Development of a Cu/MoS2/Ni Self-Lubricating Composite Clad through Laser Additive Approach over a Ti6Al4V Substrate and Its Characterizations.

Solid lubricant coatings play a critical role in enhancing the tribological properties of engineering materials, particularly in aerospace and biomedical applications. Ti6Al4V is widely used in aerospace and defense industries due to its excellent mechanical properties and high strength-to-weight ratio. In this regard, a solid lubricant metal matrix composite (MMC) clad was successfully fabricated over Ti6Al4V. A full factorial (L16) was successfully implemented to investigate the interaction of process parameters for laser power and scanning speed with response outputs, such as the clad layer thickness and microhardness. The microstructural study of the clad confirmed the presence of dark and bright phases of the microstructure with cylindrical, elliptical, and lamellar structures. This showed the presence of molybdenum and sulfide phases (MoS2, TiS, CuS) and the presence of a nickel phase (TiNi, NiS, CuNi), confirmed through X-ray diffraction (XRD) analysis and energy-dispersive X-ray (EDX) spectroscopy; these phases bestowed hardness as well as solid lubricating properties on the clad. The microhardness of the clad was found to be 2-3 times that of the substrate material. The wear behavior of the clad was studied in the load range of 5-15 N; the coefficient of friction (0.33 for clad and 0.5 for base), wear track depth profile, and wear mechanism revealed that the cladded sample has higher wear resistance as compared to the substrate material. The worn morphology showed that microcutting and microplowing are the major phenomena of wear occurrence. Further, X-ray photoelectron spectroscopy (XPS) analysis was performed to determine the binding energy of the compound formed at the clad zone, which can predict the most significant phase for the alteration of the mechanical behavior of the solid lubrication clad.

Synthesis of bioactive 28-hydroxy-3-oxolup-20(29)-en-30-al with antileukemic activity.

An easy and efficient route to partial synthesis of bioactive 28-hydroxy-3-oxolup-20(29)-en-30-al (1), starting from betulinic acid (2), has been developed (eight steps, 44% overall yield). Structures of all the compounds were determined by spectral studies (IR, (1)H, (13)C NMR, MS, NOESY, COSY, etc.). Compound 1 and the precursors (2, 3, 5, and 7) showed antiproliferative activities against human K562 leukemia, murine WEHI3 leukemia, and murine MEL erythroid progenitor.

Biological evaluation of a natural steroid ester, Stigmasta-5(6), 22(23)-dien-3-beta-yl acetate isolated from the Himalayan herb Astilbe rivularis as potential antitumor agent.

BACKGROUND: Cancer remains a major world health issue due to its high morbidity and mortality rate. Plant based natural products (NPs) have played vital role in discovery of valuable anti-cancer drugs. Darjeeling Himalayan region has a rich diversity of therapeutic plants that can be utilized for development of novel drugs. AIM: We previously reported cytotoxic potential of rhizome extract of A.rivularis, a Darjeeling himalayan herb. Present study reports isolation and characterization of a phytosteroid from the plant rhizome in a bioassay-guided approach and evaluation of its anti-tumorigenic potential. RESULTS: The phytosteroid was characterized as stigmasta-5(6), 22(23)-dien-3-beta-yl acetate (A11) by various spectrometric techniques (IR, NMR, MS etc.). The catalytic inhibition and structural alteration of human dihydrofolate reductase (hDHFR) by A11 was evaluated using methotrexate (MTX), a DHFR inhibitor anticancer drug as a reference. A11 inhibited hDHFR activity with IC50 values of 1.20 µM A11 caused concentration dependent quenching of tryptophan fluorescence of hDHFR suggesting its effect on alteration of enzyme structure. Molecular docking of A11 on crystal structure of hDHFR revealed significant interaction with free energy of binding and Ki values of -10.86 kcal/mol and 11 nM, respectively. Subsequent in vitro studies at cellular level showed a relatively greater cytotoxic effect of A11 against human kidney (ACHN, IC50 60 µM) and liver (HepG2, IC5070 µM) cancer cells than their respective normal cells (HEK-293, IC50 350 µM and WRL-68, IC50 520 µM). Scanning electron microscopy of A11 treated cells revealed the morphological feature of apoptosis, like cell rounding and surface detachment, membrane blebbing, loss of cilia and increased number of pores of decreased sizes. A11 mediated apoptosis of cancer cells was found to be correlated with induction of intracellular of reactive oxygen species (ROS) level and fragmentation of genomic DNA.

Bio-molecule functionalized rapid one-pot green synthesis of silver nanoparticles and their efficacy toward the multidrug resistant (MDR) gut bacteria of silkworms (Bombyx mori).

The present study aimed to synthesise bio-molecule functionalized silver nanoparticles (AgNPs) using leaf extract from mulberry variety S-1635 (Morus alba L.) and to explore its antibacterial efficacy against multidrug resistant (MDR) gut bacteria isolated from natural infection observed from silkworm larvae in rearing conditions. AgNPs formation was established by surface plasmon resonance at 480 nm. The crystallinity of the synthesised AgNPs was checked by HR-TEM and XRD analysis. SEM and TEM characterisation further exhibited the spherical, monodispersed, well scattered nature of the AgNPs with an average particle size of 11.8 nm ± 2.8. The presence of (111), (200), (220) and (311) planes in Bragg's reflections confirmed the face-cantered-cubic crystalline silver. EDX analysis confirmed the presence of elemental silver. FT-IR spectra revealed functional groups were responsible for the reduction of silver ions. The zeta potential value of -17.3 mV and -25.6 mV was recorded in MH and DMEM/F-12 media, respectively. The LC-QTOF/MS and HRMS spectra disclosed the presence of bioactive compounds like flavonoid, gallic acid, and stigmasterol, which are probably involved in the reduction and functionalization of AgNPs. The antibacterial efficacy of bio-molecule functionalized AgNPs and the naked AgNPs was tested on Gram-positive and Gram-negative bacteria isolated from silkworms and characterized by using 16S rDNA and gyrB genes. The cytotoxicity of AgNPs was tested on WRL-68, HEK-293, ACHN, and HUH-7 cell lines using MTT assay. This study provides an insight into the application of bio-molecule functionalized AgNPs for combating various silkworm pathogens which severely affect the agro-rural economy of developing countries.

Effect of feed supplementation with biosynthesized silver nanoparticles using leaf extract of Morus indica L. V1 on Bombyx mori L. (Lepidoptera: Bombycidae).

Herein, we report the synthesis of silver nanoparticles (AgNPs) by a green route using the aqueous leaf extract of Morus indica L. V1. The synthesized AgNPs exhibited maximum UV-Vis absorbance at 460 nm due to surface plasmon resonance. The average diameter (~54 nm) of AgNPs was measured from HR-TEM analysis. EDX spectra also supported the formation of AgNPs, and negative zeta potential value (-14 mV) suggested its stability. Moreover, a shift in the carbonyl stretching (from 1639 cm-1 to 1630 cm-1) was noted in the FT-IR spectra of leaf extract after AgNPs synthesis which confirm the role of natural products present in leaves for the conversion of silver ions to AgNPs. The four bright circular rings (111), (200), (220) and (311) observed in the selected area electron diffraction pattern are the characteristic reflections of face centered cubic crystalline silver. LC-MS/MS study revealed the presence of phytochemicals in the leaf extract which is responsible for the reduction of silver ions. MTT assay was performed to investigate the cytotoxicity of AgNPs against two human cell lines, namely HepG2 and WRL-68. The antibacterial study revealed that MIC value of the synthesized AgNPs was 80 µg/ml against Escherichia coli K12 and Staphylococcus aureus (MTCC 96). Finally, the synthesized AgNPs at 10 µg/ml dosages showed beneficial effects on the survivability, body weights of the Bombyx mori L. larvae, pupae, cocoons and shells weights via enhancing the feed efficacy.

Diversity of the genus Ocimum (Lamiaceae) through morpho-molecular (RAPD) and chemical (GC-MS) analysis.

In this present study, we have described the diversity of nine Ocimum genotypes naturally grown in the Dakshin Dinajpur district of West Bengal, India. Their diversity was determined on the basis of morphological, chemical and randomly amplified polymorphic DNA (RAPD) to determine the level of variation present in the genus Ocimum. Among nine Ocimum genotypes six (O. americanum, O. × africanum, O. basilicum, O. gratissimum, O. kilimandscharicum and O. tenuiflorum) are found to be different Ocimum species and the rest are as varieties. A total of 18 qualitative and 17 quantitative morphological traits and chemical compositions were evaluated. Significant variations were observed in the morphological traits except O. × africanum and O. basilicum species. Cluster generated from the morphological data showed two different groups viz. basilicum group and sanctum group. Chemical analysis did not show much variation between morphologically similar species viz. O. × africanum and O. basilicum. However, RAPD analyses clearly showed that O. × africanum and O. basilicum are different species. Thus the combined analyses of morphological traits, chemical and molecular markers represent the best possible approach to confirm taxonomic delineation. Moreover, we are reporting O. × africanum for the first time from this region as well as from West Bengal, India.

Biological evaluation of a halogenated triterpenoid, 2α-bromo-dihydrobelulonic acid as inhibitor of human topoisomerase IIα and HeLa cell proliferation.

BACKGROUND: The pentacyclic lupane-type (6-6-6-6-5 type) triterpenoid, Betulinic acid (BA) is a potent inhibitor of topoisomerases and is of immense interest as anticancer drugs. However, the compound being highly lipophilic, has limited in vivo uptake capacity. BA derivatives with halogen substituent at C-2 have improved membrane permeability and cytotoxicity against cancer cells. AIM: The halogenated triterpenoid, 2α-bromo-dihydrobetulonic acid (B1) was synthesized from betulinic acid (BA) isolated from Bischofia javanica. Aim of the study was to determine whether B1 could act as a more efficient inhibitor of Topo IIα activity and HeLa cell proliferation, in comparison to BA. RESULT: B1 displayed efficient inhibition of DNA relaxation activity of topoisomerase IIα and the inhibitory effect was markedly improved upon pre-incubation of the compound with enzyme. Topoisomerase IIα inhibition by B1 was relieved in presence of increasing concentrations of DNA suggesting the compound as a reversible catalytic inhibitor. Subsequent UV and fluorescence spectroscopy studies indicated that B1 interacts and intercalates with DNA at concentrations signicantly greater than that required for topoisomerase IIα inhibition. The compound showed cytotoxic activity against HeLa cells with significantly lower IC50 value (7.5 µM) as compared to that of BA (30 µM) and had very low damaging/cytotoxic effect on normal cells. Treatment of B1 impaired HeLa cell proliferation by inducing Go-G1 arrest through lowered expression of cyclin D1 and PCNA polypeptides, and enhanced expression of p21. B1 treatment also increased the accumulation of early and late apoptotic cells in a concentration dependent manner as indicated by annexin V-FITC/PI binding assay.

Oxysterols: Synthesis and anti-leishmanial activities.

Oxygenated sterols (2-16) were synthesized by skeletal rearrangement of steroidal allylic alcohols. All the derivatives were screened for their anti-leishmanial activities. Compounds 3, 11 and 12 showed potent activities. Compound 12 was found least toxic and induced highest nitric oxide (NO) at 48 h. Least toxicity of compound 12 on splenocytes validated its best anti-amastigote effect and induction of NO.

Anti-diabetic Effect of Friedelan Triterpenoids in Streptozotocin Induced Diabetic Rat.

We herein report the anti-diabetic effect of the natural friedelan tritepenoid, 4-oxa-3, 4-secofriedelan (cerin), isolated from cork tissue of Quercus suber L. and its oxygenated derivative, 4-oxa-3, 4-secofriedelan-3-oic acid (cerin(ox)) in streptozotocin (STZ)-induced diabetic rat. Male Sprague Dawley rats were randomized into four groups: non-diabetic control (Group I), STZ-induced diabetic rats (Group II), STZ-induced diabetic rats treated with cerin (Group III), and STZ-induced diabetic rats treated with cerin(ox), (Group IV). Administration of cerin (3 mg/kg) and cerin(ox), (3 mg/kg) orally to STZ-diabetic rats for three weeks improved the body weight, reduced serum glucose level and activities of alkaline phosphatase, acid phosphatase, glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase, and restored liver antioxidant status.

Risk factors associated with default among tuberculosis patients in Darjeeling district of West Bengal, India.

BACKGROUND: The treatment outcome "default" under Revised National Tuberculosis Control Program (RNTCP) is a patient who after treatment initiation has interrupted treatment consecutively for more than 2 months. AIMS: To assess the timing, characteristics and distribution of the reasons for default with relation to some sociodemographic variables among new sputum-positive (NSP) tuberculosis (TB) patients in Darjeeling District, West Bengal. SETTINGS AND DESIGN: A case-control study was conducted in three tuberculosis units (TUs) of Darjeeling from August'2011 to December'2011 among NSP TB patients enrolled for treatment in the TB register from 1(st) Qtr'09 to 2(nd) Qtr'10. Patients defaulted from treatment were considered as "cases" and those completed treatment as "controls" (79 cases and 79 controls). MATERIALS AND METHODS: The enrolled cases and controls were interviewed by the health workers using a predesigned structured pro-forma. STATISTICAL ANALYSIS USED: Logistic regression analysis, odds ratios (OR), adjusted odds ratios (AOR). RESULTS: 75% of the default occurred in the intensive phase (IP); 54.24% retrieval action was done within 1 day during IP and 75% within 1 week during continuation phase (CP); cent percent of the documented retrieval actions were undertaken by the contractual TB program staffs. Most commonly cited reasons for default were alcohol consumption (29.11%), adverse effects of drugs (25.32%), and long distance of DOT center (21.52%). In the logistic regression analysis, the factors independently associated were consumption of alcohol, inadequate knowledge about TB, inadequate patient provider interaction, instances of missed doses, adverse reactions of anti-TB drugs, Government Directly Observed Treatment (DOT) provider and smoking. CONCLUSIONS: Most defaults occurred in the intensive phase; pre-treatment counseling and initial home visit play very important role in this regard. Proper counseling by health care workers in patient provider meeting is needed.

Synthesis of friedelan triterpenoid analogs with DNA topoisomerase IIα inhibitory activity and their molecular docking studies.

Five highly oxygenated friedelan derivatives (3a, 3b, 4, 5a and 5b) were synthesized. The structures of these compounds were established on the basis of spectral (IR, 1D and 2D NMR, MS etc.) and chemical data. The molecules, including the parent compounds were screened for three-dimensional (3D) molecular docking on the crystal structure of topoisomerase IIα (1 bgw for topoisomerase IIα, PDB). Compounds 3a and 5a showed a dose dependent inhibition of catalytic activity of human topoisomerase IIα.