The potential of the South African plant Tulbaghia Violacea Harv for the treatment of triple negative breast cancer

Triple-negative breast cancer (TNBC) is difficult to treat and has a low five-year survival rate. In South Africa, a large percentage of the population still relies on traditional plant-based medicine. To establish the utility of both methanol and water-soluble extracts from the leaves of Tulbaghia violacea, cytotoxicity assays were carried out to establish the IC50 values against a TNBC cell line. Cell cycle and apoptosis assays were carried out using the extracts. To identify the molecular compounds, present in water-soluble leaf extracts, NMR spectroscopy was performed. Compounds of interest were then used in computational docking studies with the anti-apoptotic protein COX-2. The IC50 values for the water- and methanol-soluble extracts were determined to be 400 and 820 µg/mL, respectively. The water-soluble extract induced apoptosis in the TNBC cell line to a greater extent than in the normal cell line. RNAseq indicated that there was an increase in the transcription of pro-apoptotic genes in the TNBC cell line. The crude extract also caused these cells to stall in the S phase. Of the 61 compounds identified in this extract, five demonstrated a high binding affinity for COX-2. Based on these findings, the compounds within the extract show significant potential for further investigation as candidates for the development of cancer therapeutics, particularly for TNBC.

Exploring fluorinated heptose phosphate analogues as inhibitors of HldA and HldE, key enzymes in the biosynthesis of lipopolysaccharide

The growing threat of bacterial resistance to antibiotics has led to the rise of anti-virulence strategies as a promising approach. These strategies aim to disarm bacterial pathogens and improve their clearance by the host immune system. Lipopolysaccharide, a key virulence factor in Gram-negative bacteria, has been identified as a potential target for anti-virulence agents. In this study, we focus on inhibiting HldA and HldE, bacterial enzymes from the heptose biosynthesis pathway, which plays a key role in lipopolysaccharide biosynthesis. We present the synthesis of two fluorinated non-hydrolysable heptose phosphate analogues. Additionally, the inhibitory activity of a family of eight heptose phosphate analogues against HldA and HldE was assessed. This evaluation revealed inhibitors with affinities in the low μM range, with the most potent compound showing inhibition constant values of 15.4 μM for HldA and 16.9 μM for HldE. The requirement for a phosphate group at the C-7 position was deemed essential for inhibitory activity, while the presence of a hydroxy anomeric group was found to be beneficial, a phenomenon rationalized through computational modeling. Additionally, the introduction of a single fluorine atom α to the phosphonate moiety conferred a slight advantage for inhibition. These findings suggest that mimicking the structure of d-glycero-β-d-manno-heptose 1,7-bisphosphate, the product of the phosphorylation step in heptose biosynthesis, could be a promising strategy to disrupt this biosynthetic pathway. In terms of the in vivo effects, these heptose phosphate analogues neither demonstrated significant LPS-disrupting effects nor exhibited growth inhibitory activity on their own. Additionally, they did not alter the susceptibility of bacteria to hydrophobic antibiotics. The highly charged nature of these molecules may hinder their ability to penetrate the bacterial cell wall. To overcome this limitation, alternative strategies such as incorporating protecting groups that facilitate their entry and can subsequently be cleaved within the bacterial cytoplasm could be explored.

Exploring Water-Soluble South African Tulbaghia violacea Harv Extract as a Therapeutic Approach for Triple-Negative Breast Cancer Metastasis

Triple-negative breast cancer (TNBC) accounts for approximately 20% of all breast cancer cases and is characterized by a lack of estrogen, progesterone, and human epidermal growth factor 2 receptors. Current targeted medicines have been unsuccessful due to this absence of hormone receptors. This study explored the efficacy of Tulbaghia violacea, a South African medicinal plant, for the treatment of TNBC metastasis. Extracts from T. violacea leaves were prepared using water and methanol. However, only the water-soluble extract showed anti-cancer activity and the effects of this water-soluble extract on cell adhesion, invasion, and migration, and its antioxidant activity were assessed using MCF-10A and MDA-MB-231 cells. The T. violacea extract that was soluble in water effectively decreased the movement and penetration of MDA-MB-231 cells through the basement membrane in scratch and invasion tests, while enhancing their attachment to a substance resembling an extracellular matrix. The sample showed mild-to-low antioxidant activity in the antioxidant assy. Nuclear magnetic resonance spectroscopy revealed 61 chemical components in the water-soluble extract, including DDMP, 1,2,4-triazine-3,5(2H,4H)-dione, vanillin, schisandrin, taurolidine, and α-pinene, which are known to have anti-cancer properties. An in-depth examination of the transcriptome showed alterations in genes linked to angiogenesis, metastasis, and proliferation post-treatment, with reduced activity in growth receptor signaling, angiogenesis, and cancer-related pathways, such as the Wnt, Notch, and PI3K pathways. These results indicate that T. violacea may be a beneficial source of lead chemicals for the development of potential therapeutic medicines that target TNBC metastasis. Additional studies are required to identify the precise bioactive chemical components responsible for the observed anti-cancer effects.

Stereoselective synthesis of D-glycero-D-manno-heptose-1β,7-bisphosphate (HBP) from D-mannurono-2,6-lactone

The synthesis of D-glycero-D-manno-heptose-1β,7-bisphosphate (HBP) from D-mannose is described. This synthetic approach is notable for the elongation of the seventh carbon, employing mannurono-2,6-lactone, the substrate-controlled establishment of the C-6 configuration, and the nucleophilic introduction of phosphate at the C-1 position through the utilization of 4,6-O-benzylidene-α-triflate.

Synthesis of a novel fluorinated phosphonyl C-glycoside, (3-deoxy-3-fluoro-β-d-glucopyranosyl)methylphosphonate, a potential inhibitor of β-phosphoglucomutase

β-phosphoglucomutase (βPGM) catalyzes the conversion of β-glucose 1-phosphate (βG1P) to glucose-6-phosphate (G6P), a universal source of cellular energy, in a two-step process. Transition state analogue (TSA) complexes formed from substrate analogues and a metal fluoride (MgF3- and AlF4-) enable analysis of each of these enzymatic steps independently. Novel substrate analogues incorporating fluorine offer opportunities to interrogate the enzyme mechanism using 19F NMR spectroscopy. Herein, the synthesis of a novel fluorinated phosphonyl C-glycoside (3-deoxy-3-fluoro-β-d-glucopyranosyl)methylphosphonate (1), in 12 steps (0.85 % overall yield) is disclosed. A four-stage synthetic strategy was employed, involving: 1) fluorine addition to the monosaccharide, 2) selective anomeric deprotection, 3) phosphonylation of the anomeric centre, and 4) global deprotection. Analysis of βPGM and 1 will be reported in due course.

Chemical Synthesis of a Keto Sugar Nucleotide

Keto sugar nucleotides (KSNs) are common and versatile precursors to various deoxy sugar nucleotides, which are substrates for the corresponding glycosyltransferases involved in the biosynthesis of glycoproteins, glycolipids, and natural products. However, there has been no KSN synthesized chemically due to the inherent instability. Herein, the first chemical synthesis of the archetypal KSN TDP-4-keto-6-deoxy-d-glucose (1) is achieved by an efficient and optimized route, providing feasible access to other KSNs and analogues, thereby opening a new avenue for new applications.

TIFA promotes CRC cell proliferation via RSK- and PRAS40- dependent manner

Previous studies have reported that TIFA plays different roles in various tumor types. However, the function of TIFA in colorectal cancer (CRC) remains unclear. Here, we showed that the expression of TIFA was markedly increased in CRC versus normal tissue, and positively correlated with CRC TNM stages. In agreement, we found that the CRC cell lines show increased TIFA expression levels versus normal control. The knockdown of TIFA inhibited cell proliferation but had no effect on cell apoptosis in vitro or in vivo. Moreover, the ectopic expression of TIFA enhanced cell proliferation ability in vitro and in vivo. In contrast, the expression of mutant TIFA (T9A, oligomerization site mutation; D6, TRAF6 binding site deletion) abolished TIFA‐mediated cell proliferation enhancement. Exploration of the underlying mechanism revealed that the protein synthesis‐associated kinase RSK and PRAS40 activation were responsible for TIFA‐mediated CRC progression. In summary, these findings suggest that TIFA plays a role in mediating CRC progression. This could provide a promising target for CRC therapy.

Synthesis of a biotinylated heptose 1,7-bisphosphate analogue, a probe to study immunity and inflammation

d-glycero-d-manno-Heptose-1β,7-bisphosphate (HBP) is a bacterial metabolite that can induce a TIFA-dependent innate immune response in mammals. It was recently discovered that after HBP enters into the cytoplasm of the host cell, it is transformed into ADP-heptose-7-phosphate, which then leads to ALPK1-TIFA-dependent inflammatory response. In order to provide a molecular tool allowing the discovery of the proteins involved in this novel inflammatory pathway, we designed and synthesized a biotinylated analogue of HBP. This chemical probe displays an anomeric β-phosphate and a phosphonate at the 7-position, and a d-configured 6-position to which is attached the biotin moiety. To do so, different synthetic strategies were explored and described in this report. Moreover, we demonstrated that the biotinylated version of HBP is still biologically active and can activate the NF-κB pathway in HEK293T cells.