided insights into peptide lipid-mediated DNA delivery that could guide the development of the next generation of delivery systems for gene therapeutics.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4989-4989
Author(s):  
Zilton F.M. Vasconcelos ◽  
Julia Farache ◽  
Bruna M. Santos Grad ◽  
Tereza S. Palmeira Grad ◽  
Luis Fernando Bouzas ◽  
...  

Abstract Acute Graft versus host diseas (aGVHD) is a major complication of stem cell transplantation. The disease is mediated by T cells and a higher incidence/severity would be expected when higher numbers of T cells are inoculated. However, the incidence of aGVHD in PBST, which carries about 10 times more T cells then BMT, is not higher than the one found in later. This finding indicates a modulatory role for G-CSF over T cell activity. We had previously shown that T cells from G-CSF treated PBSC donors do not produce g-IFN nor IL-4 and that this inhibition was mediated by low density, G-CSF activated, granulocytes. In order to test if in fact G-CSF activated granulocytes could inhibit disease, we first checked if G-CSF could generate low density granulocytes, in vivo and in vitro. Indeed, either in vivo(21mg /day - 5 days) or in vitro (150 ng -12hs) with G-CSF generates low density granulocytes which co-purify with the mononuclear cells in the ficoll® gradient. Moreover, as we had shown in humans, these low density cells, inhibit the production of g-IFN by anti-CD3 activated T cells on flow cytometry studies (17%-T cells alone versus 3% T cells with granulocytes 1:1). Radiation quimaeras were set with (B6 X BALB/c)F1 as hosts reconstituted with T cell depleted C57Bl6 bone marrow, in the presence or absence of nylon wool selected spleen cells (NWSC), as T cell source, from normal or G-CSF treated mice. As previously shown by others, NWSC from G-CSF treated mice diminishes the incidence of acute disease on day 20 post-transplant, from 75 to 25%. In order to investigate if this inhibition was dependent on the activated granulocytes present in the NWSC from G-CSF treated mice, granulocytes were depleted with anti-GR1 and complement. In this case, the incidence of disease is the same or even higher (75% experiment#1 and 100% in experiment #2) than the one observed on the control group (NWSC from control mice). These results strongly suggest that activated granulocytes could indeed inhibit aGVHD. We then generated activated granulocytes in vitro, by treating spleen derived high density granulocytes with 150ng of G-CSF for 12 hs. After the incubation period, a new ficoll® gradient was performed and the low density cells were obtained. T cell contamination on the second gradient was eliminated by anti-CD4 and CD8 complement lysis. These activated granulocytes were inoculated together with NWSC from control mice in the radiation quimaeras at a 1:1 ratio. In this case 100% disease inhibition was observed when compared to the positive control group, where 75% of the animals got sick. Our data indicate that activated granulocytes are the major mediators of the G-CSF immunossupressive effects and that these cells can be used as a novel immune modulator in clinical transplantation to prevent acute GVHD.


2020 ◽  
pp. 153537022096696
Author(s):  
Leonardo Lima Fuscaldi ◽  
Joaquim Teixeira de Avelar Júnior ◽  
Daniel Moreira dos Santos ◽  
Daiane Boff ◽  
Vívian Louise Soares de Oliveira ◽  
...  

In the continuing search for novel antibiotics, antimicrobial peptides are promising molecules, due to different mechanisms of action compared to classic antibiotics and to their selectivity for interaction with microorganism cells rather than with mammalian cells. Previously, our research group has isolated the antimicrobial peptide LyeTx I from the venom of the spider Lycosa erythrognatha. Here, we proposed to synthesize three novel shortened derivatives from LyeTx I (LyeTx I mn; LyeTx I mnΔK; LyeTx I mnΔKAc) and to evaluate their toxicity and biological activity as potential antimicrobial agents. Peptides were synthetized by Fmoc strategy and circular dichroism analysis was performed, showing that the three novel shortened derivatives may present membranolytic activity, like the original LyeTx I, once they folded as an alpha helix in 2.2.2-trifluorethanol and sodium dodecyl sulfate. In vitro assays revealed that the shortened derivative LyeTx I mnΔK presents the best score between antimicrobial (↓ MIC) and hemolytic (↑ EC50) activities among the synthetized shortened derivatives, and LUHMES cell-based NeuriTox test showed that it is less neurotoxic than the original LyeTx I (EC50 [LyeTx I mnΔK] ⋙ EC50 [LyeTx I]). In vivo data, obtained in a mouse model of septic arthritis induced by Staphylococcus aureus, showed that LyeTx I mnΔK is able to reduce infection, as demonstrated by bacterial recovery assay (∼10-fold reduction) and scintigraphic imaging (less technetium-99m labeled-Ceftizoxime uptake by infectious site). Infection reduction led to inflammatory process and pain decreases, as shown by immune cells recruitment reduction and threshold nociception increment, when compared to positive control group. Therefore, among the three shortened peptide derivatives, LyeTx I mnΔK is the best candidate as antimicrobial agent, due to its smaller amino acid sequence and toxicity, and its greater biological activity.


2019 ◽  
Author(s):  
Shubiao Zhang ◽  
Yinan Zhao ◽  
Yanyan Du ◽  
Yingnan Cao ◽  
Yang Xuan ◽  
...  

Abstract Background: During the course of gene transfection, the interaction kinetics between liposomes and DNA is speculated to play very important role for blood stability, cellular uptake, DNA release and finally transfection efficiency.Results: As cationic peptide liposomes exhibited great gene transfer activities both in vitro and in vivo, two peptide lipids, containing a tri-ornithine head (LOrn3) and a mono-ornithine head (LOrn1), were chosen to further clarify the process of liposome-mediated gene delivery in this study. The results show that the electrostatically-driven binding between DNA and liposomes reached nearly 100% at equilibrium, and high affinity of LOrn3 to DNA led to fast binding rate between them. The binding process between LOrn3 and DNA conformed to the kinetics equation: y = 1.663631 × exp(-0.003427x) + 6.278163. Compared to liposome LOrn1, the liposome LOrn3/DNA lipoplex exhibited a faster and more uniform uptake in Hela cells, as LOrn3 with a tri-ornithine peptide headgroup had a stronger interaction with the negatively charged cell membrane than LOrn1. The efficient endosomal escape of DNA from LOrn3 lipoplexes was facilitated by the acidity in late endosomes, resulting in broken carbamate bonds, as well as the “proton sponge effect” of the lipid.Conclusions: The interaction kinetics is a key factor for DNA transfection efficiency. This work provided insights into peptide lipid-mediated DNA delivery that could guide the development of the next generation of delivery systems for gene therapeutics.


Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2866-2866
Author(s):  
Anna Lena Illert ◽  
Cornelius Miething ◽  
Rebekka Grundler ◽  
Manuel Schmidt ◽  
Andreas Burchert ◽  
...  

Abstract Interferon regulatory factors (IRF) are activating and/or repressing transcription factors induced by treatment with type I and II Interferon (IFN), other cytokines, receptor cross-linking and viral infection. In contrast to IRF-1 and IRF-2, which are widely expressed, IRF-4 and IRF-8 are tissue-restricted factors. IRF-8 is expressed mainly in cells of haematopoietic origin and has recently been shown to inhibit mitogenic activity of p210 Bcr/Abl-transformed myeloid progenitor cells by activating several genes that interfere with the c-Myc pathway. IRF-4 is most homologous with IRF-8 (approximately 70% overall homology) and its expression is highly restricted to lymphocytes of the B-cell type (pre-B, B, and plasma cells), mature T-cells and macrophages. Furthermore IRF-4 expression is significantly impaired in CML and AML patient samples predominately in T-cells. To examine a potential role of IRF-4 in Bcr/Abl mediated transformation we used a bone marrow transplant model (BMT). We transduced IRF-4 knockout (KO) bone marrow with retrovirus expressing p210 Bcr/Abl and transplanted it into lethally irradiated recipient C57/bl6 mice. For proper control we transplanted also wildtype (WT) bone marrow transduced with Bcr/Abl and mock transfected IRF-4 KO bone marrow (BM). All recipients transplanted with Bcr/Abl transduced BM (regardless of which IRF-4 KO or WT) developed rapidly a myeloproliferative disorder characterized by leukocytosis and expression of the myeloid lineage markers CD11b and Gr1. Surprisingly, IRF-4 KO Bcr/Abl infected BM recipient mice survived slightly longer than the control group transplanted with WT p210 BM (12 vs. 19 days). Histopathologic studies of the affected organs (spleen/lung) revealed extramedullary haematopoiesis in the spleens of both groups and a distinct infiltration of the tumor cells in the lung of WT Bcr/Abl transduced BM recipient mice, resulting in massive punctuated bleedings. Interestingly, preliminary analysis suggest a significantly reduced lung infiltration with almost no pulmonary bleedings in IRF-4 KO Bcr/Abl infected BM recipient mice, which we assume to be the reason for the differences in the overall survival. Taken together our data demonstrate that IRF-4 is not required for the induction of a myeloproliferative disorder by Bcr/Abl in vivo and for its ability to transform BM cells in vitro, but IRF-4 deficiency seems to have an impact on the fulminant pulmonary haemorrhage occurring in the murine CML-like disease.


Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1306-1306
Author(s):  
Ram Kalpatthi ◽  
Kathleen Nicol ◽  
Lindsay Hendey ◽  
Michael W. Boyer

Abstract Graft-versus-host disease (GVHD) remains a significant complication of allogeneic bone marrow transplantation. We and others have shown that in vitro cultured CD8 cytotoxic T cells (CTL) have attenuated GVHD compared to naïve cells, while retaining GVL activity. It has been shown that expression of α4β7 integrin on CD8 T cells is important for gut homing specificity in GVHD. Recently, retinoic acid (RA) has been shown to upregulate α4β7 expression on naïve T cells. Thus, we hypothesize that in vitro cultured CTL without RA lack the ability to cause GVHD in part due to deficient α4β7 expression. We used an established murine GVHD model in which spleen and lymph node cells from B6SJL mice were stimulated with splenocytes from DBA mice and were restimulated on day 7. Cultures were supplemented with IL-2 & IL-7 with and without addition of RA (100nm) on day 2. Day 14 comparison of CTL with and without RA revealed comparable CD4 (1.7% vs 0.7% respectively) and CD8 populations (96% vs 97% respectively). Phenotyping of CTL with and without RA showed CD8 α4β7 expression of 58% and 0.8% and CD8 CCR9 53% and 10% respectively. In vitro cytotoxicity was comparable between CTL with and without RA: 51% vs 41% at an effector target ratio of 10:1 (n=3, p=0.3). Both CTL groups had comparable in vitro migration towards to SDF, IP-10 & MIP-3α (p= ns). However RA treated CTL had increased migration towards TECK (chemokine expressed in small intestine); 17.3% vs 4.6% (n=4, p=0.01) and decreased migration towards TARC (chemokine expressed in skin); 2% vs 13% (n=4, p=0.03). For in vivo homing, 107 labeled cells from each CTL with (CFSE) and without RA (TRITC) were coinjected intravenously and mice were sacrificed 16 hours later for analysis. RA treated CTL had increased homing to peyer’s patch and MLN compared to CTL without RA. [Homing index (CTLRA/CTL) 2.3 and 2.5 respectively]. This finding is exaggerated in the radiated host [Homing index (CTLRA/CTL) 15 for PP and 11 for MLN]. CTL generated with or without RA (5x106 cells each) were injected intravenously in to irradiated (600 Rads) B6D2F1 recipients (3 groups; Radiation control, CTL with and without RA). Mice were followed for clinical GVHD scores and sacrificed when moribund. CBC and histopathologic GVHD scores (Liver, skin, lung, small and large intestines) were obtained. Both CTL groups developed lethal bone marrow (BM) aplasia around day 24 as compared to radiation control group; however, clinical and histopathologic GVHD scores were similar in all groups (Table 1). Our data demonstrate that both CTL with and without RA cause a lethal hematopoietic graft versus host reaction. Despite high α4β7 and CCR9 expression, significant in vitro migration to TECK and in vivo homing to gut associated lymphoid tissues, RA treated CTL did not cause significant GVHD in gut, liver or skin. This suggests that defective gut homing alone may not be sufficient to explain the attenuated GVHD from cultured CTL. Future studies are planned to confirm these findings in other GVHD models and to elucidate the mechanisms of attenuated GVHD from cultured CTL. Table 1 (Data from Day 24 sacrifice) Parameter (Mean) Radiation control CTL CTLRA p value* * CTL or CTLRA vs Radiation control group Hb (g/dL) 12.2 3.8 3.1 0.0001 WBC x106/L 1000 300 300 0.07 Platelets x103/L 667,200 50,200 29,500 0.003 BM cells from 2 femur (106) 15.3 0.9 1.1 0.0006 Combined GVHD histology score 4.9 4.4 4.2 0.3


2019 ◽  
Vol 37 (4_suppl) ◽  
pp. 293-293
Author(s):  
Naoki Okada ◽  
Ko Sugiyama ◽  
Hidemitsu Kitamura ◽  
Akinobu Taketomi

293 Background: Diacylglycerol kinases (DGKs), lipid kinases transforming diacylglycerol to phosphatidic acid, play important roles in intracellular signal transduction. Diacylglycerol kinase alpha (DGKa), an isozyme of DGKs, is well-known to promote proliferation of cancer cells by suppression of the apoptosis. Additionally, a previous report demonstrated that activation of DGKa induced anergy state of T lymphocytes in vivo. In this study, we investigated whether inhibition of DGKa not only suppress the tumorigenesis of cancer cells but also activate anti-tumor immunity. Methods: We first investigated the effect of DGKa inhibitor on in vitro proliferation of murine hepatoma cell lines (Hepa1-6) by cell proliferation assay. Cytokine and Granzyme B productions by CD8+ T cells from OT-1 mice after the OVA antigen stimulation were evaluated by ELISA and flowcytometry, respectively. Next, we established a tumor-bearing mice model by injection of mCherry-transfected Hepa1-6 cells into spleen. Tumorigenesis and tumor-infiltrating T cells in the liver were evaluated by in vivo imaging system, HE staining, and immunohistochemistry. CD8+ T cells were collected from the liver and stimulated with PMA and Ca2+ ionophore and the IFN-g production levels were evaluated by flowcytometry. Results: Proliferation of Hepa1-6 cells were suppressed in the presence of DGKa inhibitor in vitro. IL-2 production levels of OT-1 CD8 T cells in control group was augmented by the addition of DGKa inhibitor (246 vs 579 pg/ml, p < 0.05). Granzyme B-positive cells in OT-1 CD8+ T cells were increased by the treatment with DGKa inhibitor compared to the control group (4.4 vs 8.9 %, P < 0.05) after the antigen stimulation. In vivo administration of DGKa inhibitor significantly suppressed the tumor size (fluorescence (AU) 2.0x1010 vs 6.3x109, area (μm2) 1.5x107 vs 0.9x107, p < 0.05) in the liver of tumor bearing mice. Then, the number of tumor-infiltrating T cells (582 vs 1506, 5 HPF, p < 0.05) and the IFN-g-producing cells (9.2 vs 16.0 %) in CD8+ T cells were elevated by the DGKa treatment. Conclusions: Inhibition of DGKa not only suppressed the proliferation of hepatoma but also activated anti-tumor effector T cells in vivo.


2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Morris Wende ◽  
Simbarashe Sithole ◽  
Godloves Fru Chi ◽  
Marc Y. Stevens ◽  
Stanley Mukanganyama

Combretum zeyheri and Combretum platypetalum have been shown to have anticancer, antibacterial, antituberculosis, and antifungal effects in both in vivo and in vitro studies. This study sought to evaluate the antiproliferative effects of compounds isolated from C. zeyheri and C. platypetalum on Jurkat T and HL-60 cancer cell lines in combination with doxorubicin and/or chlorambucil. At their GI50 concentrations, the isolated compounds were combined with the corresponding GI50 of chlorambucil and doxorubicin. The cytotoxic effects of the combined compounds were determined on BALB/c mouse peritoneal cells. All the 4 isolated compounds had significant cytotoxic effects on Jurkat T cells. Compounds CP 404 (1), CP 409 (2), CZ 453 (3), and CZ 455 (4) had GI50s on Jurkat T cells of 3.98, 19.33, 6.82, and 20.28 μg/ml, respectively. CP 404 (1), CP 409 (2), CZ 453 (3), and CZ 455 (4) showed GI50s of 14.18, 28.69, 29.87, and 16.46 μg/ml on HL-60 cancer cell lines, respectively. The most potent combination against Jurkat T cells was found to be CP 404 (1) and chlorambucil. This combination showed no cytotoxic effects when tested on BALB/c mouse peritoneal cells. It was concluded that the compounds extracted from C. zeyheri and C. platypetalum inhibit the growth of Jurkat T cells in vitro. The combination of the compounds with anticancer drugs enhanced their anticancer effects. The combination of CP 404 (1) and chlorambucil was found not to be toxic to normal mammalian cells. Therefore, CP 404 (1), 3-O-β-L-rrhamnopyranosyl-5,7,3 ′ 4 ′ ,5 ′ -pentahydroxyflavone, has the potential to be a source of lead compounds that can be developed for anticancer therapy. Further structure-activity relationship studies on this compound are warranted.


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