Many
species are pathogenic, causing crop diseases during crop production and spoilage of agricultural products in both commercial and smallholder farming.
attack often results into food ...contamination, yield loss and increases in food insecurity and food prices. Synthetic fungicides have been used as a control strategy for the management of crop diseases caused by
pathogens. The negative effects associated with application of many synthetic pesticides has necessitated the need to search for alternative control strategies that are affordable and environmentally safe. Research on medicinal plants as control agents for
pathogens has received attention since plants are readily available and they contain wide variety of secondary metabolites that are biodegradable. The activities of solvent extracts, essential oils and compounds from medicinal plants have been tested against
phytopathogenic species. A summary of recent information on antifungal activity of plants against
species is valuable for the development of biopesticides. This paper reviews the antifungal research conducted on medicinal plants against
pathogens, over a 10-year period, from January 2012 to May 2021. We also highlight the challenges and opportunities of using natural products from medicinal plants in crop protection. Several databases (Science Direct and Web of Science) were used to obtain information on botanical products used to control
diseases on crops. Keywords search used included natural products, antifungal,
, crops diseases, phytopathogenic, natural compounds and essential oil.
In search for the cause leading to low reaction yields, each step along the reaction energy profile computed for the assumed oxidative nucleophilic substitution of hydrogen (ONSH) reaction between ...2-phenylquinoxaline and lithium phenylacetylide was modelled computationally. Intermolecular and intramolecular interaction energies and their changes between consecutive steps of ONSH were quantified for molecular fragments playing leading roles in driving the reaction to completion. This revealed that the two reactants have a strong affinity for each other, driven by the strong attractive interactions between Li and two N-atoms, leading to four possible reaction pathways (RP-C2, RP-C3, RP-C5, and RP-C10). Four comparable in energy and stabilizing molecular system adducts were formed, each well prepared for the subsequent formation of a C-C bond at either one of the four identified sites. However, as the reaction proceeded through the TS to form the intermediates (
-
), very high energy barriers were observed for RP-C5 and RP-C10. The data obtained at the nucleophilic addition stage indicated that RP-C3 was both kinetically and thermodynamically favored over RP-C2. However, the energy barriers observed at this stage were very comparable for both RPs, indicating that they both can progress to form intermediates
and
. Interestingly, the phenyl substituent (Ph1) on the quinoxaline guided the nucleophile towards both RP-C2 and RP-C3, indicating that the preferred RP cannot be attributed to the steric hindrance caused by Ph1. Upon the introduction of H
O to the system, both RPs were nearly spontaneous towards their respective hydrolysis products (
and
), although only
can proceed to the final oxidation stage of the ONSH reaction mechanism. The results suggest that RP-C2 competes with RP-C3, which may lead to a possible mixture of their respective products. Furthermore, an alternative, viable, and irreversible reaction path was discovered for the RP-C2 that might lead to substantial waste. Finally, the modified experimental protocol is suggested to increase the yield of the desired product.
Crop diseases caused by Fusarium pathogens, among other microorganisms, threaten crop production in both commercial and smallholder farming. There are increasing concerns about the use of ...conventional synthetic fungicides due to fungal resistance and the associated negative effects of these chemicals on human health, livestock and the environment. This leads to the search for alternative fungicides from nature, especially from plants. The objectives of this study were to characterize isolated compounds from Combretum erythrophyllum (Burch.) Sond. and Withania somnifera (L.) Dunal leaf extracts, evaluate their antifungal activity against Fusarium pathogens, their phytotoxicity on maize seed germination and their cytotoxicity effect on Raw 264.7 macrophage cells. The investigation led to the isolation of antifungal compounds characterized as 5-hydroxy-7,4′-dimethoxyflavone, maslinic acid (21-hydroxy-3-oxo-olean-12-en-28-oic acid) and withaferin A (4β,27-dihydroxy-1-oxo-5β,6β-epoxywitha-2-24-dienolide). The structural elucidation of the isolated compounds was established using nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy (MS) and, in comparison, with the available published data. These compounds showed good antifungal activity with minimum inhibitory concentrations (MIC) less than 1.0 mg/mL against one or more of the tested Fusarium pathogens (F. oxysporum, F. verticilloides, F. subglutinans, F. proliferatum, F. solani, F. graminearum, F. chlamydosporum and F. semitectum). The findings from this study indicate that medicinal plants are a good source of natural antifungals. Furthermore, the isolated antifungal compounds did not show any phytotoxic effects on maize seed germination. The toxicity of the compounds A (5-hydroxy-7,4′-dimethoxyflavone) and AI (4β,27-dihydroxy-1-oxo-5β,6β-epoxywitha-2-24-dienolide) was dose-dependent, while compound B (21-hydroxy-3-oxo-olean-12-en-28-oic acid) showed no toxicity effect against Raw 264.7 macrophage cells.
Despite major advancements in the development of various chemotherapeutic agents, treatment for lung cancer remains costly, ineffective, toxic to normal non-cancerous cells, and still hampered by a ...high level of remissions. A novel cohort of quinoxaline derivatives designed to possess a wide spectrum of biological activities was synthesized with promising targeted and selective anticancer drug activity. Hence, this study was aimed at determining in vitro anticancer activity effects of a newly synthesized class of 3-(quinoxaline-3-yl) prop-2-ynyl quinoxaline derivatives on A549 lung cancer cells. An assessment of the quinoxaline derivatives ferric reducing power, free radical scavenging activity, cytotoxic activity, and ability to induce reactive oxygen species (ROS) production was performed using the Ferric Reducing Antioxidant Power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH), 3-4,5-dimethylthiazole-2-yl-2,5-diphenyltetrazolium bromide (MTT) and 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA) assays, respectively. The ability of the quinoxaline derivatives to induce apoptosis in A549 cells was assessed using the Acridine Orange/Ethidium Bromide (AO/EB) and Annexin V-FITC/Dead Cell Assay. Of the four quinoxaline derivatives tested, 3-(quinoxaline-3-yl) prop-2-ynyl methanosulphate (LA-39B) and 3-(quinoxaline-3-yl) prop-2-yn-1-ol (LA-55) displayed a dose-dependent reducing power, free-radical scavenging activity, inhibition of cell viability, and stimulation of ROS production which was accompanied by induction of apoptosis in A549 lung cancer cells. None of the quinoxaline derivatives induced cell death or ROS production in non-cancerous Raw 267.4 macrophage cells. Cytotoxicity was observed in A549 lung cancer, HeLa cervical cancer, and MCF-7 breast cancer cells albeit inhibition was more pronounced in A549 cells. The results of the study suggest that 3-(quinoxaline-3-yl) prop-2-ynyl methanosulphate and 3-(quinoxaline-3-yl) prop-2-yn-1-ol induce apoptotic cell death in A549 lung cancer cells.
An investigation on the effect of substituent at the 2-position of mono-substituted quinoxalines in the synthesis of di-substituted quinoxaline derivatives via nucleophilic substitution reactions, is ...reported. Di-substituted quinoxalines bearing aryl-alky, aryl-aryl, aryl-heteroaryl, aryl-alkynyl, and amino-alkyl substituents were prepared in moderate to good yields. 2-Monosubstituted quinoxalines bearing a phenyl and butyl substituent reacted readily with alkyl-, aryl-, heteroaryl- and alkynyl- nucluephiles, giving di-substituted quinoxalines. 2-Monosubstituted quinoxalines bearing an amine and alkynyl substituent only reacted with alkyl nucleophiles. Oxidative rearomatization to give 2,3-disubstituted quinoxaline products occurred in atmospheric O₂.
Society urgently needs new, effective medicines for the treatment of tuberculosis. To kick-start the required hit-to-lead campaigns, the libraries of pharmaceutical companies have recently been ...evaluated for starting points. The GlaxoSmithKline (GSK) library yielded many high-quality hits, and the associated data were placed in the public domain to stimulate engagement by the wider community. One such series, the spiro compounds, are described here. The compounds were explored by a combination of traditional in-house research and open source methods. The series benefits from a particularly simple structure and a short associated synthetic chemistry route. Many members of the series displayed striking potency and low toxicity, and highly promising in vivo activity in a mouse model was confirmed with one of the analogues. Ultimately the series was discontinued due to concerns over safety, but the associated data remain public domain, empowering others to resume the series if the perceived deficiencies can be overcome.
Phytopathogenic Fusarium species are restricting factors causing diseases and yield loss in crop production. As part of exploration for pesticides from medicinal plants, this study aimed to isolate ...and characterize bioactive compounds from Lantana camara L. and evaluate their efficiency against Fusarium phytopathogens. Phytochemical investigation of ethyl acetate leaf extract led to separation of lantadene A (22-angeloyloxy-9-hydroxy-3-oxo-olean-12-en-28-oic acid) and boswellic acid (11-keto-β-boswellic acid). The chemical structures of the aforementioned compounds were confirmed using physical properties, spectroscopic analysis, and published data. Lantadene A exhibited significant antifungal activity against F. subglutinans, F. proliferatum, F. solani, F. graminearum, and F. semitectum with minimum inhibitory concentration (MIC) less than or equal to 0.63 mg/mL. Boswellic acid exhibited strong activity (MIC = 0.63 mg/mL) against F. subglutinans and F. semitectum. In terms of their toxicity towards Raw 264.7 cells, lantadene A and boswellic acid recorded half-maximal inhibitory concentration values of 84.2 μg/mL and 186.6 μg/mL, respectively. Both lantadene A and boswellic acid had no phytotoxic effect against seed germination and seedling root length. Lantadene A and boswellic acid have strong potential to be further investigated as lead natural fungicides (biopesticides) to control Fusarium crop diseases.
Antifungal activity; Antimicrobial; Boswellic acid; Biopesticide; Fusarium species; Natural fungicide; Phytotoxic.
Indole-containing compounds are widely distributed in the plant and animal kingdom, and their biological activity and pharmacological properties have prompted research into their chemical properties. ...This study developed a one-pot methodology for the synthesis of 3-aminoindole derivatives using copper- and ligand-free Sonogashira cross-coupling reaction conditions. The synthesised 3-aminoindole derivatives were confirmed using spectroscopic techniques. The resulting 3-aminoindole derivatives were biologically evaluated against Mycobacterium tuberculosis and Plasmodium falciparum. For example, indole derivatives 10a (7.813 µM) and 10j (8.332 µM) were the most active derivatives in the CAS and ADC media, respectively.
Cordyceps cicadae (Mig.) Massee is one of the oldest and well-known traditional Chinese medicine (TCM), with its uses recorded as far back as the 5th century A.D. For centuries, C. cicadae has been ...used as food, tonic and folk medicine to treat malaria, palpitations, cancer, fever, diabetes, eye diseases, dizziness, and chronic kidney diseases. Although C. cicadae has been used as TCM for over 1600 years, it is not the most popular amongst the Cordyceps family. Cordyceps Sinensis (C. sinensis) and Cordyceps militaris (C. militaris) are the most studied and widely used, with a number of commercially available products derived from these two Cordyceps species.
This review seeks to look at the research that has been conducted on C. cicadae over the past 30 years, reporting on the biological activities, development and utilization. This information was compared to that focused on C. sinensis and C. militaris.
A literature search was conducted on different scientific search engines including, but not limited to “Web of Science”, “ScienceDirect” and “Google Scholar” to identify published data on C. cicadae, I. cicadae, P. cicadae, C. sinensis and C. militaris.
Research conducted on C. cicadae over the past two decades have shown that it poses similar biological properties and chemical composition as C. sinensis and C. militaris. C. cicadae has been reported to grow in many geographic locations, as compared to C. sinensis, and can be artificially cultivated via different methods.
There exists sufficient evidence that C. cicadae has medicinal benefits and contain bioactive compounds similar to those found on C. sinensis and C. militaris. However, more research and standardization methods are still needed to directly compare C. cicadae with C. sinensis and C. militaris, in order to ascertain the suitability of C. cicadae as an alternative source of Cordyceps products.
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Smallholder farmers play a major role in crop production towards household food security, particularly in resource-poor communities. Maize is a common crop produced in smallholder farming and it is ...cultivated from seeds that has been stored and re-used for years. Spoilage of stored grains is a major challenge, which leads to yield loss and poor seed quality. The objectives of this study were to evaluate in vivo antifungal activity of selected plant extracts against
pathogens on maize seeds, and to evaluate their phytotoxicity on seed germination and seedling growth. Fresh leaves collected from eight medicinal plants were dried and selectively extracted with water, ethyl acetate or acetone. The dried extracts were evaluated for antifungal activity against
pathogens (
,
,
,
,
,
,
,
and
) inoculated on maize seeds.
acetone extract showed strong antifungal activity (97% inhibition) against
while combined acetone extracts from
and
exhibited 96%, 67% and 56% inhibition against
,
and
, respectively. With the exception of
ethyl acetate, none of the extracts significantly inhibited seed germination when compared to untreated seeds. This study showed that plant extracts could control
diseases without any adverse effects on maize seed germination or plant growth.
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