Typescript, etc.

The aim of our study was to determine whether Polyphenon G (PPG, a concentrated Camellia sinensis extract) and the individual compounds in PPG had activity against phytopathogenic fungi in vitro and in vivo. The present study reports on the sensitivity of twenty different phytopathogenic fungal species to extracts from black-, green- and rooibos tea extracts, concentrated green tea extract (Polyphenon G), caffeine, theanine, epigallocatechin gallate (EGCg), epicatechin gallate (ECg), epigallocatechin (EGC), and epicatechin (EC), and Polyphenon G combined with caffeine. The inhibition of fungal growth by the compounds was as follows (in decreasing order): caffeine > EGCg ECg > EGC EC > Polyphenon G > green tea extracts black tea extracts > rooibos tea extracts theanine. In some cases the Polyphenon G and caffeine combination reduced the IC50 values for both the compounds, indicating a synergistic effect. Phytophthora nicotianae and P. capsici were most sensitive to all the compounds, while Rhizopus stolonifer and Penicillium expansum were least sensitive. PPG and caffeine was subsequently tested individually and in combination in a greenhouse trial against seven pathogens on four crops. The combinations of Polyphenon G and caffeine gave the best overall results and effectively controlled Fusarium solani on cucumber, P. capsici and Sclerotium rolfsii on tomato, Sclerotinia sclerotiorum and Pythium F-group on lettuce. PPG individually significantly inhibited the growth of Sphaerotheca fuliginea of zucchini squash plants. In efforts to determine the mode of action of PPG, caffeine and the combination thereof, methods used in our study included determining total phenolic content by means of the Folin-Ciocalteu reagent, thin layer chromatography (TLC) bioautography to identify possible anti-microbial compounds and high performance liquid chromatography (HPLC) for identifying induced compounds based on standards included in the analysis. Results showed that ferulic, salicylic and caffeic acids increased in uninfected lettuce plants treated with a combination of PPG and caffeine. These results indicate that either the phenolic compounds in the treatments were accumulated in the roots or that the treatments induced de novo synthesis in the plants to increase the production of phenolic compounds or that the treatments caused induction of resistance in the plant. The results of the current study demonstrate the potential for tea (C. sinensis) extracts to be developed as effective crop protection agents against a range of plant diseases on a variety of crops. / Dissertation (MSc)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

Background: The emergence of viral diseases has been the major threat to public health and social stability. A hundred years ago, 1918 Spanish flu (H1N1) pandemic spread worldwide, and about 3% ~ 5% of the world's population died from the flu-related illnesses. It is known as the deadliest catastrophic pandemics in human history. There have been five Public Health Emergency of International Concern (PHEIC) declarations over the past decade, including the 2014 Ebola outbreak in west Africa, the 2016 Zika outbreak and the ongoing COVID-19 pandemic. There is always a new strain of virus emerging on the horizon. We have urgent need to develop more broad-spectrum antivirals, which work effective against multiple viruses, for thwarting outbreaks in the future. Objective: Based on our previous experience in search of anti-HIV compounds from topical plants, we aimed to discover novel antiviral lead compounds from Justicia plants collected in Hong Kong. Further, structure modification of the natural compounds can lead to optimization of their drug properties for further development as drug candidates. To determine the antiviral targets of the lead compounds will further provide insights to elucidate the mechanism of actions. The present studies are to discover the antiviral lead compounds from Justicia plants, to analyze the structure-activity relationship of the modified structures, to identify the molecular targets of the lead compounds as antiviral agents against the multiple viruses. Methodology: Four common Justicia plants were collected in Hong Kong. The plant extracts and compounds isolated from the plants were explored for their antiviral activities via our established "One-Stone-Two-Birds" antiviral assay. Time-of-addition experiments were performed to determine the target stages of the antiviral compounds on the viral replication. Computational techniques (3D-QSAR and in silico pharmacokinetics evaluation) were employed to elucidate the structure-activity relationship of the compounds and thereby optimize their structures to enhance the antiviral activity. Comprehensive activity-based protein profiling (ABPP) of biotin-linked compounds using SWATH-MS technique was performed to identify the protein target(s) of the lead compounds in an unbiased manner. The role of the molecular target in viral replication was further verified by mRNA knockdown using siRNA. Result: The extracts of Justicia procumbens and Justicia championii showed potent antiviral effects with low cytotoxicity among the collected Justicia plants. By correlating the antiviral activity with their HPLC-UV profiles, arylnaphthalene lignans (ANLs) were determined as the principle active components. Among the isolated compounds from J. procumbens, diphyllin exhibited strong antiviral activities against VSV/HIV, H5N1/HIV and EBOV/HIV pseudoviruses with EC50 values ranging from 30-100nM. In time-of-addition experiments, diphyllin mainly acts on the entry stage of the viral infection. Considering the broad-spectrum antiviral properties and antiviral mechanism together, diphyllin is probably a host-targeting antiviral agent. In a subsequent lead optimization, a reliable and predictive 3D-QSAR was established from 25 synthesized ANLs. Compound 31 was found as the most potent antiviral agent based on the 3D-QSAR model. It showed 70 times more potent antiviral activity than the parent diphyllin, with retained broad-spectrum antiviral properties and improved predicted ADMET properties. In addition, comprehensive ABPP analysis of the biotin-linked diphyllin was employed for the target identification of the ANL compounds. Total 2343 proteins were captured by the ABPP probes. By quantitative analysis, the protein TFAM showed significant affinity to the diphyllin-based ABPP probes. The viral susceptibility of TFAM-deficient cells was shown to be reduced in the subsequent validation. We thus determined TFAM as the potential antiviral drug target of the ANL compounds against a broad spectrum of viruses.

No description available.

The study investigated and analysed the baby vegetable industry in South Africa in order to understand the profile, extent and economics of the industry. The study was conducted in the Mpumalanga, Gauteng, Limpopo and the Western Cape Provinces. Four baby vegetable categories were selected namely, baby carrots, baby sweet corn, baby gems and baby marrows and enterprise budgets for these baby vegetables were developed. Baby vegetables are unique produce trading at a premium price to traditional vegetables. Unlike traditional vegetables, baby vegetables are not produced in large quantities in South Africa as only few producers are producing them on a scale smaller than traditional vegetables. Since it is such a small industry very little is known about the production, distribution and the marketing of baby vegetables, both in South Africa and in the export market. Thus the size, volumes, economics of production, distribution and marketing channels as well as the export market of the baby vegetable industry are not known. This is because research on baby vegetables is limited as data for these vegetables is not readily available and accessible. The cost involved in producing the four baby vegetables was also determined through the development of their enterprise budgets and labour costs were found to be the highest cost of production. The enterprise budgets developed are expected to assist farmers when planning and making production decisions as well as projecting future yields and cost of production. The study ascertained that the supply chain for baby vegetables in South Africa is comprised of baby vegetable producers, staging companies, distribution centres, and the different markets. Markets for baby vegetables in South Africa consist of food retail outlets, fresh produce markets, fresh fruit and vegetable outlets, individual agents and the export market. Baby vegetables are also exported from South Africa. Europe is the largest market for South African baby vegetable exports. However, African countries such as Kenya, Zambia and Zimbabwe are also major role players in baby vegetable exports to the European market, followed by Swaziland. When compared to these countries, South Africa is not a major producer and exporter of baby vegetables. The baby vegetable industry according to the study, is a competitive industry and the continuation of supply by all supply chain members is determined by adhering to set standards, which requires the supply of high quality produce which is safe for consumption and is traceable. In the South African market, also referred to as the domestic market, food retail outlets have high standards of food quality and food safety that producers must adhere to. In the export market, standards are set and monitored by the Department of Agriculture, Forestry and Fisheries and import agents and these standards include Global Good Agricultural Practices (GlobalGAP) and sanitary and phytosanitary (SPS) measures. Further research into the baby vegetable industry is essential in order to know the size of the industry, the volumes of baby vegetables produced and the farm-to-retail price spreads within the industry, and to develop enterprise budgets that are representative of the baby vegetable industry. Since the data for baby vegetable production and sales are currently combined with those for traditional vegetables, it is important to document the industry separately. / Dissertation (MCom)--University of Pretoria, 2013. / Agricultural Economics, Extension and Rural Development / unrestricted

Background: The emergence of viral diseases has been the major threat to public health and social stability. A hundred years ago, 1918 Spanish flu (H1N1) pandemic spread worldwide, and about 3% ~ 5% of the world's population died from the flu-related illnesses. It is known as the deadliest catastrophic pandemics in human history. There have been five Public Health Emergency of International Concern (PHEIC) declarations over the past decade, including the 2014 Ebola outbreak in west Africa, the 2016 Zika outbreak and the ongoing COVID-19 pandemic. There is always a new strain of virus emerging on the horizon. We have urgent need to develop more broad-spectrum antivirals, which work effective against multiple viruses, for thwarting outbreaks in the future. Objective: Based on our previous experience in search of anti-HIV compounds from topical plants, we aimed to discover novel antiviral lead compounds from Justicia plants collected in Hong Kong. Further, structure modification of the natural compounds can lead to optimization of their drug properties for further development as drug candidates. To determine the antiviral targets of the lead compounds will further provide insights to elucidate the mechanism of actions. The present studies are to discover the antiviral lead compounds from Justicia plants, to analyze the structure-activity relationship of the modified structures, to identify the molecular targets of the lead compounds as antiviral agents against the multiple viruses. Methodology: Four common Justicia plants were collected in Hong Kong. The plant extracts and compounds isolated from the plants were explored for their antiviral activities via our established "One-Stone-Two-Birds" antiviral assay. Time-of-addition experiments were performed to determine the target stages of the antiviral compounds on the viral replication. Computational techniques (3D-QSAR and in silico pharmacokinetics evaluation) were employed to elucidate the structure-activity relationship of the compounds and thereby optimize their structures to enhance the antiviral activity. Comprehensive activity-based protein profiling (ABPP) of biotin-linked compounds using SWATH-MS technique was performed to identify the protein target(s) of the lead compounds in an unbiased manner. The role of the molecular target in viral replication was further verified by mRNA knockdown using siRNA. Result: The extracts of Justicia procumbens and Justicia championii showed potent antiviral effects with low cytotoxicity among the collected Justicia plants. By correlating the antiviral activity with their HPLC-UV profiles, arylnaphthalene lignans (ANLs) were determined as the principle active components. Among the isolated compounds from J. procumbens, diphyllin exhibited strong antiviral activities against VSV/HIV, H5N1/HIV and EBOV/HIV pseudoviruses with EC50 values ranging from 30-100nM. In time-of-addition experiments, diphyllin mainly acts on the entry stage of the viral infection. Considering the broad-spectrum antiviral properties and antiviral mechanism together, diphyllin is probably a host-targeting antiviral agent. In a subsequent lead optimization, a reliable and predictive 3D-QSAR was established from 25 synthesized ANLs. Compound 31 was found as the most potent antiviral agent based on the 3D-QSAR model. It showed 70 times more potent antiviral activity than the parent diphyllin, with retained broad-spectrum antiviral properties and improved predicted ADMET properties. In addition, comprehensive ABPP analysis of the biotin-linked diphyllin was employed for the target identification of the ANL compounds. Total 2343 proteins were captured by the ABPP probes. By quantitative analysis, the protein TFAM showed significant affinity to the diphyllin-based ABPP probes. The viral susceptibility of TFAM-deficient cells was shown to be reduced in the subsequent validation. We thus determined TFAM as the potential antiviral drug target of the ANL compounds against a broad spectrum of viruses.

Over the past 200 years, much attention has been paid to natural products for their great contribution in the industry of drug development as many of them have been shown effective against various diseased conditions in humans by virtue of their structural diversity and biological potency. Therefore, they are undeniably a rich resource for the discovery of novel bioactive compounds. To date, many of the mainstay anticancer agents often lead to undesirable side effects and/or develop rapid emergence of drug resistance. Therefore, new therapeutic remedies are desperately needed. In fact, many active compounds are derived from macrocyclic natural products. The identification of their molecular targets may assist researchers to synthesize biological agents for combating particular diseased conditions. Cycloheptapeptides that modulate specific molecular pathways in suppressing the proliferation of cancer cells are potential candidates for anticancer therapeutics and/or chemopreventive agents. In the current research project, we have demonstrated that MV-A, a novel cycloheptapeptide with the unique amino acid DMCPA isolated from Maytenus variabilis (Loes.) C. Y. Cheng (Celastraceae), showed potent cytotoxic activities against a panel of human cancer cell lines, and is worthy for further investigation. Objectives--The objectives of this study were to i) evaluate the anticancer effect, ii) elucidate the mechanism of action, and iii) identify the binding target(s) of the natural cycloheptapeptide MV-A. Methods--We first carried out various kinds of cellular and animal studies for validating the in vitro and in vivo anticancer efficacy of MV-A. Next, we performed a number of bioassays to ascertain the inhibitory effect of MV-A on several major cancer-associated pathways, including apoptosis, cell cycle arrest, senescence and metastasis. The biochemical assays included sulforhodamine B colorimetric assay, flow cytometric analyses of apoptosis and cell cycle arrest, Western blotting, real-time polymerase chain reactions (qPCR) arrays, senescence-associated β-galactosidase staining, phospho-specific protein arrays, as well as migration and invasion staining experiments. Lastly, we also identified the potential protein targets of MV-A by biochemical means, particularly the drug affinity responsive target stability (DARTS) approach. Results--MV-A is a potent anti-proliferative agent against a variety of cancer cells. It inhibited the proliferation of the human colorectal carcinoma (CRC) HCT116 cells with an IC50 value of 2.28 nM. However, the application of MV-A at 2.68 nM did not induce significant apoptosis; rather it caused a notable cell-cycle arrest at the G1 phase. Moreover, the treatment with this compound (0.68 to 2.68 nM) led to a remarkable senescence in cancer cells as well as a mitigated cellular migration. Meanwhile, the expression levels of some components of the p16 cascade and PI3K-AKT pathway, so as several epithelial-to-mesenchymal transition (EMT) molecules were suppressed by MV-A. Furthermore, HSP90, calnexin, EF2, 14-3-3 and annexin A1 were identified as the direct binding targets of MV-A in our DARTS analysis.Conclusions--In the present study, our results indicated that the novel cycloheptapeptide MV-A inhibited proliferation and migration of CRC HCT116 cells via the induction of cellular senescence and modulation of multiple pathways, including the p16/Rb, PI3K-AKT and EMT signaling pathways. These results revealed a potential role of MV-A in cancer therapy. The direct binding targets of MV-A further uncovered its molecular actions against different diseased conditions. Our findings strongly support the development of MV-A as a therapeutic agent for combating cancerous pathologies, explicitly CRC.

Over the past 200 years, much attention has been paid to natural products for their great contribution in the industry of drug development as many of them have been shown effective against various diseased conditions in humans by virtue of their structural diversity and biological potency. Therefore, they are undeniably a rich resource for the discovery of novel bioactive compounds. To date, many of the mainstay anticancer agents often lead to undesirable side effects and/or develop rapid emergence of drug resistance. Therefore, new therapeutic remedies are desperately needed. In fact, many active compounds are derived from macrocyclic natural products. The identification of their molecular targets may assist researchers to synthesize biological agents for combating particular diseased conditions. Cycloheptapeptides that modulate specific molecular pathways in suppressing the proliferation of cancer cells are potential candidates for anticancer therapeutics and/or chemopreventive agents. In the current research project, we have demonstrated that MV-A, a novel cycloheptapeptide with the unique amino acid DMCPA isolated from Maytenus variabilis (Loes.) C. Y. Cheng (Celastraceae), showed potent cytotoxic activities against a panel of human cancer cell lines, and is worthy for further investigation. Objectives--The objectives of this study were to i) evaluate the anticancer effect, ii) elucidate the mechanism of action, and iii) identify the binding target(s) of the natural cycloheptapeptide MV-A. Methods--We first carried out various kinds of cellular and animal studies for validating the in vitro and in vivo anticancer efficacy of MV-A. Next, we performed a number of bioassays to ascertain the inhibitory effect of MV-A on several major cancer-associated pathways, including apoptosis, cell cycle arrest, senescence and metastasis. The biochemical assays included sulforhodamine B colorimetric assay, flow cytometric analyses of apoptosis and cell cycle arrest, Western blotting, real-time polymerase chain reactions (qPCR) arrays, senescence-associated β-galactosidase staining, phospho-specific protein arrays, as well as migration and invasion staining experiments. Lastly, we also identified the potential protein targets of MV-A by biochemical means, particularly the drug affinity responsive target stability (DARTS) approach. Results--MV-A is a potent anti-proliferative agent against a variety of cancer cells. It inhibited the proliferation of the human colorectal carcinoma (CRC) HCT116 cells with an IC50 value of 2.28 nM. However, the application of MV-A at 2.68 nM did not induce significant apoptosis; rather it caused a notable cell-cycle arrest at the G1 phase. Moreover, the treatment with this compound (0.68 to 2.68 nM) led to a remarkable senescence in cancer cells as well as a mitigated cellular migration. Meanwhile, the expression levels of some components of the p16 cascade and PI3K-AKT pathway, so as several epithelial-to-mesenchymal transition (EMT) molecules were suppressed by MV-A. Furthermore, HSP90, calnexin, EF2, 14-3-3 and annexin A1 were identified as the direct binding targets of MV-A in our DARTS analysis.Conclusions--In the present study, our results indicated that the novel cycloheptapeptide MV-A inhibited proliferation and migration of CRC HCT116 cells via the induction of cellular senescence and modulation of multiple pathways, including the p16/Rb, PI3K-AKT and EMT signaling pathways. These results revealed a potential role of MV-A in cancer therapy. The direct binding targets of MV-A further uncovered its molecular actions against different diseased conditions. Our findings strongly support the development of MV-A as a therapeutic agent for combating cancerous pathologies, explicitly CRC.

No description available.

A single tube detection kit was designed as a rapid, easy-to use and reliable test to detect Listeria spp.. Various food samples (vegetables and raw catfish fillets) were used in order to validate the performance of the detection kit. L. grayi was detected in one ready-to-eat (RTE) vegetables with the detection kit while no Listeria spp. was detected using the modified FDA-BAM method. In addition, both the detection kit and modified FDA-BAM method indicated that twelve catfish fillets were Listeria positive. The detection kit had 100% sensitivity and specificity in less detection time (24 h) than the modified FDA-BAM method (60% specificity, >72 h). There was no difference (P<0.05) between the kit and the modified FDA-BAM method on MPN for Listeria spp.