Antibacterial activity of herbal extracts against five plant pathogenic bacteria

The present study was designed to evaluate in vitro antibacterial activity of herbal extracts against five plant pathogenic bacteria (viz. Xanthomonas campestris, Xanthomonas axonopodis pv. punicae, Erwinia spp., Pseudomonas syringae and Xanthomonas citri). Herbal extracts of leaves and rinds of Garcinia indica, rhizomes of Curcuma aromatica, roots of Glyccyrrhiza glabra, leaves of Nyctanthes arbor-tristis and seeds of Vernonia anthelmintica were used for screening. Screening was done using agar well diffusion method. Relatively potent extracts were shortlisted from this study and were further studied to find out their minimum bactericidal concentration (MBC). From the studies, it was observed that extracts of C. aromatica, G. indica and G. glabra have shown lowest MBC values among other tested plant extracts. This study indicates the potential of these potent plant extracts in the management of diseases caused by plant pathogenic bacteria.     

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.     

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.     

Antimicrobial activities of extracts of Cyperus rotundus L. rhizomes against some bacterial and fungal pathogens of strawberry and tomato

Antimicrobial activities of rhizome extracts of Cyperus rotundus were investigated on selected plant pathogenic bacteria and fungi. Ethyl acetate and hexane extracts showed antibacterial activity against three isolates of Clavibacter michiganensis subsp. michiganensis at concentrations of 900 and 1000 μg/ml. However, Gram-negative bacterial pathogens of tomato; Pseudomonas syringae pv. tomato and Ralstonia solanacearum were not inhibited from the extracts. Ethyl acetate extracts at 100 μg/ml inhibited mycelial growth and spore germination of the two strawberry isolates of Botrytis cinerea; however, no significant inhibition was found in tomato fungal pathogen, Fusarium oxysporum f. sp. radicis lycopersici. Minimum inhibitory concentrations were determined as 0.0625 and 0.125 mg/ml against C. michiganensis subsp. michiganensis for ethyl acetate and hexane extracts of rhizomes, respectively. This study shows the potentials of extracts of C. rotundus rhizomes as antimicrobial agents that are effective against the tested plant pathogenic bacteria and fungi.     

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.     

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.     

小桐子枝叶提取物对植物病原真菌的生物活性

采用菌丝生长抑制法,测定了小桐子枝叶6种不同溶剂提取物对小麦赤霉病菌、稻瘟病菌、烟草疫霉菌和辣椒疫霉菌的抑制作用,从中筛选出抑制作用最强的粗提物进行进一步的活性组分分离和抑菌活性测定。结果表明小桐子枝叶的乙醇提取物对4种植物病原菌抑制活性最高,在浓度为0.8 g·L^-1时,小桐子枝叶的乙醇提取物对小麦赤霉病菌、稻瘟病菌、烟草疫霉菌、辣椒疫霉菌菌丝生长抑制率分别为：87.1%、90.3%、86.4%、77.9%,其抗菌活性与农药世高均无显著差异;在小桐子枝叶乙醇提取物的不同溶剂萃取物对稻瘟病菌和烟草疫霉病菌进行生物活性追踪测试中发现,石油醚和水萃取物都具有较好的活性,当浓度为0.8 g·L^-1时,石油醚和水萃取物对两种病菌抑制率都达50%以上。表明小桐子枝叶含有丰富的抗植物病原真菌活性物质,且主要存在于小桐子枝叶乙醇提取物的石油醚相和水相中。     

In vitro kinetics and antifungal activity of various extracts of Terminalia chebula seeds against plant pathogenic fungi

The aim of the present study was to examine the efficacy of various seed extracts of Terminalia chebula as an antifungal potential against certain important plant pathogenic fungi. The organic extracts of methanol, ethyl acetate and chloroform at the used concentration of 1500 ppm/disc revealed remarkable antifungal effect as a fungal mycelial growth inhibitor against Fusarium oxysporum, Fusarium solani, Phytophthora capsici and Botrytis cinerea, in the range of 41.6–61.3%, along with MIC values ranging from 62.5 to 500 μg/ml. Also, the extracts had a strong detrimental effect on spore germination of all the tested plant pathogens along with concentration as well as time-dependent kinetic inhibition of B. cinerea. The results obtained from this study suggest that the natural products derived from Terminalia chebula could become an alternative to synthetic fungicides for controlling such important plant pathogenic fungi.     

1‐Phenyl‐3‐pentanone,a Volatile Compound from the Edible Mushroom Mycoleptodonoides aitchisonii Active Against Some Phytopathogenic Fungi

Volatiles produced by mycelia of mushrooms with aromatic odour were investigated for their antifungal activity against plant‐pathogenic fungi. The results of the screening of 23 species of basidiomycetes revealed that volatile substances from mycelia of Mycoleptodonoides aitchisonii (TUFC10099), an edible mushroom, strongly inhibited the mycelial growth, spore germination and lesion formation on host leaves of some plant‐pathogenic fungi including Alternaria alternata, A. brassicicola, A. brassicae, Colletotrichum orbiculare and Corynespora cassiicola. The volatile compounds were isolated from the culture filtrate of M. aitchisonii, and 1‐phenyl‐3‐pentanone was identified as a major antifungal volatile. The compound had significantly inhibitory activity against plant‐pathogenic fungi at 35 ppm. This is the first report that the volatile compound produced by mycelia of M. aitchisonii has antifungal activity against plant‐pathogenic fungi.     

Investigation of HIV-1 Viral Protein R Inhibitory Activities of Twelve Thai Medicinal Plants and Their Commercially Available Major Constituents

Viral protein R (Vpr) is an accessory protein in Human immunodeficiency virus-1 (HIV-1) and has been suggested as an attractive target for HIV disease treatment. Investigations of the ethanolic extracts of twelve Thai herbs revealed that the extracts of the Punica granatum fruits, the Centella asiatica aerials, the Citrus hystrix fruit peels, the Caesalpinia sappan heartwoods, the Piper betel leaves, the Alpinia galangal rhizomes, the Senna tora seeds, the Zingiber cassumunar rhizomes, the Rhinacanthus nasutus leaves, and the Plumbago indica roots exhibited the anti-Vpr activity in HeLa cells harboring the TREx plasmid encoding full-length Vpr (TREx-HeLa-Vpr cells). Moreover, the investigation of the selected main constituents in Punica granatum, Centella asiatica, A. galangal, and Caesalpinia sappan indicated that punicalagin, asiaticoside, ellagic acid, madecassic acid, madecassoside, zingerone, brazilin, and asiatic acid possessed anti-Vpr activities at the 10 μM concentration. Among the tested extracts and compounds, the extracts from Centella asiatica and Citrus hystrix and the compounds, punicalagin and asiaticoside, showed the most potent anti-Vpr activities without any cytotoxicity, respectively.     

Antifungal activity of phytochemicals from Eucalyptus hybrid leaves against some plant pathogenic and wood decay fungi

The in vitro fungitoxicity of the essential oil (EO), crude extracts, dried fractions and ursolic acid (UA) isolated from the abundantly available and underutilised leaves of Eucalyptus hybrid (Eucalyptus camaldulensis × Eucalyptus tereticornis) was assessed against three plant pathogenic fungi Aspergillus niger, Fusarium solani and Ganoderma lucidum causing pathogenesis in seeds, seedlings and trees, respectively, and Trametes versicolor and Pycnoporous sanguineus making wood to decay. The EO, methanol extract and UA demonstrated varied antifungal activity against all the fungi with minimum inhibitory concentrations ranging from 0.5 to 3.0%. The results of the study demonstrate a new chemical utilisation approach of the leaves of Eucalyptus hybrid towards the development of biofungicides in the management of above fungi of common occurrence in Indian forestry.     

The Endophytic Mycoflora of Bark,Leaf, and Stem Tissues of <Emphasis Type="Italic">Azadirachta indica</Emphasis> A. Juss (Neem) from Varanasi (India)

A systematic study was made of the endophytes of Azadirachta indica A. Juss (the neem tree) growing in several of its natural habitats in India. A total of 233 isolates of endophytic fungi representing 18 fungal taxa were obtained from segments of bark, stem, and leaves of this tree. Hyphomycetes (62.2%) were the most prevalent followed by the Coelomycetes (27.4%) and Mycelia Sterilia (7.7%). As mathematically determined, the maximum species richness and frequency of colonization of endophytes appeared in leaf segments rather than stem and bark tissues from each location. Endophytic colonization frequency was also greater in leaves (45.5%) than bark (31.5%). The leaf samples from all locations were nearly constant in their endophytic composition, whereas bark samples showed maximum diversity at different locations. Inter-site comparisons for endophytic diversity, however, were not significantly different with Loc1 and Loc2 having a maximum of 66.67% J _c. The smallest similarity was between Loc2 and Loc3 of 54.17% J _c. The dominant endophytic fungi isolated were Phomopsis oblonga, Cladosporium cladosporioides, Pestalotiopsis sp., Trichoderma sp, and Aspergillus sp. Genera such as Periconia, Stenella, and Drechslera are reported here for the first time as endophytes from this host plant. This report illustrates the value of sampling different tissues of a given plant in several locations to obtain the greatest species diversity of endophytes. The rich and sizeable collection of endophytic fungi from this specific plant may represent a unique source of one or more of the interesting and useful bioactive compounds normally associated with A. indica such as the azadirachtins and related tetranortriterpenoids.     

AM Fungi and <i>Piriformospora indica</i> Improve Plant Growth of <i>Pinus elliottii</i> Seedlings

Pinus elliottii is an exotic afforestation pine extensively distributed in southern parts of China. In order to understand whether endophytic fungi can affect seedling growth of P. elliottii, Piriformospora indica (Pi), Funnelifcrmis mosseae (Fm), and Diversispora tortuosa (Dt) were inoculated respectively, and the non-inoculated group was set as control. The growth indexes, the contents of soluble sugar and soluble protein, and plant endogenous hormone levels in the leaves of P. elliottii, were analyzed. The results showed that Fm, Dt and Pi colonized the P. elliottii roots to form mycorrhizal structure and chlamydospores arranged in beads respectively. Three fungal inoculants exhibited the stimulated growth responses, whilst Dt illustrated the most positive effect on plant height, single fresh weight, trunk diameter and root system structure, compared with the control. On the other hand, the soluble sugar and soluble protein contents were increased distinctively in mycorrhizal plants. The endogenous IAA, GA3, ZR contents were increased, while the ABA contents were reduced in mycorrhizal plants versus non-mycorrhizal plants. The fungi-induced endogenous hormone changes triggered plant growth improvement of P. elliottii seedlings. This research unraveled the positive effect of AM fungi and P. indica on growth of pine seedlings, while, more application of endophytic fungi to fields needs to be explored.     

Molecular characterization of fungal endophytes from Calotropis procera plants in Taif region (Saudi Arabia) and their antifungal activities

Fungal endophytes were isolated from the leaves of Calotropis procera (Apocynaceae) collected from Taif region (Saudi Arabia). Thirty-three different taxa were recovered. The overall foliar colonization rate was 35.1%. A total of 161 isolates were obtained and identified into 33 distinct operational taxonomic units based on the sequencing of the internal transcribed spacer regions of the rRNA gene. The most prevalent fungi were Aspergillus flavus, Chaetomium globosum, Cochliobolus lunatus, Fusarium dimerum, F. oxysporum, and Penicillium chrysogenum. A total of 161 isolates were tested for antifungal activities against four plant pathogenic fungi (Alternaria alternata, Fusarium oxysporum, Botrytis cinerea, and Pythium ultimum), of which 33 isolates showed antifungal activity against at least one plant pathogenic fungi. Four isolates of Chaetomium globosum and three isolates of Myrothecium verrucaria showed the strongest antifungal activity. This study reported the occurrence of a much wider spectrum of fungi, when compared with previous work. Also, it confirmed the variation of different isolates from the same species in terms of antifungal activity.     

Endophytic Actinomycetes from <Emphasis Type="Italic">Azadirachta indica</Emphasis> A. Juss.: Isolation,Diversity, and Anti-microbial Activity

Endophytic actinomycetes from Azadirachta indica A. Juss. were screened and evaluated for their anti-microbial activity against an array of pathogenic fungi and bacteria. A total of 55 separate isolates were obtained from 20 plants, and 60% of these showed inhibitory activity against one or more pathogenic fungi and bacteria. Actinomycetes were most commonly recovered from roots (54.5% of all isolates), followed by stems (23.6%), and leaves (21.8%). The dominant genus was Streptomyces (49.09% of all isolates), while Streptosporangium (14.5%), Microbispora (10.9%), Streptoverticillium (5.5%), Sacchromonospora sp. (5.5%), and Nocardia (3.6%) were also recovered. Streptomyces isolates AzR 006, 011, and 031 (all from roots) had acute activity against Pseudomonas fluorescens, while AzR027, 032, and 051 (also all from roots) showed activity against Escherichia coli. Meanwhile, an isolate of Nocardia sp. from leaves (AzL025) showed antagonism against Bacillus subtilis. Overall, 32 of the 55 were found to have broad spectrum significant antimicrobial activity, while about 4% of them showed strong and acute inhibition to pathogenic fungi and bacteria. Isolates of Streptomyces AzR031, 008, and 047, Nocardia sp. AzL025, and Streptosporangium sp. AzR 021 and 048 are of particular interest because they showed significant antagonistic activity against root pathogens, including Pythium and Phytophthora sp. Thus, many of the isolates recovered from A. indica in this study may be used in developing potential bio-control agents against a range of pathogenic fungi and bacteria and in the production of novel natural antimicrobial compounds. These results not only further our understanding of plant–microbe interactions but also indicate that there is an untapped resource of endophytic microorganisms that could be exploited in the biotechnological, medicinal, and agricultural industries.     

Fungitoxic properties of selected South African plant species against plant pathogens of economic importance in agriculture

Thirty‐nine plant species, representing 20 families from the subclasses Rosidae, Asteridae, Commelinidae and Liliidae, were collected from the Blyde River Canyon Nature Reserve, Mpumalanga, South Africa. Crude extracts were prepared and bioassayed, at equal concentrations, for their antifungal potential by determining the inhibitory effects on the mycelial growth of seven economically important plant pathogenic fungi. Statistically significant differences between plants and plant parts were observed as well as the resistance of different fungi to treatment with different plant extracts. The most significant mycelial growth inhibition was obtained with extracts from two species of the subclass Liliidae, namely Aristea ecklonii and Agapanthus inapertus. The crude extract of A. ecklonii performed best of all extracts as it totally inhibited the mycelial growth of all seven of the plant pathogenic test organisms and outperformed the inhibition by a broad spectrum synthetic fungicide (carbendazim/difenoconazole). Crude extracts of A. inapertus showed complete inhibition of four and strong inhibition of the remaining three plant pathogenic fungi. Although not as efficient as the previous two species, the extract of Anisopappus junodii, from the subclass Asteridae, also showed promising antifungal activity by completely inhibiting mycelial radial growth of two and strongly inhibiting that of the remaining five fungi.     

In vitro assessment of fungicidal activity of Ageratum conyzoides and Cybopogon flexuosus weed extracts against some phytopathogenic fungi associated with fruit rot of water melon (Citrullus lunatus (Thunb.))

The ethanolic extracts of Cybopogon flexuosus and Ageratum conyzoides were tested at concentrations of 20, 40, 60, 80, 100 and 120?mg/ml for their in vitro fungicidal activities against five phytopathogenic fungi isolated from diseased watermelon fruits. The pathogens were Fusarium verticillioides, Aspergillus flavus, Botryodiplodia theobromae, Curvularia lunata and Alternaria cucumeria – Amans as confirmed by pathogenicity tests. All isolated pathogenic fungi were significantly (p?≥?0.05) highly pathogenic with the exception of A. cucumeria which had the least significant (p?≥?0.05) pathogenicity. The inhibitory effects of the extracts increased significantly (p?≥?0.05) with increase in concentrations. Some of the concentrations reduced the mycelial growth of the pathogens to a significant (p?≥?0.05) level. Very strong fungicidal activity was produced by extracts of A. conyzoides at 100?mg/ml against all the fungi. The inhibitory effects of C. flexuosus extracts at 20, 40 and 60?mg/ml were greater than those of C. flexuosus on A. flavus, F. verticillioides and A. cucumeria. The results of the investigation indicated that plant extracts possess antifungal activity that can be exploited as an ideal treatment for future plant disease management in the control of rot of water melon.     

In vitro antibacterial activities of methanol and aqueous leave extracts of selected medicinal plants against human pathogenic bacteria

People use medicinal plants as diet, and for treatment of infectious and noninfectious diseases and they use brief procedures like frying and cooking to do so. Medicinal plants; Moringa oleifera, Azadirachta indica, and Lepidium sativum which is believed to have active components that help to treat and manage various diseases were investigated for their antibacterial activities against Staphylococcus aureus, Salmonella Typhi, Streptococcus agalactiae and Shigella boydii. Solvent methanol and aqueous were used for extraction of crudes by means of maceration. Susceptibility testing was determined by using disc diffusion method and Minimum inhibitory concentration was determined by broth dilution method. Heat treated plant material activity against test pathogen was aimed to identify resistance capacity of plant material at different interval of time and temperature. All plant extracts under study was active against all tested pathogen after exposure to 45 °C for 30 min. The antibacterial activities of the non-heat-treated extracts of Azadirachta indica were relatively low; the results of this study show that extracts of Azadirachta indica have better residual antibacterial activities. Methanol extracts of all plant leaves showed highest activity as compared to the aqueous extracts. This is probably assigning the choice of extraction solvent for extracting desired active phytochemical from plants. Many of the people in the study area were illiterate and they did not have awareness about the ways use of medicinal plants. They use the medicinal plants by cooking and frying for different purposes. In the main, plant material can be affected as the temperature of treatment is increases with respect to various times of exposures.     

In vitro biopesticide effect of alkaloids and flavonoids of some plants against Fusarium oxysporum

Alkaloids and flavonoids of three plants, namely Withania somnifera, Euphorbia hirta and Terminalia chebula, were tested for their antifungal potential against plant pathogenic fungi Fusarium oxysporum. The spore counting technique was followed for the antibiotic properties of the extracts tested at three different concentrations (2.5, 5 and 10?mg/ml). Results revealed that the bound flavonoid of root of W. somnifera and free flavonoids of stem bark and fruits of T. chebula totally inhibited spore germination of the fungi (100%). The range of minimum inhibitory concentration and minimum fungicidal concentration of extracts recorded was 0.039–0.625 and 0.039–1.25?mg/ml, respectively. Bound flavonoids of selected plants were more effective than free flavonoids and alkaloids. The study suggests that both alkaloids and flavonoids extracts of selected plants have a potential antifungal properties for the control of diseases of various crops.     

Antimicrobial activity of broccoli (Brassica oleracea var. italica) cultivar Avenger against pathogenic bacteria,phytopathogenic filamentous fungi and yeast

Aims

The objective of this study was to show whether the edible part of broccoli has antibacterial and antifungal activity against micro‐organism of importance in human health and vegetable spoilage, and to test if this effect was partially due to antimicrobial peptides (AMPs).

Methods and Results

Crude extracts were obtained from florets and stems of broccoli cultivar Avenger and the inhibitory effect was demonstrated against pathogenic bacteria (Bacillus cereus, Staphylococcus xylosus, Staphylococcus aureus, Shigella flexneri, Shigella sonnei, Proteus vulgaris), phytopathogenic fungi (Colletotrichum gloeosporioides, Asperigillus niger) and yeasts (Candida albicans and Rhodotorula sp.). It was shown that samples treated with proteolytic enzymes had a reduction of approximately 60% in antibacterial activity against Staph. xylosus, suggesting that proteinaceous compounds might play a role in the inhibitory effect. Antimicrobial components in crude extracts were thermoresistant and the highest activity was observed under acidic conditions. It was shown that antifungal activity of broccoli's crude extracts might not be attributed to chitinases.

Conclusions

Organic broccoli cultivar Avenger has antimicrobial activity against pathogenic bacteria, yeast and phytophatogenic fungi. Data suggest that this effect is partially due to AMPs.

Significance and Impact of the Study

Broccoli's crude extracts have activity not only against pathogenic bacteria but also against phytophatogenic fungi of importance in agriculture. We suggest for first time that the inhibitory effect is probably due to AMPs.