Trace metals and pesticides in water-sediment and associated pollution load indicators of Netravathi-Gurupur estuary, India: Implications on coastal pollution

Various environmental indicators were used to evaluate the water and sediment quality of the Netravathi-Gurupur estuary, India, for trace metals and pesticide pollution. The descended order of studied metal concentrations (μg/L) in the water was Fe (592.71) > Mn (98.35) > Zn (54.69) > Cu (6.64) > Cd (3.24) > Pb (2.38) > Cr (0.82) and in sediment (mg/kg) was Fe (11,396.53) > Mn (100.61) > Cr (75.41) > Zn (20.04) > Cu (12.77) > Pb (3.46) > Cd (0.02). However, pesticide residues were not detected in this estuarine environment. The various metal indexes categorised the water as uncontaminated, whereas contamination factor, enrichment factor, geo-accumulation index, degree of contamination and pollution load index indicated low to moderate sediment contamination. Multivariate statistics showed that the dominance of natural sources of trace metals with little anthropogenic impact. Improvement in water/sediment quality during the study period might be due to COVID-19 imposed lockdown.

Inhibitory role of copper and silver nanocomposite on important bacterial and fungal pathogens in rice (Oryza sativa)

Rice (Oryza sativa) being among the most important food crops in the world is also susceptible to various bacterial and fungal diseases that are the major stumbling blocks in the way of increased production and productivity. The bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae and the sheath blight disease caused by Rhizoctonia solani are among the most devastating diseases of the rice crop. In spite of the availability of array of chemical control, there are chances of development of resistance. Thus, there is a need for the nanotechnological intervention for management of disease in the form of copper and silver nano-composites. The copper (CuNPs) and silver nanoparticles (AgNPs) were synthesized using green route and characterized using different high throughput techniques, i.e., UV-Vis, FT-IR, DLS, XRD, FE-SEM, TEM. The particle size and zeta potential of synthesized CuNPs and AgNPs were found 273 nm and - 24.2 mV; 95.19 nm and - 25.5 mV respectively. The nanocomposite of CuNPs and AgNPs were prepared having particle size in the range of 375-306 nm with improved stability (zeta potential - 54.7 to - 39.4 mV). The copper and silver nanoparticle composites evaluated against Xanthomonas oryzae pv. oryzae and Rhizoctonia solani were found to have higher antibacterial (inhibition zone 13 mm) and antifungal activities (77%) compared to only the copper nanoparticle (8 mm; 62% respectively). Net house trials of nano-composite formulations against the bacterial blight of rice also corroborated the potential of nanocomposite formulation. In silico studies were carried out selecting two disease-causing proteins, peptide deformylase (Xanthomonas oryzae) and pectate lyase (Rhizoctonia solani) to perform the molecular docking. Interaction studies indicatedthat both of these proteins generated better complex with CuNPs than AgNPs. The study suggested that the copper and silver nano-composites could be used for developing formulations to control these devastating rice diseases.

Abstract 3940: Validation of TFX1, a first-in-class target for cancer metastasis

Most of the drugs approved for metastatic epithelial carcinomas treat the proliferation of the tumor and not the biology of metastasis. To date, all clinical trials around metastasis that focused on proteases, kinases, or integrins have failed in clinics. As a result, metastasis biology-focused drug discovery has been deprioritized.We asked the question as to what the rate-limiting steps of metastasis were. To answer it, we created a cell-based functional assay platform, METAssay™, that dissected all metastasis biology steps into thirty cellular assays and characterization steps. The platform identified the functional differences between metastatic and proliferating cells. This platform was normalized with patient tumor cells, and a machine learning algorithm, METSCAN™, was subsequently applied to identify the weighted steps that contributed towards successful metastasis. This led to the identification of four first-in-class targets; two transcription factors, one cytokine receptor and one nuclear hormone receptor.We then validated the relevance of the first target, TFX1, by overexpressing it in both colorectal and triple-negative breast cancer cell lines. Interestingly, apart from the expected increase in migration and invasion, all cell lines showed an increase in ROS, Autophagy, PDL-1, CD-73, quiescence, exosome uptake and a decrease in apoptosis, mitosis, and exosome secretion. Conversely, the downregulation of TFX1 showed the opposite effect. TFX1 was purified, and a biochemical isothermal calorimetry (ITC) assay was standardized with a tool compound with a KD of 107 nM. The compound effectively reduced metastatic properties in the cell lines and in multiple patient samples, as analyzed by the METAssay™ platform. Colorectal cancer cell lines overexpressing TFX1 also showed increased platelet binding, which was reduced by the tool compound, but not triple-negative cancer cell lines. Also, the effect of overexpression in non-metastatic cells was more profound than in metastatic cells, suggesting a saturating effect. Further characterization of the tool compound is currently ongoing to help establish a baseline for a novel discovery programme.The ideal drug to delay metastasis should be given to primary tumor patients with no evidence of clinical metastasis, irrespective of their pathological grading. Therefore, it should have a high bar for safety. Our goal is to collaborate on a discovery journey to identify candidates and create a companion diagnostic that will identify primary tumor patients at high risk of metastasis, thereby selecting the right patient cohort for clinical trials.

Citation Format: Arnab Roy Chowdhury, Manoj Pandre, Chinmaya Amarkanth, Debabani Roy Chowdhury, John Ellingboe. Validation of TFX1, a first-in-class target for cancer metastasis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3940.

Geochemical distribution and forms of phosphorus in the surface sediment of Netravathi-Gurupur estuary, southwestern coast of India

Estuaries are the most productive transition ecosystem and phosphorus (P) plays an important role in these ecosystems. Therefore, in the present study, sequential extraction method was used to determine the abundance of five sediment P fractions (calcium (Ca-P), Iron (FeP), aluminum (AlP), exchangeable (Ex-P) and organic (OrgP) bound P) in Netravathi-Gurupur estuary, India. Total phosphorus (TP) content varied from 435-810 mg/kg (non-monsoon) and 258-699 mg/kg (monsoon). Inorganic P was dominant part. Different P fractions followed similar order (Fe-P > Ca-P > Al-P > Org-P > Ex-P) with respect to seasons. FeP was dominant fraction, indicating probable anthropogenic stress. Sediment may act as source of P as bioavailable P constituted 40-69.2 % of TP. Molar ratio of OC to Org-P in sediment indicated terrestrial sources of organic matter. However, the estimated phosphorus pollution index were lower than one except a few cases indicating less ecological risk with respect to sedimentary TP load.

Normalized difference vegetation index sensor-based nitrogen management in bread wheat (Triticum aestivum L.): Nutrient uptake, use efficiency, and partial nutrient balance

The present experiment was conducted to assess the impact of fixed and variable doses (using a normalized difference vegetation index-sensor) of nitrogen (N) on wheat yields, nutrient uptake, nitrogen use efficiency, and soil nitrogen balance through the optimization of nitrogen dose. There were 10 treatments based on fixed and variable doses with different splits, and each treatment was replicated three times under a randomized complete block design. The treatments comprised fixed doses of 120 and 150 kg N ha^-1 with different splits; variable doses based on sensor readings after application of 60, 90, and 120 kg N ha^-1; 225 kg N ha^-1 as a nitrogen-rich control; and no application of nitrogen as the absolute control. It was revealed that the application of a basal dose of 60 kg N ha^-1 and another 60 kg N ha^-1 at the crown root initiation stage followed by a sensor-guided N application significantly improved wheat grain yields and grain nitrogen uptake. However, straw nitrogen uptake was highest in N-rich plots where 225 kg N ha^-1was applied. It was found that any curtailment in these doses at basal and crown root initiation stages followed by nitrogen application using a normalized difference vegetation index sensor later could not bring about higher crop yields. On average, wheat crops responded to 152-155 kg N ha^-1 in both years of the study. Partial factor productivity along with agronomic and economic nitrogen use efficiency showed a declining trend with an increased rate of N application. Apparent N recovery values were comparable between normalized difference vegetation index sensor-based N application treatments and treatments receiving lesser N doses. Soil N status decreased in all the treatments except the nitrogen-rich strip, where there was a marginal increase in soil N status after the wheat crop harvest in the rotation. Partial nitrogen balance was negative for all the treatments except the control. From these 2-year field trials, it can be concluded that applying a normalized difference vegetation index sensor could be an essential tool for the rational management of fertilizer nitrogen in wheat grown in eastern sub-Himalayan plains.

Abstract 2868: A cell based phenotypic assay platform for cancer metastasis drug discovery and diagnostics

Metastatic cancers are difficult to treat and are the cause of about 90% of cancer related deaths. Furthermore, predictive diagnostics are not readily available, and lack of good translational assays has impaired drug discovery. Mestastop has developed a platform of cell based functional assays that aims to address these drug discovery and diagnostic gaps. The platform is comprised of a set of 14 cell based phenotypic assays that capture multiple aspects of the complex process of metastasis, including characterization of the plasticity ratios (EMT, MET) and stemness of cells, invasion, intravasation, circulation, extravasation, and survival in secondary tissues (e.g metabolic shift, exosome secretion). Wild type tumor cells (initially a set of colon tumor cell lines) are utilized in the platform. Non-metastatic wild type cells (e.g. HT-29) that have been engineered into metastatic cells are also utilized to further elucidate metastatic processes, thereby creating two baseline data sets for each assay; one for the normal growing tumor and the other for the select metastatic population. Patient derived tumors are now being analyzed in the platform to help build a translational model. Preclinical animal models are being jointly developed with Immunobiome Inc. (South Korea). As the data from all these assays present a multivariate problem, we are developing a machine learning algorithm, METSCANTM, to analyze the results. The platform will be applied to the screening of novel compounds for drug discovery and of approved drugs for repurposing. Analysis of patient derived tumors may allow for the early detection of patients with high metastatic potential. Four colon cancer cell lines and several standard chemotherapy drugs have been used to validate the platform. A group of triple negative breast cancer cell lines is now being tested. Preliminary data for a set of approved, marketed drugs has further validated the potential of the platform for drug discovery and repurposing. The Mestastop proprietary assay platform will empower biopharma in the discovery of novel drug candidates and repurposing of approved drugs for the treatment of metastasis, and the early diagnosis of cancers with high metastatic potential, thereby addressing the unmet need in the area of cancer metastasis.

Citation Format: Arnab Roy Chowdhury, Debabani Roy Chowdhury, Manoj Pandre, Samrat Roy, Sundarajan Kannan, John W. Ellingboe. A cell based phenotypic assay platform for cancer metastasis drug discovery and diagnostics [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 2868.

Limberg Flap in Pilonidal Sinus: Experience in Shaheed Suhrawardy Medical College Hospital

Pilonidal sinus disease is a common anorectal condition usually seen in young adult patients. Various methods have been described over the years and there is ongoing debate regarding the ideal method. This study was conducted to evaluate the advantages, results of rhomboid excision and Limberg flap reconstruction in the management of sacrococcygeal pilonidal sinus disease. This cross-sectional study was conducted in Surgery Unit-I of Department of Surgery, Shaheed Suhrawardy Medical College Hospital, Dhaka, Bangladesh a tertiary care centre from July 2016 to November 2017. It includes 19 patients who were treated for sacrococcygeal pilonidal sinus disease by Limberg (Rhomboid) flap. All patients that underwent the procedure had good postoperative outcome with minimal postoperative discomfort and were discharged in 3-4 days. There were 3 cases with complications. Limberg flap coverage is very effective for pilonidal disease with low complication rates, reduced hospital stay, low recurrence rates, earlier healing and shorter time off-work. This technique can be easily mastered and used as an indispensable tool for treating sacrococcygeal pilonidal sinus disease.

Measuring Sensitivity, Specificity and Accuracy of HRCT of Chest and Comparison with Biomarkers in COVID-19 Suspected Patients: A Cross Sectional Study

COVID-19 is a declared pandemic by World Health Organization. The diagnostic tests are not of high specificity and sensitivity, so far. Pro-inflammatory biomarkers and High Resolution Computed Tomography (HRCT) of chest are the common investigations performed to evaluate the diagnosis and prognosis of COVID-19. The objective of this study was to estimate the sensitivity, specificity and accuracy of HRCT and to find out the relationship between the biomarkers and HRCT findings. This was a cross-sectional descriptive study carried out in the COVID-19 suspected isolation unit of a tertiary hospital from July 2020 to November of 2020. Data were collected from electronic medical record (EMR). Relationship test were done by t-test and one-way-ANOVA test. Total 123 cases were enrolled after matching with selection criterion. Mean age of male was 62.5 years and female 57.7 years. Highest frequency of participants was observed in the 60-69 year age group. According to HRCT% findings 4 groups were made. They are below 25%, 25%-50%, 51%-75% and 76%-100%. The distribution of case among these groups was 15%, 44%, 35% and 6% respectively. The relationship between biomarkers (NLR, D-dimer, Ferritin and CRP) and HRCT% was found significant (p<0.05). In HRCT 92.5% lesion were peripherally placed and 99.2% cases were affected by both lungs. The sensitivity and specificity of HRCT were found 46% and 72.6% respectively with 62% accuracy. Raised biomarkers are significantly related to the more lung involvement in case of COVID-19 suspected pneumonia patients. These biomarkers will be helpful as diagnostic and prognostic markers for this disease. HRCT percentage can play an important role as diagnostic and prognostic tool in case of COVID-19 suspected cases.

The Spectrum of Focal Segmental Glomerulosclerosis from Eastern India: Is It Different?

Focal segmental glomerulosclerosis (FSGS) is a disease that is defined entirely by its histopathological appearance. The recent Columbian classification has grouped this disease into various types based on the light microscopic description. There is a paucity of data describing the distribution of its various subtypes from the Indian subcontinent. This study was undertaken with the aim to throw light on the epidemiology and clinical features of primary FSGS in Eastern India. This retrospective study includes our cohort of biopsy-proven FSGS who presented to us from June 2009 to July 2011 and the analysis of their presenting clinical and histopathological features from our center in East India. Out of 347 patients diagnosed with FSGS in this period, 224 patients were included in the study. A total of 167 cases were of not otherwise specified (NOS) variant (74.5%), 30 tip variant (13.39%), 14 perihilar (6.25%), 8 cellular (3.57%), and 5 to the collapsing variant (2.23%). The maximum proteinuria at presentation was seen with the tip variant (7.98 ± 6.6 g/24 h), and the renal functions were most deranged at presentation with the collapsing variant. These findings were different from those described in other populations including higher prevalence of the tip and the perihilar variant, significant difference in the degree of hypertension, proteinuria, and renal dysfunction among the different variants. The Columbian classification has helped to stratify the outcomes of this glomerular disease with respect to its clinical presentation as well as histopathological features. However, the characteristics of the various variants do show a distinctive pattern in various populations based on ethnicities.

Surgical Management of Breast Cancer under Local Anaesthesia: A Surgeon's Perspective

Background: Treatment of breast cancer without surgery may not be effective. But in elderly patients with lots of co-morbidities, surgical management often cannot be done due to the significant risks of general anesthesia. The need for a safe, easy and effective alternative anaesthetic technique that can provide adequate peroperative analgesia as well as reduced anxiety in such group of patients was the main indication for this study.Materials and method: This prospective study was done on eleven patients, with coexisting medical conditions and who were not at all fit for general anaesthesia, and underwent breast cancer surgery under local anaesthesia. The patients were studied with regard to intraoperative analgesia, haemodynamic stability and complications related to technique. The study was done in Delta Medical College Hospital, Dhaka, Bangladesh.Results: Mean±SD of study patients were 64.7±7 years old and all were suffering from coexisting medical conditions. Following local anaesthesia, mean intraoperative heart rate was 81.5±11.8 beats/min and the mean blood pressure was 127.3/79±9.6/7.0 mmHg. Patients felt no pain after infiltration of local anaesthetics, but experienced it if any place was missed before dissection. No complication occurred due to this procedure. All the candidates were fully satisfied with the procedure.Conclusion: Local anaesthesia provides satisfactory pain control along with keeping haemodynamics stable for surgical treatment of breast cancer among elderly patients having co-morbid conditions.Delta Med Col J. Jul 2017 5(2): 63-67

The Epidemiology, Clinical Features, and Outcome of Infection-related Glomerulonephritis from East India: A Single Center Experience

Infection-related glomerulonephritis (IRGN) is an example of immunological renal injury due to non-renal infections. With the changing face of IRGN over the years, renal biopsy definitely has an important role to play in differentiating this disease from the other masquerades and helps in prognosticating the long-term outcomes. This prospective study includes biopsy-proven IRGN cases who presented to us from July 2010 to July 2013 from a single center in East India. Of the 168 patients suspected and screened, 137 patients were proved to have IRGN. About 11.67% cases were proven to be immunoglobulin A-IRGN variant. The mean age of presentation was 22.7 ± 15.8 years with a slight male preponderance. A nephrotic range of proteinuria was seen in 13.8% cases and 17.5% patient required renal replacement therapy at presentation. Around 8.75% patients had persistent proteinuria despite normal renal function beyond 6 months of follow-up and 8.09% patients progressed to chronic kidney disease. It may no longer be classified as a glomerular disease with the definite favorable outcome as an important number of patients may progress to chronicity following this disease. Renal biopsy plays an important role in the assessment of prognosis of IRGN and detection of the presence of other underlying glomerulonephritis and should be considered early, especially in patients with atypical presentation.

Preclinical formulation for the pharmacokinetics and efficacy of GBO-006, a selective polo like kinase 2 (PLK2) inhibitor for the treatment of triple negative breast cancer

<p class="ADMETabstracttext">GBO-006 was shown to be a highly specific and selective PLK2 inhibitor that promoted mitotic arrest in various cancer cell lines, subsequently resulting in their apoptotic death.  Intraperitoneal alternate day dosing of GBO-006 using 100 % DMSO as formulation showed significant tumor regression in xenograft models, demonstrating proof of concept of PLK2 inhibition in vivo. These studies necessitated the development of a suitable and GRAS (generally considered as safe) preformulation for pharmacokinetic and efficacy studies. GBO-006 possesses challenging physicochemical and biopharmaceutical properties like poor solubility in aqueous media, low permeability and a crystalline nature. Different methods like cosolvency, complexation and micellar solubilization were employed to improve the solubility of GBO-006.  A strategy of co-solvency is used to solubilize the GBO-006 up to 10 mg/mL. A formulation with 20 % DMSO, 40 % PEG 400, 30 % of 100 mM citrate buffer (pH 3.0) and 10 % solutol displayed clear solution without any visual precipitation of the drug even after 2 weeks of storage. GBO-006 showed moderate clearance in rat and high systemic clearance in mouse and dog. It showed poor oral bioavailability across all species. Intraperitoneal dosing of GBO-006 demonstrated the linear exposure. GBO-006 showed significant inhibition of tumor progression.  </p><p><span style="font-family: Calibri; font-size: medium;"> </span></p><p><span style="font-family: Calibri; font-size: medium;"> </span></p>

Abstract 1661: Development of lipid-based nanosuspension formulation of first-in-class PLK2 inhibitor GBO-006 to treat triple-negative breast cancer

Introduction: The highly selective, ATP competitive PLK2 inhibitor GBO-006 was previously shown by us to arrest growth of triple negative breast cancer (TNBC) at 30mg/kg dose (mpk) in MDAMB-231 xenograft model. However, the maximum formulation strength was 20mg/ml and was not adequate for toxicology studies. GBO-006 was found to be crystalline and poorly soluble (&lt;1 mg/mL) in organic solvents/co-solvents and non-aqueous media including lipids & oils, even in the presence of complexing agents. Degradation at very high temperatures (∼346 °C) limited the use of amorphous based strategies. Efforts to dissolve GBO-006 using one solvation strategy (co-solvency, complexation, micellar solubilization) were unsuccessful. The study described herein focused on particle engineering efforts to develop a 50mg/ml nanosuspension formulation of GBO-006 stabilized by ionic, non-ionic, and polymeric and lipid stabilizers alone or in combination.

Experimental procedures: Nanosizing of GBO-006 by ‘bottom-up’ and ‘combination of bottom-up and top-down’ technologies did not yield particles in the desirable nanosize range. Nanosizing GBO-006 to less than 400 nm (d0.9) particle sizes was feasible by top-down technology using bead milling and a high shear microfluidics processor. During initial trials, lower strength formulations (5 to 25 mg/mL) were nanosized and stabilized using bead milling with non-ionic surfactant(s), Tween 80 & poloxamer 188, in addition to polymers such as PVP K12. Microfluidization was not pursued further due to clogging of the interaction chamber at higher concentrations (50 mg/mL).

Results: A crystalline, lipid nanoparticle of GBO-006 was feasible by bead milling and further assessed for pharmacokinetic evaluation and efficacy studies. Intraperitoneal dose escalation studies in mice showed a dose-dependent linear increase in plasma exposure of GBO-006. Fifty percent reduction in MDAMB-231 xenograft tumor volume was observed with 1.5 mpk of GBO-006 after qd dosing. Significant accumulation of GBO-006 was observed in spleen and liver upon chronic dosing (21 days). We hypothesized that accumulation was likely due to reticulo-endothelial system (RES) mediated uptake, which was further proven by in vitro experiments with differentiated macrophages.

Conclusion: We have successfully developed a nanosuspension formulation for GBO-006. Notably, this nanosuspension showed similar efficacy to previous formulations at much lower doses (1.5 mpk), however particle size of 260 nm accentuated RES uptake. Ongoing studies are focused on decreasing particle size below 150 nm and incorporating a negative zeta potential to bypass RES uptake and minimize tissue distribution.

Citation Format: Vijaya G. Tirunagaru, Arnab Roy Chowdhury, Jeyaraj Athisayamani Duraiswamy, Srinivasa Rao Maddi, Sayan Mitra, Chandra Deb, Ram Sudheer Adluri, Jang B. Gupta. Development of lipid-based nanosuspension formulation of first-in-class PLK2 inhibitor GBO-006 to treat triple-negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1661. doi:10.1158/1538-7445.AM2015-1661

p166, a link between the trypanosome mitochondrial DNA and flagellum, mediates genome segregation

Kinetoplast DNA (kDNA), the trypanosome mitochondrial genome, is a giant network containing several thousand interlocked DNA rings. Within the mitochondrion, kDNA is condensed into a disk-shaped structure positioned near the flagellar basal body. The disk is linked to the basal body by a remarkable transmembrane filament system named the tripartite attachment complex (TAC). Following kDNA replication, the TAC mediates network segregation, pulling the progeny networks into the daughter cells by their linkage to the basal bodies. So far TAC has been characterized only morphologically with no known protein components. By screening an RNAi library, we discovered p166, a protein localizing between the kDNA and basal body in intact cells and in isolated flagellum-kDNA complexes. RNAi of p166 has only small effects on kDNA replication, but it causes profound defects in network segregation. For example, kDNA replication without segregation causes the networks to grow to enormous size. Thus, p166 is the first reported molecular component of the TAC, and its discovery will facilitate study of kDNA segregation machinery at the molecular level.

DNA topoisomerases in life and death: implications in kinetoplastid protozoa

Current biomedical research has its focus on the search for newer intervention strategies to control public health impact of parasitic diseases. The dramatic advances of molecular and cellular biology in recent times have provided opportunities for discovering and evaluating molecular targets for drug designing, which now form a rational basis for the development of improved anti parasitic therapy. DNA topoisomerases, the "cellular magicians" involved in nearly all biological processes governing DNA, have emerged as one such biological target. Over the last two decades, interest in topoisomerases has expanded beyond the realm of the basic science laboratory into the clinical arena. This review aims at providing a comprehensive insight into the biology of DNA topoisomerases and also focus on its evolution as a drug target in the unicellular kinetoplastids.

Dihydrobetulinic acid induces apoptosis in Leishmania donovani by targeting DNA topoisomerase I and II: implications in antileishmanial therapy

Leishmaniasis is the second-most dreaded parasitic disease in the modern world, behind malaria. The lack of effective vaccines demand improved chemotherapy along with the development of lead compounds and newer targets. We report here that the pentacyclic triterpenoid, dihydrobetulinic acid (DHBA), is a novel lead compound for antileishmanial therapy. It acts by targeting DNA topoisomerases. DNA topoisomerase I and II activity was studied using relaxation and decatenation assays. Mechanistic studies were based on the decreased mobility of enzyme-bound DNA compared with free DNA and the differential mobility of nicked and supercoiled monomers in 1% agarose gel. Pulsed field gradient gel electrophoresis, confocal microscopy, and transmission electron microscopy were performed to assess cytotoxicity of the compound and ultrastructural damage of the parasite. Apoptosis was studied by the isolation of DNA from DHBA-treated parasites and subsequent electrophoresis in 1% agarose gel. DHBA inhibits growth of Leishmania donovani promastigotes and amastigotes with an IC50 of 2.6 and 4.1 microM respectively. The compound is a dual inhibitor of DNA topoisomerases that fails to induce DNA cleavage and acts by preventing the formation of enzyme-DNA binary complex, ultimately inducing apoptosis. Treatment of infected golden hamsters with the compound markedly reduces (> 92%) parasitic burden, both in spleen and liver. Interestingly, the 17-decarboxylated analogue, dihydrolupeol, does not inhibit DNA topoisomerase I and II, has no effect on parasitic growth, and also fails to induce apoptosis. DHBA is a potent antileishmanial agent that induces apoptosis by primarily targeting DNA topoisomerases. Therefore it is a strong candidate for use in designing new antileishmanial drugs.

Luteolin, an emerging anti-cancer flavonoid, poisons eukaryotic DNA topoisomerase I

Luteolin, a naturally occurring flavonoid, is abundant in our daily dietary intake. It exhibits a wide spectrum of pharmacological properties, but little is known about its biochemical targets other than the fact that it induces topoisomerase II-mediated apoptosis. In the present study, we show that luteolin completely inhibits the catalytic activity of eukaryotic DNA topoisomerase I at a concentration of 40 microM, with an IC50 of 5 microM. Preincubation of enzyme with luteolin before adding a DNA substrate increases the inhibition of the catalytic activity (IC50=0.66 microM). Treatment of DNA with luteolin before addition of topoisomerase I reduces this inhibitory effect. Subsequent fluorescence tests show that luteolin not only interacts directly with the enzyme but also with the substrate DNA, and intercalates at a very high concentration (>250 microM) without binding to the minor groove. Direct interaction between luteolin and DNA does not affect the assembly of the enzyme-DNA complex, as evident from the electrophoretic mobility-shift assays. Here we show that the inhibition of topoisomerase I by luteolin is due to the stabilization of topoisomerase-I DNA-cleavable complexes. Hence, luteolin is similar to camptothecin, a class I inhibitor, with respect to its ability to form the topoisomerase I-mediated 'cleavable complex'. But, unlike camptothecin, luteolin interacts with both free enzyme and substrate DNA. The inhibitory effect of luteolin is translated into concanavalin A-stimulated mouse splenocytes, with the compound inducing SDS-K+-precipitable DNA-topoisomerase complexes. This is the first report on luteolin as an inhibitor of the catalytic activity of topoisomerase I, and our results further support its therapeutic potential as a lead anti-cancer compound that poisons topoisomerases.

Betulinic acid, a potent inhibitor of eukaryotic topoisomerase I: identification of the inhibitory step, the major functional group responsible and development of more potent derivatives

BACKGROUND

Betulinic acid, a naturally abundant, plant derived, pentacyclic triterpenoid possesses anti-HIV, anti-malarial and anti-inflammatory properties and has recently emerged as a potent anti-tumor compound. This study explores the mode of action of betulinic acid on eukaryotic topoisomerase I and identifies the major functional group responsible along with more potent derivatives.

MATERIAL/METHODS

Topoisomerase I relaxation activity was electrophoretically measured by the decreased mobility of the relaxed monomers followed by ethidium bromide staining. DNA cleavage was studied by electrophoretic separation of the nicked monomers from the relaxed and supercoiled monomers in presence of ethidium bromide. In-vivo DNA cleavage was studied in blasted mouse splenocytes by the SDS-K+ trapping of 3H-DNA-topoisomerase I-camptothecin ternary complex.

RESULTS

Betulinic acid exerts its inhibitory effect by preventing topoisomerase I-DNA interaction as a result of which the 'cleavable complex' is not formed. In consequence, it also acts as an antagonist to camptothecin-mediated cleavage. A series of analogues modified at C-3, C-17 and C-20 positions of betulinic acid were subsequently assayed for inhibition of topoisomerase I catalytic activity. Replacement of the 17-carboxylic group reduces the inhibitory effect and decarboxylation leads to the complete loss of inhibitory effect.

CONCLUSIONS

This study is the first detail report of betulinic acid as a very potent inhibitior of eukaryotic topoisomerase I and highlights the necessity of the carboxylic functional group. Dihydro betulinic acid is the most potent (IC50=0.5 mM) pentacyclic triterpenoid to inhibit eukaryotic topoisomerase I till date and can be exploited as a strong candidate for anti-tumor drug designing.

Luteolin, an abundant dietary component is a potent anti-leishmanial agent that acts by inducing topoisomerase II-mediated kinetoplast DNA cleavage leading to apoptosis

BACKGROUND

Plant-derived flavonoids, which occur abundantly in our daily dietary intake, possess antitumor, antibacterial, and free radical scavenging properties. They form active constituents of a number of herbal and traditional medicines. Several flavonoids have been shown to exert their action by interacting with DNA topoisomerases and promoting site-specific DNA cleavage. Therefore, flavonoids are potential candidates in drug design. We report here that, although the flavonoids luteolin and quercetin are potent antileishmanial agents, luteolin has great promise for acting as a lead compound in the chemotherapy of leishmaniasis, a major concern in developing countries.

MATERIALS AND METHODS

Kinetoplast DNA (kDNA) minicircle cleavage in drug-treated parasites was measured by electrophoresis of the total cellular DNA, followed by Southern hybridization using 32P labeled kDNA as a probe. Cell cycle progression and apoptosis were measured by flow cytometry using propidium iodide and fluorescein isothiocyanate (FITC)-labeled Annexin V.

RESULTS

Luteolin and quercetin inhibited the growth of Leishmania donovani promastigotes and amastigotes in vitro, inhibited DNA synthesis in promastigotes, and promoted topoisomerase-II-mediated linearization of kDNA minicircles. The IC50 values of luteolin and quercetin were 12.5 microM and 45.5 microM, respectively. These compounds arrest cell cycle progression in L. donovani promastigotes, leading to apoptosis. Luteolin has no effect on normal human T-cell blasts. Both luteolin and quercetin reduced splenic parasite burden in animal models.

CONCLUSION

Luteolin and quercetin are effective antileishmanial agents. Quercetin has nonspecific effects on normal human T cells, but luteolin appears nontoxic. So, luteolin can be a strong candidate for antileishmanial drug design.

Metallic ion concentration during menstrual cycle in normally menstruating women

Plasma concentration of metallic ions levels during menstrual cycle of twenty normally menstruating women were observed in four phases i.e. menses, follicular, ovulatory and luteal. The concentration of magnesium, zinc, selenium and manganese was highest during menses and lowest at ovulatory phase. There was rise in ionic levels of magnesium and selenium, while fall in zinc and manganese during luteal phase. Findings demonstrate changes in metallic ions (Magnesium, zinc, selenium and manganese) level in relation to hormonal status during menstrual cycle in women.