Flavonoid glycosides and their putative human metabolites as potential inhibitors of the SARS-CoV-2 main protease (Mpro) and RNA-dependent RNA polymerase (RdRp).

BACKGROUND: Since the World Health Organization (WHO) declared Coronavirus disease 2019 (COVID-19) to be a pandemic infection, important severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) non-structural proteins (nsp) have been analysed as promising targets in virtual screening approaches. Among these proteins, 3-chymotrypsin-like cysteine protease (3CLpro), also named main protease, and the RNA-dependent RNA polymerase (RdRp), have been identified as fundamental targets due to its importance in the viral replication stages. OBJECTIVES: To investigate, in silico, two of the most abundant flavonoid glycosides from Dysphania ambrosioides; a medicinal plant found in many regions of the world, along with some of the putative derivatives of these flavonoid glycosides in the human organism as potential inhibitors of the SARS-CoV-2 3CLpro and RdRp. METHODS: Using a molecular docking approach, the interactions and the binding affinity with SARS-CoV-2 3CLpro and RdRp were predicted for quercetin-3-O-rutinoside (rutin), kaempferol-3-O-rutinoside (nicotiflorin) and some of their glucuronide and sulfate derivatives. FINDINGS: Docking analysis, based on the crystal structure of 3CLpro and RdRp, indicated rutin, nicotiflorin, and their glucuronide and sulfate derivatives as potential inhibitors for both proteins. Also, the importance of the hydrogen bond and π-based interactions was evidenced for the presumed active sites. MAIN CONCLUSIONS: Overall, these results suggest that both flavonoid glycosides and their putative human metabolites can play a key role as inhibitors of the SARS-CoV-2 3CLpro and RdRp. Obviously, further researches, mainly in vitro and in vivo experiments, are necessary to certify the docking results reported here, as well as the adequate application of these substances. Furthermore, it is necessary to investigate the risks of D. ambrosioides as a phytomedicine for use against COVID-19.

Synthesis and Inhibition Evaluation of New Benzyltetrahydroprotoberberine Alkaloids Designed as Acetylcholinesterase Inhibitors.

Secondary metabolites from natural products are a potential source of acetylcholinesterase inhibitors (AChEIs), which is a key enzyme in the treatment of many neurodegenerative diseases. Inspired by the reported activities of isoquinoline-derivative alkaloids herein we report the design, one step synthesis and evaluation by capillary enzyme reactor (ICER) of benzyl analogs (1a-1e) of the tetrahydroprotoberberine alkaloid stepholidine, which is abundant in Onychopetalum amazonicum. Docking analysis based on the crystal structure of Torpedo californica AChE (TcAChE) indicated that π-π interactions were dominant in all planned derivatives and that the residues from esteratic, anionic and peripheral subsites of the enzyme played key interaction roles. Due to the similarities observed when compared with galantamine in the AChE complex, the results suggest that ligand-target interactions would increase, especially for the N-benzyl derivatives. From a series of synthesized compounds, the alkaloids (7R,13aS)-7-benzylstepholidine (1a), (7S,13aS)-7-benzylstepholidine (1b), and (S)-10-O-benzylstepholidine (1d) are reported here for the first time. The on flow bioaffinity chromatography inhibition assay, based on the quantification of choline, revealed the N-benzylated compound 1a and its epimer 1b to be the most active, with IC50 of 40.6 ± 1 and 51.9 ± 1 µM, respectively, and a non-competitive mechanism. The proposed approach, which is based on molecular docking and bioaffinity chromatography, demonstrated the usefulness of stepholidine as a template for the design of rational AChEIs and showed how the target-alkaloid derivatives interact with AChE.

Proteomic assessment of colorectal cancers and respective resection margins from patients of the Amazon state of Brazil.

Colorectal cancer (CRC) is the third most common type of cancer in the world with a low survival rate and therapeutic efficiency. Tumor surgery implies the removal of an apparently non-tumorous tissue around the tumor in an attempt to reduce recurrence chances; this tissue is referred to as the resection margin. Our analysis employed an 8-plex iTRAQ to label four adenocarcinoma biopsies and their corresponding resection margins at 5cm; our results disclose fifty-six proteins as being differentially abundant. These proteins are mainly involved in energetic metabolism (e.g. S100 calcium binding protein A11), cell migration (e.g. transgelin), formation of the cytoskeleton (e.g. profilin 1) and degradation of extracellular matrix (e.g. carbonic anhydrase 2). A gene ontology enrichment analysis revealed several proteins related to adhesion, invasion, metastasis, death, and recognition cell. Taken together, our results highlight proteins related to invasion, cell proliferation, and linked to the metastasis of colorectal cancer in tumor tissue. Finally, we argue that the expression patterns revealed in our comparison helps shed light on the development of more effective surgical strategies and add to the comprehension of this disease. BIOLOGICAL SIGNIFICANCE: Colorectal cancer (CRC) is the third most common type of cancer in the world with a low survival rate and therapeutic efficiency. Tumor surgery implies the removal of an apparently non-tumorous tissue around the tumor in an attempt to reduce recurrence chances; this tissue is also referred to as the resection margin. In this regard, resection margins pose as a treasure trove for investigating the molecular characteristics of the tumorigenesis process. While most studies focus on comparing cancer versus control tissue, this study contrasts the proteomic profiles of colorectal cancer biopsies with their corresponding resection margin at 5cm apart. Our analysis employed an 8-plex iTRAQ labeling and a 4-step offline MudPIT online with a Velos. A gene ontology enrichment analysis revealed several proteins related to adhesion, invasion, metastasis, death, and recognition cell.

Antibacterial activity of alkaloids produced by endophytic fungus Aspergillus sp. EJC08 isolated from medical plant Bauhinia guianensis.

Bauhinia guianensis is a typical plant in the Amazon region belonging to the family Leguminosea, used by local populations for the treatment of infectious and renal diseases. Previous work on the plant B. guianensis led to the isolation of substances with anti-inflammatory and analgesic activities. Thus, compounds isolated from B. guianensis with antimicrobial activities had not been identified. Given that there is a possibility of biological activity reported for a given plant being found in the endophytic fungi, we decided to isolate endophytic fungi from B. guianensis and test their antimicrobial activities. The alkaloids known as fumigaclavine C and pseurotin A were isolated by column chromatography and identified by 1D and 2D NMR techniques and mass spectrometry. The alkaloids are first reported as broad-spectrum antibacterial agents with good activity.