Genetic transformation and micropropagation of Thapsia garganica L. - a medicinal plant.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.No abstract available

Mass spectrometry metabolomics and feature-based molecular networking reveals population-specific chemistry in some species of the Sceletium genus

The Sceletium genus has been of medicinal importance in southern Africa for millennia and Sceletium tortuosum (Aizoaceae), one of eight species in the genus has gained pharmaceutical importance as an anxiolytic and anti-depressant due to the presence of mesembrine alkaloids. S. tortuosum is used for the manufacture of herbal teas, dietary supplements and other phytopharmaceutical products. This study aimed to provide a metabolomic characterization of S. tortuosum and its sister species as these are not easy to distinguish using morphology alone. Plant samples were thus collected from various locations in the succulent Karoo (South Africa) and analyzed through liquid chromatography-mass spectrometry (LC-MS), using MSE fragmentation as a putative tool for chemical identities. Metabolomics-based analyses in combination with molecular networking were able to distinguish between the four species of Sceletium based on the presence of 4-(3,4-dimethyoxyphenyl)-4-[2-acetylmethlamino)ethyl]cyclohexanone (m/z 334.2020; RT 6.60 min), mesembrine (m/z 290.1757; RT 5.10 min) and 4’-O-demethylmesembrenol (m/z 276.1597; RT 4.17 min). Metabolomic profiles varied according to the different localities and metabolites occurred at variable quantitative levels in Sceletium ecotypes. Molecular networking provided the added advantage of being able to observe mesembrine alkaloid isomers and coeluting metabolites (from the joubertiamine group) that were difficult to discern without this application. By combining high-throughput metabolomics together with global and feature basedmolecular networking, a powerful metabolite profiling platform that is able to discern chemical patterns within and between populations was established. These techniques were able to reveal chemotaxonomic relationships and allowed for the discovery of chemical markers that may be used as part of monitoring protocols during the manufacture of phytopharmaceutical and dietary products based on Sceletium.The National Research Foundation of South Africa and Medical Research Council (South Africa).http://frontiersin.org/Nutritiondm2022Plant Production and Soil Scienc

Effect of drying on the bioactive compounds, antioxidant, antibacterial and antityrosinase activities of pomegranate peel

CITATION: Mphahlele, R. R., et al. 2016. Effect of drying on the bioactive compounds, antioxidant, antibacterial and antityrosinase activities of pomegranate peel. BMC Complementary and Alternative Medicine, 16(1): 143, doi: 10.1186/s12906-016-1132-y.The original publication is available at http://bmcmusculoskeletdisord.biomedcentral.comPublication of this article was funded by the Stellenbosch University Open Access Fund.The use of pomegranate peel is highly associated with its rich phenolic concentration. Series of drying methods are recommended since bioactive compounds are highly sensitive to thermal degradation. The study was conducted to evaluate the effects of drying on the bioactive compounds, antioxidant as well as antibacterial and antityrosinase activities of pomegranate peel. Methods Dried pomegranate peels with the initial moisture content of 70.30 % wet basis were prepared by freeze and oven drying at 40, 50 and 60 °C. Difference in CIE-LAB, chroma (C*) and hue angle (h°) were determined using colorimeter. Individual polyphenol retention was determined using LC-MS and LC-MSE while total phenolics concentration (TPC), total flavonoid concentration (TFC), total tannins concentration (TTC) and vitamin C concentration were measured using colorimetric methods. The antioxidant activity was measured by radical scavenging activity (RSA) and ferric reducing antioxidant power (FRAP). Furthermore, the antibacterial activity of methanolic peel extracts were tested on Gram negative (Escherichia coli and Klebsiella pneumonia) and Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) using the in vitro microdilution assays. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin as positive controls. Results Oven drying at 60 °C resulted in high punicalin concentration (888.04 ± 141.03 mg CE/kg dried matter) along with poor red coloration (high hue angle). Freeze dried peel contained higher catechin concentration (674.51 mg/kg drying matter) + catechin and –epicatechin (70.56 mg/kg drying matter) compared to oven dried peel. Furthermore, freeze dried peel had the highest total phenolic, tannin and flavonoid concentrations compared to oven dried peel over the temperature range studied. High concentration of vitamin C (31.19 μg AAE/g dried matter) was observed in the oven dried (40 °C) pomegranate peel. Drying at 50 °C showed the highest inhibitory activity with the MIC values of 0.10 mg/ml against Gram positive (Staphylococcus aureus and Bacillus subtili. Likewise, the extracts dried at 50 °C showed potent inhibitory activity concentration (22.95 mg/ml) against monophenolase. Principal component analysis showed that the peel colour characteristics and bioactive compounds isolated the investigated drying method. Conclusions The freeze and oven dried peel extracts exhibited a significant antibacterial and antioxidant activities. The freeze drying method had higher total phenolic, tannin and flavonoid concentration therefore can be explored as a feasible method for processing pomegranate peel to ensure retention of the maximum amount of their naturally occurring bioactive compounds.http://bmccomplementalternmed.biomedcentral.com/articles/10.1186/s12906-016-1132-yPublisher's versio

Applications of cytokinins in horticultural fruit crops : trends and future prospects

CITATION: Aremu, Adeyemi O. et al. 2020. Applications of cytokinins in horticultural fruit crops : trends and future prospects. Biomolecules, 10(9):1222, doi:10.3390/biom10091222.The original publication is available at: https://mdpi-res.comCytokinins (CKs) are a chemically diverse class of plant growth regulators, exhibiting wide-ranging actions on plant growth and development, hence their exploitation in agriculture for crop improvement and management. Their coordinated regulatory effects and cross-talk interactions with other phytohormones and signaling networks are highly sophisticated, eliciting and controlling varied biological processes at the cellular to organismal levels. In this review, we briefly introduce the mode of action and general molecular biological effects of naturally occurring CKs before highlighting the great variability in the response of fruit crops to CK-based innovations. We present a comprehensive compilation of research linked to the application of CKs in non-model crop species in different phases of fruit production and management. By doing so, it is clear that the effects of CKs on fruit set, development, maturation, and ripening are not necessarily generic, even for cultivars within the same species, illustrating the magnitude of yet unknown intricate biochemical and genetic mechanisms regulating these processes in different fruit crops. Current approaches using genomic-to-metabolomic analysis are providing new insights into the in planta mechanisms of CKs, pinpointing the underlying CK-derived actions that may serve as potential targets for improving crop-specific traits and the development of new solutions for the preharvest and postharvest management of fruit crops. Where information is available, CK molecular biology is discussed in the context of its present and future implications in the applications of CKs to fruits of horticultural significance.Publisher's versio

African medicinal flora in the limelight

The original publication is available at http://www.sajs.co.za/In the past few years, African medicinal plants have received considerable attention, and it has been lamented that the documentation of the continent’s species that are used in traditional medicine lags behind China and India in terms of ‘internationally recognised phytochemical standards’. This book not only redresses this issue, but is the first to include plants from the south, north, east and west of Africa. In South Africa alone, there are over 3000 species that are used for medicinal purposes, with over 70% of the Black African population relying on medicinal flora as part of their primary health care and 84% of clinic patients confirming their preference for wildcrafted raw herbal medicines in spite of having access to western health care.1 Both traditional and Western healing systems are used – many educated Black people retain traditional practices as they are regarded as an important cultural link to their predecessors. Throughout Africa, plants are viewed as contributors to health; they are also used in religious and cultural ceremonies. The African continent has a rich biodiversity and this is matched by a commensurate proliferation of medicinal plant use. So the trade of medicinal plants in Africa is substantial, but largely informal, and consists of plant collectors as well as traders at herbal markets.Publishers' versio

cDNA-AFLP-based transcript profiling for genome-wide expression analysis of jasmonate-treated plants and plant cultures

cDNA-AFLP is a commonly used, robust, and reproducible tool for genome-wide expression analysis in any species, without requirement of prior sequence knowledge. Quantitative expression data are generated by gel-based visualization of cDNA-AFLP fingerprints obtained by selective PCR amplification of subsets of restriction fragments from a double-stranded cDNA template. Differences in gene expression levels across the samples are reflected in different band intensities on the high-resolution polyacrylamide gels. The differentially expressed genes can be identified by direct sequencing of re-amplified cDNA-AFLP tags purified from the gels. The cDNA-AFLP technique is especially useful for profiling of transcriptional responses of jasmonate-treated plants or plant (tissue) cultures and the discovery of jasmonate-responsive genes

Antibacterial, antioxidant and tyrosinase-inhibition activities of pomegranate fruit peel methanolic extract

The original publication is available at http://www.biomedcentral.com/1472-6882/12/200Publication of this article was funded by the Stellenbosch University Open Access Fund.Abstract Background This study evaluated, using in vitro assays, the antibacterial, antioxidant, and tyrosinase-inhibition activities of methanolic extracts from peels of seven commercially grown pomegranate cultivars. Methods Antibacterial activity was tested on Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Klebsiella pneumonia) using a microdilution method. Several potential antioxidant activities, including radical-scavenging ability (RSA), ferrous ion chelating (FIC) and ferric ion reducing antioxidant power (FRAP), were evaluated. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin and kojic acid as positive controls. Furthermore, phenolic contents including total flavonoid content (TFC), gallotannin content (GTC) and total anthocyanin content (TAC) were determined using colourimetric methods. HPLC-ESI/MSn analysis of phenolic composition of methanolic extracts was also performed. Results Methanolic peel extracts showed strong broad-spectrum activity against Gram-positive and Gram-negative bacteria, with the minimum inhibitory concentrations (MIC) ranging from 0.2 to 0.78 mg/ml. At the highest concentration tested (1000 μg/ml), radical scavenging activities were significantly higher in Arakta (83.54%), Ganesh (83.56%), and Ruby (83.34%) cultivars (P< 0.05). Dose dependent FIC and FRAP activities were exhibited by all the peel extracts. All extracts also exhibited high inhibition (>50%) against monophenolase and diphenolase activities at the highest screening concentration. The most active peel extract was the Bhagwa cultivar against monophenolase and the Arakta cultivar against diphenolase with IC50 values of 3.66 μg/ml and 15.88 μg/ml, respectively. High amounts of phenolic compounds were found in peel extracts with the highest and lowest total phenolic contents of 295.5 (Ganesh) and 179.3 mg/g dry extract (Molla de Elche), respectively. Catechin, epicatechin, ellagic acid and gallic acid were found in all cultivars, of which ellagic acid was the most abundant comprising of more than 50% of total phenolic compounds detected in each cultivar. Conclusions The present study showed that the tested pomegranate peels exhibited strong antibacterial, antioxidant and tyrosinase-inhibition activities. These results suggest that pomegranate fruit peel could be exploited as a potential source of natural antimicrobial and antioxidant agents as well as tyrosinase inhibitors.Publishers' Versio

Community harvesting of trees used as dens and for food by the tree hyrax (Dendrohyrax arboreus) in the Pirie forest, South Africa

CITATION: Opperman, E. J., Cherry, M. I. & Makunga, N. P. 2018. Community harvesting of trees used as dens and for food by the tree hyrax (Dendrohyrax arboreus) in the Pirie forest, South Africa. Koedoe, 60(1):a1481, doi:10.4102/koedoe.v60i1.1481.The original publication is available at https://koedoe.co.zaPublication of this article was funded by the Stellenbosch University Open Access Fund.Forests in South Africa are harvested by local communities for multiple purposes and this affects the animals that inhabit them. The tree hyrax (Dendrohyrax arboreus) has a restricted distribution and utilises various tree species as dens and a source of food. In this article, we determined, through a series of interviews in the communities surrounding the Pirie forest, which plant species are harvested by local people and whether these overlap with those used by the tree hyrax. In addition, we determined the extent to which tree hyraxes are hunted by these communities. Of the trees used by the hyrax as dens in the Pirie forest, Afrocarpus falcatus, Schotia latifolia, Andrachne ovalis, Teclea natalensis and Apodytes dimidiata are important resources for local communities. But as these are harvested at relatively low levels, it is unlikely that current harvesting has a large impact on the tree hyrax. Opportunistic hunting occurs, but the hyrax is not targeted by hunters. Very limited commercial harvesting of A. falcatus has been taking place in the Pirie forest since 1975, but its impact on the hyrax population, although undetermined, is also unlikely to be high. We recommend that the Pirie forest tree hyrax population should be monitored by forest management in order to ascertain the impact of both commercial and community harvesting over the past quarter-century.https://koedoe.co.za/index.php/koedoe/article/view/1481Publisher's versio

The implication of chemotypic variation on the anti-oxidant and anti-cancer activities of sutherlandia frutescens (L.) R.Br. (Fabaceae) from different geographic locations

CITATION: Zonyane, S., et al. 2020. The implication of chemotypic variation on the anti-oxidant and anti-cancer activities of sutherlandia frutescens (L.) R.Br. (Fabaceae) from different geographic locations. Antioxidants, 9(2):152, doi:10.3390/antiox9020152.The original publication is available at http://www.mdpi.comPublication of this article was funded by the Stellenbosch University Open Access FundExtracts of Sutherlandia frutescens (cancer bush) exhibit considerable qualitative and quantitative chemical variability depending on their natural wild origins. The purpose of this study was thus to determine bioactivity of extracts from different regions using in vitro antioxidant and anti-cancer assays. Extracts of the species are complex and are predominantly composed of a species-specific set of triterpene saponins (cycloartanol glycosides), the sutherlandiosides, and flavonoids (quercetin and kaempferol glycosides), the sutherlandins. For the Folin-Ciocalteu phenolics test values of 93.311 to 125.330 mg GAE/g DE were obtained. The flavonoids ranged from 54.831 to 66.073 mg CE/g DE using the aluminum chloride assay. Extracts from different sites were also assayed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging method and ferric reducing anti-oxidant power (FRAP) methods. This was followed by an in vitro Cell Titer-Glo viability assay of various ecotypes using the DLD-1 colon cancer cell line. All test extracts displayed anti-oxidant activity through the DPPH• radical scavenging mechanism, with IC50 values ranging from 3.171 to 7.707 µg·mL−1. However, the degree of anti-oxidant effects differed on a chemotypic basis with coastal plants from Gansbaai and Pearly Beach (Western Cape) exhibiting superior activity whereas the Victoria West inland group from the Northern Cape, consistently showed the weakest anti-oxidant activity for both the DPPH• and FRAP methods. All extracts showed cytotoxicity on DLD-1 colon cancer cells at the test concentration of 200 µg·mL−1 but Sutherlandia plants from Colesburg (Northern Cape) exhibited the highest anti-cancer activity. These findings confirm that S. frutescens specimens display variability in their bioactive capacities based on their natural location, illustrating the importance of choosing relevant ecotypes for medicinal purposes.https://www.mdpi.com/2076-3921/9/2/152Publisher's versio

Comparative cardio and developmental toxicity induced by the popular medicinal extract of Sutherlandia frutescens (L.) R.Br. detected using a zebrafish Tuebingen embryo model

CITATION: Chen, L., et al. 2018. Comparative cardio and developmental toxicity induced by the popular medicinal extract of Sutherlandia frutescens (L.) R.Br. detected using a zebrafish Tuebingen embryo model. BMC Complementary and Alternative Medicine, 18:273, doi:10.1186/s12906-018-2303-9.The original publication is available at https://bmccomplementalternmed.biomedcentral.comBackground: Sutherlandia frutescens is one of the most promising commercialized, indigenous and medicinal plants of South Africa that is used as an immune-booster, and a traditional treatment for cancer. However, few studies report on its toxicology and dosage in vivo. There is still room to better understand its cytotoxicity effects in animal systems. Methods: We prepared two extracts, one with 80% (v/v) ethanol, and the other, with water. Both were studied to determine the maximum tolerable concentration when extracts were applied at 0 to 200 μg/ml to a Tuebingen zebrafish embryo line. The development of zebrafish embryos after 24 h post fertilization (hpf) was studied. A concentration range of 5 μg/ml to 50 μg/ml was then chosen to monitor the ontological development of cultured embryos. A liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method was used to study the differences of the two experimental extracts. Chemical variation between the extracts was illustrated using chemometrics. Results: Both extracts led to bleeding and pericardial cyst formation when applied at high concentrations to the zebrafish embryo culture. Chronic teratogenic toxicities, leading to pericardial edema, yolk sac swelling, and other abnormal developmental characteristics, were detected. The aqueous extracts of S. frutescens were less toxic to the larvae than the ethanol extracts, validating preference for aqueous preparations when used in traditional medicine. Chemical differences between the water extracts and alcoholic extracts were analysed using LC-MS/MS. A supervised metabolomics approach, targeting the sutherlandiosides and sutherlandins using orthogonal partial least squares-discriminant analysis (OPLS-DA), illustrated that sutherlandiosides were the main chemical features that can be used to distinguish between the two extracts, despite the extracts being highly similar in their chemical constituents. Conclusion: The water extract caused less cytotoxic and abnormal developmental effects compared to the ethanolic extract, and, this is likely due to differences in concentrations of extracted chemicals rather than the chemical profile per se. This study provides more evidence of cytotoxicity effects linked to S. frutescens using the zebrafish embryo bioassay as a study tool.https://bmccomplementalternmed.biomedcentral.com/articles/10.1186/s12906-018-2303-9Publisher's versio