Antifungal activity of herbal extracts against plant pathogenic fungi

The present study was designed to evaluate in vitro antifungal activity of herbal extracts against three plant pathogenic fungi (viz. Rhizopus stolonifer, Botrytis cinerea and Colletotrichum coccodes). Extracts of leaves and rinds of Garcinia indica, rhizomes of Curcuma aromatica, roots of Glycyrrhiza gahliae, leaves of Nyctanthes arbour-tristis and seeds of Vernonia anthelmintica were used for screening. Screening was done using poisoned food technique. Relatively potent extracts were shortlisted from this study and were further assayed to find out their minimum fungicidal concentration (MFC). From the above studies, it was observed that ethyl acetate extract of rhizomes of C. aromatica and unripe fruit rinds of G. indica have shown the lowest MFC values amongst the other tested plant extracts. This study indicates that the potential of these plant extracts in the management of diseases caused by plant pathogenic fungi.     

Enhancement of shelf life of tomatoes by postharvest herbal treatment,during storage under ambient conditions

Fruits and vegetables are the most perishable agricultural commodities, and the postharvest loss of these is tremendous. The objective of this study is to reduce postharvest losses of perishables with a very simple approach. The study was conducted to find out the effect of postharvest herbal treatment on shelf life of tomatoes under ambient conditions. Three different herbal formulations of Curcuma aromatica (A), Glycyrrhiza glabra (B) and Garcinia indica (C) each at concentration of 1% w/v were studied. The tomatoes stored were evaluated on 7th and 14th day for physicochemical parameters (viz. Vitamin C, Titrable acidity, pH and total soluble solids) and percent spoilage. It was observed that the formulation of G. indica was found to be most effective. Tomatoes treated with formulation of G. indica were rated for organoleptic evaluation and got very good ratings. This study has revealed the possibility of utilisation of herbal formulations to reduce postharvest losses of tomatoes.     

甘草根际土壤微生物群落对长期连作的响应

光果甘草连年种植所引起的甘草产量下降、植株发育不良、根腐病频发严重影响甘草产业的持续发展,造成了重大的经济损失。然而,其机制却并不清楚。应用下一代测序技术,对未种植过光果甘草的土壤（Control）,生长1a （Gg1）和生长5a （Gg5）光果甘草的根际土壤行16S rDNA和18S rDNA ITS测序,并对比分析了甘草根际土壤和对照组之间,以及不同种植年限甘草根际土壤之间的微生物群落结构差异,以期探究光果甘草连作障碍的原因。结果表明,光果甘草连作增加了根际土壤细菌群落的丰富度,降低了真菌群落的丰富度（P>0.05）。主坐标分析显示,光果甘草的根际土壤微生物组成与对照组之间存在显著差异,并且光果甘草的种植年限显著地影响了根际土壤微生物的群落组成。在门水平上,光果甘草连作显著地增加了真菌Blastocladiomycota和Mortierellomycota的相对多度（P<0.05）。在属水平上,光果甘草连作显著地降低了有益细菌Arthrobacter和Pseudomona及有益真菌Naganishia的相对多度,而增加了病原真菌Fusarium和Thanatephorus的相对多度。由此推测,光果甘草根际土壤微生物群落结构的改变,以及有益微生物相对多度的降低和病原微生物相对多度的增加可能是导致光果甘草发生连作障碍的重要原因之一。     

Broad-spectrum antibacterial and antifungal properties of certain traditionally used Indian medicinal plants

Ethanolic extracts of 22 traditionally used Indian medicinal plants were studied for their antimicrobial activity against seven bacteria (Staphylococcus aureus, Salmonella typhimurium, S. paratyphi, S. typhi, E. coli, Shigella dysenteriae and Pseudomonas aeruginosa) and five filamentous fungi (Aspergillus niger, Alternaria alternata, Fusarium chlamydosporum, Rhizoctonia bataticola and Trichoderma viride) and a yeast Candida albicans of clinical origin. Of these, 16 plant extracts showed varied level of antibacterial activity against one or more test bacteria. Similarly antifungal and anticandidal activity was detected among 17 and 9 plant extracts respectively. Broad-spectrum antimicrobial activity (both antibacterial and antifungal) was detected among crude extracts of Bryophyllum pinnatum (leaves), Caesalpinia bonducella (seeds), Delonix regia (flower), Hedychium spicatum (fruits), Mangifera indica (leaves), Murraya coenigii (leaves) and Syzgium cumini (seeds). Similarly extracts of Cichorium intybus (roots), Ficus religiosa (leaves) and Trigonella foenum-graecum (leaves) demonstrated more antibacterial activity with less antifungal activity. On the other hand Pistacia integerrima (stems) and Rheum emodi (roots) demonstrated more antifungal activity with less antibacterial activity.     

Antimicrobial Constituents of the Leaves of Mikania micrantha H. B. K

Background

To isolate plant-derived compounds with antimicrobial activity from the leaves of Mikania micrantha, to determine the compounds configuration, and to evaluate their antimicrobial activity against eight plant pathogenic fungi (Exserohilum turcicum, Colletotrichum lagenarium, Pseudoperonispora cubensis, Botrytis cirerea, Rhizoctonia solani, Phytophthora parasitica, Fusarium solani, and Pythium aphanidermatum,) and four plant pathogenic bacteria (gram negative bacteria: Ralstonia dolaanacearum, Xanthomonas oryzae pv. Oryzae, Xanthomonas Campestris pv. Vesicatoria, and Xanthomonas campestris pv. Citri), and four bacteria (gram positive bacteria: Staphyloccocus aureus, Bacillus subtilis, Micrococcus luteus, and Bacillus cereus).

Methods and Results

Antimicrobial constituents of the leaves of M. micrantha were isolated using bioactivity- guided fractionation. The antifungal activity of the isolated compounds was evaluated by the inhibit hypha growth method and inhibit spore germination method. Characterization of antibacterial activity was carried out using the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs). MIC and MBC were determined by the broth microdilution method. Six compounds – deoxymikanolide, scandenolide, dihydroscandenolide, mikanolide, dihydromikanolide, and m - methoxy benzoic acid – have been isolated from leaves of Mikania micrantha H. B. K. Deoxymikanolide, scandenolide, and dihydroscandenolide were new compounds. The result of bioassay showed that all of isolated compounds were effective against tested strains and deoxymikanolide showed the strongest activity.

Conclusions and Significance

The leaves of M. micrantha may be a promising source in the search for new antimicrobial drugs due to its efficacy and the broadest range. Meanwhile, adverse impact of M. micrantha will be eliminated.     

Induced resistance against Alternaria brassicae blight of mustard through plant extracts

An experiment was conducted to study the effect of plant extracts on soluble sugar, soluble phenol and defence-related enzymes response against Alternaria blight in mustard crop. The efficacy of six selected plant extracts (5 and 10%) used as foliar sprays at 60 and 70 days after sowing and mustard leaves was used for investigation. The results indicate that soluble phenol and sugar content in mustard leaves significantly increases in response to spraying of Azadirachta indica seed kernel, Calotropis procera and A. indica leaf extracts. The soluble protein, viz. peroxidase, polyphenol oxidase and phenylalanine ammonia lyase content, was higher in mustard leaves sprayed with C. procera leaves extract, A. indica seed kernel and Allium sativum bulb extract.     

Feeding inhibition of Helicoverpa armigera （HiJbner） by Eucalyptus camaldulensis and Tylophora indica extracts

Crude leaf extracts of Eucalyptus camaldulensis and Tylophora indica were evaluated for their antifeedancy against Helicoverpa armigera larvae in no-choice bioassays. Cabbage leaf-disc dipped in different concentrations of leaf extracts was used for feeding fifth instars of H. armigera for 24 hours. Ethanol extracts from both the plant species exhibited significant feeding inhibition, activity. The effective concentrations of ethanol extracts that caused 50% reduction in larval feeding （EI50） were 6.9% for E. camaldulensis and 2.8% for T. indica, while these values of hexane extracts were 9.3% and 5.2%, respectively. Compared to the crude leaf extracts, crude alkaloids from T. indica and crude tannins from E. camaldulensis were more potent in reducing larval feedings.     

Antifungal and antibacterial potential of methanol and chloroform extracts of Marchantia polymorpha L.

The methanol and chloroform extracts of Marchantia polymorpha were tested against three Gram-negative bacterial strains, viz. Xanthomonas oryzae pv. oryzae, Salmonella enterica and Pasturella multocida and four fungal strains, viz. Tilletia indica Mitra, Fusarium oxysporum f. sp. lini, Sclerotium rolfsii Sacc. and Rhizoctonia solani Kuhn. by using disc diffusion and micro broth dilution techniques. Both the extracts showed unique activity against X. oryzae and P.multocida [per cent inhibition (PI) 11.58 and 12.55, minimum inhibitory concentration (MIC) 2.50 and 1.25 μg/mL, minimum bactericidal concentration (MBC) 2.75 and 1.25 μg/mL, respectively] but for fungi, it was shown against S.rolfsii and F. oxysporum [PI 32.65 and 33.44, MIC 2.50 and 0.65 μg/mL, minimum fungicidal concentration (MFC) 4.50 and 0.65 μg/mL, respectively].The extracts possessed antimicrobial activity with different potency against variety of micro-organisms pathogenic to plants as well as animals. Some extracts were fungistatic and bacteriostatic (methanol extract against R. solani and chloroform extract against F. oxysporum and methanol extract for bacteria, respectively), while rest showed fungicidal/bactericidal potential. The results suggest the potential of M. polymorpha for developing a broad spectrum antimicrobial formulation in future.     

In Vitro Antimicrobial Activity of <Emphasis Type="Italic">Acacia catechu</Emphasis> and Its Phytochemical Analysis

Acacia catechu, commonly known as catechu, cachou and black cutch is an important medicinal plant and an economically important forest tree. The methanolic extract of this plant was found to have antimicrobial activities against six species of pathogenic and non-pathogenic microorganisms: Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The maximum zone of inhibition (20 mm) was found to be exhibited against S. aureus. For this organism the minimum bactericidal concentration (MBC) of the crude extract was 1,000 μg/ml. The extract was found to be equally effective against gram positive and gram negative bacteria. The antimicrobial activity of the extract was found to be decreased during purification. The chemical constituents of organic plant extracts were separated by thin layer chromatography (TLC) and the plant extracts were purified by column chromatography and were further identified by Gas chromatography–mass selection (GC–MS) analysis. The composition of A. catechu extract had shown major components of terpene i.e. camphor (76.40%) and phytol (27.56%) along with other terpenes in minor amounts which are related with their high antibacterial and antifungal properties.     

基于转录组学和代谢组学联合分析草珊瑚萜类化合物生物合成的组织特异性分布

本研究旨在探究草珊瑚叶和根中萜类化合物的组织特异性分布差异,解析其药效品质差异形成的分子机制。采用液相色谱-质谱联用技术(liquid chromatography-mass spectrometry, LC-MS)和Illumina HiSeq^TM高通量测序技术获得草珊瑚[Sarcandra glabra (thunb) naka]叶和根的代谢组学和转录组学数据。代谢组学结果表明参与叶和根中萜类合成的差异代谢物有50个,包括法尼西基半胱氨酸、甘油醛-3-磷酸、甲羟戊酸-5-磷酸等。转录学结果表明差异代谢酶基因有57条,包括ACTC、HMGCR、MVK、DXS与KS等,并预测了MYB、C2H2、AP2/ERF-ERF等7个转录因子参与调控草珊瑚不同组织部位中萜类的合成和积累差异。实时荧光定量PCR (quantitative real-time polymerase chain reaction, qRT-PCR)结果显示,随机选取的8个参与萜类合成的酶基因在草珊瑚不同组织部位中的表达趋势与转录组学测序结果一致。本研究有助于阐明草珊瑚叶和根临床疗效差异形成的分子机制,同时为草珊瑚的资源开发利用奠定基础。     

Assessment of Antibacterial Activity of Colebrookia oppositifolia against Waterborne Pathogens Isolated from Drinking Water of the Pothwar Region in Pakistan

An attempt was made to control waterborne pathogens by using medicinal plant extracts. One hundred and twenty-six water samples from filtration plants, tube wells, and water supplies were collected and analyzed for total and faecal Coliform bacteria as well as for total viable count. Results showed that waterborne pathogens were numerous and significantly higher than the World Health Organization's recommended guidelines. The methanolic and aqueous extracts of different parts of Colebrookia oppositifolia (Labiateae) were examined for antibacterial activities in vitro by an agar diffusion method. Antibacterial activity of leaves, shoots, and roots of Colebrookia oppositifolia was assessed against Gram positive and Gram negative bacteria that were isolated and identified from water samples by the API 20E method. Extract of roots showed more antibacterial activities against Staph. aureus and B. cereus var. mycoides, Pseudomonas aeruginosa, Klebsiella pneumonia, and Shigella flexneri at 37°C, than extracts from leaves and shoots. The lowest MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) were observed in roots as compared to shoots and leaves. These results suggest that there is an urgent need for improvement in existing water quality treatment. Secondly, the fruit extract can be practical for protection and to avoid risk of contamination by waterborne pathogens and to promote indigenous solutions for disease-control and environmental management.     

Comparative bioactivity of selected extracts from Meliaceae and some commercial botanical insecticides against two noctuid caterpillars, <Emphasis Type="Italic">Trichoplusia ni</Emphasis> and <Emphasis Type="Italic">Pseudaletia unipuncta</Emphasis>

Plant-derived extracts and phytochemicals have long been a subject of research in an effort to develop alternatives to conventional insecticides but with reduced health and environmental impacts. In this review we compare the bioactivities of some plant extracts with those of commercially available botanical insecticides against two important agricultural pests, the cabbage looper, Trichoplusia ni and the armyworm, Pseudaletia unipuncta. Test materials included extracts of Azadirachta indica (neem), A. excelsa (sentang), Melia volkensii, M. azedarach (Chinaberry) and Trichilia americana, (all belonging to the family Meliaceae) along with commercial botanical insecticides ryania, pyrethrum, rotenone and essential oils of rosemary and clove leaf. Most of the extracts and botanicals tested proved to be strong growth inhibitors, contact toxins and significant feeding deterrents to both lepidopteran species. However, there were interspecific differences with T. ni generally more susceptible to the botanicals than the armyworm, P. unipuncta. All botanicals were more inhibitory to growth and toxic (through feeding) to T. ni than to P. unipuncta, except for M. azedarach which was more toxic to P. unipuncta than to T. ni. Athough, pyrethrum was the most toxic botanical to both noctuids, A. indica, A. excelsa, and M. volkensii were more toxic than ryania, rotenone, clove oil and rosemary oil for T. ni. As feeding deterrents, pyrethrum was the most potent against T. ni, whereas A. indica was the most potent against the armyworm. Based upon growth inhibition, chronic toxicity, and antifeedant activity, some of these plant extracts have levels of activity that compare favorably to botanical products currently in commercial use and have potential for development as commercial insecticides.     

Appraisal of plant extracts and streptomycin sulfate against citrus canker disease

Abstract

Plant extracts and streptomycin sulfate were evaluated against Xanthomonas axonopodis pv. citri. In first experiment, Azadirachta indica, Allium cepa, Catharanthus roseus, Allium sativum, Zingiber officinale (Roscoe) were investigated in vitro through inhibition zone technique against the growth of X. a. pv. citri. Results indicated that A. indica exhibited statistically significant inhibition (4?cm) zone over control. In second experiment, A. indica and streptomycin sulfate disjointedly and in amalgamation were evaluated in vitro. Streptomycin alone and in permutation with A. indica articulated significant inhibition of the bacterium. In third study, streptomycin sulfate and A. indica (S) and in combination were evaluated against citrus canker disease in green house. Results showed that streptomycin sulfate reduced disease significantly than control. In fourth experiment, streptomycin sulfate, A. indica, in combination and their interaction with days were evaluated under field condition. Streptomycin sulfate proved to be most effective and reduced the disease severity as compared to control.     

Antimicrobial activity of LFchimera synthetic peptide against plant pathogenic bacteria

The present study was designed to evaluate potential antibacterial activities of synthetic LFchimera against five plant pathogenic bacteria such as Ralstonia solanacearum, Erwinia amylovora, Xanthomonas campestris, Pseudomonas syringae and Pectobacterium carotovorum. The agar disc-diffusion method with different concentrations (0.2, 0.4, 0.6 and 0.8 μM) of peptide was used to study the antibacterial activity of LFchimera against bacteria. The Minimum Inhibitory Concentration (MIC) of the LFchimera peptide were tested using serial dilution method at concentration ranging from 0 to 10 μM. The Results from agar disc-diffusion method revealed that LFchimera was effective against all bacterial strain in a dose-dependent manner. LFchimera showed highest activity in 0.8 μM which was significant compared to the standard antibiotic. LFchimera pepetide showed low MIC values (4 μM) against all tested bacteria. LFchimera peptide was found to show antibacterial activity against important phytopathogenic bacteria and can improve the potential of an antimicrobial peptide in plant disease management.     

Isolation, Identification and Study of Antimicrobial Property of a Bioactive Compound in an Indian Medicinal Plant Acalypha indica (Indian-Nettle)

Summary Fresh, dried and powdered samples of leaf, stem and root of Acalypha indica were subjected to fractional distillation in a soxhlet apparatus using solvents such as hexane, chloroform, acetone and methanol. The plant extracts and a synthetic antifungal compound, Clotrimazole (authentic standard) were subjected to TLC and HPLC analyses. The R_f (relative front) value of Clotrimazole was 0.371. The plant’s leaf, root and stem extracts also gave distinct spots respectively at R_f value of 0.371 ± 0.0009. In HPLC, the TLC-separated active compound and Clotrimazole resolved at 1.90 ± 0.2 min (retention time). The amounts of active compound present in root, leaf and stem extracts were 538, 415 and 171 μg/g respectively. From the results of our study, we infer that the active compound isolated from Acalypha indica is more potent in controlling Candida albicans, Aspergillus niger and Escherichia coli. The Active compound present in the plant had more than 100% activity when compared to standard Clotrimazole.     

Antifungal activity of plants extracts against Alternaria solani,the causal agent of early blight of tomato

Aqueous extracts of 39 plants selected from local flora were evaluated for antifungal potential against Alternaria solani, causing early blight of tomato, at 4% concentration in Potato Dextrose Agar by poison food technique. Out of these, 13 plant extracts significantly reduced the mycelial growth of the pathogen, according to ANOVA, Tukey’s post-test. Inhibition rate of above 20% was shown by seven plant extracts namely Crotalaria trichotoma (36.6%), Citrus aurantifolia (27.3%), Azadirachta indica (23.7%), Polyalthia longifolia (23.3%), Datura metel (21.3%), Muntingia calabura (20.09%) and Oxalis latifolia (20.09%). At 2% concentration, six extracts showed significant growth inhibition namely, C. trichotoma (16.6%), A. indica (10%), Capsicum annum (7.1%), D. metel (6.6%), P. longifolia (6.3%) and C. aurantifolia (5.5%). The plant extracts shortlisted for pathogen inhibition have potential to be developed as potent fungicides in organic farming.     

Studies on the efficiency of different extraction procedures on the anti microbial activity of selected medicinal plants

Many doubts still persist even today when it comes to selection of the solvents for extracting the active constituents from various Indian medicinal plants. This study was aimed at assessing and establishing the best solvent for extracting the active constituents from 10 plant extracts. Thin layer chromatography (TLC) was used to separate and establish the active constituents present in each of the medicinal plants. Active constituents from each plant were extracted by using three different solvent systems namely diethyl ether, chloroform and hexane and were tested against three species of gram negative and three species of gram positive bacteria (Escherichia coli, Pseudomonas aureginosa, Streptococcus pneumoniae, Aeromonas hydrophila, Staphylococcus aereus, Bacillus cereus) by means of agar well diffusion assay. Studies on the antioxidant activity studies were also carried out for these plant extracts by using Diphenylpicryl-hydrazyl (DPPH) method. For the antimicrobial activity, the study revealed that among the selected plants, Azadiracta indica, Pongamia pinnata, Aloe barbadensis had the maximum antibacterial activity. Among the extraction procedures diethyl ether was found to be the best solvent that could be used for the extraction procedure. On the antioxidant activity part, Coleus amboinicus and Calotropis procera were found to have high antioxidant activity of 91.64% and 88.72% respectively and the further results are reported and discussed.     

Antifungal activity of six Saudi medicinal plant extracts against five phyopathogenic fungi

Six medicinal plants such as Amaranthus spinosus, Barbeya oleoides, Clutia lanceolata, Lavandula pubescens, Maerua oblongifolia and Withania somnifera collected from different locations in the southwestern part of Saudi Arabia were tested for antifungal activities against five plant pathogenic fungi causing serious diseases of vegetable crops. These fungi were Alternaria brassicae, Alternaria solani, Botrytis fabae, Fusarium solani and Phytophthora infestans. Aqueous plant extracts reduced mycelial growth and inhibited spore germination of all fungi tested. It is clear that the aqueous extract of Lavandula pubescens leaves was the best for controlling all phytopathogenic fungi under study. These results suggested that medicinal plant extracts play an important role in controlling the phytopathogenic fungi.     

Xanthan is not essential for pathogenicity in citrus canker but contributes to<Emphasis Type="Italic"> Xanthomonas</Emphasis> epiphytic survival

Xanthan-deficient mutants of Xanthomonas axonopodis pv. citri, the bacterium responsible for citrus canker, were generated by deletion and marker exchange of the region encoding the carboxy-terminal end of the first glycosyltransferase, GumD. Mutants of gumD did not produce xanthan and remained pathogenic in citrus plants to the same extent as wild-type bacteria. The kinetics of appearance of initial symptoms, areas of plant material affected, and growth of bacteria inside plant tissue throughout the disease process were similar for both wild-type and mutant inoculations. Moreover, exopolysaccharide deficiency did not impair the ability of the bacteria to induce hypersensitive response on non-host plants. Apart from variations in phenotypic aspects, no differences in growth or survival under different stress conditions were observed between the xanthan-deficient mutant and wild-type bacteria. However, gumD mutants displayed impaired survival under oxidative stress during stationary phase as well as impaired epiphytic survival on citrus leaves. Our results suggest that xanthan does not play an essential role in citrus canker at the initial stages of infection or in the incompatible interactions between X. axonopodis pv. citri and non-host plants, but facilitates the maintenance of bacteria on the host plant, possibly improving the efficiency of colonization of distant tissue.     

Antifungal activity of some plant extracts on some pathogenic fungi

The inhibitory activity of five plant extracts viz. Artemisia absinthium L., Rumex obtusifolius L., Taraxacum officinale Weber ex Wiggers, Plantago lanceolata L. and Malva sylvestris L. were evaluated against the mycelial growth of three fungi Alternaria alternata (Fr.) Keissler, Penicillium expansum Link ex Thom. and Mucor piriformis Fisher that cause rot diseases in fruits and vegetables resulting in low yield and quality of fruits and vegetables. Results revealed that all the concentrations of plant extracts brought about significant inhibition in the mycelial growth of these pathogenic fungi. However, the highest concentration caused maximum inhibition in the mycelial growth followed by lower concentrations of plant extracts. The extract of A. absinthium leaves at highest concentration (S) proved highly effective in inhibiting the mycelial growth of all these pathogenic fungi followed by other plant extracts. These plants thus may have potential as the new natural fungicide for management of fungal rot diseases.