PHYTOCHEMICAL, ANTIBACTERIAL AND ANTIOXIDANT STUDIES ON LEAF EXTRACTS OF PIPER BETLE L.

Objective: In the present research, a clear systematic investigation of antibacterial and antioxidant potential of ambadi variety of P. betle of Mysore region has been carried out.Methods: Antibacterial activity of aqueous and solvent extracts of Piper betle L. was evaluated by agar cup diffusion and disc diffusion methods against some common pathogenic bacteria. The antioxidant property of all the solvent extracts were evaluated by diphenyl picryl hydrazyl (DPPH), nitric oxide (NO) and hydrogen peroxide scavenging assay. The IC50 values were calculated and compared with standard BHT and AA.Results: The results indicated that methanol and chloroform extracts of this variety recorded significant antibacterial activity and all the extracts recorded good radical scavenging capacity. Phytochemical analysis revealed that phenols, tannins, flavanoids, glycosides and proteins are present in aqueous, methanol and petroleum ether extracts.Conclusion: The results obtained in this study clearly indicate that P. betle extracts has a significant potential to use as antibacterial agent. The free radical scavenging capability by DPPH was better and IC50 value found was lesser than the standard used for all the extracts, which suggest that P. betle extracts have potent antioxidant activity. The solvent extracts are effective against free radical mediated diseasesÂ

Beneficial microbes promote plant growth and induce systemic resistance in sunflower against downy mildew disease caused by Plasmopara halstedii

Seven plant growth promoting fungi (PGPF) native to the rhizosphere soil were screened for their potential to promote growth and to induce resistance in sunflower against Plasmopara halstedii, an incitant of sunflower downy mildew disease. Effect of seed priming with each of these seven PGPF isolates on seed quality parameters and resistance induction were studied under in vitro and green house conditions. Root colonization ability of these PGPF was also studied under green house conditions. The results showed that seed priming with conidial suspension of PGPF at 1 x 108 cfu ml-1 significantly increased seed germination and seedling vigor compared to non primed control. Plants raised with primed seeds demonstrated a significant reduction in downy mildew disease severity and provided a maximum of 61% protection under green house conditions when compared to the untreated control. The experimental results proved that the tested PGPF, promoted growth and induced systemic resistance (ISR) in sunflower plants against the downy mildew disease caused by P. halstedii, due to their growth promoting and biocontrol abilities. Present study has revealed the fact that there is a strong correlation between root colonization and resistance induction in PGPF treated plants

Screening for plant growth promoting fungi and their ability for growth promotion and induction of resistance in pearl millet against downy mildew disease

A total of forty nine plant growth promoting fungi (PGPF) were successfully isolated from the rhizosphere of various grass species in Karnataka State, India. All the PGPF isolates were tested for their ability to enhance pearl millet seed quality parameters and to induce resistance against downy mildew disease in pearl millet. Susceptible pearl millet seeds 7042S were treated with PGPFs conidial suspension (1 x 108 cfu ml-1) and barley grain inocula (BGI) at 5%, 10% and 20% concentrations. Only six isolates among the forty nine tested recorded significant (P < 0.001) enhancement of seed germination and vigor when compared with the untreated control. Of the PGPF, Penicillium sp. (UOM PGPF 27) at 5% (w/w) concentration recorded highest seed germination of 92% and 1701.9 seedling vigor. The in planta colonization of the six PGPF isolates determined successfully in re-isolating the fungus from the basal root segments of 6 cm and 4 cm plated on PDA plates and also from the rhizosphere serial dilution of 10 3 to 10 5. Among the PGPFs tested in two modes, in BGI treatments, Penicillium sp. (UOM PGPF 27) at 5% (w/w) and Pythium sp. (UOM PGPF 41) at 10% (w/w) showed maximum disease protection of 67% and 61% respectively against downy mildew disease of pearl millet In case of conidial suspension treatments Penicillium sp. (UOM PGPF 27) and Trichoderma sp. (UOM PGPF 37) recorded highest disease protection of 71% and 66%, respectively under greenhouse conditions. Thus, the present study suggests that the tested PGPF, both as BGI inocula and conidial suspensions, can be used for pearl millet downy mildew disease management and also for plant growth. &nbsp

Genotoxic and antibacterial nature of biofabricated zinc oxide nanoparticles from Sida rhombifolia linn

Phyto-assisted synthesis of zinc oxide nanoparticles (ZnO-NPs) has gained importance because of their stable and eco-friendly nature with significant biological properties compared to chemically synthesized NPs. In the present study biofabrication of ZnO-NPs were carried out using aqueous leaf extract of Sida rhombifolia Linn. The biofabricated ZnO-NPs showed an absorption peak at 307 nm and bandgap energy of 3.51 eV with an average size of similar to 30 nm. The XRD analysis revealed stiff narrow peaks confirming the particles were of no impurities, which were in agreement with EDS analysis. The biofabricated ZnO-NPs exhibited significant antibacterial activity with a MIC of 0.25 mg mL(-1) against E. coli, while it was 0.5 mg mL(-1) against B. subtilis and S. typhi. The live and dead cell analysis of the nanoparticles confirmed that the antibacterial activity was due to damage in the cell walls of the test pathogens. Further, the nanoparticles also offered significant antioxidant and genotoxic properties with an IC50 of 974.5 mu g mL(-1) and 548.4 mu g mL(-1), respectively

Cytochrome P450-derived eicosanoids: the neglected pathway in cancer

Endogenously produced lipid autacoids are locally acting small molecule mediators that play a central role in the regulation of inflammation and tissue homeostasis. A well-studied group of autacoids are the products of arachidonic acid metabolism, among which the prostaglandins and leukotrienes are the best known. They are generated by two pathways controlled by the enzyme systems cyclooxygenase and lipoxygenase, respectively. However, arachidonic acid is also substrate for a third enzymatic pathway, the cytochrome P450 (CYP) system. This third eicosanoid pathway consists of two main branches: ω-hydroxylases convert arachidonic acid to hydroxyeicosatetraenoic acids (HETEs) and epoxygenases convert it to epoxyeicosatrienoic acids (EETs). This third CYP pathway was originally studied in conjunction with inflammatory and cardiovascular disease. Arachidonic acid and its metabolites have recently stimulated great interest in cancer biology; but, unlike prostaglandins and leukotrienes the link between cytochome P450 metabolites and cancer has received little attention. In this review, the emerging role in cancer of cytochrome P450 metabolites, notably 20-HETE and EETs, are discussed

Chitin oligomers and polyunsaturated fatty acids act synergistically in inducing resistance in pearl millet against downy mildew disease

Several glycosidic components from the cellwall of pathogenic fungi have been implicated in inducing plant defense response in many host-pathogen systems. Chitin oligomers, released from fungal cellwalls by endochitinase act also as immuno-modulators. Polyunsaturated fatty acids (PUFAs) have been already developed specifically against oomycete pathogens. Downy mildew of pearl millet, caused by Sclerospora graminicola, is a devastating disease, resulting in considerable losses in the semi-arid regions of the world. The efficacy of two combinations of chitin oligomers and PUFAs was examined in vitro and also under epiphytotic conditions in inducing downy mildew resistance in pearl millet. When applied to seeds in greenhouse experiments, chitin oligomers and PUFAs induced 64 and 69% protection, resp. Chitin oligomers-supplemented with PUFAs when applied in combination to pearl millet seeds followed by foliar spray offered higher protection against downy mildew (73%). Plants raised from treated seeds and challenge inoculated at the tillering and inflorescence stages showed disease resistance, resulting in higher grain yield compared to untreated plants. Kinetic anal. of endochitinase elicitation by chitin oligomers and PUFA treatment resulted in increased chitinase activity. The enzyme activity was initiated 6h after the treatment and pathogen inoculation and was maximum at 24 h. The chitin oligomers and PUFAs have the potentiality to develop into future candidate mols. as ecofriendly pesticides in inducing resistance against downy mildew. Many biowastes are now being considered to obtain chitin and PUFA-based compounds to develop com. biopesticides for future plant disease management

Studies on phytochemical analysis and antioxidant activity of taxillus tomentosus (roth.) van tiegh

Taxillus tomentosus (Roth.) Van Tiegh., a stem parasite belonging to the family Loranthaceae growing on Emblica officinalis Gaertn. was collected from Western Ghats of Karnataka. In the present study, an investigation was carried out on phytoconstituents in petroleum ether, chloroform, ethyl acetate and methanol extracts which revealed the presence of reducing compounds, alkaloids, flavonoids, saponins, tannins, cardiac glycosides, glycosides, carbohydrates, sterols and terpenoids and absence of anthraquinones, proteins and amino acids. The methanolic extract of the plant showed total phenolic content of about 31ìg of GAE in 100 ìg of extract. Antioxidant and reducing power activities of methanol extract revealed dose dependent activity, which increased with increase in the concentration of the extract

Plant growth-promoting fungus penicillium oxalicum enhances plant growth and induces resistance in pearl millet against downy mildew disease

Plant Growth-promoting Fungus (PGPF) Penicillium oxalicum was isolated from rhizosphere soil of pearl millet and was tested for its ability to promote growth and induce systemic resistance in pearl millet against downy mildew disease. The fungal isolate P.oxalicum UOM PGPF 16 was identified as P.oxalicum using ITS sequencing and morphological analysis and sequence was deposited at NCBI with accession number KF150220. Pearl millet susceptible seeds were treated with three different inducers (CS, CF and LCF) of PGPF P.oxalicum and all the inducers significantly reduced the downy mildew disease and enhanced plant growth. Among the inducers tested, CS treatment recorded highest seed germination of 91% and 1427 seedling vigour followed by LCF and CF treatments. The vegetative growth parameter and NPK uptake studies under greenhouse conditions revealed that the CS treatment of P.oxalicum remarkably enhanced the parameters tested when compared to control plants. A significant disease protection of 62% and 58% against downy mildew disease was observed in plants pretreated with CS of P.oxalicum under greenhouse and field conditions, respectively. The spatio-temporal studies revealed that inducers P.oxalicum required a minimum of 3days for developing maximum disease resistance which was maintained thereafter. The maximum Peroxidase (POX) activity (62.7U) was observed at 24h in seedlings treated with CS of PGPF P.oxalicum and the activity gradually reduced at later time points after pathogen inoculation. Chitinase (CHT) activity was significantly higher in inducer treated seedlings when compared to control seedlings inoculated with pathogen after 48h and remained constant at all time points

Evaluation of antibacterial and antioxidant potential of Euphorbia cotinifolia linn. Leaf extracts

Antibacterial activity of aqueous and solvent extracts of Euphorbia cotinifolia leaves was tested against some human pathogenic bacteria, viz. Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, Bacillus cereus, Salmonella typhi, Enterobacter aerogenes and Staphylococcus aureus by agar cup diffusion and broth microdilution methods. Antioxidant properties were evaluated for different solvent extracts by di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH), nitric oxide (NO) and hydrogen peroxide methods and IC50 values were calculated and compared with the standard ascorbic acid and butylated hydroxyanisole. Among the aqueous and organic solvent extracts, methanol and ethyl acetate showed significant activity against B. subtilis and E. aerogenes, which recorded a maximum inhibition zone of 17.25 mm. Minimum inhibitory concentrations of methanol and ethyl acetate extracts for different bacteria ranged from 0.3-1.25 mg/mL. In DPPH method, IC50 values of chloroform, petroleum ether, ethyl acetate and methanol were found to be 15, 17, 18 and 19 mg/mL, respectively, lesser than the standard, ascorbic acid (25 mg/mL). Phytochemical analysis of aqueous, ethyl acetate and methanol extract showed the presence of flavonoids, terpenoids, tannins and steroids. Further work is in progress to isolate the active compound(s)