Meenu Katoch

Disruption of the PI3K/AKT/mTOR signaling cascade and induction of apoptosis in HL-60 cells by an essential oil from Monarda citriodora.

We have isolated an essential oil from Monarda citriodora (MC) and characterized its 22 chemical constituents with thymol (82%), carvacrol (4.82%), β-myrcene (3.45%), terpinen-4-ol (2.78%) and p-cymene (1.53%) representing the major constituents. We have reported for the first time the chemotherapeutic potential of MC in human promyelocytic leukemia HL-60 cells by means of apoptosis and disruption of the PI3K/AKT/mTOR signaling cascade. MC and its major constituent, thymol, inhibit the cell proliferation in different types of cancer cell lines like HL-60, MCF-7, PC-3, A-549 and MDAMB-231. MC was found to be more cytotoxic than thymol in HL-60 cells with an IC50 value of 22 μg/ml versus 45 μg/ml for thymol. Both MC and thymol induce apoptosis in HL-60 cells, which is evident by Hoechst staining, cell cycle analysis and immuno-expression of Bcl-xL, caspase-3,-8,-9 and PARP-1 cleavage. Both induce apoptosis by extrinsic and intrinsic apoptotic pathways that were confirmed by enhanced expression of death receptors (TNF-R1, Fas), caspase-9, loss of mitochondrial membrane potential and regression of Bcl-2/Bax ratio. Interestingly, both MC and thymol inhibit the downstream and upstream signaling of PI3K/AKT/mTOR pathway. The degree of apoptosis induction and disruption of the PI3K signaling cascade by MC was significantly higher when compared to thymol.

An overview of diagnostics for viruses infecting gladiolus

Abstract In order to improve the crop productivity, quality of germplasm and minimise infection in different cultivars of gladiolus, its proper diagnosis and control is essential. In addition, diagnosis also helps in exporting planting material to countries wherein strict quarantine conditions have been imposed. During the last two decades much advance has been made in diagnostics for the detection of viral diseases, but incidence of viral infection is increasing. In plants, emphasis has always been given to the diagnosis of viral infection in different parts of plants, particularly in the propagating material as it indirectly helps in the control of the infection. As well as Immuno-diagnostics, molecular biology has also provided techniques like the use of DNA/RNA probes, the polymerase chain reaction, etc. to detect the viruses. These techniques have shown great potential as far as specificity and sensitivity are concerned. The aim of this review is to discuss immuno-diagnostics and molecular-diagnostics used in the field of disease diagnosis of gladiolus, most particularly to diagnose Bean Yellow Mosaic Virus (BYMV) and Cucumber Mosaic Virus (CMV). DAS-ELISA, DTBIA, ISEM and RT-PCR are found to be the most suitable techniques to detect the various BYMV and CMV infecting gladiolus. These tests not only provide information for epidemiological purposes, but also to develop disease-free stock of gladiolus, which ultimately helps to control the infection.

Endophytic fungi found in association with Bacopa monnieri as potential producers of industrial enzymes and antimicrobial bioactive compounds

This study aimed to screen the endophytic fungal species of ethano-medicinal plant Bacopa monnieri (L.) Pennell for their ability to produce antimicrobial substances against Bacillus subtilis, Pseudomonas aeroginosa, Salmonella typhimurium, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Candida albicans. Endophytes were also screened for their ability to produce amylase, cellulase, protease and lipase to evaluate their ecological role within the host plant. Twenty-six endophytes were isolated and seventeen were identified. All the isolated endophytes exhibited amylolytic activity. Lipolytic, cellulolytic, proteolytic activity was shown by 98, 28 and 31% isolates, respectively. Similarly, all the endophytes (100%) exhibited significant antimicrobial activity against K. pneumonia, while seventeen endophytes (89.5%) were active against S. aureus. Fourteen endophytes (78.9%) showed significant antimicrobial activity against B. subtilis and C. albicans. Eleven (57.8%), nine (50%), four (21%) endophytes were active against S. typhimurium, E. coli and P. aeruginosa, respectively.

Status of bean yellow mosaic virus on Gladiolus

Abstract The status of bean yellow mosaic virus (BYMV) in 32 cultivars of Gladiolus was investigated by examining the plants visually as well as by using the techniques like ELISA. Incidence of the disease was found to range from 0% to 100% on visual basis, whereas ELISA revealed almost 100% infection in plants, which were showing the symptoms. Almost 30% of the symptomless Gladiolus plants were also the carrier of the virus. Plants found positive for BYMV by ELISA were confirmed to carry the virus with immuno electron microscopy, cytopathological studies and by RT-PCR analysis employing primers specific to BYMV. The present investigation revealed the wide spread occurrence of BYMV in various Gladiolus cultivars whether with or without symptoms and the study suggested that symptomless plants must be examined for the presence of the virus before using them for healthy propagule production.

Evaluation of the catalase promoter for expressing the alkaline xylanase gene (alx) in Aspergillus niger.

Aspergillus niger represents a promising host for the expression of recombinant proteins, but only a few expression systems are available for this organism. In this study, the inducible catalase promoter (PcatR) from A. niger was characterized. For this, constructs were developed and checked for the expression of the alkaline xylanase gene transcriptionally fused under the cat R promoter. Two versions of the catalase (catR) promoter sequence from A. niger (P(cat300,) P(cat924)) were isolated and tested for their ability to drive expression of the alkaline xylanase (alx) gene. P(cat924) showed better efficiency (more than 10-fold increase in AlX activity compared to P(cat300)) under the optimized culture conditions. Induction of the catR promoter with 0.20% H(2)O(2) and 1.5% CaCO(3) in the culture medium, further increased expression of AlX 2.61- and 2.20-fold, respectively, clarifying its inducible nature. Specific induction or repression of the catR promoter provides the possibility for utilization of this promoter in heterologous protein production.

Immunosuppressive potential of Botryosphaeria dothidea, an endophyte isolated from Kigelia africana.

Abstract Context: For years, natural products from microbes have been used as drugs. Endophytes are the most important fungi that produce many novel metabolites for potential use in pharmacology and agriculture. Objective: The objective of the present study was to explore new endophytes for novel natural products. Materials and methods: An endophyte BAK-I was isolated from the bark of Kigelia africana (Lam.) Beneth (Bignoniaceae). BAK-I was characterized morphologically and on the basis of ITS-5.8S rDNA sequences. BAK-I was fermented to yield an extract, which was evaluated for its anticancer, antimicrobial, and immunomodulatory activities, using MTT, agar well-diffusion, tube dilution method, lymphocyte proliferation, and pro-inflammatory cytokines (TNF-α) (by macrophages) evaluation assays. For lymphocyte proliferation and pro-inflammatory cytokines studies, four concentrations were evaluated 10, 30, 100, and 1000 µg/mL and the experiments were conducted for 72 and 48 h, respectively. Results and discussion: The BAK-I showed pink cottony growth. SEM studies showed smooth fusoid-oblong conidia with a truncated base. Furthermore, ITS-5.8S rDNA sequence showed 99% homology with the Botryosphaeria dothidea strain suggesting that the endophyte is a strain of the genus Botryosphaeria. Less than 50% growth inhibition of SF295, Lung A-549, and THP-1 cancer cell lines after treatment with BAK-I extract suggested that it did not have significant cytotoxic potential, whereas it is bactericidal for Gram-positive pathogens MRSA and VRE with MIC value 200 and 250 µg/mL, respectively. To elucidate its immunomodulation potential, splenocyte proliferation studies showed that BAK-1 suppressed the T cell proliferation by 50%. TNF-α evaluation studies also showed that the extract inhibited TNF-α production in a concentration-dependent manner suggesting that it had immunosuppressive potential. Inhibition at 10 µg/mL was found to be 55% as against 48% using β-methasone. Conclusion: The results suggested that BAK-I extract can be used as a potential immunosuppressive agent.

Endophytic fungi associated with Monarda citriodora, an aromatic and medicinal plant and their biocontrol potential

Abstract Context: The Food and Agriculture Organization has estimated that every year considerable losses of the food crops occur due to plant diseases. Although fungicides are extensively used for management of plant diseases, they are expensive and hazardous to the environment and human health. Alternatively, biological control is the safe way to overcome the effects of plant diseases and to sustain agriculture. Since Monarda citriodora Cerv. ex Lag. (Lamiaceae/Labiatae) is known for its antifungal properties, it was chosen for the study. Objective: The isolation of endophytic fungi from M. citriodora and assessing their biocontrol potential. Material and methods: The isolated endophytes were characterized using ITS-5.8 S rDNA sequencing. Their biocontrol potential was assessed using different antagonistic assays against major plant pathogens. Results: Twenty-eight endophytes representing 11 genera were isolated, of which, around 82% endophytes showed biocontrol potential against plant pathogens. MC-2 L (Fusarium oxysporum), MC-14 F (F. oxysporum), MC-22 F (F. oxysporum) and MC-25 F (F. redolens) displayed significant antagonistic activity against all the tested pathogens. Interestingly, MC-10 L (Muscodor yucatanensis) completely inhibited the growth of Sclerotinia sp., Colletotrichum capsici, Aspergillus flavus and A. fumigatus in dual culture assay, whereas MC-8 L (A. oryzae) and MC-9 L (Penicillium commune) completely inhibited the growth of the Sclerotinia sp. in fumigation assay. Conclusions: Endophytes MC-2 L, MC-14 F, MC-22 F and MC-25 F could effectively be used to control broad range of phytopathogens, while MC-10 L, MC-8 L and MC-9 L could be used to control specific pathogens. Secondly, endophytes showing varying degrees of antagonism in different assays represented the chemo-diversity not only as promising biocontrol agents but also as a resource of defensive and bioactive metabolites.

Short hybrid peptides incorporating β- and γ-amino acids as antimicrobial agents

HIGHLIGHTSThe hybrid peptides containing &bgr;‐ and &ggr;‐amino acids were synthesized, characterized and evaluated as antimicrobial agents.&agr;&ggr; hybrid peptide, LA‐Lys(Z)‐Gpn‐PEA, P4 was found more active against P. aeruginosa and S. aureus.Peptide P4 exhibited lowest haemolytic activity and negligible cytotoxicity against human cancer cell lines A549, PC‐3 and HCT‐116 at its MIC concentration. ABSTRACT The peptides containing &bgr;‐ and &ggr;‐amino acids, LA‐Lys(Z)‐PEA, P1; LA‐Lys(Z)‐&bgr;3,3‐Ac6c‐PEA, P2; LA‐Orn(Z)‐&bgr;3,3‐Ac6c‐PEA, P3; LA‐Lys(Z)‐Gpn‐PEA, P4; LA‐Orn(Z)‐Gpn‐PEA, P5; LA‐Lys(Z)‐&ggr;4‐Phe‐PEA, P6, LA‐&ggr;4‐Leu‐Lys(Z)‐PEA, P7 and LA‐&bgr;3,3‐Pip(Ac)‐Lys(Z)‐PEA, P8 were synthesized, characterized and evaluated against Gram‐positive and Gram‐negative bacteria. Among all, peptides P2, P3, P4 and P5 exhibited potent activity (MIC 6.25 &mgr;M) against S. aureus MTCC 737 and P. aeruginosa MTCC 424. In order to understand the efficacy of peptides and mechanism of action, time kill kinetics and fluorescence microscopic studies were performed against S. aureus and P. aeruginosa for the peptides P2, P3, P4 and P5. P4 took half time to show the bactericidal effect on P. aeruginosa and S. aureus in comparison to P2 at their 2x MICs. Fluorescence microscopic studies suggested that peptides P2 and P4 both killed the bacteria via membrane disruption. Further, P4 exhibited lowest haemolytic activity among active peptides and negligible cytotoxic activity against human cancer cell lines A‐549, PC‐3 and HCT‐116 at its MIC.

In vitro acaricidal activity of Piper nigrum and Piper longum fruit extracts and their active components against Rhipicephalus (Boophilus) microplus ticks

In vitro acaricidal activity of Piper nigrum and P. longum fruit extracts and their active components (piperine for P. nigrum and piperine and piperlonguminine for P. longum) was evaluated against adults engorged females of Rhipicephalus (Boophilus) microplus using adult immersion test. Three concentrations of each extract with four replications were used in the bioassay. Extracts significantly affected mortality rates of ticks in dose-dependent manner ranged 12.5–95.8% for P. nigrum and 29.2–87.5% for P. longum, with an additional effect on the reproductive physiology of ticks by inhibiting oviposition (28.1–96.9% by P. nigrum and 36.1–89.3% by P. longum). However, the acaricidal and oviposition limiting properties were decreased significantly when the active component(s) of each extract was tested separately. However, the combination of piperine and piperlonguminine (obtained from P. longum extract) caused 79.2% mortality of ticks which is equivalent to the corresponding concentration (~ 5%) of the extract. It can be concluded that the fruit extracts of P. nigrum and P. longum had both acaricidal and oviposition limiting actions against the adults of R. (B.) microplus which could make it a valuable component of developing sustainable strategy for integrated tick management.

Chromium(III) complexes of dimethyl diphenyldithiophosphates: Synthesis, characterization, and antibacterial studies

GRAPHICAL ABSTRACT ABSTRACT Dimethyl diphenyldithiophosphate complexes of Cr(III), [{(ArO)2PS2}3Cr] [Ar = 2,4-(CH3)2C6H3 (1), 2,5-(CH3)2C6H3 (2),3,4-(CH3)2C6H3 (3), and 3,5-(CH3)2C6H3 (4)], have been synthesized and structurally characterized by IR, heteronuclear NMR (1H, 13C, and 31P) spectroscopic and single crystal X-ray analyses. The crystal structure of complex 4 reveals mononuclear units with the Cr(III) centre chelated in bidentate fashion by six S atoms of the three diphenyldithiophosphate ligands to form octahedral geometry. The main core of the system comprised of four membered (CrS2P)3 heteroatomic ring and Cr(III) center. The ligands and complexes were evaluated for their antibacterial potential against six bacterial strains (K. pneumoniae, E.coli, P. aeruginosa, B. subtilis, S. aureus, and S. typhimurium). The metal derivatives of diphenyldithiophosphate ligands were found to be more active against the bacterial strains as compared to the free ligands.