SIRT1 Activation Enhancing 8,3′-Neolignans from the Twigs of Corylopsis coreana Uyeki

Three undescribed 8,3′-neolignans, corynol (1), 3-methoxy-corynol (2) and 3′-deoxy-corynol (3), together with two bergenin derivatives, three flavonoids, two hydrolysable tannins and six simple phenolic compounds, were isolated from the twigs of Corylopsis coreana Uyeki. The structures of the 8,3′-neolignans were elucidated by analyzing their NMR, HRESIMS and ECD spectra. All the isolated compounds were evaluated for their SIRT1 stimulatory activity, and 3′-deoxy-corynol (3) showed SIRT1 stimulation activity. Furthermore, a docking study of 3 was performed with three representative binding pockets of SIRT1.

Detection of differentially culturable tubercle bacteria in sputum using mycobacterial culture filtrates

Rapid detection of tuberculosis (TB) infection is paramount to curb further transmission. The gold standard for this remains mycobacterial culture, however emerging evidence confirms the presence of differentially culturable tubercle bacteria (DCTB) in clinical specimens. These bacteria do not grow under standard culture conditions and require the presence of culture filtrate (CF), from axenic cultures of Mycobacterium tuberculosis (Mtb), to emerge. It has been hypothesized that molecules such as resuscitation promoting factors (Rpfs), fatty acids and cyclic-AMP (cAMP) present in CF are responsible for the growth stimulatory activity. Herein, we tested the ability of CF from the non-pathogenic bacterium Mycobacterium smegmatis (Msm) to stimulate the growth of DCTB, as this organism provides a more tractable source of CF. We also interrogated the role of Mtb Rpfs in stimulation of DCTB by creating recombinant strains of Msm that express Mtb rpf genes in various combinations. CF derived from this panel of strains was tested on sputum from individuals with drug susceptible TB prior to treatment. CF from wild type Msm did not enable detection of DCTB in a manner akin to Mtb CF preparations and whilst the addition of RpfABMtb and RpfABCDEMtb to an Msm mutant devoid of its native rpfs did improve detection of DCTB compared to the no CF control, it was not statistically different to the empty vector control. To further investigate the role of Rpfs, we compared the growth stimulatory activity of CF from Mtb, with and without Rpfs and found these to be equivalent. Next, we tested chemically diverse fatty acids and cAMP for growth stimulation and whilst some selective stimulatory effect was observed, this was not significantly higher than the media control and not comparable to CF. Together, these data indicate that the growth stimulatory effect observed with Mtb CF is most likely the result of a combination of factors. Future work aimed at identifying the nature of these growth stimulatory molecules may facilitate improvement of culture-based diagnostics for TB.

Characterization of Green and Yellow Papaya for Antioxidation and Glucose Uptake Stimulatory Activity in HepG2 Liver Cells

Objectives The long-term objective of present research is to evaluate papaya for anti-diabetic properties. The current objectives were (1) To determine polyphenolic contents and antioxidation activity of leaves, skin, pulp, and seeds of green and yellow papaya and (2) to evaluate their effects on glucose uptake in HepG2 liver cells. Methods The leaves, skin, pulp, and seeds samples were freeze dried and then extracted in water or 80% Methanol. The total phenolic contents of each extracted sample was determined using the Folin- Ciocalteu method. The antioxidation activity in each sample was determined using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and Ferric ion reducing antioxidation power (FRAP) assays. Effect of each fraction on glucose uptake was determined using a fluorescent-tagged NBD-Glucose derivative. Results The concertation of polyphenols was highest in both water and methanol extracts of seeds from yellow papaya compared to that in seeds from green papaya. Leaves and skin fractions contained modest concentration of polyphenols whereas pulp contained the lowest concentration of polyphenols. FRAP assay indicates that both water and methanol extracts of leaves, skin, pulp, and seeds from yellow papaya exhibited higher antioxidation activity compared to that of green papaya. A similar antioxidation activity pattern was observed by DPPH assay. Leaves and skin from both green and yellow papaya showed modest to high antioxidation activity whereas pulp from both green and yellow papaya contained a low antioxidation activity. In contrast, green papaya extracts significantly stimulated glucose uptake in HepG2 liver cells compared to that of yellow papaya extracts. Both water and methanol extract of pulp from green papaya showed the greatest stimulation of glucose uptake followed by leaves and skin. Conclusions Although the seeds from yellow papaya contained highest concentration of polyphenols and exhibited highest antioxidation activity, pulp from green papaya showed significantly higher stimulation of glucose uptake in liver cells. Our data indicates that polyphenolic content and/or antioxidation activity in papaya may not be related to their glucose uptake stimulatory activity in liver cells. This study concludes that regular consumption of green papaya may be beneficial for preventing diabetes. Funding Sources Capacity Building Grant, USDA.

De novo variants in SIAH1, encoding an E3 ubiquitin ligase, are associated with developmental delay, hypotonia and dysmorphic features

BackgroundUbiquitination has a central role in numerous biological processes, including cell development, stress responses and ageing. Perturbed ubiquitination has been implicated in human diseases ranging from cancer to neurodegenerative diseases. SIAH1 encodes a RING-type E3 ubiquitin ligase involved in protein ubiquitination. Among numerous other roles, SIAH1 regulates metabotropic glutamate receptor signalling and affects neural cell fate. Moreover, SIAH1 positively regulates Wnt signalling through ubiquitin-mediated degradation of Axin and accumulation of β-catenin.MethodsTrio exome sequencing followed by Sanger validation was undertaken in five individuals with syndromic developmental delay. Three-dimensional structural modelling was used to predict pathogenicity of affected residues. Wnt stimulatory activity was measured by luciferase reporter assays and Axin degradation assays in HEK293 cells transfected with wild-type and mutant SIAH1 expression plasmids.ResultsWe report five unrelated individuals with shared features of developmental delay, infantile hypotonia, dysmorphic features and laryngomalacia, in whom exome sequencing identified de novo monoallelic variants in SIAH1. In silico protein modelling suggested alteration of conserved functional sites. In vitro experiments demonstrated loss of Wnt stimulatory activity with the SIAH1 mutants, suggesting variant pathogenicity.ConclusionOur results lend support to SIAH1 as a candidate Mendelian disease gene for a recognisable syndrome, further strengthening the connection between SIAH1 and neurodevelopmental disorders. Furthermore, the results suggest that dysregulation of the Wnt/β-catenin pathway may be involved in the pathogenesis.