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Articles by D.S. Grierson
Total Records ( 12 ) for D.S. Grierson
  A.O.T. Ashafa , D.S. Grierson and A.J. Afolayan
  The effect of various methods of drying on the content and chemical quality of the essential oil of this herb was studied. The most prominent components in the fresh, air-dried, sun-dried and oven-dried oils extracted by hydrodistillation were the monoterpenes, α-pinene (9.1, 7.4, 10.2 and 6.8%), β-pinene (3.5, 3.6, 9.6 and 7.0%), myrcene (18.7, 18.4, 22.0 and 16.4%), limonene (26.5, 26.5, 24.4 and 27.4%), cis-ocimene (2.2, 1.9, 2.8 and 2.0%), trans-ocimene (4.8, 5.6, 12.4 and 11.6%) and α-terpineol (3.4, 2.7, 2.2 and 3.2%). Methyl-eugenol, β-caryophyllene, trans-farnesene and bicyclogermacrene were the major sesquiterpenes and all were in minute quantity. Cis-lachnophyllum ester (16.2, 18.1, 19.2 and 16.1%, respectively), was the dominating non-terpenoid polyacetylinic compound. The different drying methods have no significant effect on the quality and composition of essential oil from F. muricata.
  O.T. Asekun , D.S. Grierson and A.J. Afolayan
  Helichrysum odoratissimum is one of the most commonly used medicinal plants in South Africa. The essential oil from the herb was extracted and characterized for the first time using different drying methods. The oils isolated from fresh, air-dried, sun-dried and oven-dried aerial parts of the plant yielded 0.28, 0.46, 0.33 and 0.36%, respectively. The fresh leaf oil was characterized by a high content of oxygenated monoterpenes with the main constituents as p-menthone (35.4%), pulegone (34.2%) and 1, 8-cineole (13.0%). The dried plant oils had limonene (31.6-22.6%), β-caryophyllene (13.0-12.0%) and α-pinene (10.0-7.7%) as their major constituents. Generally, the yield and chemical profile of H. odoratissimum were affected by the drying methods utilized. There were noteworthy chemical alterations in the major components of the essential oils using different methods of drying. The compounds pulegone and menthone were reported as potentially harmful compounds, hence their substantial reduction in the dried oils as compared to the fresh leaf oil is noteworthy as it aids reduction of toxicity in the oils.
  A.O.T. Ashafa , D.S. Grierson and A.J. Afolayan
  The essential oil was extracted by hydrodistillation. A total of thirty-eight compounds were identified with α-pinene (9.1%) β-pinene (3.5%), myrcene (18.7%), limonene (26.5%), cis-ocimene (2.2%), trans-ocimene (4.8%) and terpineol (3.4%) as the major monoterpenes, while, cis-lachnophyllum ester (16.2%) was the major non-terpenoid polyacetylenic compound. The antibacterial activity of the oil was investigated against 16 bacterial strains using broth microdilution method. The oil inhibited all the test organisms with more pronounced activity on Gram-positive than the Gram-negative bacteria. The Minimum Inhibitory Concentration (MIC) for Gram-positive bacteria range from 0.08-2.50 mg mL–1, whereas, it was 0.08-5.00 mg mL–1 for the Gram-negative bacteria. The ability of the oil from F. muricata to inhibit a range of nosocomial pathogenic bacterial strains at a concentration less than that of streptomycin makes the oil a candidate for possible development of antibiotic drug.
  A.O.T. Ashafa , D.S. Grierson and A.J. Afolayan
  The antimicrobial activities of the acetone, methanol and water extracts from the leaves, stems and roots of this herb were investigated against 10 bacterial and 5 fungal species using the dilution method on solid agar medium. The acetone extracts from the leaf and root were active against Gram-positive bacteria with Minimum Inhibitory Concentration (MIC) ranging between 1.0 and 7.0 mg mL-1, whereas the acetone stem extract was able to inhibit all the bacterial strains at 0.5-7.0 mg mL-1. The methanol extracts of the 3 plant parts showed activity against all the bacterial isolates with MIC values ranging between 0.1 and 10.0 mg mL-1. Again all the extracts exhibited appreciable activity against all the fungi species investigated. The methanol extract of the root showed 100% inhibition against Aspergillus niger, A. flavus and Penicilium notatum at 5 mg mL-1 while it was 88.61% inhibition in Mucor hiemalis. The ability of the extracts of F. muricata to inhibit the growth of several bacteria and fungi is an indication of its broad-spectrum antimicrobial potential which may be employed in the management of bacterial and fungal infections.
  Srinivas Koduru , F.O. Jimoh , D.S. Grierson and A.J. Afolayan
  In this study two steroid glycosides were isolated from the berries of this plant, which were identified as tomatidine and solasodine by spectroscopic techniques. Antioxidant activities of these compounds were investigated using DPPH, ABTS and reducing power assays. The IC50 confirmed the antioxidant potentials of tomatidine and solasodine. DPPH free radical activity was examined at 30 and 60 min. The highest inhibition was observed when the two compounds were combined, followed by solasodine while tomatidine showed the least inhibition. On the other hand, the activity of ABTS was greater than the DPPH and the activity of the combined compounds was faintly less than solasodine. The activity observed in the reducing power assay was higher in the combined compounds and followed by solasodine and tomatidine. This study has revealed strong antioxidant activity and synergistic effect of the isolated compounds from S. aculeastrum berries.
  A.O.T. Ashafa , D.S. Grierson and A.J. Afolayan
  The foliar micromorphology of Felicia muricata (Thunb.) Nees (Asteraceae) was observed with the JEOL (JSM-6390LV) Scanning Electron Microscope (SEM). Both the abaxial and adaxial surfaces were characterized by anisocytic stomata which were more prevalent on the abaxial surface than the adaxial surface. The leaves have only one type of multicellular non-glandular trichomes that are long and cylindrical, tapering to a sharp point and running parallel to the leaf surface in the direction of the apices. Crystal deposits were also observed on the surfaces of the leaves near the stomata. Energy dispersive X-ray spectroscopy-SEM shows that Na, Al, Si, and K were the major constituents of the crystal analyzed. Since no glandular trichomes were present on the leaves of this herb, the bioactive components present in this plant may be produced in some other tissues in the leaf other than the trichomes.
  S.C. Pendota , D.S. Grierson and A.J. Afolayan
  Foliar micromorphology of Hippobromus pauciflorus (L.f.) Radlk (Sapindaceae) was investigated by scanning electron microscope examination. The leaves were characterized by anisocytic stomata which were found only on the abaxial surface. The leaves have long unicellular non-glandular trichomes which were distributed over the mid rib and densely populated at the edges of the upper and lower surfaces. Crystal deposits were also observed on the abaxial surface of the leaves. Energy dispersive X-ray spectroscopy SEM of the crystals showed predominant mineral components of Na, Al, Si, K and Ca ions. These micro (Si, Na and Al) and macro (K and Ca) elements are very essential to plant growth. Their presence in the trichomes could contribute to the mechanical stability of the leaf appendages.
  J.R. Appidi , D.S. Grierson and A.J. Afolayan
  The structure and distribution of foliar appendages on the leaves of this plant were investigated with the JEOL (JSM-6390LV) scanning electron microscope (SEM). Both glandular and non-glandular trichomes were observed, which differed from each other in morphology and location on the leaves. Long stalked glandular trichomes were present on both the abaxial and adaxial surfaces while short stalked glandular trichomes were present only on the adaxial surface. Glandular trichomes were capitate while non-glandular trichomes were stellate with many arms. Some crystal deposits were observed on the surfaces of the leaves. Energy dispersive X-ray spectroscopy-SEM of these crystals showed that Al, Ca, K, Na, Ti and Si were the major constituents. We hypothesize that the bioactive therapeutic compounds secreted by H. incana may be produced in the glandular trichomes.
  S.C. Pendota , D.S. Grierson and A.J. Afolayan
  Information on medicinal plants, used by the people of the Eastern Cape for the treatment of eye infections, was collected through questionnaires which were administered to herbalists, traditional healers and rural dwellers. The information collected revealed 12 plant species. These plants belong to 9 families, of which Sapindaceae was the most prominent. The leaves were reported to be the most used part of the plants, constituting 75% of herbal preparations. This was followed by bark and roots which constituted 25%. Generally, the plant parts are crushed and the sap squeezed directly into the infected eyes. In few cases, the material is mixed with water and boiled; after cooling, the extract is applied to the infected eyes. Hippobromus pauciflorus was the most commonly used plant species for the treatment of eye infections in the province. Majority of the plants used have been reported in literature to possess some other pharmacological activities.
  J.R. Appidi , D.S. Grierson and A.J. Afolayan
  An ethnobotanical study of plants used for the treatment of diarrhoea in the Eastern Cape Province, South Africa was carried out, using a questionnaire which was administered to herbalists, traditional healers and rural dwellers. Information collected revealed the names of plants used for the treatment of diarrhoea, the parts used and the methods of preparation. This survey indicated a total of 17 plant species from 14 families used in the Province. Elephantorrhiza elephantina, Hermannia incana, Pelargonium reniforme, Alepidea amatymbica and Bulbine latifolia were the most frequently mentioned and highly recommended plants for the treatment of diarrhoea by both the traditional healers and rural dwellers. Roots, bark and leaves are the common parts of plants used, while decoctions and infusions are the main methods of preparation.
  A.A. Aliero , P.O. Adebola , D.S. Grierson and A.J. Afolayan
  The response of Solanum pseudocapsicum to watering periods and nitrogen levels was investigated in a glasshouse experiment. The two factors studied significantly affected the vegetative growth and biomass production at p≤0.05. A significant interaction was also determined for 70% of the parameters studied. The application of 100 kg N ha-1 was found to be optimum for vegetative growth and biomass production no matter the watering period. Beyond this level, fertilizer application did not increase the magnitude of the growth parameters. The result of this study showed that this plant, although grows in the wild, is intolerant to drought condition and require small amount of fertilizer for its successful propagation. This might explain its adaptation to moist and shaded habitats and its survival ability as indoor ornamental plant.
  J.R. Appidi , D.S. Grierson and A.J. Afolayan
  Hermannia incana Cav. (Sterculiaceae) is a prostrate herb used to treat stomachache and diarrhea, and as an emetic by the people of Eastern Cape Province, South Africa. Acetone, methanol, and water extracts from the leaves and roots of the plant were investigated for antibacterial and antimycotic activities. The methanol extracts of the plant showed appreciable activity against Gram-positive and Gram-negative bacteria at concentrations ranging from 0.5 to 7 mg/mL. The acetone and water extracts of both the leaves and the roots showed moderate activity against Gram-positive bacteria and less activity against Gram-negative bacteria. All the extracts inhibited the growth of the fungi Aspergillus flavus, Aspergillus niger, and Mucor hiemalis with growth inhibition based on MIC ranging from 54% to 96% at 0.1- 10 mg/mL. None of the extracts suppressed the growth of Candida albicans at the maximum concentration (10 mg/mL) tested. This study has pointed to the potential application of Hermannia incana as a bacteriocide and fungicide.
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