scholarly journals Screening the antifungal properties of essential oils against Phytophthora colocasiae

Author(s):  
Muhammad Talib Kalhoro ◽  
Hong Zhang ◽  
Ghulam Mujtaba Kalhoro ◽  
Yahya Faqir ◽  
Fukai Wang ◽  
...  

Abstract Recently Microbicidal and micro-static activities of naturally obtained botanicals have been extensively explored, generally in response to the devastating apprehension of consumers towards the safety of edible products. However, scientists are paying more interest in using bio pesticides and phytochemicals that constitute environmentally favorable, non-toxic, long-lasting, and productive substitutes for preventing many hazardous plant pathogens. This research aimed to investigate the antifungal capabilities of sage and tea tree essential oils towards taro leaf blight, the most important cause of worldwide production losses. Using synthetic fungicides is a rapid and effective approach for controlling plant diseases, but it also creates human health risks, environmental threats, and chances of pathogen resistance. The essential oils of sage and tea tree were obtained by microwave-assisted hydro-distillation, and their chemical components were analyzed using FTIR spectroscopy. The main components of the oil were Thujone and Terpinen-4-ol, in sage and tea, respectively. A casual disease agent isolated from symptomatic taro leaves is used as a test fungus and identified as Phytophthora colocasiae. The antifungal properties of both essential oils were evaluated against mycelium, sporangium, zoospores, leaf necrosis, and corm lesions. Repeated experiments showed that the minimum concentrations for obtaining 100% inhibition of mycelium, zoospore germination, sporangia formation, and leaf necrosis were estimated at 2.5 and 5.0 mg/mL of sage and tea tree oils, respectively. Outcomes of this study provide an allusion for the prevention and curation of plant diseases promptly, economically, and environmentally by using phytochemicals and plant essential oil derivatives.

Author(s):  
Zhang Hong ◽  
Kalhoro Muhammad Talib ◽  
Kalhoro Ghulam Mujtaba ◽  
Hou Dabin ◽  
Faqir Yahya ◽  
...  

Abstract Background Taro leaf blight, caused by a severely destructive oomycete fungus Phytophthora colocasiae, is responsible for threatening yield loss worldwide. The pathogen has the ability to germinate and spread rapidly to other plants during favorable conditions resulting in acute decline and even death, causing 100% crop loss. Farmers usually rely on highly toxic systemic fungicides to control the disease, which is effective, but residual effects and resistance of these agrochemicals is still a concern. Recently as returning to nature people tend to use chemical-free products, especially edible stuff produced in organic agriculture. Therefore, the use of bio-pesticides and phytochemicals is gaining special attention by scientists as they are ecofriendly non-hazardous, sustainable, and potent alternatives to control many virulent plant pathogens The present research was conducted to assess the antifungal potential of cinnamon essential oils against P. colocasiae. Materials and methods The essential oils from cinnamon bark were extracted using microwave-assisted hydrodistillation equipment, and then their chemical constituents were evaluated using ATR FTIR spectroscopy. The antifungal potential of essential oil was assessed against mycelium, sporangia, zoospore, leaf necrosis, and corms lesions under laboratory conditions at, 0.156, 0.312, 0.625, 1.25, 2.5, 5.0 mg/mL concentrations. Hymexazol was used as positive control and no essential oil as negative control, while each treatment have three replications and experiment repeated twice. Results The main component of oil was identified as cinnamaldehyde. The pathogen isolated from infected taro leaves was identified as P.colocasiae and then was used as a test fungus in the current study. Repeated experiments show maximum inhibition percentage of mycelial growth, zoospore germination, and sporulation of the fungus were observed at 0.625 mg/mL, whereas leaf necrosis was 100% inhibited at 1.25 mg/mL concentration. Conclusion This research can be a reference for easy, cost-effective and environment-friendly management and control of taro leaf blight with phytochemicals and plant essential oil derivatives. Graphic abstract


Foods ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 365 ◽  
Author(s):  
Robin Raveau ◽  
Joël Fontaine ◽  
Anissa Lounès-Hadj Sahraoui

Naturally produced by aromatic plants, essential oils (EO) contain a wide range of volatile molecules, including mostly secondary metabolites, which possess several biological activities. Essential oils properties such as antioxidant, antimicrobial and anti-inflammatory activities are known for a long time and hence widely used in traditional medicines, cosmetics and food industries. However, despite their effects against many phytopathogenic fungi, oomycetes and bacteria as well as weeds, their use in agriculture remains surprisingly scarce. The purpose of the present review is to gather and discuss up-to-date biological activities of EO against weeds, plant pathogenic fungi, oomycetes and bacteria, reported in the scientific literature. Innovative methods, potentially valuable to improve the efficiency and reliability of EO, have been investigated. In particular, their use towards a more sustainable agriculture has been discussed, aiming at encouraging the use of alternative products to substitute synthetic pesticides to control weeds and plant diseases, without significantly affecting crop yields. An overview of the market and the recent advances on the regulation of these products as well as future challenges to promote their development and wider use in disease management programs is described. Because of several recent reviews on EO insecticidal properties, this topic is not covered in the present review.


Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 69
Author(s):  
Xiaohui Li ◽  
Hejing Zhao ◽  
Xiaolin Chen

Plant diseases have been threatening food production. Controlling plant pathogens has become an important strategy to ensure food security. Although chemical control is an effective disease control strategy, its application is limited by many problems, such as environmental impact and pathogen resistance. In order to overcome these problems, it is necessary to develop more chemical reagents with new functional mechanisms. Due to their special living environment, marine organisms have produced a variety of bioactive compounds with novel structures, which have the potential to develop new fungicides. In the past two decades, screening marine bioactive compounds to inhibit plant pathogens has been a hot topic. In this review, we summarize the screening methods of marine active substances from plant pathogens, the identification of marine active substances from different sources, and the structure and antibacterial mechanism of marine active natural products. Finally, the application prospect of marine bioactive substances in plant disease control was prospected.


2020 ◽  
Vol 5 (1) ◽  
pp. 404-440 ◽  
Author(s):  
Mehrdad Alizadeh ◽  
Yalda Vasebi ◽  
Naser Safaie

AbstractThe purpose of this article was to give a comprehensive review of the published research works on biological control of different fungal, bacterial, and nematode plant diseases in Iran from 1992 to 2018. Plant pathogens cause economical loss in many agricultural products in Iran. In an attempt to prevent these serious losses, chemical control measures have usually been applied to reduce diseases in farms, gardens, and greenhouses. In recent decades, using the biological control against plant diseases has been considered as a beneficial and alternative method to chemical control due to its potential in integrated plant disease management as well as the increasing yield in an eco-friendly manner. Based on the reported studies, various species of Trichoderma, Pseudomonas, and Bacillus were the most common biocontrol agents with the ability to control the wide range of plant pathogens in Iran from lab to the greenhouse and field conditions.


Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 114
Author(s):  
Armina Morkeliūnė ◽  
Neringa Rasiukevičiūtė ◽  
Lina Šernaitė ◽  
Alma Valiuškaitė

The Colletotrichum spp. is a significant strawberry pathogen causing yield losses of up to 50%. The most common method to control plant diseases is through the use of chemical fungicides. The findings of plants antimicrobial activities, low toxicity, and biodegradability of essential oils (EO), make them suitable for biological protection against fungal pathogens. The aim is to evaluate the inhibition of Colletotrichum acutatum by thyme, sage, and peppermint EO in vitro on detached strawberry leaves and determine EO chemical composition. Our results revealed that the dominant compound of thyme was thymol 41.35%, peppermint: menthone 44.56%, sage: α,β-thujone 34.45%, and camphor: 20.46%. Thyme EO inhibited C. acutatum completely above 200 μL L−1 concentration in vitro. Peppermint and sage EO reduced mycelial growth of C. acutatum. In addition, in vitro, results are promising for biological control. The detached strawberry leaves experiments showed that disease reduction 4 days after inoculation was 15.8% at 1000 μL L−1 of peppermint EO and 5.3% at 800 μL L−1 of thyme compared with control. Our findings could potentially help to manage C. acutatum; however, the detached strawberry leaves assay showed that EO efficacy was relatively low on tested concentrations and should be increased.


Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 786
Author(s):  
Hamza Ouakouak ◽  
Adel Benarfa ◽  
Mohammed Messaoudi ◽  
Samir Begaa ◽  
Barbara Sawicka ◽  
...  

This study describes the chemical composition, antitumor, antioxidant, and antimicrobial activities of the plant Thymus algeriensis Boiss. Essential oils (EOs) were collected in different periods (before, during, and after flowering stage) from the El-Guetfa region, M’sila, Algeria. The EOs extraction was achieved using three distinguishing techniques: hydro (Clevenger trap), steam, and microwave distillations, targeting different aerial parts of the plant (stems, flowers, and leaves). The EOs chemical components were estimated using GC-FID and GC-MS apparatuses. The resulting yield of the extracted oil was moderate and ranged between 0.84 and 1.53% (wt/vol). In total, eighty-five components were identified, in which the oxygenated monoterpenes family formed the main portion, starting from 40.56 up to 70.66%. The obtained essential oil was dominated by five major components that varied from low to quite moderate percentages: camphor (17.45–32.56%), borneol (11.16–22.2%), camphene (7.53–12.86%), 1.8-cineole (5.16–11.21%), and bornyl acetate (3.86–7.92%). The biological results of this oil pointed out that the EOs extracted from the leaves part exposed a weak radical scavenging activity afterward using two well-known antioxidant assays DPPH (IC50 = 8.37 mg/mL) and ABTS (10.84 mg/mL). Meanwhile, this oil presented strong inhibition activity against colon cancer cell line HCT116 (LC50 = 39.8 µg/mL) and a moderate inhibitory against hepatocellular cancer cells HePG2 (LC50 > 100 µg/mL). In addition, this oil antimicrobial activity was quite important against Micrococcus luteus (M. luteus), Staphylococcus aureus CIP 7625, Escherichia coli ATCC 10536, Saccharomyces cerevisiae ATCC 4226, Candida albicans IPA200, Candida tropicalis (Ct), and Candida glabrata (Cg) after using Amoxicillin and Itraconazole as references.


Author(s):  
Xinli Liang ◽  
Xinli Wang ◽  
Guowei Zhao ◽  
Xiaoying Huang ◽  
Xiqiang Xu ◽  
...  

: Depression is a mood disorder or affective disorder disease with depression as the main symptom. It has become a kind of mental disease that cannot be ignored in the world that seriously endangers human physical and mental health. Antidepressants commonly used in clinics generally have some defects including slow action, unremarkable effects and large side-effects. Therefore, there has a huge developing space for the research of new and effective therapeutic drugs to supplement or replace traditional drugs. Essential oil has obvious advantages in the treatment of depression and other emotional diseases, its aromatic odor can directly stimulate the olfactory nerves, and the lipophilic small- molecular compounds can cross the blood-brain barrier easily, to play its regulatory role of releasing of neurotransmitters and hormones related to depression, or adjusting the expression of brain-derived neurotrophic factor and proinflammatory cytokines. The pathogenesis of depression and the problems in traditional medication was illustrated, the research on the antidepressant effects and mechanism of essential oils in recent years was summarized and the antidepressant chemical components in plant essential oils were reviewed in this article. It could provide scientific basis for essential oil to be a new choice for relieving depression and treating depression.


2015 ◽  
Vol 78 (1) ◽  
Author(s):  
Nur Athirah Hashim ◽  
Farediah Ahmad ◽  
Deny Susanti

The study was aimed to investigate the chemical components of stem and fruit volatile oils of Piper. maingayi Hk. with their antioxidant and antityrosinase activities. GC and GC-MS analysis of the essential oils obtained from the fresh stem and fruit of P. maingayi Hk. resulted in the identification of 34 and 18 components accounting for 83.6% and 78.7% of the total amount, respectively. Sesquiterpene hydrocarbons and oxygenated sesquiterpenes were the most highly represented classes as the former ranging from 64.7% to 70.7%, and the latter varying from 7.4% to 8.6%. The main constituents of the stem oil were: β-caryophyllene (26.2%), a-cedrene (8.4%), caryophyllene oxide (6.7%) and cis-calamenene (6.2%), while the fruit oil was dominated by δ-cadinene (22.6%), β-caryophyllene (18.8%), a-copaene (11.2%) and a-cadinol (7.1%). The stem and fruit of P. maingayi oils showed significant value for antioxidant and antityrosinase activities. 


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