Evaluation of therapeutic role of harmaline: in vitro cytotoxicity targeting nucleic acids

Use of small molecules as valuable drugs against diseases is still an indefinable purpose due to the lack of in-detail knowledge regarding proper bio-target identification, specificity aspects, mode-mechanism of binding and proper in vitro study. Harmaline, an important beta-carboline alkaloid, shows effective anti-proliferative action against different types of human cancers and is also found to be a nucleic acid targeting natural molecule. This review sought to address the different signal pathways of apoptosis by harmaline in different cancer cell lines and simultaneously to characterize the structure activity aspects of the alkaloid with different motifs of nucleic acid to show its preference, biological efficacy and genotoxicity. The results open up new insights for the design and development of small molecule-based nucleic acid therapeutic agents.

Exploring spatiotemporal dynamics of flower visitor association pattern on two Avicennia mangroves: a network approach

Plant-flower visitor interaction is one of the most important relationships regarding the co-existence of the floral and faunal communities. The implication of network approaches is an efficient way to understand the impact of community structure on ecosystem functionality. To understand the association pattern of flower visitors, we performed this study on Avicennia officinalis and Avicennia marina mangroves from the islands of Indian Sundarban over three consecutive years. We found that visiting time and sites (islands) influenced the abundance of visitors. The bipartite networks showed a significant generalized structure for both site-visitor and visiting time-visitor networks where the strength and specialization of visitor species showed a highly and moderately significant positive correlation between both networks respectively. All the site-wise visiting time-visitor networks and year-wise site-visitor networks were significantly modular in structure. For both the plants, most of the visitors showed a generalized association pattern among islands and also among visiting times. Additionally, the study of the foraging behavior of dominant visitors showed Apis dorsata and Apis mellifera as the potential visitors for these plants. Our results showed that flower visitor networks are spatiotemporally dynamic. The interactions of visitors with flowers at different times influence their contribution to the network for becoming a generalist or peripheral species in the context of their visiting time, which may subsequently change over islands. This approach will help to devise more precise plant species-specific conservation strategies by understanding the contribution of visitors through the spatiotemporal context.

RGS7-ATF3-Tip60 Complex Promotes Hepatic Steatosis and Fibrosis by Directly Inducing TNFα

Aims: The pathophysiological mechanism(s) underlying non-alcoholic fatty liver disease (NAFLD) have yet to be fully delineated and only a single drug, peroxisome proliferator-activated receptor (PPAR) α/γ agonist saroglitazar, has been approved. Here, we sought to investigate the role of Regulator of G Protein Signaling 7 (RGS7) in hyperlipidemia-dependent hepatic dysfunction. Results: RGS7 is elevated in the livers of NAFLD patients, particularly those with severe hepatic damage, pronounced insulin resistance, and high inflammation. In the liver, RGS7 forms a unique complex with transcription factor ATF3 and histone acetyltransferase Tip60, which is implicated in NAFLD. The removal of domains is necessary for ATF3/Tip60 binding compromises RGS7-dependent reactive oxygen species generation and cell death. Hepatic RGS7 knockdown (KD) prevented ATF3/Tip60 induction, and it provided protection against fibrotic remodeling and inflammation in high-fat diet-fed mice translating to improvements in liver function. Hyperlipidemia-dependent oxidative stress and metabolic dysfunction were largely reversed in RGS7 KD mice. Interestingly, saroglitazar failed to prevent RGS7/ATF3 upregulation but it did partially restore Tip60 levels. RGS7 drives the release of particularly tumor necrosis factor α (TNFα) from isolated hepatocytes, stellate cells and its depletion reverses steatosis, oxidative stress by direct TNFα exposure. Conversely, RGS7 overexpression in the liver is sufficient to trigger oxidative stress in hepatocytes that can be mitigated via TNFα inhibition. Innovation: We discovered a novel non-canonical function for an R7RGS protein, which usually functions to regulate G protein coupled receptor (GPCR) signaling. This is the first demonstration for a functional role of RGS7 outside the retina and central nervous system. Conclusion: RGS7 represents a potential novel target for the amelioration of NAFLD. Antioxid. Redox Signal. 38, 137-159.

A Mini Review on Molecules Inducing Caspase-Independent Cell Death: A New Route to Cancer Therapy

Most anticancer treatments trigger tumor cell death through apoptosis, where initiation of proteolytic action of caspase protein is a basic need. But under certain circumstances, apoptosis is prevented by the apoptosis inhibitor proteins, survivin and Hsp70. Several drugs focusing on classical programmed death of the cell have been reported to have low anti-tumorogenic potency due to mutations in proteins involved in the caspase-dependent programmed cell death with intrinsic and extrinsic pathways. This review concentrates on the role of anti-cancer drug molecules targeting alternative pathways of cancer cell death for treatment, by providing a molecular basis for the new strategies of novel anti-cancer treatment. Under these conditions, active agents targeting alternative cell death pathways can be considered as potent chemotherapeutic drugs. Many natural compounds and other small molecules, such as inorganic and synthetic compounds, including several repurposing drugs, are reported to cause caspase-independent cell death in the system. However, few molecules indicated both caspase-dependent as well caspase-free cell death in specific cancer lines. Cancer cells have alternative methods of caspase-independent programmed cell death which are equally promising for being targeted by small molecules. These small molecules may be useful leads for rational therapeutic drug design, and can be of potential interest for future cancer-preventive strategies.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Island Based Assemblage Pattern and Foraging Profile of Insect Flower Visitors on Aegialitis rotundifolia -a Near Threatened Mangrove Plant from Indian Sundarban

Understanding the association pattern and foraging behaviour of flower visitors is crucial to determine their role in the interaction with plants. To analyse the insect flower visitor association as well as their foraging profile on Aegialitis rotundifolia Roxb.-a near threatened mangrove plant, present study has been conducted among four islands of Indian Sundarban for three consecutive years. Results using first three Hill numbers depicted that, the species richness and Shannon and Simpson diversity of flower visitors were higher among the islands situated far from the sea than the islands neighbouring to the sea. NMDS analysis showed moderately ordinate data structure for island-year-based flower visitor association. Furthermore, network analysis for island-based visitor assemblage showed a significantly generalised network with no specialisation among islands. Five abundant visitors were further analysed for foraging profile, where the highest foraging rate was shown by Apis dorsata Fabricius, 1793 and the highest handling time was shown by Micraspis discolor (Fabricius, 1798). Moreover, all the visitors except M. discolor showed a significant variation in their foraging rate among different time frames. Furthermore, only M. discolor showed significant variation in their foraging behaviour when compared individually with each visitor in all the time frames. Present findings conclude that, flower visitors showed a generalised assemblage pattern among islands. Both honey bees provided excellent foraging on this plant and butterflies were good foragers too. Therefore, to device conservation strategies for this plant, protection of flower visitors must be of paramount concern.

Structure-activity insights of harmine targeting DNA, ROS inducing cytotoxicity with PARP mediated apoptosis against cervical cancer, anti-biofilm formation and in vivo therapeutic study

Harmine exhibits pH dependent structural equilibrium and possesses numerous biological and pharmacological activities. Mode and mechanism of DNA binding and its cytotoxicity were studied by multiple spectroscopic, calorimetric, molecular docking and in vitro apoptotic as well as in vivo biochemical and histological studies. It exists as cationic (structure I) and decationic form (structure II) in the pH range 3.0-7.8 and 8.5-12.4, respectively, with a pK_a of 8.0. Structure I at pH 6.8 binds strongly to DNA with a cooperative mode of binding of K_iω 1.03 × 10⁶ M^-1and stoichiometry of 5.0 nucleotide phosphates. Structure I stabilized DNA by 10 °C, showed85%quenching of fluorescence intensity, perturbation in circular dichroism, partial intercalation and enthalpy driven exothermic binding. While, structure II at pH 8.5 has very weak interaction with CT DNA. Cytotoxic potencies of structure I was tested on four different cancer cell lines along with normal embryonic cell. It showed maximum cytotoxicity with GI₅₀of 20 µM, against HeLa causing several apoptotic induction abilities. Harmine exhibited G2M arrest with ROS induced effective role in PARP mediated apoptosis as well as anti-inflammatory action on HeLa cells. Harmine further presented MIC and antibiofilm activity against Staphylococcus aureus in presence of <160 and 30 µg/ml, respectively. Mice with post harmine treatment (30 mg/kg b.w., I.P.) showed maximum recovery from damaged to near normal architecture of cervical epithelial cells. This study may be of prospective use in a framework to design novel beta carboline compounds for improved therapeutic applications in future against cervical cancer. HighlightsHarmine exists in structure I and structure II forms in the pH 6.8 and 8.5with a pK_a of 8.0.Structure I at pH 6.8 binds strongly to DNA compared to structure II.Structure I showed maximum cytotoxicity with GI₅₀ of 20 µM against HeLa.ROS mediated cytotoxicitywithG2M arrest with PARP mediated apoptosis was studied.Harmine (30µg/ml) exhibited antibiofilm activity against Staphylococcus aureus.Post harmine dose (30 mg/kg b.w., I.P.) in mice showed recovery of cervical epithelial cells.Communicated by Ramaswamy H. Sarma.

Synthetic carboline compounds targeting protein: biophysical and biological perspective

Pictet-Spengler cyclization method has been adopted for the synthesis of three carboline derived compounds: two compounds with tetrahydro gama- and beta-having CF₃ group and amino alkyl chain at delta and alpha position, respectively, and another with guanidine alkyl chain at alpha-position. Structure-activity relationship of the analogues with human serum albumin was studied by fluorescence and Fourier-transform infrared spectroscopy  followed by molecular docking. The data showed maximum affinity of human serum albumin with comp7 (S0-820) followed by comp3 (S0-1040) and least with comp1 (S0-728). The compounds were tested for cytotoxic potencies. Comp3, showed maximum cytotoxicity with GI₅₀ 6.2 µM, against HCT-116, followed by comp7, and poor cytotoxicity with comp1. Comp3 and 7 induced oxidative stress mediated autophagy led programmed cell death in HCT-116. Furthermore, the compounds effectively inhibit DNA topoisomerase I activity and showed anti-inflammatory actions. In vivo studies regarding therapeutic protective action of Comp3, as a representative carboline analogue, against colon toxicant, 1,2-dimethylhydrazine dihydrochloride (DMH), showed the efficacy of the compound against organ toxicity. The existing studies on biological evaluation showed that these synthetic compounds may have a major role as anticancer agents having myriad of proven therapeutic applications. Communicated by Ramaswamy H. Sarma.

α,ß-Didehydrosuberoylanilide hydroxamic acid (DDSAHA) as precursor and possible analogue of the anticancer drug SAHA

An alternate synthetic route to the important anticancer drug suberoylanilide hydroxamic acid (SAHA) from its α,ß-didehydro derivative is described. The didehydro derivative is obtained through a cross metathesis reaction between a suitable terminal alkene and N-benzyloxyacrylamide. Some of the didehydro derivatives of SAHA were preliminarily evaluated for anticancer activity towards HeLa cells. The administration of the analogues caused a significant decrease in the proliferation of HeLa cells. Furthermore, one of the analogues showed a maximum cytotoxicity with a minimum GI₅₀ value of 2.5 µg/mL and the generation of reactive oxygen species (ROS) as some apoptotic features.

Carbon dots derived from lychee waste: Application for Fe3+ ions sensing in real water and multicolor cell imaging of skin melanoma cells

Exploit of biomass as an inexhaustible resource has accepted much more curiosity to the present research world. Herein, a simple, one-step solvothermal action has been used to synthesize an ascendable amount of fluorescent carbon dots (CDs) with an average size of~3.13 nm, from Low-reasonable and green source lychee waste. The excitation/emission maxima of CDs have 365/443 nm with high quantum yield (23.5%). The present ingredient predominantly contained carboxylic acid and hydroxyl group that acted as a passive agent for stabilizing the CDs. The structural and optical properties were evaluated through HRTEM, FTIR, UV-vis, zeta potential, XPS, fluorescence, and fluorescence lifetime experiments. We investigated the manoeuvre of our synthesized CDs as a probe for detection of Fe³⁺ ions in water bodies; This sensing approach showed impressive selectivity and sensitivity towards Fe³⁺ions with LOD 23.6 nM. The sensing mechanism took place through static quenching which was entrenched through fluorescence lifetime measurements. Fe³⁺ ions detection was basically carried out with efficacy in real water. For its lofty Photo-stability, low cytotoxicity and cell viability the probe were substantially applied for bio-imaging experiment i.e. intracellular multi-color cell imaging in skin melanoma cells (A375 cells) with and without Fe³⁺ ions exemplifying its real applications in living cells.

In vitro relationship between serum protein binding to beta-carboline alkaloids: a comparative cytotoxic, spectroscopic and calorimetric assays

The work highlighted interaction of harmalol, harmaline and harmine with human serum albumin by biophysical and biochemical assays. Presence of serum protein in the media negatively affects the cytotoxicity of the alkaloids. MTT assay indicates concentration-dependent growth inhibitory effect of the alkaloids on A375, MDA-MB-231, HeLa, A549, ACHN and HepG₂ cell, having maximum cytotoxicity with GI₅₀ value of 6.5 μM on ACHN by harmine in 1% of fetal bovine serum. Detail cytotoxic studies on ACHN cell by harmine, the most cytotoxic among the three, reveal nucleosomal fragmentation, formation of comet tail, generation of reactive oxygen species, decreased mitochondrial membrane potential, up regulation of p53, caspase 3 and significant increase in G₂/M population that made the cancer cells prone to apoptosis. Furthermore, the findings unequivocally pointed out that harmine binds strongly to the protein with a binding constant of 5.53 × 10⁴ M^-1 followed by harmaline and least with harmalol. Thermodynamic results revealed enthalpy dominated, entropy favored, 1:1 binding. Molecular docking and circular dichroism suggested changed conformation of protein by partial unfolding on complexation. Further supported by infrared analysis where protein secondary structure was altered with a major decrease of α-helix from 53.68% (free protein) to 8-11% and change in β-sheet from 25.31% (free protein) to 1-6% upon binding, inducing partial protein destabilization. Site markers demonstrated site I (subdomain IIA) binding of the alkaloids to the protein. The results serve as data for the future development of serum protein-based targeted drugs. AbbreviationsCD: circular dichroism; FBS: fetal bovine serumFRETForster resonance energy transferFTIRFourier transform infraredHSAhuman serum albumin; ROS: reactive oxygen speciesCommunicated by Ramaswamy H. Sarma.

Superb-selective chemodosimetric signaling of sulfide in the absence and in the presence of CT-DNA and imaging in living cells by a plant alkaloid berberine analogue

New berberine analogue (BER-S), as a colorimetric probe in the absence of DNA and turn-on fluorometric probe in the presence of DNA towards S²⁻ detection is reported.

Therapeutic Role of Harmalol Targeting Nucleic Acids: Biophysical Perspective and in vitro Cytotoxicity

BACKGROUND

Harmalol, a beta carboline alkaloid, shows remarkable importance in the contemporary biomedical research and drug discovery programs. With time, there is emerging interest in search for better anti-cancer drugs of plant origin with high activity and lower toxicity. Most of the chemotherapeutic agents due to their non-specific target and toxicity on active healthy cells, use is often restricted, necessitating search for newer drugs having greater potentiality.

OBJECTIVE

The review highlighted the interaction of harmalol with nucleic acids of different motifs as sole target biomolecules and in vitro cytotoxicity of the alkaloid in human cancer cell lines with special emphasis on its apoptotic induction ability.

METHODS

Binding study and in vitro cytotoxicity was performed using several biophysical techniques and biochemical assays, respectively.

RESULTS

Data from competition dialysis, UV and fluorescence spectroscopic analysis, circular dichroism, viscometry and isothermal calorimetry shows binding and interaction of harmalol with several natural and synthetic nucleic acids, both DNA and RNA, of different motifs. Furthermore, apoptotic hallmarks like internucleosomal DNA fragmentation, membrane blebbing, cell shrinkage, chromatin condensation, change of mitochondrial membrane potential, comet tail formation and ROS (reactive oxygen species) dependent cytotoxicity being analyzed in the harmalol treated cancer cells.

CONCLUSION

These results stating the therapeutic role of harmalol, will lead to the interesting knowledge on the cytotoxicity, mode, mechanism, specificity of binding and correlation between structural aspects and energetics enabling a complete set of guidelines for design of new drugs.

Prevalence of risk factors for coronary artery disease in an urban Indian population

OBJECTIVE

The objective of this study was to assess the prevalence of risk factors for coronary artery disease (CAD) in government employees across India.

METHODS

The study population consisted of government employees in different parts of India ({n=10,642 men and n=1966 women; age 20-60 years}) and comprised various ethnic groups living in different environmental conditions. Recruitment was carried out in 20 cities across 14 states, and in one union territory. All selected individuals were subjected to a detailed questionnaire, medical examinations and anthropometric measurements. Blood samples were collected for blood glucose and serum lipid profile estimation, and resting ECG was recorded. Results were analysed using appropriate statistical tools.

RESULTS

The study revealed that 4.6% of the study population had a family history of premature CAD. The overall prevalence of diabetes was 16% (5.6% diagnosed during the study and the remaining 10.4% already on medication). Hypertension was present in 21% of subjects. The prevalence of dyslipidemia was significantly high, with 45.6% of study subjects having a high total cholesterol/high density lipoprotein ratio. Overall, 78.6% subjects had two or more risk factors for CAD.

CONCLUSIONS

The present study demonstrates a high prevalence of CAD risk factors in the Indian urban population. Therefore, there is an immediate need to initiate measures to raise awareness of these risk factors so that individuals at high risk for future CAD can be managed.

Sequence specific binding of beta carboline alkaloid harmalol with deoxyribonucleotides: binding heterogeneity, conformational, thermodynamic and cytotoxic aspects

BACKGROUND

Base dependent binding of the cytotoxic alkaloid harmalol to four synthetic polynucleotides, poly(dA).poly(dT), poly(dA-dT).poly(dA-dT), poly(dG).poly(dC) and poly(dG-dC).poly(dG-dC) was examined by various photophysical and calorimetric studies, and molecular docking.

METHODOLOGY/PRINCIPAL FINDINGS

Binding data obtained from absorbance according to neighbor exclusion model indicated that the binding constant decreased in the order poly(dG-dC).poly(dG-dC)>poly(dA-dT).poly(dA-dT)>poly(dA).poly(dT)>poly(dG).poly(dC). The same trend was shown by the competition dialysis, change in fluorescence steady state intensity, stabilization against thermal denaturation, increase in the specific viscosity and perturbations in circular dichroism spectra. Among the polynucleotides, poly(dA).poly(dT) and poly(dG).poly(dC) showed positive cooperativity where as poly(dG-dC).poly(dG-dC) and poly(dA-dT).poly(dA-dT) showed non cooperative binding. Isothermal calorimetric data on the other hand showed enthalpy driven exothermic binding with a hydrophobic contribution to the binding Gibbs energy with poly(dG-dC).poly(dG-dC), and poly(dA-dT).poly(dA-dT) where as harmalol with poly(dA).poly(dT) showed entropy driven endothermic binding and with poly(dG).poly(dC) it was reported to be entropy driven exothermic binding. The study also tested the in vitro chemotherapeutic potential of harmalol in HeLa, MDA-MB-231, A549, and HepG2 cell line by MTT assay.

CONCLUSIONS/SIGNIFICANCE

Studies unequivocally established that harmalol binds strongly with hetero GC polymer by mechanism of intercalation where the alkaloid resists complete overlap to the DNA base pairs inside the intercalation cavity and showed maximum cytotoxicity on HepG2 with IC50 value of 14 µM. The results contribute to the understanding of binding, specificity, energetic, cytotoxicity and docking of harmalol-DNA complexation that will guide synthetic efforts of medicinal chemists for developing better therapeutic agents.

Dihydroxy-isosteviol methyl ester of Pulsatilla nigricans extract reduces arsenic-induced DNA damage in testis cells of male mice: its toxicity, drug-DNA interaction and signaling cascades

OBJECTIVE

To evaluate the ameliorative efficacy of dihydroxy-isosteviol methyl ester (DIME) of Pulsatilla nigricans extract in arsenic-induced DNA damage in testis cells of mice.

METHODS

The mice were treated with sodium arsenite (SA) solution intragastrically at a dose of 20 mg/kg per day and examined at 30, 60, and 90 d after treatment. We divided SA-intoxicated mice into two sub-groups: one fed with DIME at a dose of 35 mg/kg and the other with 85% alcohol. We analyzed the expressions of apoptotic signal proteins like CYP1A1, p53 and caspase 3, ascertained the level of cellular and DNA damage and estimated the level of testicular-toxicity biomarkers. We studied the interaction of DIME with calf thymus DNA as target through circular dichroism spectra and melting temperature profiles.

RESULTS

We observed an elevation in all apoptotic and toxicity biomarkers leading to cellular and DNA damage in the SA-intoxicated mice which showed significant inhibition or reversal on administration of DIME. Results also showed that DIME interacted with DNA, bringing in discernible changes in structure and conformation.

CONCLUSION

DIME has potentials for therapeutic use in amelioration of arsenic-induced reproductive toxicity.

Ethanolic extract of the Goldenseal, Hydrastis canadensis, has demonstrable chemopreventive effects on HeLa cells in vitro: Drug-DNA interaction with calf thymus DNA as target

This study tested chemotherapeutic potential of Hydrastis canadensis (HC) extract in HeLa cells in vitro, with emphasis on its drug-DNA interaction and apoptosis induction ability. Nuclear uptake of HC by DAPI, Ao/Eb staining and internucleosomal DNA damage by comet assay was studied through fluorescence microscopy. Possible changes in MMP and apoptotic signalling events were critically analyzed. Cell cycle progression studied through FACS and fragmented DNA through "TUNEL" assay were critically analyzed. RT-PCR studies were conducted for analyzing Cyt-C and Bax translocation in mitochondrial and cytosolic extracts, and Caspase 3 in whole cell lysate. Role of p53-mediated regulation of NF-κβ and TNF-α was elucidated by Western blot analysis. Data of CD and Tm profile of CT-DNA were analyzed. Overall results indicated anti-cancer potential of HC through its ability to induce apoptosis, and interaction with CT-DNA that changed structural conformation of DNA, proving HC to be a promising candidate for chemoprevention.

Poly (lactide-co-glycolide) encapsulated extract of Phytolacca decandra demonstrates better intervention against induced lung adenocarcinoma in mice and on A549 cells

We tested relative efficacy of the extract of Phytolacca decandra (PD) and its PLGA nano-encapsulated form (NPD) in mice intoxicated with benzo[a]pyrene (BaP) (25 mg/kg b.w.) plus sodium-arsenite (SA) (10 mg/kg b.w.) and on A549 lung cancer cells in vitro. We characterized nanoparticles by physico-chemical and morphological studies using dynamic light scattering, scanning electron and atomic force microscopies. We also conducted FTIR and (1)H NMR studies to determine if NPD had a co-polymeric nature and analyzed drug-DNA interaction through circular dichroism spectra (CD) and melting temperature profiles (T(m)) taking calf thymus DNA as target. An oral dose of 0.3mg/kg b.w. for NPD and 30 mg/kg b.w. for PD in mice showed chemopreventive effects in regard to DNA fragmentation, comet tail length and toxicity biomarkers like ROS generation, NFκβ, p53, PARP, CYP1A1 and caspase 3. NPD showed greater effects than that by PD. Results of in vivo studies showed similar effects on A549 in regard to cell viability, DAPI and PI staining, Comet tail length, DNA fragmentation. To further confirm the biological molecule present in PD we analyzed its chromatographic fraction through mass spectroscopy, NMR and FT-IR studies and characterized it to be a tri-terpenoid, a derivative of betulinic acid with a molecular formula C(30)H(46)O(2.) Thus, overall results suggest that nano-encapsulation of PD (NPD) increases drug bioavailability and thereby has a better chemo-preventive action against lung cancer in vivo and on A549 cells in vitro than that of PD.

Bone health in healthy Indian population aged 50 years and above

One thousand six hundred healthy subjects aged more than 50 years, residing in Delhi, were evaluated for bone mineral metabolic parameters. High prevalence of osteoporosis (35.1% subjects) was observed in this population. Bone mineral density (BMD) correlated positively with body mass index (BMI) and negatively with PTH levels. No correlation was observed with serum 25(OH)D levels.

INTRODUCTION

To assess the bone health status in elderly Indians and compare peripheral DXA (pDXA) with central DXA in evaluation of osteoporosis.

METHODS

The study involved 1,600 healthy subjects more than 50 years of age residing in Delhi, India, who underwent anthropometric, biochemical, and hormonal evaluation. BMD was measured by DXA at lumbar spine, hip, and distal radius; and by pDXA at forearm and calcaneum.

RESULTS

Seven hundred ninety-two males and 808 postmenopausal females, with a mean age of 57.67 ± 9.46 years were evaluated. Osteoporosis was present in 35.1% subjects (M-24.6%, F-42.5%) and osteopenia in 49.5% (M-54.3%, F-44.9%). Prevalence of osteoporosis increased with age in females, but not in males. BMD at all sites, except distal radius, was positively correlated with BMI (r=0.037, p=0.14). Total body BMD was negatively correlated with alkaline phosphatase (r= -0.184, p<0.00001) and PTH levels (r= -0.099, p<0.00001), respectively. No significant correlation was observed between serum 25(OH)D levels and BMD at any site. BMD at forearm and calcaneum, measured using pDXA, showed strong positive correlation with BMD measured by central DXA. pDXA had sensitivity of 88%, specificity of 55%, and negative and positive predictive values of 89% and 52%, respectively, at T-score -2.5 at peripheral sites compared to central DXA.

CONCLUSIONS

A high prevalence of osteoporosis was observed in elderly Indian subjects. pDXA has high negative predictive value, making it a useful tool in population screening for osteoporosis.

Targeting RNA by small molecules: comparative structural and thermodynamic aspects of aristololactam-β-D-glucoside and daunomycin binding to tRNA(phe)

BACKGROUND

Interaction of aristololactam-β-D-glucoside and daunomycin with tRNA(phe) was investigated using various biophysical techniques.

METHODOLOGY/PRINCIPAL FINDINGS

Absorption and fluorescence studies revealed that both the compounds bind tRNA(phe) non-cooperatively. The binding of daunomycin was about one order of magnitude higher than that of aristololactam-β-D-glucoside. Stronger binding of the former was also inferred from fluorescence quenching data, quantum efficiency values and circular dichroic results. Results from isothermal titration calorimetry experiments suggested that the binding of both compounds was predominantly entropy driven with a smaller but favorable enthalpy term that increased with temperature. A large favorable electrostatic contribution to the binding of daunomycin to tRNA(phe) was revealed from salt dependence data and the dissection of the free energy values. The electrostatic component to the free energy change for aristololactam-β-D-glucoside-tRNA(phe) interaction was smaller than that of daunomycin. This was also inferred from the slope of log K versus [Na(+)] plots. Both compounds enhanced the thermal stability of tRNA(phe). The small heat capacity changes of -47 and -99 cal/mol K, respectively, observed for aristololactam-β-D-glucoside and daunomycin, and the observed enthalpy-entropy compensation phenomenon confirmed the involvement of multiple weak noncovalent interactions. Molecular aspects of the interaction have been revealed.

CONCLUSIONS/SIGNIFICANCE

This study presents the structural and energetic aspects of the binding of aristololactam-β-D-glucoside and daunomycin to tRNA(phe).

Possible signaling cascades involved in attenuation of alloxan-induced oxidative stress and hyperglycemia in mice by ethanolic extract of Syzygium jambolanum: drug-DNA interaction with calf thymus DNA as target

We injected alloxan (100 mg/kg b.w.) in mice (Mus musculus) intra-peritoneally to induce hyperglycemia and divided the hyperglycemic mice into two sub-groups: one was fed ethanolic extract of Syzygium jambolanum (EESJ) (20 mg/kg b.w. for 8 weeks) and the other 85% ethyl alcohol ("vehicle"-control). Chromatographic and mass spectroscopic studies of EESJ revealed two principal components, one corresponding to an iridoid glycoside. We estimated blood glucose, glycosylated hemoglobin, glucokinase, and fructosamine and analyzed the expression of marker proteins like insulin, GLUT2, and GLUT4. We also studied anti-oxidant biomarkers like lipid peroxidase, superoxide dismutase, total thiole and catalase. We assayed generation of reactive oxygen species (ROS) and several inflammatory and apoptotic signal proteins like NFkB, IFNγ, iNOS, Bcl(2,) Bax, STAT1 and Caspase3. We further evaluated the effects of hyperglycemia on DNA through comet assay and DNA fragmentation study and assessed drug-DNA interaction by comparative analysis of circular dichroism (CD) spectral data and melting temperature profiles (T(m)) of calf thymus DNA treated with or without EESJ. We observed an elevation of all biomarkers for oxidative stress, generation of ROS and activation of NFkB and down regulation in expression of insulin, GLUT2 and glucokinase in hyperglycemic mice. Administration of EESJ reversed these changes. Histo-pathological observations of pancreas, liver and kidney also revealed relevant changes. Data of CD and (T(m)) indicated an interaction of EESJ with calf thymus DNA, indicating change in structure and conformation. Thus, EESJ has anti-oxidant as well as anti-hyperglycemic activities in diabetic mice, and potentially useful in management of hyperglycemia.

Reference intervals of serum lipid profile in healthy Indian school children and adolescents

OBJECTIVE

To develop age and sex specific reference intervals of serum lipid parameters in healthy Indian children in the age group of 6-17 years.

PARTICIPANTS

Study subjects were selected from the schools of Delhi. Children with BMI either in overweight or obese category were excluded to generate reference intervals. The final analysis included 3076 children with BMI in normal range for age.

RESULTS

The mean±SD, 3rd, 10th, 25th, 50th, 75th, 90th and 97th centile values of lipid parameters are presented. All these parameters were significantly higher in girls than in boys. About 89.2% subjects had total cholesterol in acceptable range while 9.1% had borderline elevated and 1.5% had elevated TC. Optimal serum triglyceride levels were seen in 45.1% subjects while optimal levels of HDL cholesterol were seen in 0.3% subjects only.

CONCLUSIONS

Reference intervals of serum lipid parameters for healthy Indian children (6-17 years) are presented.

Interaction of aristololactam-β-D-glucoside and daunomycin with poly(A): spectroscopic and calorimetric studies

The binding of two sugar containing antibiotics viz. aristololactam-β-D-glucoside and daunomycin with single and double stranded poly(A) was investigated by spectroscopic and calorimetric studies. The binding affinity of daunomycin to ss poly(A) was of the order of 10⁶ M⁻¹ and that to ds poly(A) was of the order of 10⁵ M⁻¹. Aristololactam-β-D-glucoside showed a relatively weaker binding with an affinity of the order of 10⁴ M⁻¹ with both the conformations of poly(A). Fluorescence studies showed maximum quenching for daunomycin-ss poly(A) complexes. The binding constants calculated from fluorescence spectroscopy were in good agreement with that obtained from UV spectroscopy. Moderate perturbation of circular dichroic spectra of both the conformations of poly(A) in presence of these molecules with concomitant formation of prominent extrinsic CD bands in the 300-450 nm region further revealed the association. Isothermal titration calorimetry results showed an overall entropy driven binding in all the four systems though the entropy change was maximum in daunomycin-ss poly(A) binding. The binding affinity was also maximum for daunomycin-ss poly(A) and varied as daunomycin-ds poly(A) > aristololactam-β-D-glucoside-ds poly(A) > aristololactam-β-D-glucoside-ss poly(A). A 1:1 binding stoichiometry was observed in all the cases, as confirmed by Job plot analysis, indicating the interaction to consist of a single binding mode. Ferrocyanide quenching studies showed good stacking interaction in all cases but was best for daunomycin-ss poly(A) interaction. No self-structure formation was observed in poly(A) with both daunomycin and aristololactam-β-D-glucoside suggesting the hindrance of the sugar moiety for such structural organization.

Identification of a sulfonoquinovosyldiacylglyceride from Azadirachta indica and studies on its cytotoxic activity and DNA binding properties

Chromatographic separation of the methanolic extract of the leaves of Azadirachta indica led to the isolation of a sulfonoglycolipid characterized as a sulfonoquinovosyldiacylglyceride (SQDG), by extensive 2D NMR and mass spectral analysis. SQDG induces apoptosis in a dose dependent manner with IC(50) 8.3 μM against acute lymphoblastic leukemia (ALL) MOLT-4 cell lines. The compound showed significant DNA binding properties as evidenced by the enhancement of melting temperature and perturbation of the characteristic B-form in CD evidence of calf thymus DNA. The DNA binding was also characterized by isothermal calorimetry where a predominantly enthalpy driven binding to CT DNA was revealed.

Interaction of isoquinoline alkaloids with polymorphic DNA structures

The interaction of berberine, palmatine, and coralyne with the B, Z, and H(L) form of poly[d(G-C)] was studied. Berberine and palmatine showed moderate binding to the B form, while coralyne showed higher binding, as revealed from spectroscopic and thermodynamic data. Berberine and coralyne binding to the B form was exothermic and enthalpy-driven, while palmatine showed exothermic binding which was favored by both negative enthalpy and negative entropy changes. Berberine and palmatine neither bind nor converted the Z-form structure to B form. Coralyne, on the other hand, exhibited a strong binding affinity to Z DNA structure that was enthalpy-driven. Berberine binding to the H(L) form was cooperative, exothermic, and favored by both negative enthalpy and negative entropy changes with the formation of an induced CD band. Palmatine showed weak binding, while coralyne showed a strong binding with the H(L) form. The structural differences in the isoquinoline alkaloids appear to influence the affinity and mode of interactions with these polymorphic DNA structures.

Molecular recognition of DNA by small molecules: AT base pair specific intercalative binding of cytotoxic plant alkaloid palmatine

The base dependent binding of the cytotoxic alkaloid palmatine to four synthetic polynucleotides, poly(dA).poly(dT), poly(dA-dT).poly(dA-dT), poly(dG).poly(dC) and poly(dG-dC).poly(dG-dC) was examined by competition dialysis, spectrophotometric, spectrofluorimetric, thermal melting, circular dichroic, viscometric and isothermal titration calorimetric (ITC) studies. Binding of the alkaloid to various polynucleotides was dependent upon sequences of base pairs. Binding data obtained from absorbance measurements according to neighbour exclusion model indicated that the intrinsic binding constants decreased in the order poly(dA).poly(dT)>poly(dA-dT).poly(dA-dT)>poly(dG-dC).poly(dG-dC)>poly(dG).poly(dC). This affinity was also revealed by the competition dialysis, increase of steady state fluorescence intensity, increase in fluorescence quantum yield, stabilization against thermal denaturation and perturbations in circular dichroic spectrum. Among the polynucleotides, poly(dA).poly(dT) showed positive cooperativity at binding values lower than r=0.05. Viscosity studies revealed that in the strong binding region, the increase of contour length of DNA depended strongly on the sequence of base pairs being higher for AT polymers and induction of unwinding-rewinding process of covalently closed superhelical DNA. Isothermal titration calorimetric data showed a single entropy driven binding event in the AT homo polymer while that with the hetero polymer involved two binding modes, an entropy driven strong binding followed by an enthalpy driven weak binding. These results unequivocally established that the alkaloid palmatine binds strongly to AT homo and hetero polymers by mechanism of intercalation.

The binding of DNA intercalating and non-intercalating compounds to A-form and protonated form of poly(rC).poly(rG): spectroscopic and viscometric study

Polymorphic RNA conformations may serve as potential targets for structure specific antiviral agents. As an initial step in the development of such drugs, the interaction of a wide variety of compounds which are characterized to bind to DNA through classical or partial intercalation or by mechanism of groove binding, with the A-form and the protonated form of poly(rC).poly(rG), been evaluated by multifaceted spectroscopic and viscometric techniques. Results of this study suggest that (i) ethidium intercalates to the A-form of RNA, but does not intercalate to the protonated form, (ii) methylene blue intercalates to the protonated form of the RNA but does not intercalate to the A-form, (iii) actinomycin D does not bind to either conformations of the RNA, and (iv) berberine binds to the protonated form by partial intercalation process, while its binding to the A-form is very weak. The DNA groove binder distamycin A has much higher affinity to the protonated form of the RNA compared to the A-form and binds to both structures by non-intercalative mechanism. We conclude that the binding affinity characteristics of these DNA binding molecules to the RNA conformations are vastly different and may serve as data for the development of RNA based antiviral drugs.

Protonated structures of naturally occurring deoxyribonucleic acids and their interaction with berberine

Protonation-induced conformational changes in natural DNAs of diverse base composition under the influence of low pH, low temperature, and low ionic strength have been studied using various spectroscopic techniques. At pH3.40, 10mM [Na+], and at 5 degrees C, all natural DNAs irrespective of base composition adopted an unusual and stable conformation remarkably different from the canonical B-form conformation. This protonated conformation has been characterized to have unique absorption and circular dichroic spectral characteristics and exhibited cooperative thermal melting profiles with decreased thermal melting temperatures compared to their respective B-form counterparts. The nature of this protonated structure was further investigated by monitoring the interaction of the plant alkaloid, berberine that was previously shown from our laboratory to differentially bind to B-form and H(L)-form of poly[d(G-C)] [Bioorg. Med. Chem.2003, 11, 4861]. Binding of berberine to protonated conformation of natural DNAs resulted in intrinsic circular dichroic changes as well as generation of induced circular dichroic bands for the bound berberine molecule with opposite signs and magnitude compared with B-form structures. Nevertheless, the binding of the alkaloid to both the B and protonated forms was non-linear and non-cooperative as revealed from Scatchard plots derived from spectrophotometric titration data. Steady state fluorescence studies on the other hand showed remarkable increase of the rather weak intrinsic fluorescence of berberine on binding to the protonated structure compared to the B-form structure. Taken together, these results suggest that berberine can detect the formation of significant population of H(L)-form structures under the influence of protonation irrespective of heterogeneous base compositions in natural DNAs.

Berberine, a strong polyriboadenylic acid binding plant alkaloid: spectroscopic, viscometric, and thermodynamic study

The interaction of berberine with single stranded poly(rA) structure was investigated using a combination of spectrophotometric, spectrofluorimetric, circular dichroic, viscometric, and thermodynamic studies. The interaction process was characterized by typical hypochromic and bathochromic effects in the absorption spectrum of berberine, enhancement of fluorescence intensity of berberine, increase of viscosity, and perturbation of circular dichroic spectrum of single stranded poly(rA). Scatchard plot obtained from spectrophotometric analysis showed that berberine bound strongly to single stranded poly(rA) in a non-cooperative manner. In contrast, berberine does not show any significant effect (i) in its absorbance and fluorescence spectra on binding to double stranded poly(rA), (ii) alter the circular dichroic spectrum of double stranded poly(rA), or (iii) increase of viscosity of double stranded poly(rA) indicating that it does not bind at all to double stranded poly(rA) structure. Thermodynamic parameters indicated that the binding of the alkaloid to single stranded poly(rA) is an endothermic process and entropy driven. All these findings, taken together clearly support that berberine binds strongly to single stranded poly(rA) structure by a mechanism of partial intercalation leading to its use in gene regulation in eukaryotic cells.

Protonated forms of poly[d(G-C)] and poly(dG).poly(dC) and their interaction with berberine

The pH -induced structural changes on the conformation of homo- and hetero-polymers of guanosine-citydine (G.C) sequences were investigated using spectrophotometric and circular dichroic techniques. At pH 3.40, 10 mM [Na(+)] and 10 degrees C both polynucleotides adopted a unique and stable structural conformation different from their respective B-form structures. The protonated hetero-polymer is established as left-handed structure with Hoogsteen base pairing (H(L)-form) while the homo-polymer favored Watson-Crick base pairing with different stacking arrangements from that of B-form structure as evident from thermal melting and circular dichroic studies. The interaction of berberine, a naturally occurring protoberberine group of plant alkaloid, with the protonated structures was studied using various biophysical techniques. Binding of berberine to the H(L)-form structure resulted in intrinsic circular dichroic changes and generation of extrinsic circular dichroic bands with opposite sign and magnitude compared to its B-form structure while with the homo-polymer of G.C no such reversal of extrinsic circular dichroic bands was seen indicating different stacking arrangement of berberine at the interaction site. Scatchard analysis of the binding data, however, indicated non-cooperative binding to both the protonated forms similar to that of their respective B-form structure. Fluorescence spectral studies, on the other hand, showed remarkable increase in the intrinsic fluorescence of the alkaloid in presence of the protonated forms compared to their respective B-form structure. These results suggest that berberine could be used as a probe to detect the alteration of structural handedness due to protonation and may potentiate its use in regulatory roles for biological functions.