Colonization on banana roots and on the pathogenic fungus. Fusarium oxysporum f. sp. cubense race 4, causing banana wilt disease, by the endophyte Burkholderia cepacia isolated from asparagus, which might be used as a biological control agent, was investigated with the aid of scanning and transtnission electron microscopy. B, cepacia was able to colonize the surface of hyphae of F, oxvsporum f. sp. cubense and the ftingal macrospores. In vitro colonization of the fungtis by the endophyte resulted in mycelial deformation with terminal and intercalary swelling. In the banana plant B. cepacia was closely associated with banana roots. A matrix was frequently found to be present between the bacterium and the plant surface. Transmission electron microscopy observations showed that B, cepacia exists mainly in the intercellular space of the banana root tissues.
The growing number of bacterial infections and antibiotic resistance have become a major threat to global health, food security, and development. Without effective antibiotics, modern medical treatments including organ transplantations, chemotherapy, and surgeries become much more risky (WHO 2017a). On the other hand, noncommunicable diseases (NCDs) are now the leading cause of death globally, responsible for 40 million deaths each year, equivalent to 70% of all deaths across the world (WHO 2017b). Many NCDs are associated with an increased oxidative stress which is caused by an imbalance between excess freeradical production and endogenous antioxidant levels in the body (Pham-Huy et al 2008). Among NCDs, cancer is the second leading cause of death, accounting for 8.8 million deaths in 2015 (WHO 2017c). Besides the exploration of antioxidants and chemotherapeutic drugs in the management of NCDs such as cancer, research on the inhibition of key enzymes in the body for the treatment of NCDs has recently intensified. For instance, inhibition of tyrosinase, a key enzyme involved in melanin biosynthesis, may prevent excess formation and accumulation of melanin in the skin, preventing hyperpigmentation disorders including melasma, freckles, lentigines, and geriatric pigment spots (Ya
The nutrient composition of Myrothamnus flabellifolius leaf tea extract (MLTE) and its protective effect against oxidative hepatic cell injury were evaluated. Gallic acid, caffeic acid, ferulic acid, methyl gallate, and epicatechin were identified in MLTE by high‐performance liquid chromatography (HPLC). The tea extract showed an appreciable nutritional content of proximate, sugar, vitamin E, monounsaturated fatty acids, omega 6 and 9 unsaturated fatty acids, as well as considerable amounts of various mineral elements. Nineteen amino acids were found. Moreover, MLTE exhibited potent in vitro antioxidant activities, presumably because of its richness in polyphenols (gallic acid and ferulic acid) and vitamin E. In Chang liver cells, pretreatment with MLTE suppressed oxidative lipid peroxidation (IC50 = 113.11 μg/ml) and GSH depletion (IC50 = 70.49 μg/ml) without causing cytotoxicity. These data support the local consumption of M. flabellifolius herbal tea, which may be used against oxidative stress‐induced diseases while providing the body with necessary nutrients.
Practical application
Herbal teas are one of the most consumed beverages in the world today, due to their refreshing taste and additional health benefits. Myrothamnus flabellifolius herbal tea is a widely used traditional herbal tea in Southern Africa with potentials for commercialization due to its pleasant flavor. This study, for the first time, reported the nutritional composition of the leaf decoction of M. flabellifolius and its protective effect on hepatic oxidative insults. These results can inform the dietary and nutritional use of the tea for optimum benefits, as well as provide preliminary scientific validation of the use of the herbal tea as an antioxidant beverage with good nutritional value.
Background
Annona muricata L. was identified as a popular medicinal plant in treatment regimens among cancer patients in Jamaica by a previously conducted structured questionnaire. Ethnomedically used plant parts, were examined in this study against human prostate cancer cells for the first time and mechanisms of action elucidated for the most potent of them, along with the active phytochemical, annonacin.
Methods
Nine extracts of varying polarity from the leaves and bark of A. muricata were assessed initially for cytotoxicity using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on PC-3 prostate cancer cells and the ethyl acetate bark (EAB) extract was identified as the most potent. EAB extract was then standardized for annonacin content using High-performance Liquid Chromatography - Mass Spectrometry (HPLC-MS) and shown to be effective against a second prostate cancer cell line (DU-145) also. The mode of cell death in DU-145 cells were assessed via several apoptotic assays including induction of increased reactive oxygen species (ROS) production, reduction of mitochondrial membrane potential, activation of caspases and annexin V externalization combined with morphological observations using confocal microscopy. In addition, the potential to prevent metastasis was examined via inhibition of cell migration, vascular endothelial growth factor (VEGF) and angiogenesis using the chorioallantoic membrane assay (CAM).
Results
Annonacin and EAB extract displayed selective and potent cytotoxicity against the DU-145 prostate carcinoma cells with IC50 values of 0.1 ± 0.07 μM and 55.501 ± 0.55 μg/mL respectively, without impacting RWPE-1 normal prostate cells, in stark contrast to chemotherapeutic docetaxel which lacked such selectivity. Docetaxel’s impact on the cancerous DU-145 was improved by 50% when used in combination with EAB extract. Insignificant levels of intracellular ROS content, depolarization of mitochondrial membrane, Caspase 3/7 activation, annexin V content, along with stained morphological evaluations, pointed to a non-apoptotic mode of cell death. The extract at 50 μg/mL deterred cell migration in the wound-healing assay, while inhibition of angiogenesis was displayed in the CAM and VEGF inhibition assays for both EAB (100 μg /mL) and annonacin (0.5 μM).
Conclusions
Taken together, the standardized EAB extract and annonacin appear to induce selective and potent cell death via a necrotic pathway in DU-145 cells, while also preventing cell migration and angiogenesis, which warrant further examinations for mechanistic insights and validity in-vivo.
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