The CD33xCD123xCD70 Multispecific CD3-Engaging DARPin MP0533 Induces Selective T Cell-Mediated Killing of AML Leukemic Stem Cells

The prognosis of patients with acute myeloid leukemia (AML) is limited, especially for elderly or unfit patients not eligible for hematopoietic stem cell (HSC) transplantation. The disease is driven by leukemic stem cells (LSCs), which are characterized by clonal heterogeneity and resistance to conventional therapy. These cells are therefore believed to be a major cause of progression and relapse. We designed MP0533, a multispecific CD3-engaging DARPin (designed ankyrin repeat protein) that can simultaneously bind to three antigens on AML cells (CD33, CD123, and CD70), aiming to enable avidity-driven T cell-mediated killing of AML cells co-expressing at least two of the antigens. In vitro, MP0533 induced selective T cell-mediated killing of AML cell lines, as well as patient-derived AML blasts and LSCs, expressing two or more target antigens, while sparing healthy HSCs, blood, and endothelial cells. The higher selectivity also resulted in markedly lower levels of cytokine release in normal human blood compared to single antigen-targeting T-cell engagers. In xenograft AML mouse models, MP0533 induced tumor-localized T-cell activation and cytokine release, leading to complete eradication of the tumors while having no systemic adverse effects. These studies show that the multispecific-targeting strategy used with MP0533 holds promise for improved selectivity towards LSCs and efficacy against clonal heterogeneity, potentially bringing a new therapeutic option to this group of patients with high unmet need. MP0533 is currently being evaluated in a dose-escalation phase 1 study in patients with relapsed or refractory AML (NCT05673057).

Apelin-driven endothelial cell migration sustains intestinal progenitor cells and tumor growth

Stem and progenitor cells residing in the intestinal crypts drive the majority of colorectal cancers (CRCs), yet vascular contribution to this niche remains largely unexplored. VEGFA is a key driver of physiological and tumor angiogenesis. Accordingly, current anti-angiogenic cancer therapies target the VEGFA pathway. Here we report that in CRC expansion of the stem/progenitor pool in intestinal crypts requires VEGFA-independent growth and remodeling of blood vessels. Epithelial transformation induced expression of the endothelial peptide apelin, directs migration of distant venous endothelial cells towards progenitor niche vessels ensuring optimal perfusion. In the absence of apelin, loss of injury-inducible PROX1+ epithelial progenitors inhibited both incipient and advanced intestinal tumor growth. Our results establish fundamental principles for the reciprocal communication between vasculature and the intestinal progenitor niche and provide a mechanism for resistance to VEGFA-targeting drugs in CRCs.

Abstract 1733: MP0317, a CD40xFAP targeting multi-specific DARPin® therapeutic, drives immune activation and reverts myeloid-mediated T-cell suppression in vitro and ex vivo

Therapeutic agonists targeting CD40 have shown encouraging signs of anti-tumor efficacy in patients. Despite their initial promise however, optimal dosing of systemically active agents has been limited by toxicity and their full therapeutic potential not achieved. We have previously demonstrated in vitro the ability of MP0317, a novel multi-specific DARPin® therapeutic, to selectively activate CD40 bearing B-cells, dendritic cells and macrophages in the presence of fibroblast activation protein (FAP). FAP is highly expressed in the stroma of many solid tumors and is found only at lower levels in other tissues. MP0317 utilizes FAP and CD40 binding domains to selectively cross-link and activate CD40 in the presence of FAP and thus avoid systemic CD40 activation classically associated with toxicity. Here we present new data which confirm the unique therapeutic potential of MP0317 in ex vivo model systems, demonstrate modulation of macrophage phenotype and reveal a release of T-cells from macrophage-mediated suppression. Ex vivo functional assays performed with MP0317 on dissociated human tumors demonstrated FAP-dependent activation of CD40-expressing B-cell and myeloid cell populations. Immunohistochemical analysis of tissue micro-arrays demonstrated FAP levels consistent with those required for immune cell activation in a broad range of solid tumor indications. Furthermore, by mining publicly available data, we classified tumor indications based on their immune cell content, pathway activation and MP0317 ex vivo mode of action (T cell/macrophage ratio, FAP and CD40 expression) and proposed patient populations and indications for the upcoming clinical trials. To further investigate the functional impact of MP0317, macrophages were differentiated in vitro using canonical polarising cytokines. Suppressive tumor-associated macrophage (TAM)-like cells, were repolarized by MP0317 to an anti-tumor-like phenotype. Furthermore, we explored whether modulation of macrophage phenotype by MP0317 could relieve their suppressive effect on T-cells. TAM-like macrophages potently supressed anti-CD3/28 driven T-cell activation and indeed the addition of MP0317 was found to restore T-cell response. Together these data further support MP0317's FAP targeted multimodal mechanism of action in human tumors, provide evidence for an improved therapeutic window over existing CD40 agonists and support progression to the clinic with an informed target patient profile.

Citation Format: Kyriaki Ioannou, Simone Ragusa, Joanna Roquette, Ana Florescu, Mariam Gachechiladze, Eliane Müller, Julia M. Martinez-Gomez, Sophie Barsin, Sarah Jetzer, Nicolo Rigamonti, Clara Domke, Tamara Lekishvili, Karolin Rommel, Ivana Tosevski, Anne Goubier, Philippe Legenne, Vladimir Kirkin, Mitch Levesque, Hong Ji, Rupert Kenefeck. MP0317, a CD40xFAP targeting multi-specific DARPin® therapeutic, drives immune activation and reverts myeloid-mediated T-cell suppression in vitro and ex vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1733.

Antiangiogenic immunotherapy suppresses desmoplastic and chemoresistant intestinal tumors in mice

Mutations in APC promote colorectal cancer (CRC) progression through uncontrolled WNT signaling. Patients with desmoplastic CRC have a significantly worse prognosis and do not benefit from chemotherapy, but the mechanisms underlying the differential responses of APC-mutant CRCs to chemotherapy are not well understood. We report that expression of the transcription factor prospero homeobox 1 (PROX1) was reduced in desmoplastic APC-mutant human CRCs. In genetic Apc-mutant mouse models, loss of Prox1 promoted the growth of desmoplastic, angiogenic, and immunologically silent tumors through derepression of Mmp14. Although chemotherapy inhibited Prox1-proficient tumors, it promoted further stromal activation, angiogenesis, and invasion in Prox1-deficient tumors. Blockade of vascular endothelial growth factor A (VEGFA) and angiopoietin-2 (ANGPT2) combined with CD40 agonistic antibodies promoted antiangiogenic and immunostimulatory reprogramming of Prox1-deficient tumors, destroyed tumor fibrosis, and unleashed T cell-mediated killing of cancer cells. These results pinpoint the mechanistic basis of chemotherapy-induced hyperprogression and illustrate a therapeutic strategy for chemoresistant and desmoplastic CRCs.

Optimized low-dose combinatorial drug treatment boosts selectivity and efficacy of colorectal carcinoma treatment

The current standard of care for colorectal cancer (CRC) is a combination of chemotherapeutics, often supplemented with targeted biological drugs. An urgent need exists for improved drug efficacy and minimized side effects, especially at late‐stage disease. We employed the phenotypically driven therapeutically guided multidrug optimization (TGMO) technology to identify optimized drug combinations (ODCs) in CRC. We identified low‐dose synergistic and selective ODCs for a panel of six human CRC cell lines also active in heterotypic 3D co‐culture models. Transcriptome sequencing and phosphoproteome analyses showed that the mechanisms of action of these ODCs converged toward MAP kinase signaling and cell cycle inhibition. Two cell‐specific ODCs were translated to in vivo mouse models. The ODCs reduced tumor growth by ~80%, outperforming standard chemotherapy (FOLFOX). No toxicity was observed for the ODCs, while significant side effects were induced in the group treated with FOLFOX therapy. Identified ODCs demonstrated significantly enhanced bioavailability of the individual components. Finally, ODCs were also active in primary cells from CRC patient tumor tissues. Taken together, we show that the TGMO technology efficiently identifies selective and potent low‐dose drug combinations, optimized regardless of tumor mutation status, outperforming conventional chemotherapy.

The NAD-Booster Nicotinamide Riboside Potently Stimulates Hematopoiesis through Increased Mitochondrial Clearance

It has been recently shown that increased oxidative phosphorylation, as reflected by increased mitochondrial activity, together with impairment of the mitochondrial stress response, can severely compromise hematopoietic stem cell (HSC) regeneration. Here we show that the NAD⁺-boosting agent nicotinamide riboside (NR) reduces mitochondrial activity within HSCs through increased mitochondrial clearance, leading to increased asymmetric HSC divisions. NR dietary supplementation results in a significantly enlarged pool of progenitors, without concurrent HSC exhaustion, improves survival by 80%, and accelerates blood recovery after murine lethal irradiation and limiting-HSC transplantation. In immune-deficient mice, NR increased the production of human leucocytes from hCD34+ progenitors. Our work demonstrates for the first time a positive effect of NAD⁺-boosting strategies on the most primitive blood stem cells, establishing a link between HSC mitochondrial stress, mitophagy, and stem-cell fate decision, and unveiling the potential of NR to improve recovery of patients suffering from hematological failure including post chemo- and radiotherapy.

Tannins from Syzygium guineense suppress Wnt signaling and proliferation of Wnt-dependent tumors through a direct effect on secreted Wnts

Triple-negative breast cancer (TNBC) and colon cancer (CC) are two stigmatic examples of poorly treatable tumors, whose progression critically depends upon hyperactivation of the Wnt signaling. Development of specific anti-Wnt inhibitors is required to develop drugs against these and other Wnt-dependent cancers. Natural products, especially plants, have been used for the treatment of various diseases from ancient times. We examined extracts from several indigenous Cameroonian herbs and tested their effects on proliferation and Wnt signaling in TNBC and CC cells. Extracts from "fruit rouge", Syzygium guineense Wall. (Myrtaceae), demonstrated a strong activity against these cancer cells, as well as CC organoids. We found TNBC cells to significantly upregulate expression of Wnt3a, and the effects of S. guineense extracts on TNBC cell proliferation correlated with inhibition of the Wnt3a-induced β-catenin stabilization and transcriptional response. HPLC analysis revealed that the active components belong to tannins. We found a direct destabilizing effect of S. guineense extract on Wnt3a and other Wnt proteins, identifying a novel mechanism of action of tannins on the Wnt signaling pathway and cancer cell proliferation. Being edible, this African plant may have an important cancer-preventive nutritional value.

Abstract P2-06-05: Development and validation of a new non-parametric breast cancer risk assessment model on US and European screening populations

Background: Stratified breast cancer (BC) prevention is a major option for the future but requires clinically meaningful internationally validated risk models. Non parametric models may be alternate methods for modeling in very large cohorts. We have previously shown that a non-parametric similarity-based k-nearest neighbors' (kNN) model performs better than the BCRAT/Gail model to on 65 000 women of the E3N French national cohort (Dartois et al 2015). We used this method to develop and validate a mammographic density-based model in larger general screening populations (pops).

Methods: A modified version of a data-mining based algorithm, the kNN method, was implemented and adapted as previously described [ref Dartois]. Core concept of kNN algorithm is to gather similar profiles using a distance computation.

We developed a BC risk prediction model on 629 229 women (wn) from the US Breast Cancer Research Consortium (BCSC), with 5 times random selection of learning and validation sets (75/25 %) within the cohort. 5 parameters were included: age, family history, previous breast biopsy, mammographic density and race. The model's performances (discrimination using c-stat (AUC) and calibration using E/0 ratio) were evaluated and compared to the parametric model developed on the same pop (param/BCSC)(Tice et al 2008). This kNN/BCSC model was then tested on two French screening pops after adjustment on French BC incidence: an urban area (Paris suburbs, N=316 775) and a rural area (Côte d'Or, N=32 930). Its performances were compared to those of a model directly developed (same methods) on the Paris cohort (kNN/Paris). Levels of individual risks assessed by the models were assigned into 4 risk categories. The sensitivity of the models was defined as the number of wn who had BC whose 5 yrs-risk category was intermediate (median risk at 50-yrs - 1.66%), high (> 1.66%) or very high (> 20% lifetime) divided by the total number of wn who had BC.

Results: The performances of the different models are shown in Table 1. The kNN model developed on BCSC performed well (c-stat 0.653 and E/0 1.001). It had equivalent performances as the parametric model developed previously on the same pop. This kNN/BCSC had a good discrimination on French pops, although slightly lower than that on US pops. This is expected since French screening starts at 50 (vs 40 in BCSC) and French parameters do not include race. The calibration of such model was excellent on Paris, while it overestimated the risk on Côte d'Or, in which BC incidence is lower. It performed as well as the kNN/Paris model directly developed on Paris' pop. The sensitivity of the kNN/BCSC on US and French pops was good.

Conclusions: A new non parametric kNN breast cancer risk model developed on an American screening cohort (BCSC) was successfully validated on two French screening cohorts. This new international model could allow stratified prevention.

Performances of the models Param/BCSC on BCSCParam/BCSC on PariskNN/BCSC on BCSCkNN/BCSC on PariskNN/BCSC on Cote d'OrkNN/Paris on ParisN629 229313 817629 229313 81732 930313 817c-statistic0.6580.6020.6530.6020.5930.605E/0 global1.031.071.0011.061.521.00Sensitivity--76.18%72.87%72.58%-

Citation Format: Ragusa S, Gauthier E, Dartois L, Tice J, Dancourt V, Arveux P, Brixi Z, Bernoux A, Soyer P, Delattre H, Brechenade S, Catajar N, Kaufmanis A, Hélin VM, Clavel F, Kerlikowske K, Miglioretti D, Delaloge S. Development and validation of a new non-parametric breast cancer risk assessment model on US and European screening populations [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-06-05.

Abstract P3-10-03: Receipt of breast cancer risk assessment and personalized prevention information among women diagnosed with a benign breast lesion (BBL) in a one stop breast unit: A prospective assessment

Background: Women's awareness about their personal breast cancer (BC) risk in the general population is generally low. Mass screening and mass prevention interventions have as yet been moderately efficient in breast oncology. "Personalized prevention" including risk communication, personalized screening and primary prevention recommendations is a promising. A personal history of BBL slightly increases subsequent BC risk.

Objectives: the main objective was to evaluate the acceptability of a mathematical tool- based breast cancer risk assessment and subsequent proposal of a personalized BC prevention program in a BBL population. Secondary objectives were to evaluate information receipt, awareness, satisfaction, and anxiety.

Methods: Women were eligible for the study if aged 40-74, were recently diagnosed with a benign breast lesion at the one stop breast Unit of the center, had no personal history of cancer or atypical lesions and were not BRCA carriers. Women were proposed a personalized risk assessment using a mathematical tool (BCSC score adapted to the French population-Ragusa et al) together with personalized information on risk, BC screening and prevention, release of a personalized program and evaluation of their receipt. The main end point was the proportion of women willing to have a risk assessment and personalized counseling. A cut-off point of 70% was considered critical to consider acceptability. Secondary end points were perceived BC risk, satisfaction, anxiety and distress levels at day 2 using standardized questionnaires, as well as adherence with the proposed programs.

Results: Of 150 women proposed BC risk assessment and personalized prevention information between 02/2014 and 03/2015, 129 (86%) accepted. Median age: 53.6 years. 33% had a low BC risk (< 1.1% at 5 yrs [mean risk of 50 yrs-old women in France]), 53% a moderate risk (1.1-1.66% at 5 yrs), while 14% were high risk (> 1.66% at 5 yrs). 87% had never had any previous information on BC risk. 3 pts required a genetic assessment.

Participants were globally very satisfied with physicians' and nurses' interpersonal skills, availability and provision of information (mean score > 4; range 2-5). The mean scores of clarity of the BC risk information (4.14±1;range 2-5) and screening program information (4.21±0.93; range 2-5) were high.

The mean score of perceived risk level was estimated to 33.5% (SD=21.9).

Mean scores of state anxiety (36.7±12.2; range 20-71), trait anxiety (39.5±8.9; range 23-59), depressive symptoms (3.4±3.3; range 0-12) and psychological distress indicated low levels of all. Higher level of state-anxiety was associated with lower scores of satisfaction with doctors and nurses human qualities (r = 0.26, p<.05) and with lower scores of clarity of information about screening program (r = 0.25, p<.05).

Conclusion: The receipt of breast cancer risk assessment and personalized prevention information among women diagnosed with BBL was high (86%). Information need is high given the low level of real risk awareness. Such population may benefit from personalized prevention. Anxiety and distress scores were low and satisfaction rates high.

Citation Format: Tlemsani C, Boinon D, Yung MF, Ragusa S, Mazouni C, Balleyguier C, Saghatchian M, Ghouadni A, Rivera S, Michiels S, Delaloge S. Receipt of breast cancer risk assessment and personalized prevention information among women diagnosed with a benign breast lesion (BBL) in a one stop breast unit: A prospective assessment. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-10-03.

DLL4 promotes continuous adult intestinal lacteal regeneration and dietary fat transport

The small intestine is a dynamic and complex organ that is characterized by constant epithelium turnover and crosstalk among various cell types and the microbiota. Lymphatic capillaries of the small intestine, called lacteals, play key roles in dietary fat absorption and the gut immune response; however, little is known about the molecular regulation of lacteal function. Here, we performed a high-resolution analysis of the small intestinal stroma and determined that lacteals reside in a permanent regenerative, proliferative state that is distinct from embryonic lymphangiogenesis or quiescent lymphatic vessels observed in other tissues. We further demonstrated that this continuous regeneration process is mediated by Notch signaling and that the expression of the Notch ligand delta-like 4 (DLL4) in lacteals requires activation of VEGFR3 and VEGFR2. Moreover, genetic inactivation of Dll4 in lymphatic endothelial cells led to lacteal regression and impaired dietary fat uptake. We propose that such a slow lymphatic regeneration mode is necessary to match a unique need of intestinal lymphatic vessels for both continuous maintenance, due to the constant exposure to dietary fat and mechanical strain, and efficient uptake of fat and immune cells. Our work reveals how lymphatic vessel responses are shaped by tissue specialization and uncover a role for continuous DLL4 signaling in the function of adult lymphatic vasculature.

PROX1 promotes metabolic adaptation and fuels outgrowth of Wnt(high) metastatic colon cancer cells

The Wnt pathway is abnormally activated in the majority of colorectal cancers, and significant knowledge has been gained in understanding its role in tumor initiation. However, the mechanisms of metastatic outgrowth in colorectal cancer remain a major challenge. We report that autophagy-dependent metabolic adaptation and survival of metastatic colorectal cancer cells is regulated by the target of oncogenic Wnt signaling, homeobox transcription factor PROX1, expressed by a subpopulation of colon cancer progenitor/stem cells. We identify direct PROX1 target genes and show that repression of a pro-apoptotic member of the BCL2 family, BCL2L15, is important for survival of PROX1(+) cells under metabolic stress. PROX1 inactivation after the establishment of metastases prevented further growth of lesions. Furthermore, autophagy inhibition efficiently targeted metastatic PROX1(+) cells, suggesting a potential therapeutic approach. These data identify PROX1 as a key regulator of the transcriptional network contributing to metastases outgrowth in colorectal cancer.

Oxidative profile in patients with colon cancer: effects of Ruta chalepensis L

AIM

To verify the involvement of free radicals in tumor progression and to investigate the effects of an ethanolic extract of Ruta Chalepensis L. and of rutin in blood of patients with colon cancer.

MATERIALS AND METHODS

Leaves of Ruta Chalepensis L. were collected in the area around Catania (Italy). For the preparation of the ethanol extract of leaves, an exhaustive extraction of 100 g of the drug was carried out in Soxhlet with 800 ml of 95% ethanol. Fifty-six patients with colorectal cancer were randomly selected for this study; among these, 34 were affected by an early stage (T1 N0 M0 according to scale), while 22 were affected by an advanced stage (T4, N1-2, M0) of cancer. Data obtained from these patients were compared with those of a control group consisting of 20 healthy subjects. Plasma of each sample was used for determining non-proteic antioxidant capacity, thiol groups, lipid hydroperoxides and nitrite/nitrate levels, evaluated by spectrophotometric tests. In addition, percentage of haemolysis was evaluated incubating (for 2 hours at 37 degrees C) erythrocyte suspension with a free radical donor (50 mM 2,2'-azobis-amidino propane chloridrate), in the presence or absence of ethanolic extract of Ruta Chalepensis L. (250 microg/ml) or rutin (1 mM).

RESULTS

Non-proteic antioxidant capacity was significantly lower in cancerous patients than in healthy subjects (p < 0.001). This decrease was stage-related. In fact, non-proteic antioxidant capacity resulted lower in advanced than in early colorectal cancer (p < 0.001). The same significant stage-related decrease was observed in plasma thiol groups (p < 0.001). Coherently with the decrease in non-proteic antioxidant capacity and thiol groups, higher levels of lipid hydroperoxides and nitrite/nitrate were observed in patients with colorectal cancer with respect to healthy subjects (p < 0.001) and the increase in these markers of oxidative stress was related to the cancer stadiation. Neoplastic patients also showed an increased percentage of oxidative hemolysis respect to controls and the haemolytic damage was correlated with the stage of colon cancer. Both the extract of Ruta Chalepensis L. and rutin were able to protect erythrocytes from oxidative stress induced by the free radical donor, but the extract of Ruta Chalepensis L. was more effective than rutin. This protective effect was significant only in erythrocytes from patients with early colorectal group, whereas no significant modification was induced by Ruta Chalepensis L. or rutin in red blood cells from advanced colorectal cancer patients exposed to the same experimental conditions.

CONCLUSION

Oxidative stress correlates with colon cancer stadiation and both the extract of Ruta chalepensis and rutin are able to protect red blood cells from radical-induced damage. However, their effects are significant in early stages of cancer. So these natural antioxidants might be usefull to prevent carcinogenesis and/or tumor progression.

Antibacterial activity of Helleborus bocconei Ten. subsp. siculus root extracts

AIM OF THE STUDY

Roots of Helleborus bocconei Ten. subsp. siculus (Schiffner) Merxm. & Podl. are widely used in veterinary folk medicine in Sicily (Italy) to diagnose and cure lower respiratory tract infections in cattle. This study intended to evaluate the in vitro antibacterial activity of the methanolic root extract of Helleborus bocconei Ten. subsp. siculus, and of the bufadienolide and ecdysteroid fractions extracted from its roots, against strains belonging to species commonly associated with respiratory tract infections.

MATERIALS AND METHODS

The phytochemical screening of the previously prepared plant extracts was carried out by chemical, thin-layer chromatography and spectroscopic methods. The in vitro antibacterial activity of the extracts against seven different standard bacterial strains was evaluated by broth microdilution.

RESULTS

According to the present study, Helleborus bocconei Ten. subsp. siculus roots contain bufadienolides and ecdysteroids, and the extracts containing these compounds, as well as the crude methanolic root extract, show antibacterial activity against microorganisms responsible for respiratory infections. In particular, the bufadienolide extract has the highest inhibitory activity against all the tested organisms, and, as the other extracts, shows the lowest MIC values (100mug/ml) against Moraxella catarrhalis and Streptococcus pneumoniae.

CONCLUSIONS

Since the roots of Helleborus bocconei Ten. subsp. siculus contain substances with antibacterial activity, the traditional use of this plant may also derive from its antibacterial properties.

Effects of a mixture of vegetable and essential oils and fatty acid potassium salts on Tetranychus urticae and Phytoseiulus persimilis

Laboratory trials were carried out to evaluate the toxicity and the influence of a commercial mixture of vegetal, essential oils, and potassium salts of fatty acids (Acaridoil 13SL) on the population growth rate (r(i)--instantaneous rate of increase) of two mite species, the phytophagous Tetranychus urticae Koch and the predator Phytoseiulus persimilis Athias-Henriot. A residue of 1.3 mg/cm(2) of pesticide solution was harmless for Ph. persimilis eggs, while a moderate mortality of eggs and of larvae from treated eggs of T. urticae, was observed (53.8%). The pesticide also caused a delay in the postembryonic development of the tetranychid. Moreover, 83.4% mortality was reported for treated females tetranychids and only 24.0% for Ph. persimilis females. The pesticide influenced negatively the population growth of T. urticae which showed a very low rate of increase (r(i)=0.07), compared to that obtained in the control (r(i)=0.68). The pesticide did not affect negatively the reproductive potential of Ph. persimilis (r(i)=0.54 and r(i)=0.57 for test and control, respectively). These results suggest a considerable acaricidal activity of potassium salts of fatty acids and caraway oil on T. urticae and a good selectivity on Ph. persimilis.

Berberis aetnensis C. Presl. extracts: antimicrobial properties and interaction with ciprofloxacin

Previous research showed that berberine-containing Berberis species synthesise the substances 5'-methoxyhydnocarpin-D (5'-MHC-D) and pheophorbide a, which have no antimicrobial activity but inhibit the expression of multidrug resistant efflux pumps (MDRs) in Staphylococcus aureus and potentiate the action of berberine. The MDR pumps extrude synthetic and natural antimicrobials from bacterial cells. We searched for these compounds in Berberis aetnensis C. Presl. (Berberidaceae), an endemic plant of the volcano Mount Etna. This work confirms the presence of pheophorbide a and permits us to hypothesise the presence of 5'-MHC-D in leaf extracts. In fact, the activity of ciprofloxacin was improved when two chromatographic fractions isolated from leaf extracts were added. These results are indicative of the presence of MDR pump inhibitors. Moreover, crude extracts were tested on several micro-organisms and showed antimicrobial activity mainly against Gram-positive bacteria and yeasts.

Properties of purified cytosolic isoenzyme I of Cu,Zn-superoxide dismutase from Nicotiana plumbaginifolia leaves

The isoenzyme I of cytosolic Cu,Zn-superoxide dismutase (SOD) from Nicotiana plumbaginifolia (tobacco) leaves has been purified to apparent homogeneity. The relative molecular mass of the native isoenzyme, determined by gel filtration chromatography, is about 33.2 kDa. SDS-polyacrylamide gel electrophoresis shows that the enzyme is composed of two equal subunits of 16.6 kDa The isolectric point, assayed by isoelectric focusing, in the pH range of 3.5-6.5, is 4.3. The enzyme stability was tested at different temperatures, pH, and concentration of inhibitors (KCN and H(2)O(2)). The catalytic constant (k(cat)) was 1.17 +/- 0.14 x 10(9) M(-1) s(-1) at pH 9.9 and 0.1 M ionic strength. The activation energy of the thermal denaturation process is 263 kJ mol(-1). The electrostatic surface potential of the modeled tobacco Cu,Zn-SOD I was calculated showing that the functional spatial network of charges on the protein surface has been maintained, independently of the amino acid substitution around the active sites.

Trichilia roka Chiov. (Meliaceae): pharmacognostic researches

The dried aqueous extract of Trichilia roka Chiov. (Meliaceae) root was evaluated for its potential antipyretic activity on yeast-induced hyperthermia in rats. The drug showed a significant reduction of body temperature when administered orally at the doses of 0.25, 0.5 and 1.0 g/kg. The antipyretic activity of T. roka was compared to indomethacin treatment (50 mg/kg), used as a reference drug. The results of this study confirm the validity of traditional usage of T. roka as an antipyretic agent. Moreover, micromorphological investigations were carried out by scanning electron microscopy obtaining useful phytognostic elements for the correct identification of the drugs both in scraped and powdered forms because this is of great interest for quality control in basic research and drug production, especially for imported items and for raw material sold by traditional herborists.

Micromorphological investigations on Entada africana Guill. et Perr. (Mimosaceae)

Entada africana Guill. et Perr., known in Mali by the common local name 'Samanéré' in the Bambara language, is one of the traditional Malian medicines prescribed for many illnesses. In the present investigation, micromorphological studies were carried out by scanning electron microscopy on the roots and the leaves. The correct identification of the morphological characters of drugs is of great interest for quality control in basic research and drug production, especially for imported items and for raw materials sold by traditional herbalists.

Production, purification, and properties of an extracellular laccase from Rigidoporus lignosus

Laccase from Rigidoporus lignosus, a white-rot basidiomycete, has been isolated from culture filtrates. The enzyme was purified to homogeneity and some of its structural and kinetic parameters have been determined. The effects of pH, temperature, and organic solvents on the activity and stability of the enzyme, under different conditions, were also assayed. The results we have obtained, including the rather broad substrate specificity of enzyme, combined with their relatively easy production and purification, suggest that laccase may be efficiently employed in a variety of biotechnology applications.

Thiazole derivatives as inhibitors of purified bovine liver mitochondrial monoamine oxidase-B: structure-activity relationships and theoretical study

Structure-activity relationships were performed on a new series of thiazole derivatives which selectively inactivate monoamine oxidase-B (MAO-B), purified from mitochondrial beef liver. All of the synthesized and tested compounds showed non-competitive inhibition, suggesting the formation of a stable adduct between the tertiary amine function, linked to the thiazolyl derivatives and the active site of the enzyme. The mechanism of MAO-B inhibition is discussed in terms of the Ionization Potential of the amine nitrogen atom and the conformational flexibility of the inhibitors.

Substrate recognition and selectivity of peptide deformylase. Similarities and differences with metzincins and thermolysin

The substrate specificity of Escherichia coli peptide deformylase was investigated by measuring the efficiency of the enzyme to cleave formyl- peptides of the general formula Fo-Xaa-Yaa-NH2, where Xaa represents a set of 27 natural and unusual amino acids and Yaa corresponds to a set of 19 natural amino acids. Substrates with bulky hydrophobic side-chains at the P1' position were the most efficiently cleaved, with catalytic efficiencies greater by two to five orders of magnitude than those associated with polar or charged amino acid side-chains. Among hydrophobic side-chains, linear alkyl groups were preferred at the P1' position, as compared to aryl-alkyl side-chains. Interestingly, in the linear alkyl substituent series, with the exception of norleucine, deformylase exhibits a preference for the substrate containing Met in the P1' position. Next, the influence in catalysis of the second side-chain was studied after synthesis of 20 compounds of the formula Fo-Nle-Yaa-NH2. Their deformylation rates varied within a range of only one order of magnitude. A 3D model of the interaction of PDF with an inhibitor was then constructed and revealed indeed the occurrence of a deep and hydrophobic S1' pocket as well as the absence of a true S2' pocket. These analyses pointed out a set of possible interactions between deformylase and its substrates, which could be the ground driving substrate specificity. The validity of this enzyme:substrate docking was further probed with the help of a set of site-directed variants of the enzyme. From this, the importance of residues at the bottom of the S1' pocket (Ile128 and Leu125) as well as the hydrogen bond network that the main chain of the substrate makes with the enzyme were revealed. Based on the numerous homologies that deformylase displays with thermolysin and metzincins, a mechanism of enzyme:substrate recognition and hydrolysis could finally be proposed. Specific features of PDF with respect to other members of the enzymes with motif HEXXH are discussed.

Design and synthesis of substrate analogue inhibitors of peptide deformylase

Series of substrates derivatives of peptide deformylase were systematically synthesized and studied for their capacities to undergo hydrolysis. Data analysis indicated the requirement for a hydrophobic first side chain and for at least two main chain carbonyl groups in the substrate. For instance, Fo-Met-OCH3 and Fo-Nle-OCH3 were the minimal substrates of peptide deformylase obtained in this study, while positively charged Fo-Nle-ArgNH2 was the most efficient substrate (kcat/Km = 4.5 x 10(5) M-1.s-1). On the basis of this knowledge, 3-mercapto-2-benzylpropanoylglycine (thiorphan), a known inhibitor of thermolysin, could be predicted and further shown to inhibit the deformylation reaction. The inhibition by this compound was competitive and proved to depend on the hydrophobicity at the P1' position. Spectroscopic evidence that the sulfur group of thiorphan binds next to the active site metal ion on the enzyme could be obtained. Consequently, a small thiopseudopeptide derived from Fo-Nle-OCH3 was designed and synthesized. This compound behaved as a competitive inhibitor of peptide deformylase with KI = 52 +/- 5 microM. Introduction of a positive charge to this thiopeptide via addition of an arginine at P2' improved the inhibition constant up to 2.5 +/- 0.5 microM, a value 4 orders of magnitude smaller than that of the starting inhibitors. Evidence that this inhibitor, imino[(5-methoxy-5-oxo-4-[[2-(sulfanylmethyl)hexanoyl]amino]pentyl )am ino]methanamine, binds inside the active site cavity of peptide deformylase, while keeping intact the 3D fold of the protein, was provided by NMR. A fingerprint of the interaction of the inhibitor with the residues of the enzyme was obtained.

Solution structure of nickel-peptide deformylase

In the accompanying paper, we report that zinc is unlikely to be the co-factor supporting peptide deformylase activity in vivo. In contrast, nickel binding promotes full enzyme activity. The three-dimensional structure of the resulting nickel-containing peptide deformylase (catalytic domain, residues 1 to 147) was solved by NMR using a 13C-15N-doubly labelled protein sample. A set of 2261 restraints could be collected, with an average of 15.4 per amino acid. The resolution, which shows a good definition for the position of most side-chains, is greatly improved compared to that previously reported for the zinc-containing, inactive form. A comparison of the two stuctures indicates however that both share the same 3D organization. This shows that the nature of the bound metal is the primary determinant of the hydrolytic activity of this enzyme. Site-directed mutagenesis enabled us to determine the conserved residues of PDF involved in the structure of the active site. In particular, a buried arginine appears to be critical for the positioning of Cys90, one of the metal ligands. Furthermore, the 3D structure of peptide deformylase was compared to thermolysin and metzincins. Although the structural folds are very different, they all display a common structural motif involving an alpha-helix and a three-stranded beta-sheet. These conserved structural elements build a common scaffold which includes the active site, suggesting a common hydrolytic mechanism for these proteases. Finally, an invariant glycine shared by both PDF and metzincins enables us to extend the conserved motif from HEXXH to HEXXHXXG.

Control of peptide deformylase activity by metal cations

Previous work indicated that peptide deformylase behaves as a metalloenzyme since the Escherichia coli enzyme was shown to copurify with a zinc ion. The present study establishes that nickel:enzyme complexes can also be isolated provided that nickel salts were added in the buffers throughout the purification. Similar results were obtained with the deformylases from Thermus thermophilus and Bacillus stearothermophilus. As a result of nickel binding, the catalytic efficiencies of peptide deformylases increased by two to three orders of magnitude with respect to those of the forms previously characterized. Using the model substrate N-formyl-Met-Ala-Ser, kcat/Km values of 5.4, 1.2 and 25 10(4)M-1s-1 could be obtained for the E. coli, T. thermophilus and B. stearothermophilus enzymes, respectively. This value satisfyingly accounts for the deformylation turnover required in the cell. In vitro characterization of the E. coli enzyme shows that zinc can readily substitute for the bound nickel with the catalytic efficiency decreasing to 80 M-1s-1 in turn. Conversely, the activity of the zinc-containing protein can be significantly improved by addition of nickel to the enzymatic assay.

In vitro antimicrobial activity of Pistacia lentiscus L. extracts: preliminary report

The in vitro antimicrobial activity of Pistacia lentiscus L. extracts was determined. Pistacia lentiscus L. extracts were tested on bacteria (Sarcina lutea, Staphylococcus aureus and Escherichia coli) and fungi (Candida albicans, Candida parapsilosis, Torulopsis glabrata and Cryptococcus neoformans). Of the different plant extractions, decoctions showed the best antibacterial activity, but the activity against fungal cells appears to be much more interesting.

Leaf extracts of some Cordia species: analgesic and anti-inflammatory activities as well as their chromatographic analysis

Leaf preparations of several species of Cordia are used in traditional medicine as remedies for osteoarticular diseases. The analgesic, anti-inflammatory and anti-arthritic activities in the rat of different extracts of C. francisci, C. martinicensis, C. myxa, C. serratifolia and C. ulmifolia leaves were studied. The results obtained showed that the petroleum ether and alcoholic extracts especially of C. francisci, C. myxa and C. serratifolia leaves have a significant analgesic, anti-inflammatory and anti-arthritic activity in the rat. The flavonoids and phenolic derivative content of the five species of genus Cordia leaves was investigated by TLC and determined by reversed-phase HPLC with an acetonitrile/water/acetic acid buffer solvent gradient. UV detection was carried out at 255 and 280 nm. Four flavonoid glycosides, robinin, rutin, datiscoside and hesperidin, one flavonoid aglycone, dihydrorobinetin, two phenolic derivatives, chlorogenic and caffeic acid, were evidenced and determined.

Effect of cadmium on germination, growth and active principle contents of Matricaria recutita L

The effects on Matricaria recutita L. of an increase of cadmium concentration in soil and in atmosphere were investigated. Data on germination, survival, growth and dry weight were collected and methilenic extracts of the drugs were analyzed. Cd pollution affects Matricaria germination and growth and GLC analysis of extracts shows a significant difference in active principles between the plants subject undergone different treatments.

Effect of cadmium on germination, growth and active principle contents of Achillea millefolium L

The effects on germination, growth and active principle contents of Achillea millefolium L. of an increase of cadmium concentration in soil and in atmosphere were investigated. Soil pollution reduced germination and growth. No significant differences were found in GLC analysis of all plants extracts.