Thesis ( |b(MSc. (Biochemistry)) -- University of Limpopo, 2017 / Medicinal plants have been used as a key source for medication and they remain to provide new therapeutic remedies to date. Extracts of Olea europaea subspecies africana leaves are used extensively in South Africa to treat various diseases traditionally. The diseases have been noted to be associated with free radicals, bacterial infections, and inflammation. However, there is little information about the antioxidant, antibacterial, and anti-inflammatory activities of the leaves of this plant in literature and the cytotoxicity of the leaf extracts is still a concern. The information about the Isolated compounds is also minimal hence this study was aimed at filling in those gaps in relation to the traditional use of the leaves in southern Africa and subsequently isolating and identifying the active compounds using bioassay-guided fractionation. Preliminary screening of the crude extracts for antioxidant, antibacterial and antiinflammatory activities indicated that the extracts possessed all biological activities. The presence of major phytochemicals in the crude extracts was determined through the use of standard chemical methods and TLC analysis. The colorimetric methods (Folin-Ciocalteau and Aluminum chloride) were used for quantification purposes. TLC-DPPH assay was used to screen antioxidant activities of the crude extracts. The observed activity was quantified using the spectrophotometric method of DPPH and reducing power. The antibacterial properties of the leaf extracts were determined by direct bioautography and the serial broth microdilution assay using E. coli, P. aeruginosa, E. faecalis and S. aureus as test bacteria. Screening of the acetone crude extract for anti-inflammatory activities was done using the LPSstimulated RAW 264.7, cells where the inhibition of ROS generation was studied. MTT assay was used to determine the cytotoxicity effects of the leaves. Isolation of bioactive compounds started with serial exhaustive extraction, followed by column chromatography packed with silica gel. NMR analysis was conducted to identify the isolated compound. The results revealed the presence of tannins, terpenoids, steroids and flavonoids with the total phenolic (99.67 ± 2.52 mg of GAE/g) and tannin content (114.33 ± 9.02 mg of GAE/g) found in high amounts. All crude extracts exhibited antioxidant activities and the antioxidant activity quantified via the DPPH assay demonstrated to xxi have EC50 value of 1.05 ± 0.0071 mg/mL. The reducing capacity was found to be dose-dependent and great significance was seen at concentration 0.5 mg/mL to 1 mg/mL that was about 2/3 of that of L-ascorbic acid (standard) at a similar concentration. Screening of the crude extracts for antibacterial activity revealed that all crude extracts except n-hexane and water extracts, inhibited the growth of the tested bacteria on the previously developed TLC plates. The activity was seen as clear zones on the bioautograms. Serial broth microdilution assay indicated that dichloromethane, acetone and ethanol had average MIC values of 0.30, 0.32 and 0.35 mg/mL against all tested bacteria, respectively. Good anti-inflammatory activity of the crude extract was demonstrated at the highest concentration of 0.90 mg/mL. MTT assay indicated that the crude extract had no adverse cytotoxic effects. This was demonstrated by the LC50 values greater than 20 µg/mL and considered non-cytotoxic according to the National Cancer Institute (NCI). Isolation following the bioassay-guided-fractionation resulted in the selection of acetone extract to isolate the bioactive compounds from as it demonstrated good antioxidant and antibacterial activities. Fractionation of the compound by column chromatography yielded three combinations (pools) of fractions and of the three from which only pool 1 was considered for further fractionation. NMR spectra information identified the isolated compound as a mixture of ursolic acid (minor) and oleanolic acid (major). This compound had antibacterial and anti-inflammatory activities and no cytotoxic effects. The leaves of Olea europaea subspecies africana have been proven to possess antioxidant, antibacterial and anti-inflammatory properties. Evaluation of the biological activities of the crude extracts was to validate the use of the leaves traditionally to treat free radical and bacterial-related diseases and potential drug that are safe and has less side effects may be produced from the leaves. / National Research Foundation (NRF)

Tropical African forests are thought to be declining due to human activity, resulting in serious threat to local communities and wildlife. The threatened status of populations of Juniperus procera and Olea africana was studied in Loliondo, Tanzania. Three hundred persons were interviewed in ten Maasai communities concerning tree utilization for fence and house construction, firewood, traditional medicine and gourd sterilization. By comparing the indices for 169 species, J. procera and O. africana usage was significantly higher than all other species (Kruskal-Wallis, chi2 = 15.3, DF = 2, p = 0.0005). Ninety-six percent of interviewees have witnessed local decline in J. procera and O. africana. In conjunction with interviews, ecological sampling was carried out in community forests to determine species status. The correlations of size class distributions are not typical of "healthy" plant populations. If current trends continue local extinction of J. procera and O. africana may occur.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Cardiovascular disease is a major health problem and remains the number one cause of death worldwide. For centuries, medicinal plants have been used in different cultures as medicines for the treatment and control of various diseases. Olea africana, also known as the wild olive, is amongst the herbal plants used by people to treat many ailments.Recently, scientific studies on the hypotensive, vasodilatory and antidysarrhythmic effects of O. africana have been reported. Triterpenoids isolated from the O. africana leaves, for example, have antioxidant properties. The aqueous extract from the leaves of O. africana also have angiotensin-converting enzyme (ACE) inhibitory effects. ACE inhibitors and antioxidants protect the heart against ischemic-reperfusion injury. The serine / threonine protein kinase B (PKB) also known as Akt is activated downstream of phosphoinositide 3- (PI-3) kinase (PI-3-Kinase) and is involved in cardioprotection against ischemia-reperfusion injury. Angiotensin II (AII) decreases the intrinsic PI-3-kinase activity. In this study, we hypothesized that ACE inhibitors increase PI-3-kinase activity and thus activates PKB. The aims of this study were: 1) to determine whether treatment with the crude aqueous extract of leaves of O. africana protect the heart against ischemic-reperfusion injury and 2) if so, to determine whether the protection is mediated via the PKB signaling mechanism. Hearts isolated from male Wistar rats were perfused with different concentrations of the plant extract. In one set of experiments, male Wistar rats were treated with the plant extract (1000 mg/kg/day) for 5 weeks for the evaluation of cardiac function before and after ischemia. At the end of the experiments, hearts were freeze-clamped and kept for PKB / Akt determination. In another set of experiments, we determined the effect of O. africana extract (1000 mg/kg/day) or captopril (50 mg/kg/day) on infarct size. Rats fed jelly served as controls for captopril. In a subset of experiments, hearts were frozen immediately after treatment with O. africana extract (1000 mg/kg/day) or captopril (50mg/kg/day) and PKB were determined.Perfusion with the plant extract significantly decreased coronary flow (p<0.05). The heart function was decreased as evidenced by observed decreases in the force of contraction and heart rate, although these were not measured. Chronic treatment with the crude aqueous plant extract had no effect on cardiac function before ischemia, functional recovery (% left ventricular developed pressure and % rate pressure product) and PKB /Akt phosphorylation (p>0.05). Both the aqueous extract of O. africana leaves and captopril had no effect on infarct size compared to the control group (p>0.05). Captopril,however, improved the recovery of the left ventricular developed pressure. Non-perfused hearts isolated from rats treated with O. africana extract and captopril did not show any response to both captopril and the O. africana extract treatment as measured by PKB /Akt phosphorylation. The results of the present study suggest that the crude aqueous extract of O. africana is not cardioprotective against ischemia-reperfusion injury in this system of the isolated perfused rat heart.

The research aim was to assess the vegetation and soils of the Rora /' Habab plateau, Eritrea and to develop methods of propagating the native tree species, juniper and olive. The research consisted of vegetation and soil surveys, interviews with local people, archival research, and experiments on propagation of olive and juniper. Junipers are now confined to the north of the plateau. Olives are more abundant in the north but have very few individuals in the centre, where there are many dead trees, or south. Soil erosion was ubiquitous and often severe. Soil morphology and nutrient status were related to vegetation, topography, land use, and erosion status, and varied greatly over short distances. Soil texture was coarser and most chemical factors (except total Ca and exchangeable Na) were lower in the south. Organic C, total N, exchangeable Ca, percent day, CEC and the sum of bases were higher in soils from grazed land than in cultivated fields. Germination of olive seeds was 92% when the endocarp was removed; stratification had little effect. Rooting of olive stem cuttings attained 76% under mist when parent plants were fertilised and cuttings were treated with rooting hormone. Germination for juniper was 56% after stratification at 5°C for 30 to 60 days. Juniper stem cuttings rooted in only one of three experiments, where rooting was 78% in a well ventilated, cool, low-mist environment. Olive seedlings which were fertilised and watered every 7, 14, or 21 days for two months, were taller, had lower root:shoot ratios and soil moisture than unfertilised plants. Fertilised seedlings watered every 28 days died. Root volume was less for plants watered every 21 days but watering interval had little effect on other variables in unfertilised seedlings. Ecological restoration is urgently required to rehabilitate the Rora plateau, which has Africa's most northerly remnant juniper / olive woodlands.

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