Synthesis, characterization and biological evaluation of benzo[d]isothiazole ring systems, fused to nitrogen heterocycles

We have developed a simple and efficient synthetic route, starting from easily available starting materials, to the novel ring system benzo[4,5]isothiazolo[2,3-a]pyrazine-6,6-dioxide. A series of chalcones were synthesized which were subsequently reacted with chlorosulphonic acid to generate the chalcone sulphonyl chlorides. The chalcone sulphonyl chlorides were then treated with bromine to generate the dibromo chalcone sulphonyl chlorides. These were subsequently reacted with 1,2-diaminopropane and 2-methyl-1,2-diaminopropane in boiling ethanol resulting in compounds 22-30 and 31-39 respectively, in 12-80% yields. The products were recrystallized using appropriate solvents and were characterized by spectral analysis, melting point, infrared spectroscopy, 1H and 13C NMR and mass spectrometry. In addition to spectral analysis, X-ray crystallography data was also collected for compound 31, confirming the definitive structure of the synthesized compounds. The reaction is believed to occur by the domino effect. The less sterically hindered amino group reacts with the sulphonyl chloride group to from the sulphonamide. The sulphonamide group then reacts with the β-carbon by nucleophilic substitution to form the isothiazole ring system and then the second amino group reacts with the α-carbon with elimination of the bromide ion to form the pyrazine ring. X-Ray data confirmed the structure of compound 31 and clearly confirmed that the dimethyl groups were on the carbon atom adjacent to the NH group. The synthesized compounds have been screened for potential antimicrobial properties against Bacillus subtilis, Escherichia coli, Proteus hauseri and Staphylococcus aureus. Compound 27 displayed antibacterial activity against B. subtilis at a concentration of 416 µgml-1. Compounds 23, 24, 25, 26, 34, 35 and 36 all showed activity against B. subtilis at a concentration of 6.67 mg ml-1, generally the compounds synthesized displayed activity at the highest concentration and were more active against gram positive bacteria. A simple, efficient method for the synthesis of the novel benzo[4,5]isothiazolo[2,3-a]pyrazine-6,6-dioxide ring system which should be applicable to generate other fused pyrazine ring systems of biological interest has been developed

Dance/movement therapy and the psychosocial well-being of learners with visual impairment : a case study

This transformative mixed method case study investigated the influence of Dance/Movement Therapy (DMT) as a physical activity on the psychosocial well-being of learners with the visual impairment of low vision in a school for the visually impaired in Gauteng. A study of existing literature indicated a series of psychological and social dynamics which shape a person with low vision’s self-esteem and subsequent psychosocial well-being. A DMT intervention programme was designed accordingly. Through a filtering process, six female, adolescent participants with possible self-esteem challenges were identified. These participants completed the Rosenberg Self-Esteem Scale (RSES) prior to taking part in the eight 60 minute sessions of the DMT intervention programme. The RSES was completed again post-intervention. Results indicated an increase in the self-esteem levels of all six participants to various degrees. Qualitative measures, including observations schedules, process notes in a researcher’s diary and participant reflections in DMT Journey Journals supported quantitative findings.Mokgwa o, o o tswakantseng was diphetogo wa dithuto o batlisitse thotloetso ya Motantsho/ Motsamao wa pholo jaaka ikatiso ya mmele mo go itekanelong/ boitekanelong jwa tlhaloganyo ya barutwana ba ba sa boneng sentle mo sekolong sa bana ba ba sa boneng mo kgaolong/ porofinsi ya Gauteng. Dipatlisiso tsa dikwalo tse di leng teng di supa tatelano ya tlhaloganyo le loago e e farologaneng e e bopang go tlhoka go itshepa ga motho yo a neng le pono e e bokowa le tlhaloganyo le botho jwa gagwe. Ka jalo lenaneo la tseregano la DMT le ile la diriwa. Ka mokgwa wa go tlhopha, makgarebe a baša a le marataro, a a nang le mathata a go tlhoka boitshepo a ile a tlhopiwa. Ba tsaya karolo ba ba ile ba tlatsa kgotsa ba konosetsa selekano sa boitshepo sa Rosenberg (RSES) pele ba tsaya karolo mo go lenaneong la dikarolo tse robedi tsa metsotso e le 60 ya tserenanyo ya DMT. Morago ga tsereganyo selekano se ile sa tladiwa gape. Dipholo di supile kgolo e e farologaneng ya boitshepo mo go batsayakarolo botlhe ba le barataro. Ditekanyetso tsa boleng, tse di akaretsang lenaneo la ditlhokomediso, dintlha tsa tiriso tsa letsatsi le letsatsi mmatlisisi le maikutlo a batsaakarolo di totobatsa dipholo tse.dintsi mo dikwalong tsa tsela ya DMT.Die invloed van die fisiese aktiwiteit van Dans/Bewegingsterapie op die psigososiale welstand van leerders met lae visie in ‘n skool vir gesiggestremde leerders in Gauteng is deur hierdie transformatiewe gemengde metode gevallestudie ondersoek. ‘n Studie van bestaande literatuur het ‘n reeks sielkundige en sosiale faktore wat die persoon met lae visie se self-beeld en gevolglike psigososiale welstand vorm uitgelig en ‘n Dans/Bewegingsterapie intervensieprogram is daarvolgens ontwerp. Ses vroulike adolesente deelnemers met moontlike self-beeld uitdagings is deur middel van ‘n filtreringsproses geïdentifiseer. Hierdie deelnemers het die Rosenberg Self-Esteem Scale (RSES) voor en na hulle deelname aan 8 60 minute sessies van die Dans/Bewegingsterapie intervensieprogram voltooi. Resultate het onderskeidelik ‘n toename in selfbeeldvlakke van al ses deelnemers tot in verskillende mates aangedui. Kwalitatiewe maatstawwe soos die gebruik van obserwasieskedules, prosesnotas in ‘n navorserdagboek en deelnemers se refleksies in hulle persoonlike Dans/Bewegingsterapie joernale het die kwantitatiewe bevindinge ondersteun.Psychology of EducationM. Ed. (School Guidance and Counselling

In Silico and In Vitro Investigation into the Next Generation of New Psychoactive Substances

New Psychoactive Substances (NPS) were designed to be legal alternatives to existing established recreational drugs. They have fast become a very popular and up until 2016, NPS were legal, cheap and freely accessible via the internet and high street “head shops”. The rapid expansion in the number of these drugs has reached epidemic proportions, whereby hundreds of NPS have been developed and sold within the last five-year period. As NPS are synthesized in clandestine laboratories there is little to no control in the manufacture, dosage and packaging of these drugs. The public health risks posed by these drugs are therefore far-reaching. Fatalities and severe adverse reactions associated with these compounds have become an ongoing challenge to healthcare services, primarily because these drugs have not previously been abused and therefore there is little pharmacological information available regarding NPS. There are a number of different biological receptors that are implicated in the effects of NPS and the mechanism of action for the majority of these drugs is still largely unknown. It is of great importance to try and establish an understanding of how various classes of NPS interact on a molecular level. In this thesis, structure-based and ligand-based in Silico methodologies were employed to gain a better understanding of how NPS may interact with monoamine transporters (MAT). Key findings included both molecular docking studies and a number of robust and predictive QSAR models for the dopamine and serotonin transporters provided insight into how promiscuity of NPS between the different MAT isoforms could arise. In addition, pharmacophore models were generated to identify chemical entities that were structurally dissimilar to known existing NPS that had the potential to interact with the cannabinoid 1 receptor (CB1) and hence were hypothesised could elicit similar biological responses to known potent synthetic cannabinoids. Thirteen of these compounds were identified and carried forward for in vitro and ex vivo analyses, where preliminary results have shown that two compounds activate the CB1 receptor. Further optimisation of these compounds could yield a novel SC scaffold that was previously unseen. Additionally, the compounds identified and the methodology employed in the generation of these new chemical scaffolds could be used to guide Early Warning Systems (EWS) and facilitate law enforcement with respect to emergent NPS

Understanding the contribution of individual amino acid residues in the binding of psychoactive substances to monoamine transporters

© 2020 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Omega, Vol 5, Iss 28, p.17223–17231, after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsomega.0c01370.The development of point-of-care detection methodologies for biologically relevant analytes that can facilitate rapid and appropriate treatment is at the forefront of current research efforts and interests. Among the various approaches, those exploiting host–guest chemistries where the optoelectronic signals of the chemical sensor can be modulated upon interaction with the target analyte are of particular interest. In aiding their rational development, judicious selection of peripheral functional groups anchored to core motifs with desired properties is critical. Herein, we report an in-depth investigation of the binding of three psychoactive substances, MDAI, mexedrone, and phenibut, to receptors of the monoamine transporters for dopamine, norepinephrine, and serotonin, particularly focusing on the role of individual amino acid residues. We first evaluated the conformational flexibility of the ligands by comparing their experimentally determined crystal structure geometries to those optimized by means of quantum as well as molecular mechanics, observing significant changes in the case of phenibut. Molecular docking studies were employed to identify preferential binding sites by means of calculated docking scores. In all cases, irrespective of the monoamine transporter, psychoactive substances exhibited preferred interaction with the S1 or central site of the proteins, in line with previous studies. However, we observed that experimental trends for their relative potency on the three transporters were only reproduced in the case of mexedrone. Subsequently, to further understand these findings and to pave the way for the rational development of superior chemical sensors for these substances, we computed the individual contributions of each nearest neighbor amino acid residue to the binding to the target analytes. Interestingly, these results are now in agreement with those experimental potency trends. In addition, these observations were in all cases associated with key intermolecular interactions with neighboring residues, such as tyrosine and aspartic acid, in the binding of the ligands to the monoamine transporter for dopamine. As a result, we believe this work will be of interest to those engaged in the rational development of chemical sensors for small molecule analytes as well as to those interested in the use of computational approaches to further understand protein–ligand interactions.Peer reviewe

What drives grassland-forest boundaries? Assessing fire and frost effects on tree seedling survival and architecture

1. Fire and frost represent two major hurdles for the persistence of trees in open grassy biomes and have both been proposed as drivers of grassland-forest boundaries in Africa. 2. We assess the response of young tree seedlings, which represent a vulnerable stage in tree recruitment, to traumatic fire and frost disturbances. 3. In a greenhouse experiment, we investigated how seedling traits predicted survival and resprouting ability in response to fire versus frost; we characterized survival strategies of seedlings in response to the two disturbances, and we documented how the architecture of surviving seedlings is affected by fire versus frost injury. 4. Survival rates were similar under both treatments. However, different species displayed different levels of sensitivity to fire and frost. Seedling survival was higher for older seedlings and seedlings with more basal leaves. Survivors of a fire event lost more biomass than the survivors of a frost event. However, the architecture of recovered fire- and frost-treated seedlings was mostly similar. Seedlings that recovered from fire and frost treatments were often shorter than those that had not been exposed to any disturbance, with multiple thin branches, which may increase vulnerability to the next frost or fire event. 5. Synthesis. Fire caused more severe aboveground damage compared with a single frost event, suggesting that fire is an important driver of tree distribution in these open grassland systems. However, the impact of repeated frost events may be equally severe and needs to be investigated. Also, woody species composition may be influenced by phenomena that affect the timing and frequency of seedling exposure to damage, as mortality was found to be dependent on seedling age. Therefore, changes in fire regime and climate are likely to result in changes in the composition and the structure of the woody components of these systems.The National Research Foundation and the University of the Witwatersrand, Johannesburg.http://www.ecolevol.orgpm2021Plant Production and Soil Scienc

The Psychonauts’ Benzodiazepines; Quantitative Structure-Activity Relationship (QSAR) Analysis and Docking Prediction of Their Biological Activity

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Designer benzodiazepines (DBZDs) represent a serious health concern and are increasingly re-ported in polydrug consumption-related fatalities. When new DBZDs are identified, very limited information is available on their pharmacodynamics. Here, computational models (e.g., quantita-tive structure-activity relationship/QSAR and Molecular Docking) were used to analyse DBZDs identified online by an automated web crawler (NPSfinder®) and to predict their possible activi-ty/affinity on the gamma-aminobutyric acid receptors (GABA-ARs). The computational software MOE was used to calculate 2D QSAR models, perform docking studies on crystallised GABA-A receptors (6HUO, 6HUP) and generate pharmacophore queries from the docking conformational results. 101 DBZDs were identified online by NPSfinder®. The validated QSAR model predicted high biological activity values for 41% of these DBDZs. These predictions were supported by the docking studies (good binding affinity) and the pharmacophore modelling confirmed the im-portance of the presence and location of hydrophobic and polar functions identified by QSAR. This study confirms once again the importance of web-based analysis in the assessment of drug scenarios (DBZDs), and how computational models could be used to acquire fast and reliable in-formation on biological activity for index novel DBZDs, as preliminary data for further investiga-tions.Peer reviewe

The influence of oily vehicle composition and vehicle-membrane interactions on the diffusion of model permeants across barrier membranes

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)In many instances, one or more components of a pharmaceutical or cosmetic formulation is an oil. The aims of this study were two-fold. First, to examine the potential of preferential uptake of one oily vehicle component over another into a model barrier membrane (silicone) from blended vehicles (comprising two from the common excipients isohexadecane (IHD), hexadecane (HD), isopropyl myristate (IPM), oleic acid (OA) and liquid paraffin). Second, to study the effect of membrane-vehicle interactions on the diffusion of model permeants (caffeine (CF), methyl paraben (MP) and butyl paraben (BP)) from blended vehicles. Selective sorption and partition of some oils (especially IHD and IPM) at the expense of other oils (such as OA) was demonstrated to take place. For example, the membrane composition of IHD was enriched compared to a donor solution of IHDOA: 41%, 63% and 82% IHD, compared to donor solution composition of 25%, 50% and 75% IHD, respectively. Pre-soaking the membrane in IHD, HD or LP, rather than phosphate buffer, enhanced the flux of MP through the membrane by 2.6, 1.7 and 1.3 times, respectively. The preferential sorption of individual oil components from mixtures altered the barrier properties of silicone membrane, and enhanced the permeation of CF, MP and BP, which are typically co-formulated in topical products.Peer reviewedFinal Published versio

Multivariate analytical approaches to identify key molecular properties of vehicles, permeants and membranes that affect permeation through membranes

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)There has been considerable recent interest in employing computer models to investigate the relationship between the structure of a molecule and its dermal penetration. Molecular permeation across the epidermis has previously been demonstrated to be determined by a number of physicochemical properties, for example, the lipophilicity, molecular weight and hydrogen bonding ability of the permeant. However little attention has been paid to modeling the combined effects of permeant properties in tandem with the properties of vehicles used to deliver those permeants or to whether data obtained using synthetic membranes can be correlated with those obtained using human epidermis. This work uses Principal Components Analysis (PCA) to demonstrate that, for studies of the diffusion of three model permeants (caffeine, methyl paraben and butyl paraben) through synthetic membranes, it is the properties of the oily vehicle in which they are applied that dominated the rates of permeation and flux. Simple robust and predictive descriptor-based quantitative structure–permeability relationship (QSPR) models have been developed to support these findings by utilizing physicochemical descriptors of the oily vehicles to quantify the differences in flux and permeation of the model compounds. Interestingly, PCA showed that, for the flux of co-applied model permeants through human epidermis, the permeation of the model permeants was better described by a balance between the physicochemical properties of the vehicle and the permeant rather than being dominated solely by the vehicle properties as in the case of synthetic model membranes. The important influence of permeant solubility in the vehicle along with the solvent uptake on overall permeant diffusion into the membrane was substantiated. These results confirm that care must be taken in interpreting permeation data when synthetic membranes are employed as surrogates for human epidermis; they also demonstrate the importance of considering not only the permeant properties but also those of both vehicle and membrane when arriving at any conclusions relating to permeation data.Peer reviewedFinal Published versio

Synthesis and antibacterial activity of benzo[4,5]isothiazolo[2,3-a]pyrazine-6,6-dioxide derivatives

Using a routine procedure, a number of derivatives of the benzo[4,5]isothiazolo[2,3-a]pyrazine-6,6-dioxide ring system have been synthesized from readily available starting materials. A series of chalcones were synthesized, which were subsequently reacted with chlorosulfonic acid to generate chalcone sulfonyl chlorides. The chalcone sulfonyl chlorides were then treated with bromine to generate dibromo chalcone sulfonyl chlorides. These were subsequently reacted with 1,2-diaminopropane and 2-methyl-1,2-diaminopropane in boiling ethanol resulting in compounds 2–10 and 11–19 respectively, in 12–80% yields. The products were characterized by spectral analysis and the definitive structure of compound 11 was determined by X-ray crystallography. The synthesized compounds were screened for potential antibacterial properties against Bacillus subtilis, Escherichia coli, Proteus vulgaris and Staphylococcus aureus

Basal bud banks are the primary determinants of survival in woody legume seedlings after clipping

Disturbances determine the structure of savannas by influencing growth at all stages of a tree's life. Since the seedling stage is such a significant part of a tree's life cycle, greater knowledge of this stage informs woody management and encroachment prevention. In this study, we tested the effect of a suite of seedling functional traits on seedling survival after experimentally-induced disturbance. Twelve mimosoid legume tree species, an important group in African savannas, with different provenances, were grown from seed under experimental conditions. Seedlings were clipped at 1 cm above ground at age 30 days, to simulate disturbance, and their survival recorded. A number of above- and below-ground traits quantifying height, biomass, bud bank and architecture were measured prior to clipping in order to assess what traits could be responsible for post-clipping survival. We also quantified root contraction by calculating the change in height of the lowest bud between the ages of 6 and 60 days. Fire regime and browser biomass of the native range of each species were calculated to test whether these factors predicted seedling survival. Seedling survival was primarily predicted by the whether the plant possessed a bud below 1 cm above ground level, i.e. below the height of clipping. For the first time we report that, in several Vachellia species, root contraction occurred, bringing basal buds closer to the ground, and in some cases below the ground, thus increasing seedling survival after clipping. No environmental variables were significant predictors of survival. Our results suggest that, at this young age, buds close to the soil surface are the most important trait predicting seedling survival, while other traits that are important for saplings and adults do not significantly influence the survival of seedlings. At the seedling stage, herbivory and fire are possibly inflicting the same degree of selection pressures and thus little trait differentiation is evident across the environmental gradient.The South African National Research Foundation through Competitive Funding and Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL).http://www.elsevier.com/locate/sajbhj2023Plant Production and Soil Scienc