Euclea Undulata Research Articles

Variations in the accumulation of three secondary metabolites in Euclea undulata Thunb. var. myrtina as a function of seasonal changes

Euclea undulata Thunb. var. myrtina is a widely distributed shrub in South Africa. The roots are used by traditional healers in the treatment of diabetes. Research indicated that the roots of this plant contain epicatechin and α-amyrin-3O-β-(5-hydroxy) ferulic acid, two secondary metabolites that show potential to treat diabetes. It was found that α-amyrin-3O-β-(5-hydroxy) ferulic acid inhibits α-glucosidase, while epicatechin lowers blood glucose levels. However, existing literature also indicated the presence of the naphthoquinone 7-methyl-juglone in the roots and due to its cytotoxic nature, 7-methyl-juglone poses a potential threat when E. undulata is used in the treatment of diabetes.In order to assist in the effective and safe use of this plant in the treatment of diabetes, this project aimed to determine whether the presence of these metabolites is seasonal. It further aimed to contribute to more sustainable harvesting methods by investigating stems and leaves in addition to roots for the presence of these secondary metabolites.Leaves, stems and roots were harvested from E. undulata plants in three different localities with different climatic conditions, with a specific focus on winter and summer rainfall regions. The plant material was air dried at room temperature and ground to a powder, which was subjected to NMR metabolomic analysis.Multivariate data analysis resulted in clustering of samples collected in the rainy and dry seasons for both winter and summer rainfall regions, as well as delineations between roots, stems and leaves due to their secondary metabolite contents. Clustering of samples in the rainy and dry seasons of the same plants was also observed with the OPLS-DA plots indicated clustering of samples harvested during the dry and rainy seasons.Results for the summer rainfall area indicate seasonal fluctuations in the levels of α-amyrin-3O-β-(5-hydroxy) ferulic acid in roots. It is also noteworthy that the roots always contain 7-methyl-juglone and only found in the leaves on the rainy season of the summer rainfall area. The stems can be harvested for α-amyrin-3O-β-(5-hydroxy) ferulic acid and the leaves for epicatechin in both seasons in the summer rainfall area. Results from the winter rainfall area indicate far less seasonal fluctuation. Most metabolites appear to be either present or absent in the respective organs regardless of season with the exception of epicatechin that is absent in the roots in the rainy season. Fluctuations were, however, detected in epicatechin levels in stems and 7-methyl-juglone levels in roots. From the results obtained it is evident that α-amyrin-3O-β-(5-hydroxy) ferulic acid occurs in roots, stems and leaves in the winter rainfall area and is independent of temperature whereas 7-methyl-juglone is present only in the roots. Leaves can replace the use of roots when harvested in a winter rainfall area irrespective of season as α-amyrin-3O-β-(5-hydroxy) ferulic acid and epicatechin are present and 7-methyl-juglone are absent.

Euclea undulata Thunb.: Review of its botany, ethnomedicinal uses, phytochemistry and biological activities.

Euclea undulata (E.undulata) is traditionally used for the treatment of body pains, chest complaints, cough, diabetes, diarrhoea, headaches, heart diseases and toothaches in southern Africa. This study was aimed at reviewing the botany, ethnopharmacology and biological activities of E.undulata in southern Africa. Results presented in this study are based on review of literature using search engines such as Science Direct, Springerlink, Scopus, PubMed, Web of Science, BioMed Central and Google Scholar. Herbal medicine is prepared from the decoctions of the roots, bark and leaves, and extracts of these plant parts have demonstrated anticholinesterase, anti-inflammatory, antimicrobial, antimycobacterial, antiplasmodial, antioxidant and hypoglycaemic activities. Multiple classes of phytochemical compounds such alkaloids, diterpenes, fatty acids, flavonoids, glycosides, naphthoquinones, phenolics, phytosterols, reducing sugars, saponins and tannins have been isolated from the species. E.undulata has a lot of potential as herbal medicine in tropical Africa, and advanced research is required aimed at correlating its medicinal uses with the phytochemistry and pharmacological properties.

Diet and seasonal dispersal of extralimital giraffe at Sanbona Wildlife Reserve, Little Karoo, South Africa

South African giraffe (Giraffa camelopardalis giraffa) have been introduced as an extralimital species to private farms in the Little Karoo on the basis of economic sustainability, and the need to create a competitive tourism product. However, little is known about the medium- to long-term impacts and ecological sustainability of such introductions. The diet of a population of giraffe on Sanbona Wildlife Reserve, near the town of Ladismith, was assessed via direct observations between January and October 2014, in order to determine their potential impact on the world’s most species-rich semi-desert, the Succulent Karoo. Unlike giraffe in their native range, the Sanbona population showed seasonal preference for browse species. Acacia karroo (sweet thorn) appears to be the preferred browse species during autumn and spring, with Schotia afra being the preferred species in winter, and no significant preference being shown in summer. Giraffe also appeared to seasonally move between catchments where tree species other than A. karroo occurs, especially during winter and spring when the tributaries of the Brak River, containing mixed Acacia with S. afra (karoo boer-bean) and Euclea undulata (small-leaved guarri), were visited with increasing frequency. These results largely confirm the importance of A. karroo as the main browse species in this environment but also suggest that other species may be important components of the diet of extralimital giraffe in the Little Karoo. On farms where A. karroo is dominant, supplementary feed may be needed when A. karroo browse is unavailable due to leaf drop.Conservation implications: Acacia karroo was the main browse species of extralimital G. c. giraffa at Sanbona Wildlife Reserve, but it switched to S. afra during winter. This suggests that an assessment of alternative food species forms part of suitability assessments for the introduction of extralimital G. c. giraffa for areas similar to Sanbona.

Increasing the Effectiveness of the “Great Green Wall” as an Adaptation to the Effects of Climate Change and Desertification in the Sahel

The Great Green Wall (GGW) has been advocated as a means of reducing desertification in the Sahel through the planting of a broad continuous band of trees from Senegal to Djibouti. Initially proposed in the 1980s, the plan has received renewed impetus in light of the potential of climate change to accelerate desertification, although the implementation has been lacking in all but two of 11 countries in the region. In this paper, we argue that the GGW needs modifying if it is to be effective, obtain the support of local communities and leverage international support. Specifically, we propose a shift from planting trees in the GGW to utilizing shrubs (e.g., Leptospermum scoparium, Boscia senegalensis, Grewia flava, Euclea undulata or Diospyros lycioides), which would have multiple benefits, including having a faster growth rate and proving the basis for silvo-pastoral livelihoods based on bee-keeping and honey production.

Antimicrobial activity of Euclea undulata, Euclea divinorum and Diospyros lycioides extracts on multi- drug resistant Streptococcus mutans

The antimicrobial activities of three Zimbabwean chewing sticks (Euclea undulata, Euclea divinorum and Diospyros lycioides) on multi-drug resistant (MDR) Streptococcus mutans were determined. Thirty one isolates of S. mutans were obtained from 47 carious teeth and antibiotic sensitivity testing was done using the disc diffusion assay for all isolates. The resistance pattern of each isolate against eight antibiotics was noted. Eight resistance patterns were identified, and 19 isolates showed resistance to at least 4 antibiotics; these were considered MDR. Eight MDR and 2 multi-drug sensitive isolates were then assayed against methanol, acetone, diethyl ether and aqueous extracts of E. undulata, E. divinorum and D. lycioides. The broth macro-dilution assay was used to determine the minimum inhibitory concentration (MIC) of the extracts. All E. divinorum extracts showed no antimicrobial activity. Stem methanol extracts of E. undulata and root and stem methanol extracts of D. lycioides showed anti S. mutans activity. The largest inhibition zones were exhibited by methanol extracts of E. undulata (60 mm) and D. lycioides (54 mm). MICs ranged from 0.385 to 11.22 mg/ml and minimum bactericidal concentration (MBCs) from 0.485 to 20.20 mg/ml. D. lycioides and E. undulata extracts have potential use as anticariogenic agents. Key words: Streptococcus mutans, dental caries, antimicrobial activity, multi-drug resistant

Hypoglycemic evaluation of a new triterpene and other compounds isolated from Euclea undulata Thunb. var. myrtina (Ebenaceae) root bark

Investigate the hypoglycaemic activity of the four isolated compounds from a crude acetone extract of the root bark of Euclea undulata var. myrtina, which is used by traditional healers in the Venda area, Limpopo Province in the treatment of diabetes. The hypoglycaemic activity of the four compounds isolated from Euclea undulata was determined by in vitro screening of glucose utilization by C2C12 myocytes at a concentration of 25 μg/ml or 50 μg/ml. The inhibition of α-glucosidase was also tested at concentrations ranging from 0.02 to 200.00 μg/ml. Assay-guided isolation of the crude acetone extract of the root bark of Euclea undulata var. myrtina afforded a new triterpene, α-amyrin-3O-β-(5-hydroxy) ferulic acid (1), in addition to three known compounds; betulin (2), lupeol (3) and epicatechin (4). The in vitro results on C2C12 myocytes suggest that compound 4 may have some effect to lowers blood glucose levels, whereas compound 1 has the ability to inhibit α-glucosidase at a concentration of 200.0 μg/ml with an IC₅₀ value of 4.79 that correlates with that of the positive control acarbose IC₅₀ value 4.75. The results suggest that 4 may have some ability to lower blood glucose levels, whereas 1 has the ability to inhibit α-glucosidase. These findings corroborate the ethnomedicinal use of Euclea undulata by traditional healers for the treatment of diabetes as two substances was isolated from the acetone plant extract that exhibit hypoglycaemic activity.

Antioxidant activity of selected plants of the Great Fish River Reserve,Eastern Cape, South Africa

The Great Fish River Reserve (GFRR), in the Eastern Cape, has proved to be particularly suitable for the black rhinoceros that have been introduced over the past 20 years. In captivity, these animals often suffer from a number of disease conditions, certain of which may be related to antioxidant deficiencies in their diet. Therefore, the antioxidant capacities of the leaves of 25 bush species in the GFRR was determined by the DPPH, ABTS and FRAP methods and the total phenolics by the Folin-Ciocalteau procedure. The plant species Ozoroa mucronata, Putterlickia pyracantha, Phyllanthus verrucosus, Maytenus capitata, Euclea undulata and Jatropha capensis were found to have the highest antioxidant capacity by the three methods, whereas for total phenols Putterlickia pyracantha was replaced in the top six by Carissa bispinosa. The black rhinoceros in this area appear to favour plants of varying antioxidant capacity and do not seem to select browse species for this property.

Isolation and identification of a novel anti-diabetic compound from Euclea undulata Thunb

Isolation and identification of a novel anti-diabetic compound from Euclea undulata Thunb

Hypoglycaemic activity of four plant extracts traditionally used in South Africa for diabetes

Aim To validate plant species for hypoglycaemic activity. Materials and methods Four plants were investigated for hypoglycaemic activity by evaluating inhibiting effects on carbohydrate-hydrolising enzymes: α-glucosidase and α-amylase. Acetone plant extracts were screened against C2C12 myocytes, 3T3-L1 preadipocytes and Chang liver cells by measuring glucose uptake. Cytotoxicity was done in preadipocytes and hepatocytes. Results Extract of Euclea undulata rootbark exhibited highest activity, displaying a glucose uptake of 162.2% by Chang liver cells at 50 μg/ml. An inhibition concentration of 50% for Euclea undulata was found to be 49.95 μg/ml for α-glucosidase and 2.8 μg/ml for α-amylase. No cytotoxicity was recorded for Euclea undulata, while Schkuhria pinnata and Elaeodendron transvaalense exhibited cytotoxicity at 12.5 μg/ml. α-Glucosidase and α-amylase assays showed inhibitory activity on enzymes for three plant extracts. Conclusion Euclea undulata, Schkuhria pinnata and Elaeodendron transvaalense showed in vitro hypoglycaemic activity. Schkuhria pinnata and Elaeodendron transvaalense indicated cytotoxicity on 3T3-L1 preadipocytes and Chang liver cells. Euclea undulata, Pteronia divaricata and Elaeodendron transvaalense inhibited α-glucosidase and α-amylase enzymes. Ethnopharmacological relevance Screening of plant extracts scientifically validated traditional use of Euclea undulata for treatment of diabetes. Cytotoxicity results revealed that acetone extracts of Schkuhria pinnata and Elaeodendron transvaalense are toxic and raise concern for chronic use.

Litter dynamics across browsing-induced fenceline contrasts in succulent thicket, South Africa

Semi-arid succulent thicket in South Africa has experienced extensive livestock-induced transformation, reflected in extensive structural changes and loss of biodiversity, biomass and soil carbon. The ecological mechanisms contributing to this transformation are not fully understood but are believed to include the breakdown of ecosystem processes including litter production and decomposition, which are rate-limiting steps in nutrient cycling and incorporation of organic matter into the soil. In this study we investigated the effect of transformation on litter production and decomposition in succulent thicket. We measured litter production and decomposition of four dominant perennial woody plants ( Euclea undulata, Pappea capensis, Portulacaria afra and Rhus longispina) across replicated fenceline contrasts. Litter production was measured over 14 months using mesh traps. Decomposition was measured over 15 months using a combination of litterbags and leaf packs. Litter production in succulent thicket was very high for a semi-arid system (approaching that of temperate forests), with the leaf- and stem-succulent P. afra contributing the largest component. Transformation caused a significant reduction in litter production at a landscape scale (4126 vs 2881 kg/ha/yr), primarily due to reduced cover of P. afra. Surprisingly, transformation had few significant effects on the rate of decomposition of litter, possibly due to a switch from biotic to abiotic decomposition processes. The perennial vegetation in succulent thicket, particularly P. afra, appears to play a critical role in the maintenance of the ecosystem by facilitating the incorporation of organic matter into soil. Transformation of succulent thicket leads to a disruption of the carbon cycle, ultimately resulting in degradation of the ecosystem. Successful restoration is likely to depend on increasing the rates of organic matter return to soils. P. afra is a potential carbon restoration pump as it is both drought-resistant and easily propagated from cuttings.

Performance of Tswana goats fed Acacia mellifera, Euclea undulata, and Peltophorum africanum as a supplement to buffel grass

Performance of Tswana goats fed Acacia mellifera, Euclea undulata, and Peltophorum africanum as a supplement to buffel grass

New cercosporoid fungi from southern Africa

Seven cercosporoid fungi are newly described from leaf spots on various plants in South Africa. An eighth species, Stigmina dieramae Crous & B, Sutton is described from leaf spots on a Dierama K. Koch species collected in Lesotho. Cercostigmina ekebergiae Crous & B. Sutton is newly described from Ekebergia Sparrm., while a new coelomycete genus, Phaeophloeosporella Crous & B. Sutton, is described as the pigmented analogue of Phloeosporella Hohn. to accommodate Cercosporella ekebergiae Syd. Additional species treated are Cercospora lotononidis Crous & B. Sutton on Lotononis bainesii Bak., Passalora tecomariae Crous & B. Sutton on a Tecomaria Spach species, Phaeoramularia digitariae Crous & B. Sutton on Digitaria diagonalis (Nees) Stapf, Pseudocercospora capensis Crous & B. Sutton on Cunonia capensis L. and Pseudocercospora eucleae Crous & B. Sutton on Euclea undulata Thunb.

Measurement and spatial variation of thermal infrared surface emissivity in a savanna environment

Knowledge of the surface thermal emissivity is necessary for the application of thermal infrared remote sensing, which forms the basis for water and surface energy balance monitoring from space. Thermal emissivity was measured in the wavelength band 8–14 μm for a series of representative surfaces within a natural bush‐savanna environment intermixed with cultivated fields in Botswana. The measurements were performed with an emissivity box, which may be constructed with different dimensions to meet the general requirements of the user. The device is well‐suited for bare soil, grass, and other types of soil and low‐vegetation cover combinations. The measured emissivity varied between 0.914 for bare soil (loamy sand) and 0.986 for a surface completely covered with savanna shrub (Euclea undulata). Calculations are based on the measurements of the radiative surface temperature of three different reflecting configurations of the box. Repetitive estimates of the emissivity were found to be very reproducible for the same surface types and showed the large spatial variability of surface emissivity within the study area. This paper describes the emissivity box together with other versions of the box concept found in the literature, and it describes the operation and calibration procedure as well as the results and consequences of the emissivity measurements for the application of thermal infrared remote sensing.