ETD Collection

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Subject: search.filters.subject.Phytochemicals

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    A phytochemical and pharmacological investigation of South African Vitex species
    (2004-09-03) Nyiligira., Eric.
    As part of investigation of the biological activities of South African plant, a phytochemical and pharmacological investigation was carried out on five indigenous Vitex species; V. obovata ssp. obovata, V.obovata ssp. wilmsii, V. pooara, V. rehmannii and V. zeyheri . The chemical composition of the essential oils was determined using gas chromatography and mass spectrometry, and 1.8-cineole, a- copaene , caryophyllene oxide and y-muurolene were found to be the most abundant constituents in the essential oils of both V. obovatassp. obovataand V. obovata sssp. wilmsii.
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    Screening and phytochemical characterization of a South African herbal concoction for anti-HIV-1 activity
    (2017) Hlatshwayo, Vincent Nkosinathi
    In South Africa, the anti-HIV-1 activity of various indigenous plants has not been studied extensively. Most of the phytochemical screening work has focused on anti-cancer activity with less attention given to infectious diseases. A large proportion of South Africans (70-80%) still rely on traditional medicines for treatment of various ailments. And, therefore, there is a need to evaluate and validate the effectiveness of the traditional medicines. The aim of this study was to identify, screen, phytochemically characterize and isolate bioactive compounds from a South African herbal extract that exhibit the best anti-HIV-1 activity. Three extracts were prepared: an ethanol extract, a dereplicated ethanol extract and an aqueous extract from a herbal concoction comprised of a mixture of six plants. These herbal concoctions were investigated for anti-HIV-1 subtype C activity. Phytochemical profiling of the ethanol- and dereplicated ethanol- extracts from the herbal concoctions showed the presence of intermediate polar compounds (flavonoids, alkaloids, sugars and terpenes) for both extracts, while the aqueous extract contained predominantly highly polar compounds. Anti-HIV-1 screening of the three extracts showed that the ethanol and dereplicated ethanol herbal- extracts had the best anti-reverse transcriptase activity. The ethanol extract had mean IC50 values of 56.53, 53.96 and 55.39 μg/ml against MJ4, Du179 and CM9 HIV-1 subtypes C isolates, respectively. The dereplicated ethanol extract had mean IC50 values of 51.87, 47.56 and 52.81 μg/ml against MJ4, Du179 and CM9 HIV-1 isolates, respectively. The aqueous extract was inactive against HIV-1 activity. Moreover, both the ethanol- and dereplicated ethanol- extracts showed activity against HIV neutralization. The ethanol- and dereplicated ethanol- extracts had mean IC50 values of 36.33 and 32.06 μg/ml, respectively. Furthermore, they also potently neutralized Vesicular stomatitis virus (VSV) yielding mean IC50 values of 24.91 and 20.82 μg/ml for ethanol- and dereplicated ethanol- extracts, respectively. All extracts were inactive against Murine leukemia virus (MLV). The isolation and phytochemical characterization of the bioactive compound(s) was done by utilizing various chromatographic and spectroscopic methods. Four homoisoflavanoids were isolated and tested for anti-HIV-1 subtype C activity. Three compounds (1, 3a and 3b) were inactive while compound 2 was found to be bioactive against HIV-1 reverse transcriptase (RT) and yielded mean IC50 values of 7.23 ± 1.88, 12.83 ± 0.41 & 12.81 ± 0.10 μg/ml for MJ4, CM9 and Du179 HIV-1 subtype C isolates, respectively. Compound 2 had a mean CC50 value of 23.08 ± 0.1981 μg/ml against HEK293T cells. Overall, the data suggested that ethanol- and dereplicated ethanol- herbal extracts possess direct and indirect anti-HIV-1 activity. They possess a cocktail of phytochemicals that can inhibit HIV-1 RT, HIV-1 entry. Furthermore, these extracts possess phytochemicals that can lower the activation of inflammatory responses during an infection and, hence, reduction in the number new cells infected during the course of HIV-1 infection. Moreover, they possess phytochemicals that have antioxidant activity which, in relation to HIV infection, results in a boosted immune system response in order to ward off the virus.
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    Phytochemical analysis of dodonaea viscosa var angustifolia and their beneficial effects against streptococcus mutans
    (2016-11-04) Ngabaza, Thamsanqa
    Introduction: The link between Streptococcus mutans and dental caries is well documented. The use of natural plant products in the treatment of oral diseases is gaining popularity. One plant that has gained recognition as a source of traditional medicine is Dodonaea viscosa var. angustifolia. The aim of this study was to analyse the phytochemical constituents of D. viscosa var. angustifolia (DVA) and establish their beneficial effects against S. mutans. Materials and methods Cultures of S. mutans ATCC 10923 and SM1 were obtained from the Oral Microbiology laboratory and the DVA was collected from the Pypeklipberg, Mkhunyane Eco Reserve, South Africa. Dry DVA leaves were extracted with methanol. The crude extract was fractionated into six fractions (F1-F6) using silica gel column chromatography and thin layer chromatography. The Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentration (MBC) of the crude extract and six fractions were determined using microtitre plate dilution technique. The effect of the crude extract and fractions on biofilm formation and acid production were investigated using standard techniques. The bioautography technique was also used to identify fractions with bioactive compounds. The most active fraction (F5) was further fractionated and purified into two subfractions, 5.1 and 5.2. Both subfractions were further screened to identify the most beneficial subfraction (5.1). Subfraction 5.1 was identified and elucidated using GC-MS and NMR. The effect of the purified compound on biofilm formation and acid production on S. mutans was repeated to establish reproducibility of the results. Cytotoxic effect of the crude extract and identified subfraction (5.1) was studied using human embryonic kidney cells (HEK). The results were analyzed using Wilcoxon rank-sum test (Mann-Whitney). Results The MIC and MBC of the six fractions and crude extract ranged from 0.39 to 12.5 mg/ml. On preliminary screening of 6 fractions, F5 showed lowest MBC of 0.39 mg/ml and highest total activity value of 2000. In addition, at 0.2 mg/ml, F5 reduced biofilm formation by 93.3% and reduced acid production in S. mutans. Purification of F5 produced subfraction 5.1 and 5.2. Subfraction 5.1 showed higher antimicrobial activity (MIC-0.05 mg/ml) compared to the crude extract (MIC-0.78 mg/ml) and subfraction 5.2 (MIC-0.78 mg/ml). At a concentration of 0.05 mg/ml, subfraction 5.1 exhibited an inhibitory effect on biofilm formation at both 6 hours (94% reduction) and 24 hours (99% reduction) which was higher compared to the crude extract (87% reduction at 0.78 mg/ml after 6 hours). Subfraction 5.1 also exhibited a higher inhibitory effect on acid production compared to the crude extract. Subfraction 5.1 was identified as, 5,6,8-Trihydroxy-7,4l-dimethoxyflavone. Cytotoxicity analysis of the crude extract and subfraction 5.1 (5,6,8-Trihydroxy-7,4l-dimethoxyflavone) on HEK 293 cells showed IC50 values of 0.09 mg/ml and 0.03 mg/ml respectively. Conclusion Phytochemical analysis of D. viscosa var. angustifolia produced an anticariogenic constituent, 5,6,8-Trihydroxy-7,4l-dimethoxyflavone. The compound showed improved antimicrobial and anticariogenic activity at lower concentrations than the crude extract. At subinhibitory concentrations, the compound significantly inhibited biofilm formation and acid production by S. mutans. Cytotoxicity analysis established the safe use of this newly isolated compound therefore it has potential to be used in the oral cavity to prevent dental caries.