PhD (Microbiology) / Department of Microbiology / See the attached abstract below

MSc (Microbiology) / Department of Microbiology / BACKGROUND: Medicinal plants form an important part of the Southern African cultural heritage. Indigenous populations, for example the Vha-Venda people, tend to use medicinal plants in formulations rather than western medicines for health and survival. In order to certify and give scientific credibility to the use of medicinal plants formulations used by Vha-Venda people for the treatment of diseases, several assays were carried out. The present study was aimed at assessing phytochemical content, antimicrobial, antioxidant and cytotoxic activities of four indigenous Venda medicinal plants in a formulation and compare their activity with each plant used individually. METHODS: Peltophorum africanum (roots), Pterocarpus angolensis (bark), Terminalia sericea (roots) and Ximenia caffra (roots) were collected from the Thohoyandou area. The collected plant parts were extracted with methanol and water respectively. Individual plant extracts and Five designed formulations were tested for their antimicrobial activity against Staphylococcus aureus ATCC 25923 (Methicillin Resistant), Staphylococcus aureus ATCC 33591(Methicillin Susceptible), beta lactamase producing Klebsiella pneumonia (ATCC 700603) and extended spectrum beta lactamase producing E. coli (ATCC 35218), four clinical isolates of Candida spp and Cryptococcus neoformans using the Broth dilution method. Minimum bactericidal concentration (MBC) of the extracts was determined by culturing the contents of minimum inhibitory concentration (MIC) on nutrient agar. Similarly, minimum fungicidal concentration (MFC) was also determined by culturing contents of MIC in sabouraud dextrose agar (SDA). Extracts were further assessed for their total phenolic content, total flavonoid content and Qualitative phytochemical analysis. The antioxidant ability of the plants extracts and formulations to scavenge free radical DPPH was also determined. The plant formulations were assessed for their anti-HIV activity using the reverse transcriptase colorimetric assay kit. Cytotoxicity against human lymphatic endothelial cells (HLEC) was determined using MTT assay. RESULTS: Methanolic and aqueous extracts of T. sericea exhibited the best antifungal and antibacterial activities whilst P. angolensis and X. caffra showed poor activities. Methanolic plant formulations showed good activities compared to aqueous formulations. However, Fractional Inhibition Concentration Index showed that there was 1 synergistic interaction, 25 additive interactions and 14 antagonistic interactions between the plant extracts. The methanolic formulation 3 showed the best overall phenolic content at 11.85±0.109 mgGAE/g whilst aqueous X. caffra extract showed the least content at 4.546±0.104 mgGAE/g. Higher total flavonoid contents were seen in methanolic formulation 4 at 2.75±0.02 mgQE/g. Qualitative phytochemical analysis revealed the presence of flavonoids, phenolics, terpenoids, tannins, saponins and steroids in 80% of the tested plant extracts and formulations. All plant extracts and formulations exhibited good antioxidant activity against DPPH. The methanolic formulation showed the best antioxidant activity with IC50 of 0.094 ± 0.33μg/ml. For anti- HIV inhibition, all formulations at 200μg/ml exhibited higher percentage of HIV-1 reverse transcriptase inhibition with methanolic mixture 3 being the best overall at 97.5% activity whilst aqueous mixture5 was the least active with 63.03% inhibition activity. Moreover, the best anti-HIV activity at 100μg/ml was exhibited by methanolic mixture 3 at 71% inhibition. Furthermore, aqueous X. caffra, mixture 2 inhibited 26% and 51% at 12.5mg/ml and 3.125mg/ml respectively. Peltophorum africanum and mixture 5 inhibited 34%, 54% and 43% at 3.125mg/ml, 6.25mg/ml and 12.5 mg/ml respectively of Human Lymphatic Endothelial cells growth. CONCLUSIONS: The results from the study indicated that most of the commonly used traditional medicinal Plants in the Venda region when mixed together have merit for use in traditional medical practice as they have shown good antimicrobial activities, good antioxidant xviii activities, good phytochemical activities and good cell proliferation activity. However some formulations showed antagonistic interaction against bacteria. Some Individual medicinal plants showed toxicity at higher concentrations against immune cells. Whereas formulations promoted cell proliferation, therefore, the use of such individual plants in the treatment of infections should be highly monitored as they may pose a health threat to normal immune cells. Generally, plants are potential pharmacological agents which needs to be preserved and harvested with care. / NRF

Les substances pharmaceutiques font partie du groupe des contaminants émergents du fait de leur intérêt récent dans les études environnementales comparativement à des polluants étudiés depuis plus longtemps tels que les pesticides. Elles correspondent aux principes actifs des médicaments et, à ce titre, sont responsables des propriétés pharmacologiques des médicaments. Ce sont donc des molécules biologiquement actives qui peuvent agir sur les organismes vivants présents dans les écosystèmes impactés. L’origine des substances pharmaceutiques dans l’environnement est variable mais les principales sources sont liées à leur utilisation en médecine humaine ou vétérinaire. Une fois consommées, les substances pharmaceutiques sont excrétées dans les urines ou les fèces et se retrouvent dans les eaux usées (consommation humaine) ou dans les déchets d’élevage (consommation vétérinaire). Dans le premier cas, elles peuvent être rejetées directement dans le milieu, ou indirectement, avec les eaux usées traitées ou les boues résiduaires, après traitement dans les stations d’épuration (STEP). Dans le deuxième cas, elles atteignent directement le milieu lorsque les animaux sont élevés en prairie ou indirectement lorsque les déchets d’élevage sont épandus sur les sols agricoles pour les fertiliser. Ces travaux de thèse se sont attachés à étudier l’origine et le devenir de ces substances dans ces 2 cas de figure. Ainsi en se basant sur des critères de consommation, de présence dans l’environnement par rapport à des études antérieures, de toxicité et d’écotoxicité, d’originalité et de disponibilité des composés standards de référence, 32 puis 78 molécules appartenant aux classes thérapeutiques des antibiotiques, des anticancéreux, des béta-bloquants, des anti-VIH et des inhibiteurs de phosphodiestérase de type 5 (PDE 5) ont été étudiées dans 2 continuums : i) effluents hospitaliers - eaux usées brutes et traitées – eaux de surface, et ii) eaux usées brutes et traitées - eaux de surface - eaux de captage souterraines. En s’appuyant sur les mêmes critères de sélection, le devenir de 7 antibiotiques a été étudié dans des lisiers porcins dans des filières simples de traitement du lisier (fosse de stockage), dans des filières complexes de traitement du lisier (système de traitement ressemblant à des mini STEP) et dans des mésocosmes en conditions contrôlées. Pour pouvoir réaliser l’ensemble de ces études, des protocoles analytiques mettant en œuvre une étape d’extraction par SPE (Solide Phase Extraction) ou d’extraction ASE (Extraction Accélérée par Solvant) puis de purification par SPE et d’analyse par LC/MS/MS (Chromatographie en phase liquide couplée à la spectrométrie de masse en tandem) ont été développés. Ces protocoles, en remplissant des critères de qualité tels que des limites de détection et de quantification compatibles avec des analyses environnementales (de l’ordre du ng/l à la dizaine de ng/l), une bonne linéarité, précision, justesse et performance, ont permis d’analyser la phase dissoute des échantillons d’eaux et la phase dissoute et solide des échantillons de lisiers. Il ressort des analyses des échantillons aqueux que : i) les béta-bloquants, les anti-VIH et les antibiotiques appartenant aux familles des macrolides, des fluoroquinolones et des sulfonamides, sont les molécules les plus représentatifs de la contamination du milieu naturel parmi les classes étudiées ; ii) les rejets de STEP sont une source majeure de la contamination des systèmes aquatiques ; iii) les eaux usées sont davantage contaminées en hiver qu’en été ; et iv) les eaux de surface sont davantage contaminées en été qu’en hiver. / Pharmaceutical substances belong to the group of emerging contaminants due to their recent interest in environmental studies in comparison with pollutants who have been studied for a longer time like pesticides. They correspond to the active ingredient of drugs and by this mean are responsible for their pharmacological properties. Consequently they are biologically active molecules that can act on living organisms present in impacted ecosystems. The origin of pharmaceuticals in the environment is variable but the main sources are related to their use in human and veterinary medicine. Once consumed, pharmaceutical substances are excreted in urine or feces and are found in wastewater (human consumption) or animal manure (veterinary consumption). In the first case, they can be discharged directly in the environment, or indirectly, with treated wastewater or sludge from sewage treatment plants (SWTP). In the second case, they directly reach the environment when animals are bred on grassland or indirectly when livestock wastes are spread on agricultural soils as fertilizer. This PhD work has been focused on the study of the origin and fate of pharmaceutical substances in these 2 cases. Thus according to consumption data, occurrence in the environment reported in previous studies, toxicity and ecotoxicity data, originality and availability of reference standard compounds, 32 then 78 molecules belonging to 5 different therapeutic classes (antibiotics, antineoplastics, beta-blockers, anti-HIV, phosphodiesterase type 5 inhibitors (PDE 5 inhibitors)) were studied in 2 continuums : i) hospital wastewater effluents – raw and treated wastewater – surface water, and ii) raw and treated wastewater – surface water – ground water. Based on the same selection criteria, the fate of 7 antibiotics was studied in pig manure in simple manure storage facilities (storage tank), in aerobic manure treatment facilities (treatment system like in small SWTP) and in mesocosms under controlled conditions. In order to achieve all these studies, analytical protocols implementing an extraction step by SPE (Solid Phase Extraction) or an ASE extraction (Accelerated Solvent Extraction) followed by a SPE purification and an analytical step by LC / MS / MS (liquid chromatography tandem mass spectrometry) have been developed. These protocols, by filling out quality criteria such as limits of detection and quantification compatible with environmental analysis (ng/l to dozen of ng/l), good linearity, precision, accuracy and performance, were used to analyze the dissolved phase of water samples and dissolved and solid phases of pig manure samples. The water samples analysis shows : i) beta-blockers, anti-HIV and antibiotic belonging to the families of macrolides, fluoroquinolones and sulfonamides are the most representative molecules of the environmental contamination from the classes studied; ii) SWTP releases are a major source of aquatic systems’ contamination; iii) wastewaters are more contaminated in winter than in summer; and iv) surface water are more contaminated in summer than in winter. The pig manure samples analysis shows : i) the levels of contamination of manure by antibiotics are high, from a few µg/l to mg/l; ii) the manure level of contamination is not related to the physiological stage of pigs; iii) the interest to store manure before spreading in order to reduce the antibiotics contamination is not highlighted; iv) oxytetracycline, tetracycline, tylosin and marbofloxacin are mainly present in the solid phase whereas sulfadiazine, lincomycin and monensin are mainly present in the liquid phase of manure; v) the separation of solid and liquid phases reduce manure contamination in aerobic treatment facilities; and vi) antibiotics degradation is mainly aerobic.Key words: ,

Albert Font Haro ABSTRACT Modulation of plasmacytoid dendritic cell function: role of immunoreceptors TIM-3 and BDCA-2 Plasmacytoid dendritic cells (pDCs) are key players in the antiviral response as well as in linking innate and adaptive immune response. They express endosomal toll-like receptors 7 and 9, which can detect ssRNA and unmethylated CpG DNA, respectively. Due to the constitutive expression of the transcription factor IRF7, pDCs are able to rapidly produce massive quantities of type I (α, β, ω) and type III (1, 2, 3, 4) interferons (IFN-I and IFN-III) as well as pro- inflammatory cytokines such as IL-1, IL-6 and TNF-α. After maturation, they also function as antigen-presenting cells. Despite intense research, the mechanisms of IFN and pro-inflammatory cytokines production and regulation are still poorly understood. Using the pDC cell line GEN2.2 and also primary human pDCs, we shed light on the role of kinases MEK and SYK in IFN-I production and regulation. We found that SYK is not only involved in the regulatory receptor (RR)-mediated BCR-like pathway that represents the negative regulation of IFN-I and IFN-III secretion but also in the positive TLR7/9-mediated signal transduction pathway that leads to IFN-I production, representing the immunogenic function. We also found that MEK plays a...