Kinetic derivation of common isotherm equations for surface and micropore adsorption

t The Langmuir equation is one of the most successful adsorption isotherm equations, being widely used tofit Type I adsorption isotherms. In this article we show thatthe kinetic approach originally used by Langmuir for 2Dmonolayer surface adsorption can also be used to derive a1D analogue of the equation, applicable in ultramicroporeswith single-file diffusion. It is hoped that such a demonstration helps dispel the idea that the Langmuir isothermequation cannot apply to some micropores as more than amathematical correlation. We furthermore seek to extendthe insight provided by the simple kinetic derivation of theLangmuir equation to other isotherm equations capable ofmodelling Type I isotherms. The same kinetic approach isthus also used to derive the Volmer, Fowler-Guggenheimand Hill-de Boer equations, both for surface (2D adsorbedphase) and micropore adsorption (1D and 3D adsorbedphases). It is hoped that this will help make more intuitively clear that these equations can be used as phenomenological models in some instances of adsorption inmicropore

Production of orotic acid by a Klura3 mutant of Kluyveromyces lactis

We demonstrated that a Klura3, mutant of the yeast Kluyveromyces lactis is able to produce and secrete into the growth medium considerable amounts of orotic acid. Using yeast extractpeptoneglucose (YPD) based media we optimized production conditions in flask and bioreactor cultures. With cells grown in YPD 5% glucose medium, the best production in flask was obtained with a 1:12.5 ratio for flask: culture volume, 180 rpm, 28°C and 200 mM MOPS for pH stabilization at neutral values (initial culture pH at 8.0). The best production in a 2 L bioreactor was achieved at 500 rpm with 1 vvm aeration, 28°C and pH 7.0. Under these optimum conditions, similar rates of orotic acid production were obtained and maximum concentration achieved after 96 h was 6.7 g/L in flask and bioreactor cultures. These results revealed an excellent reproducibility between both systems and provided evidence for the biotechnological potential of Klura3 strain to produce orotic acid since the amounts obtained are comparable to the production in flask using a similar mutant of the industrially valuable Corynebacterium glutamicum.This work was funded by FEDER funds through the Operational Competitiveness Programme - COMPETE and by National funds through FCT - Fundacao para a Ciencia e a Tecnologia under the project FCOMP-01-0124-FEDER-037277 (PEst-C/SAU/LA0002/2013). Nuno Carvalho was supported by a FCT fellowship (SFRH/BD/19571/2004)

Semi-synthesis of small molecules of aminocarbazoles: tumor growth inhibition and potential impact on p53

The tumor suppressor p53 is inactivated by mutation in approximately 50% of human cancers. Small molecules that bind and stabilize those mutants may represent effective anticancer drugs. Herein, we report the tumor cell growth inhibitory activity of carbazole alkaloids and amino derivatives, as well as their potential activation of p53. Twelve aminocarbazole alkaloids were semi-synthesized from heptaphylline (1), 7-methoxy heptaphylline (2), and 7-methoxymukonal (3), isolated from Clausena harmandiana, using a reductive amination protocol. Naturally-occurring carbazoles 1–3 and their amino derivatives were evaluated for their potential effect on wild-type and mutant p53 activity using a yeast screening assay and on human tumor cell lines. Naturally-occurring carbazoles 1–3 showed the most potent growth inhibitory effects on wild-type p53-expressing cells, being heptaphylline (1) the most promising in all the investigated cell lines. However, compound 1 also showed growth inhibition against non-tumor cells. Conversely, semi-synthetic aminocarbazole 1d showed an interesting growth inhibitory activity in tumor cells expressing both wild-type and mutant p53, exhibiting low growth inhibition on non-tumor cells. The yeast assay showed a potential reactivation of mutant p53 by heptaphylline derivatives, including compound 1d. The results obtained indicate that carbazole alkaloids may represent a promising starting point to search for new mutp53-reactivating agents with promising applications in cancer therapy.The authors thank to national funds provided by FCT—Foundation for Science and Technology and European Regional Development Fund (ERDF) and COMPETE under the Strategic Funding of CIIMAR UIDB/04423/2020 (Natural Products and Medicinal Chemistry) and LAQV/REQUIMTE (UID/QUI/50006/2020), the project PTDC/SAU-PUB/28736/2017 (reference POCI-01–0145-FEDER028736), PTDC/DTP-FTO/1981/2014-POCI-01-0145-FEDER-016581). We also thank FCT for the fellowship SFRH/BD/128673/2017 (J. Loureiro). Ploenthip Puthongking thanks Thailand Research Fund (DBG6080006), Thailand

Towards a structural understanding of the fibrillization pathway in Machado-Joseph’s disease: trapping early oligomers of non-expanded ataxin-3

Machado-Joseph’s disease is caused by a CAG trinucleotide repeat expansion that is translated into an abnormally long polyglutamine tract in the protein ataxin-3. Except for the polyglutamine region, proteins associated with polyglutamine diseases are unrelated, and for all of these diseases aggregates containing these proteins are the major components of the nuclear proteinaceous deposits found in the brain. Aggregates of the expanded proteins display amyloid-like morphological and biophysical properties. Human ataxin-3 containing a non-pathological number of glutamine residues (14Q), as well as its Caenorhabditis elegans (1Q) orthologue, showed a high tendency towards self-interaction and aggregation, under nearphysiological conditions. In order to understand the discrete steps in the assembly process leading to ataxin-3 oligomerization, we have separated chromatographically high molecular mass oligomers as well as medium mass multimers of non-expanded ataxin-3. We show that: (a) oligomerization occurs independently of the poly(Q)-repeat and it is accompanied by an increase in b-structure; and (b) the first intermediate in the oligomerization pathway is a Josephin domain-mediated dimer of ataxin- 3. Furthermore, non-expanded ataxin-3 oligomers are recognized by a specific antibody that targets a conformational epitope present in soluble cytotoxic species found in the fibrillization pathway of expanded polyglutamine proteins and other amyloid-forming proteins. Imaging of the oligomeric forms of the non-pathological protein using electron microscopy reveals globular particles, as well as short chains of such particles that likely mimic the initial stages in the fibrillogenesis pathway occurring in the polyglutamine-expanded protein. Thus, they constitute potential targets for therapeutic approaches in Machado-Joseph’s disease, as well as valuable diagnostic markers in disease settings

Xanthene Derivatives Targeting Bacterial Efflux Pumps, Quorum-Sensing, and Biofilm Formation

The rise of multidrug resistance (MDR) bacteria in nosocomial and health-care institutions is widespread and is currently recognized as a major medical challenge. Mechanisms of bacterial resistance, namely, quorum sensing (QS), biofilm formation, and efflux pumps, have been identified as critical biological processes in MDR bacteria. Following previous reports on the activity of phenothiazines against mechanisms of bacterial resistance, in this work we focus on the synthesis of xanthene derivatives aiming to discover phenothiazine bioisosteres with improved activity. Four compounds were obtained from the conjugation of xanthydrol with sulfonamides and aniline and were fully characterized. Their antibacterial activity was assessed considering their minimum inhibitory concentration (MIC) against Gram-positive and Gram-negative strains, efflux pump inhibition, influence on biofilm formation and quorum-sensing (QS) inhibition. It was observed that the MIC of all the tested compounds was above 64 µg/mL The four 9-xanthenyl derivatives obtained, particularly the xanthene sulfonamide derivatives 3b and 3c, showed promising results on QS inhibition with a reduction of pigment production of 48 and 41 mm, and on biofilm formation with a reduction of 78 and 79%, respectively

Ataxin-3 phosphorylation decreases neuronal defects in spinocerebellar ataxia type 3 models

Different neurodegenerative diseases are caused by aberrant elongation of repeated glutamine sequences normally found in particular human proteins. Although the proteins involved are ubiquitously distributed in human tissues, toxicity targets only defined neuronal populations. Changes caused by an expanded polyglutamine protein are possibly influenced by endogenous cellular mechanisms, which may be harnessed to produce neuroprotection. Here, we show that ataxin-3, the protein involved in spinocerebellar ataxia type 3, also known as Machado-Joseph disease, causes dendritic and synapse loss in cultured neurons when expanded. We report that S12 of ataxin-3 is phosphorylated in neurons and that mutating this residue so as to mimic a constitutive phosphorylated state counters the neuromorphologic defects observed. In rats stereotaxically injected with expanded ataxin-3–encoding lentiviral vectors, mutation of serine 12 reduces aggregation, neuronal loss, and synapse loss. Our results suggest that S12 plays a role in the pathogenic pathways mediated by polyglutamine-expanded ataxin-3 and that phosphorylation of this residue protects against toxicity

Tegsedi (Inotersen): An Antisense Oligonucleotide Approved for the Treatment of Adult Patients with Hereditary Transthyretin Amyloidosis

Tegsedi (Inotersen) is a chemically modified antisense oligonucleotide that inhibits the hepatic production of transthyretin (TTR). Several single-point mutations in TTR destabilize its structure, leading to the aggregation and accumulation of amyloid deposits in the nervous system, heart, kidneys and eyes. In July 2018, Tegsedi was approved by the European Commission for use in adults with stage one and two polyneuropathies. Later on, in October 2018, the FDA and Health Canada also approved its use for the treatment of the polyneuropathy of hereditary transthyretin-mediated amyloidosis (hATTR) in adults in the U.S. and Canada. Tegsedi was developed by Ionis Pharmaceuticals, the company that holds the global marketing license, together with its subsidiary Akcea Therapeutics

Tegsedi (Inotersen): An Antisense Oligonucleotide Approved for the Treatment of Adult Patients with Hereditary Transthyretin Amyloidosis

Tegsedi (Inotersen) is a chemically modified antisense oligonucleotide that inhibits the hepatic production of transthyretin (TTR). Several single-point mutations in TTR destabilize its structure, leading to the aggregation and accumulation of amyloid deposits in the nervous system, heart, kidneys and eyes. In July 2018, Tegsedi was approved by the European Commission for use in adults with stage one and two polyneuropathies. Later on, in October 2018, the FDA and Health Canada also approved its use for the treatment of the polyneuropathy of hereditary transthyretin-mediated amyloidosis (hATTR) in adults in the U.S. and Canada. Tegsedi was developed by Ionis Pharmaceuticals, the company that holds the global marketing license, together with its subsidiary Akcea Therapeutics