scholarly journals Electrochemical Screening and Evaluation of Lamiaceae Plant Species from South Africa with Potential Tyrosinase Activity

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1035 ◽  
Author(s):  
Ninon Etsassala ◽  
Tesfaye Waryo ◽  
Olugbenga Popoola ◽  
Adewale Adeloye ◽  
Emmanuel Iwuoha ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Kojic Acid ◽  
Screening Method ◽  
Tyrosinase Activity ◽  
Minimum Concentration ◽  
Methanolic Extracts ◽  
Fast Screening ◽  
African Flora ◽  
Tyrosinase Inhibitors

South Africa is a country with a wide variety of plants that may contain excellent anti-tyrosinase inhibitors. With wide applications in cosmetics, pharmaceuticals and food products, tyrosinase inhibitors have received very special attention in the recent past as a way of preventing the overproduction of melanin in epidermal layers which often over time brings detrimental effects on human skin. In this present study, a fast screening method using a cyclic voltammetry technique was applied in the evaluation of methanolic extracts of twenty-five species of plants from the Lamiaceae family for anti-tyrosinase activity. Among these plants, those that showed a fast current inhibition rate at a minimum concentration when compared to a kojic acid standard were classified as having the greatest anti-tyrosinase activity. These include Salvia chamelaeagnea, S. dolomitica, Plectranthus ecklonii, P. namaensis, and P. zuluensis. The results presented herein focused in particular on providng firsthand information for further extensive research and exploration of natural product materials with anti-tyrosinase activity from South African flora for use in cosmetics, skin care and medicinal treatments.

Maireana brevifolia (Chenopodiaceae: Camphorosmeae), a new naturalized alien plant species in South Africa

Bothalia ◽  
2011 ◽  
Vol 41 (2) ◽  
pp. 235-238 ◽  
Author(s):  
L. Mucina ◽  
D. A. Snijman
Keyword(s):  
South Africa ◽  
Alien Species ◽  
South African ◽  
Plant Species ◽  
Western Cape ◽  
Alien Plant Species ◽  
The South ◽  
Alien Plant ◽  
African Flora

We describe and discuss the distribution of a new, naturalized alien species, Maireana brevifolia (R.Br.) Paul G.Wilson (Chenopodiaceae), a native of Australia, in the western regions of South Africa. First discovered near Worcester, Western Cape in 1976, the species is now established in disturbed karoo shrubby rangelands, along dirt roads and on saline alluvia, from northern Namaqualand to the western Little Karoo. In the South African flora, M. brevifolia is most easily confused with the indigenous Bassia salsoloides (Fenzl) A.J.Scott, from which it is distinguished by the flat to cup-shaped and almost glabrous perianth with woolly-ciliate lobes, and the hardened and winged fruiting perianth.

scholarly journals Novel Anti-Melanogenic Compounds, (Z)-5-(Substituted Benzylidene)-4-thioxothiazolidin-2-one Derivatives: In Vitro and In Silico Insights

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4963
Author(s):  
Heejeong Choi ◽  
Il Young Ryu ◽  
Inkyu Choi ◽  
Sultan Ullah ◽  
Hee Jin Jung ◽  
...  
Keyword(s):  
Active Site ◽  
Kojic Acid ◽  
Docking Simulation ◽  
Tyrosinase Activity ◽  
In Vitro Assays ◽  
Mushroom Tyrosinase ◽  
Tyrosinase Inhibitors ◽  
Melanin Contents ◽  
Human Tyrosinase

To confirm that the β-phenyl-α,β-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the β-phenyl-α,β-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC50 = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies’ results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors.

Plants as a Promising Reservoir of Tyrosinase Inhibitors

2020 ◽  
Vol 17 ◽  
Author(s):  
Rabia Riaz ◽  
Paolo Zucca ◽  
Antonio Rescigno ◽  
Stefania Peddio ◽  
Rahman Shah Zaib Saleem ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Secondary Metabolites ◽  
Biosynthetic Pathway ◽  
Kojic Acid ◽  
Structure Optimization ◽  
Tyrosinase Activity ◽  
Plant Origin ◽  
Current Review ◽  
Tyrosinase Inhibitors ◽  
Mechanistic Investigations

Abstract:: The process of melanogenesis, that takes place in the melanocytes of the epidermis, leads to hyperpigmentation. The biosynthetic pathway for production of melanin involves the enzyme tyrosinase that has been an attractive target for cosmaceutical research. Numerous synthetic, semisynthetic and natural, especially plant-based, inhibitors of tyrosinase have been reported in the literature. In plants, the secondary metabolites like flavonoids, chalcones, stilbenes, tannins, hydroquinone and kojic acid, etc... have been shown to possess the anti-tyrosinase activity. In the current review, we have covered the progress in this sphere that would be useful for not only further mechanistic investigations but also for the optimization of the structure of the metabolites for improved activity and selectivity. Thus the review presents a comprehensive report on tyrosinase inhibitors of plant origin reported in the extract form or as isolated compounds. Huge gap has been found between research and industry due to inconsistent pursual of the potent plant based extracts. There is a need to completely evaluate the extracts for structure optimization using molecular docking and evaluation of the safety inorder to benefit the industry with non toxic biological friendly products through invivo and exvivo optimization.

scholarly journals Inhibitory and Acceleratory Effects ofInonotus obliquuson Tyrosinase Activity and Melanin Formation in B16 Melanoma Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Zheng-Fei Yan ◽  
Yang Yang ◽  
Feng-Hua Tian ◽  
Xin-Xin Mao ◽  
Yu Li ◽  
...  
Keyword(s):  
Nicotinic Acid ◽  
Therapeutic Agent ◽  
Kojic Acid ◽  
Ethyl Acetate Extract ◽  
Tyrosinase Activity ◽  
Mushroom Tyrosinase ◽  
Melanin Content ◽  
Inonotus Obliquus ◽  
Nmr Data ◽  
Tyrosinase Inhibitors

The aim of the present study is to preliminarily investigate the antimelanogenesis effect ofInonotus obliquusextracts by cell-free mushroom tyrosinase assay. It was found that petroleum ether and n-butanol extracts might contain unknown potential tyrosinase inhibitors, while its ethyl acetate extract might contain some unknown accelerators. Six compounds were isolated and their structures were identified by interpretation of NMR data and nicotinic acid was first discovered inInonotus obliquus. In cells testing, betulin and trametenolic acid decreased tyrosinase activity and melanin content, while inotodiol and lanosterol significantly increased tyrosinase activity and melanin content, showing anAC⁡50of 9.74 and 8.43 μM, respectively. Nicotinie acid, 3β,22,25-trihydroxy-lanosta-8-ene, had a little or no effect on tyrosinase. Betulin exhibited a mode of noncompetitive inhibition with aKI=KISof 0.4 μM on tyrosinase activity showing an IC50of 5.13 μM and being more effective than kojic acid (6.43 μM), and trametenolic acid exhibited a mode of mixed inhibition with aKIof 0.9 μM,KISof 0.5 μM, and anIC50of 7.25 μM. We proposed betulin and trametenolic acid as a new candidate of potent tyrosinase inhibitors and inotodiol and lanosterol as accelerators that could be used as therapeutic agent.

Reframing Xenophobia in South Africa as Colour-Blind: The Limits of the Afro Phobia Thesis

2020 ◽  
Vol 17 (3) ◽  
pp. 433-444
Author(s):  
Amanuel Isak Tewolde
Keyword(s):  
South Africa ◽  
South African ◽  
Analytical Framework ◽  
Conflict Theory ◽  
Black African ◽  
South Africans ◽  
Theoretical Perspectives ◽  
Online Newspaper ◽  
Close Proximity ◽  
Realistic Conflict Theory

Many scholars and South African politicians characterize the widespread anti-foreigner sentiment and violence in South Africa as dislike against migrants and refugees of African origin which they named ‘Afro-phobia’. Drawing on online newspaper reports and academic sources, this paper rejects the Afro-phobia thesis and argues that other non-African migrants such as Asians (Pakistanis, Indians, Bangladeshis and Chinese) are also on the receiving end of xenophobia in post-apartheid South Africa. I contend that any ‘outsider’ (White, Asian or Black African) who lives and trades in South African townships and informal settlements is scapegoated and attacked. I term this phenomenon ‘colour-blind xenophobia’. By proposing this analytical framework and integrating two theoretical perspectives — proximity-based ‘Realistic Conflict Theory (RCT)’ and Neocosmos’ exclusivist citizenship model — I contend that xenophobia in South Africa targets those who are in close proximity to disadvantaged Black South Africans and who are deemed outsiders (e.g., Asian, African even White residents and traders) and reject arguments that describe xenophobia in South Africa as targeting Black African refugees and migrants.

Region of Birth and Child Mortality among Black Migrants to South Africa: Is there a foreign-born advantage?

2016 ◽  
Vol 13 (3) ◽  
pp. 359-376 ◽  
Author(s):  
Tiffany L Green ◽  
Amos C Peters
Keyword(s):  
South Africa ◽  
South African ◽  
Child Mortality ◽  
Southern Africa ◽  
Strong Relationship ◽  
Developed Countries ◽  
Black Immigrants ◽  
Foreign Born ◽  
Region Of Origin ◽  
Child Deaths

Much of the existing evidence for the healthy immigrant advantage comes from developed countries. We investigate whether an immigrant health advantage exists in South Africa, an important emerging economy.  Using the 2001 South African Census, this study examines differences in child mortality between native-born South African and immigrant blacks.  We find that accounting for region of origin is critical: immigrants from southern Africa are more likely to experience higher lifetime child mortality compared to the native-born population.  Further, immigrants from outside of southern Africa are less likely than both groups to experience child deaths.  Finally, in contrast to patterns observed in developed countries, we detect a strong relationship between schooling and child mortality among black immigrants.

Some Reflections on Reparation in Post-Apartheid South Africa, using a Couple Therapy Intervention as a Microcosm of South African Society

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Andrea Hill ◽  
Sylvia Poss
Keyword(s):  
South Africa ◽  
South African ◽  
Couple Therapy ◽  
South African Society ◽  
Depressive Position ◽  
Central Hypothesis ◽  
Transference And Countertransference ◽  
Constructive Engagement ◽  
The Impact ◽  
Therapy Intervention

The paper addresses the question of reparation in post-apartheid South Africa. The central hypothesis of the paper is that in South Africa current traumas or losses, such as the 2008 xenophobic attacks, may activate a ‘shared unconscious phantasy’ of irreparable damage inflicted by apartheid on the collective psyche of the South African nation which could block constructive engagement and healing. A brief couple therapy intervention by a white therapist with a black couple is used as a ‘microcosm’ to explore this question. The impact of an extreme current loss, when earlier losses have been sustained, is explored. Additionally, the impact of racial difference on the transference and countertransference between the therapist and the couple is explored to illustrate factors complicating the productive grieving and working through of the depressive position towards reparation.

The Final ‘Thank You’

Derrida Today ◽  
2010 ◽  
Vol 3 (1) ◽  
pp. 21-36
Author(s):  
Grant Farred
Keyword(s):  
South Africa ◽  
South African ◽  
Jacques Derrida ◽  
Political Transition ◽  
The Other ◽  
World Cup ◽  
The Core ◽  
Nelson Mandela ◽  
Black President ◽  
The Moment

‘The Final “Thank You”’ uses the work of Jacques Derrida and Friedrich Nietzsche to think the occasion of the 1995 rugby World Cup, hosted by the newly democratic South Africa. This paper deploys Nietzsche's Zarathustra to critique how a figure such as Nelson Mandela is understood as a ‘Superman’ or an ‘Overhuman’ in the moment of political transition. The philosophical focus of the paper, however, turns on the ‘thank yous’ exchanged by the white South African rugby captain, François Pienaar, and the black president at the event of the Springbok victory. It is the value, and the proximity and negation, of the ‘thank yous’ – the relation of one to the other – that constitutes the core of the article. 1

Apartheid Aesthetics and Insignificant Art

2016 ◽  
Vol 33 (1) ◽  
pp. 45-69
Author(s):  
Stephanus Muller
Keyword(s):  
South Africa ◽  
Secondary School ◽  
South African ◽  
Cultural Production ◽  
Art Songs ◽  
Cultural Significance ◽  
European Culture ◽  
Small House ◽  
The Rich ◽  
Selection Of

Stephanus Le Roux Marais (1896−1979) lived in Graaff-Reinet, South Africa, for nearly a quarter of a century. He taught music at the local secondary school, composed most of his extended output of Afrikaans art songs, and painted a number of small landscapes in the garden of his small house, nestled in the bend of the Sunday’s River. Marais’s music earned him a position of cultural significance in the decades of Afrikaner dominance of South Africa. His best-known songs (“Heimwee,” “Kom dans, Klaradyn,” and “Oktobermaand”) earned him the local appellation of “the Afrikaans Schubert” and were famously sung all over the world by the soprano Mimi Coertse. The role his ouevre played in the construction of a so-called European culture in Africa is uncontested. Yet surprisingly little attention has been paid to the rich evocations of landscape encountered in Marais’s work. Contextualized by a selection of Marais’s paintings, this article glosses the index of landscape in this body of cultural production. The prevalence of landscape in Marais’s work and the range of its expression contribute novel perspectives to understanding colonial constructions of the twentieth-century South African landscape. Like the vast, empty, and ancient landscape of the Karoo, where Marais lived during the last decades of his life, his music assumes specificity not through efforts to prioritize individual expression, but through the distinct absence of such efforts. Listening for landscape in Marais’s songs, one encounters the embrace of generic musical conventions as a condition for the construction of a particular national identity. Colonial white landscape, Marais’s work seems to suggest, is deprived of a compelling musical aesthetic by its very embrace and desired possession of that landscape.

ROLE OF LIBRARIANS IN TEACHING INFORMATION LITERACY IN ZIMBABWEAN AND SOUTH AFRICAN UNIVERSITIES: A COMPARATIVE STUDY

Mousaion ◽  
2016 ◽  
Vol 33 (1) ◽  
pp. 23-42 ◽  
Author(s):  
Tinashe Mugwisi
Keyword(s):  
South Africa ◽  
South African ◽  
Information Literacy ◽  
Ethical Issues ◽  
University Libraries ◽  
Information And Communications Technologies ◽  
Communications Technologies ◽  
Information Skills ◽  
The University

Information and communications technologies (ICTs) and the Internet have to a large extent influenced the way information is made available, published and accessed. More information is being produced too frequently and information users now require certain skills to sift through this multitude in order to identify what is appropriate for their purposes. Computer and information skills have become a necessity for all academic programmes. As libraries subscribe to databases and other peer-reviewed content (print and electronic), it is important that users are also made aware of such sources and their importance. The purpose of this study was to examine the teaching of information literacy (IL) in universities in Zimbabwe and South Africa, and the role played by librarians in creating information literate graduates. This was done by examining whether such IL programmes were prioritised, their content and how frequently they were reviewed. An electronic questionnaire was distributed to 12 university libraries in Zimbabwe and 21 in South Africa. A total of 25 questionnaires were returned. The findings revealed that IL was being taught in universities library and non-library staff, was compulsory and contributed to the term mark in some institutions. The study also revealed that 44 per cent of the total respondents indicated that the libraries were collaborating with departments and faculty in implementing IL programmes in universities. The study recommends that IL should be an integral part of the university programmes in order to promote the use of databases and to guide students on ethical issues of information use.

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