Common NLRP3 inflammasome inhibitors and Covid-19: Divide and conquer

Severe SARS-CoV-2 infection causes systemic inflammation, cytokine storm, and hypercytokinemia due to activation of the release of pro-inflammatory cytokines that have been associated with case-fatality rate. The immune overreaction and cytokine storm in the infection caused by SARS-CoV-2 may be linked to NLRP3 inflammasome activation which has supreme importance in human innate immune response mainly against viral infections. In SARS-CoV-2 infection, NLRP3 inflammasome activation results in the stimulation and synthesis of natural killer cells (NKs), NFκB, and interferon-gamma (INF-γ), while inhibiting IL-33 expression. Various efforts have identified selective inhibitors of NLRP3 inflammasome. To achieve this, studies are exploring the screening of natural compounds and/or repurposing of clinical drugs to identify potential NLRP3 inhibitors. NLRP3 inflammasome inhibitors are expected to suppress exaggerated immune reaction and cytokine storm-induced-organ damage in SARS-CoV-2 infection. Therefore, NLRP3 inflammasome inhibitors could mitigate the immune-overreaction and hypercytokinemia in Covid-19 infection.

Reassessing vascular endothelial growth factor (VEGF) in anti-angiogenic cancer therapy

Vascularization is fundamental to the growth and spread of tumor cells to distant sites. As a consequence, angiogenesis, the sprouting of new blood vessels from existing ones, is a characteristic trait of cancer. In 1971, Judah Folkman postulated that tumour growth is angiogenesis dependent and that by cutting off blood supply, a neoplastic lesion could be potentially starved into remission. Decades of research have been devoted to understanding the role that vascular endothelial growth factor (VEGF) plays in tumor angiogenesis, and it has been identified as a significant pro-angiogenic factor that is frequently overexpressed within a tumor mass. Today, anti-VEGF drugs such as Sunitinib, Sorafenib, Axitinib, Tanibirumab, and Ramucirumab have been approved for the treatment of advanced and metastatic cancers. However, anti-angiogenic therapy has turned out to be more complex than originally thought. The failure of this therapeutic option calls for a reevaluation of VEGF as the major target in anti-angiogenic cancer therapy. The call for reassessment is based on two rationales: first, tumour blood vessels are abnormal, disorganized, and leaky; this not only prevents optimal drug delivery but it also promotes hypoxia and metastasis; secondly, tumour growth or regrowth might be blood vessel dependent and not angiogenesis dependent as tumour cells can acquire blood vessels via non-angiogenic mechanisms. Therefore, a critical assessment of VEGF, VEGFRs, and their inhibitors could glean newer options such as repurposing anti-VEGF drugs as vascular normalizing agents to enhance drug delivery of immune checkpoint inhibitors.

Anticancer Properties of Curcumin Against Colorectal Cancer: A Review

Colorectal cancer (CRC) is one of the most common and reoccurring diseases, as well as the world’s second largest cause of mortality. Despite existing preventative, diagnostic, and treatment methods, such as chemotherapy, the number of instances rises year after year. As a result, new effective medications targeting specific checkpoints should be developed to combat CRC. Natural compounds, such as curcumin, have shown significant anti-colorectal cancer characteristics among medications that can be used to treat CRC. These chemicals are phenolic compounds that belong to the curcuminoids category. Curcumin exerts its anti-proliferative properties against CRC cell lines in vitro and in vivo via a variety of mechanisms, including the suppression of intrinsic and extrinsic apoptotic signaling pathways, the stoppage of the cell cycle, and the activation of autophagy. Curcumin also has anti-angiogenesis properties. Thus, this review is aimed at emphasizing the biological effect and mode of action of curcumin on CRC. Furthermore, the critical role of these substances in CRC chemoprevention was emphasized.

Hydroethanolic Extracts of Senna alata Leaves Possess Antimalarial Effects and Reverses Haematological and Biochemical Pertubation in Plasmodium berghei-infected Mice

The current work investigated the chemical profile, antimalarial potential and capacity of hydroethanolic Senna alata extract (SAE) to reverse hematological and biochemical pertubation in Plasmodium berghei infected mice. Results of the phytochemical analysis revealed the presence of alkaloids, flavonoids, phenolics, tannins, terpenoids, saponins, steroids and cardiac glycosides. Total phenolic and flavonoid content was estimated to be 45.29 ± 2.34 mg GAE/g and 25.22 ± 2.26 mg QE/g respectively. In vitro analysis of the extract also confirmed its antioxidant property. Results of the test for prophylaxis of P. berghei indicated that SAE suppressed parasitemia significantly in treated groups in a dose dependent manner when compared with negative control group. Similarly, SAE improved the mean survival time (MST) and packed cell volume (PCV) of infected mice. The test for curative effect showed that SAE significantly suppressed parasitemia to 4.50 ± 1.05% compared to untreated group 29.83 ± 3.49%. Results of liver and kidney functions indices of treated animals indicated that whereas infection with P. berghei caused increase in the levels of AST, ALT, ALP, urea and creatinine, treatment with SAE significantly reversed the perturbation. Similarly, infected mice were dyslipidemic with concomitant increased activity of HMG CoA reductase and decreased activity of antioxidant enzymes with increase in lipid peroxides levels. However, these alterations were significantly reversed by administration of SAE. Results of this study shows that Senna alata possess antimalarial activity and therefore justify the traditional use of plant for the treatment of malaria.

Common NLRP3 inflammasome inhibitors and Covid-19: Divide and Conquer

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Combination of donepezil and gallic acid improves antioxidant status and cholinesterases activity in aluminum chloride-induced neurotoxicity in Wistar rats

The present study compared the effect of donepezil only and combination of donepezil and gallic acid on oxidative status and cholinesterase activity in the brain of Wistar rats administered AlCl₃ for 60 days. Twenty-eight rats (180 - 200 g) were arbitrarily distributed into four groups of seven animals apiece. Group 1 served as normal control and received distilled water throughout the study. Group 2 animals received only AlCl₃ throughout the study while animals in groups 3 and 4 were administered donepezil only (10 mg/kg) and combination of donepezil (10 mg/kg) and gallic acid (50 mg/kg), respectively, in addition to AlCl₃. Treatments were administered orally by gavage. At the end of the study, animals were sacrificed and activities of acetylcholinesterase, butyrylcholinesterase, superoxide dismutase (SOD) and catalase as well as levels of malondialdehyde (MDA), total thiol and nitric oxide (NO) were evaluated in the brain. Histopathological study was conducted on the hippocampus of experimental animals. Results showed that AlCl₃ significantly (p < 0.05) increased brain activities of cholinesterases and levels of MDA and NO with a concomitant decrease in total thiol level as well as activities of SOD and catalase. Donepezil only and combination of donepezil and gallic acid reversed these alterations. Also, combination of donepezil and gallic acid significantly (p < 0.05) improved antioxidant status better than donepezil only. It could be concluded that a synergy might exist between gallic acid and donepezil especially in ameliorating oxidative stress associated with AlCl₃-induced neurotoxicity.

Novel ketogenic diet formulation improves sucrose-induced insulin resistance in canton strain Drosophila melanogaster

This study investigates the antidiabetic effect of a ketogenic diet (KD) on sucrose-induced insulin resistance in the fruit fly model. The fruit flies were divided and grouped into four: Group A, B, C, and D, representing the control, high-sucrose diet (HSD), KD, and HSD + KD, respectively. The administration of the various treatments to the groups proceeded for 7 days. The flies were thereafter immobilized, homogenized, and the homogenates used for biochemical parameters determination. This includes glucose concentration, antioxidant status, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, total cholesterol (TC), triglycerides (TG), and protein concentration. There was a significant increase (p < .05) in weight gain, glucose concentration, TG, HMG-CoA reductase activity, TC, and lipid peroxidation status of the HSD group compared with the control and KD groups. The antioxidant enzymes measured (superoxide dismutase, catalase, and reduced glutathione) and protein concentrations were repressed significantly (p < .05) in the HD groups but significantly elevated (p < .05) in the KD, HSD + KD, and the control groups. The KD improved biochemical parameters altered during the onset of sucrose-induced insulin resistance. With further research on this, KD may emerge as the much-awaited treatment option for diabetes mellitus type 2 (T2DM) with almost reduced toxicity concerns. PRACTICAL APPLICATIONS: Novel KD are sources of dietary phytocompounds with proven antioxidant activities. The antidiabetic activity of the KD was investigated. The results showed that the KD proves to serve as a better effective antidiabetic option in Drosophila melanogaster. The observed results could provide the potential application of the KD as an alternative therapy for diabetes management.

Contraceptive and biochemical effect of juice extract of Allium cepa, Allium sativum, and their combination in Canton S fruit flies

This study determines the contraceptive activity of Allium sativa (Garlic) and Allium cepa (Onion) juices on reproductive output and development of Drosophila melanogaster. The fruit flies were divided and grouped into 5, group A serves as the control, group B serves as the onion group, group C serves as the garlic group, group D serves as the onion + garlic group, while group E serves as the standard contraceptive group. Biochemical parameters measured were superoxide dismutase (SOD), Catalase (CAT), Glutathione-S-transferase (GST), malondialdehyde (MDA), nitric oxide (NO), total cholesterol (TC), triglyceride, mating test, and negative geotaxis. There was a significant reduction in the levels of MDA in onion, garlic, onion + garlic groups when compared with the control, in contrast, a significant increase was observed in SOD, CAT, and GST activities. Furthermore, there was a significant reduction in nitric oxide levels in garlic, onion + garlic extract with a corresponding increase in the standard contraceptive group. There was a significant reduction in the concentration of TC and HMG-CoA in garlic and standard contraceptive groups when compared with the control while triglyceride revealed a considerable increase in the garlic group when compared with the control. The mating test showed there was a considerable reduction in the onion, garlic, onion + garlic, and standard contraceptive when compared with the control. Taken together, Allium sativum proved to serve as a better contraceptive in D. melanogaster as a possible effective option for contraceptives, which is further, supported by their strong antioxidant activity. PRACTICAL APPLICATIONS: A. cepa and A. sativum are sources of dietary phytocompounds with proven antioxidant activities. The contraceptive activity of A. cepa and A. sativum juice extract was investigated. The results showed that A. cepa and A. sativum and their combination prove to serve as a better effective option for contraceptives in D. melanogaster. The observed results could provide the potential application of A. cepa and A. sativum as an alternative therapy for contraceptives.

Computational study of the therapeutic potentials of a new series of imidazole derivatives against SARS-CoV-2

Owing to the urgent need for therapeutic interventions against the SARS-coronavirus 2 (SARS-CoV-2) pandemic, we employed an in silico approach to evaluate the SARS-CoV-2 inhibitory potential of newly synthesized imidazoles. The inhibitory potentials of the compounds against SARS-CoV-2 drug targets - main protease (Mpro), spike protein (Spro) and RNA-dependent RNA polymerase (RdRp) were investigated through molecular docking analysis. The binding free energy of the protein-ligand complexes were estimated, pharmacophore models were generated and the absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of the compounds were determined. The compounds displayed various levels of binding affinities for the SARS-CoV-2 drug targets. Bisimidazole C2 scored highest against all the targets, with its aromatic rings including the two imidazole groups contributing to the binding. Among the phenyl-substituted 1H-imidazoles, C9 scored highest against all targets. C11 scored highest against Spro and C12 against Mpro and RdRp among the thiophene-imidazoles. The compounds interacted with HIS 41 - CYS 145 and GLU 288 – ASP 289 – GLU 290 of Mpro, ASN 501 of Spro receptor binding motif and some active site amino acids of RdRp. These novel imidazole compounds could be further developed as drug candidates against SARS-CoV-2 following lead optimization and experimental studies.

Exploring the potentials of some compounds from Garcinia kola seeds towards identification of novel PDE-5 inhibitors in erectile dysfunction therapy

Erectile dysfunction (ED) is one of the main challenges occurring among men worldwide, and is characterised by trouble getting or keeping steady erection during sexual intercourse. Various drugs like sildenafil, a phosphodiesterase-5 inhibitor (PDE-5) are freely available in the pharmacies, though normally associated with several adverse. This study was designed to assess the molecular relations obtainable between catechin, garcinal, garcinoic acid and d-tocotrienol compounds isolated from Garcinia kola and targeted receptor linked to ED. These processes include the molecular docking of catechin, garcinal, garcinoic acid, d-tocotrienol, and sildenafil to receptor: PDE-5 via AutoDock Vina. Following the docking of catechin, garcinal, garcinoic acid and d-tocotrienol with the PDE-5-receptor protein, we observed that all are protein inhibitors with garcinoic acid showing better binding affinity -10.0 kcal/mol with PDE-5 receptor relevant to ED. Hence, the results provided insights into the development of garcinoic acid as a replacement for present ED management, with further analysis worth considering.

Quercetin Caused Redox Homeostasis Imbalance and Activated the Kynurenine Pathway (Running Title: Quercetin Caused Oxidative Stress)

The search for new and better antimicrobial therapy is a continuous effort. Quercetin is a polyphenol with promising antimicrobial properties. However, the understanding of its antimicrobial mechanism is limited. In this study, we investigated the biochemical mechanistic action of quercetin as an antibacterial compound. Isolates of Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia, and Staphylococcus aureus were initially exposed to quercetin for antibacterial evaluation. Subsequently, S. aureus (Gram-positive) and E. coli (Gram-negative) cells were exposed to quercetin with or without ascorbic acid, and cells were harvested for selected biochemical assays. These assays included redox homeostasis (lipid peroxidation, total thiol, total antioxidant capacity), nitric oxide, and kynurenine concentration as well as DNA fragmentation. The results revealed that quercetin caused lipid peroxidation in the bacterial isolates. Lipid peroxidation may indicate ensuing oxidative stress resulting from quercetin treatment. Furthermore, tryptophan degradation to kynurenine was activated by quercetin in S. aureus but not in E. coli, suggesting that local L-tryptophan concentration might become limiting for bacterial growth. These findings, considered together, may indicate that quercetin restricts bacterial growth by promoting oxidative cellular stress, as well as by reducing the local L-tryptophan availability by activating the kynurenine pathway, thus contributing to our understanding of the molecular mechanism of the antimicrobial action of quercetin.

Apoferritin and Apoferritin-Capped Metal Nanoparticles Inhibit Arginine Kinase of Trypanosoma brucei

The aim of this study was to explore the inhibitory potential of apoferritin or apoferritin-capped metal nanoparticles (silver, gold and platinum) against Trypanosomabrucei arginine kinase. The arginine kinase activity was determined in the presence and absence of apoferritin or apoferritin-capped metal nanoparticles. In addition, kinetic parameters and relative inhibition of enzyme activity were estimated. Apoferritin or apoferritin-capped metal nanoparticles’ interaction with arginine kinase of T. brucei led to a >70% reduction in the enzyme activity. Further analysis to determine kinetic parameters suggests a mixed inhibition by apoferritin or apoferritin-nanoparticles, with a decrease in V_max. Furthermore, the K_m of the enzyme increased for both ATP and L-arginine substrates. Meantime, the inhibition constant (K_i) values for the apoferritin and apoferritin-nanoparticle interaction were in the submicromolar concentration ranging between 0.062 to 0.168 nM and 0.001 to 0.057 nM, respectively, for both substrates (i.e., L-arginine and ATP). Further kinetic analyses are warranted to aid the development of these nanoparticles as selective therapeutics. Also, more studies are required to elucidate the binding properties of these nanoparticles to arginine kinase of T. brucei.

Silver nanoparticles restrict microbial growth by promoting oxidative stress and DNA damage

Bacterial infections remain a serious health issue; hence there is a need for continuous search for improved antimicrobials. In addition, it is important to understand the antibacterial mechanism of prospective antimicrobials to fully harness their benefits. In this study, the antimicrobial action of silver nanoparticles was investigated. The antimicrobial potential of silver nanoparticles against different strains of bacteria was evaluated after which Escherichia coli and Staphylococcus aureus were selected as model for gram-negative and gram-positive bacteria respectively. Additionally, to determine mechanism of action, some biochemical assays including determination of kynurenine level, DNA fragmentation, lipid peroxidation and antioxidant status were carried out. Results showed that silver nanoparticles caused DNA damage and induced oxidative stress as reflected in elevated nitric oxide production and lipid peroxidation level. In contrast silver nanoparticles increased the antioxidant capacity viz-a-viz, elevated levels of total thiol, superoxide dismutase (SOD), and total antioxidant capacity (TAC) compared to untreated cells. They also initiated inconsistent alteration to the kynurenine pathway. Taken together, the findings indicate that silver nanoparticles exhibited antimicrobial action through the promotion of oxidative stress.

Imidazole derivatives as antiparasitic agents and use of molecular modeling to investigate the structure-activity relationship

Toxoplasmosis is a common parasitic disease caused by Toxoplasma gondii. Limitations of available treatments motivate the search for better therapies for toxoplasmosis. In this study, we synthesized a series of new imidazole derivatives: bis-imidazoles (compounds 1-8), phenyl-substituted 1H-imidazoles (compounds 9-19), and thiopene-imidazoles (compounds 20-26). All these compounds were assessed for in vitro potential to restrict the growth of T. gondii. To explore the structure-activity relationships, molecular analyses and bioactivity prediction studies were performed using a standard molecular model. The in vitro results, in combination with the predictive model, revealed that the imidazole derivatives have excellent selectivity activity against T. gondii versus the host cells. Of the 26 compounds screened, five imidazole derivatives (compounds 10, 11, 18, 20, and 21) shared a specific structural moiety and exhibited significantly high selectivity (> 1176 to > 27,666) towards the parasite versus the host cells. These imidazole derivatives are potential candidates for further studies. We show evidence that supports the antiparasitic action of the imidazole derivatives. The findings are promising in that they reinforce the prospects of imidazole derivatives as alternative and effective antiparasitic therapy as well as providing evidence for a probable biological mechanism.

Antibacterial and antioxidant potentials of leave extracts of Helianthus annuus

Helianthus annuus has been widely used for its medicinal and nutritional properties. This study was aimed at assessing the ethyl acetate, n-hexane and methanol extracts of Helianthus annuus for antibacterial and antioxidant potentials.  The phytochemical screening, total phenols, DPPH radical scavenging assay and nitric oxide radical scavenging activity were carried out following standard procedures. Preliminary screening of the antibacterial activities of the extracts was carried out on five bacterial species (Bacillus subtilis, E. coli, Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae), using the agar-diffusion method. Growth rate studies in presence of the extract was investigated on two bacterial species (Bacillus subtilis and E. coli). The methanol extract was observed to inhibit the growth of the five bacterial species while ethyl acetate and N-hexane extracts showed inhibition against Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. Extended lag periods of 5 – 6 h were observed when the Bacillus subtilis and Escherichia coli were grown in broth medium that contained the respective extracts. In broth medium with mixture of extract and ascorbic acid, there was no observed growth of the Bacillus subtilis and Escherichia coli throughout the 7 h incubation period. The total phenolics content of the extracts revealed concentrations of 6.66 ±0.45, 5.58 ±0.11 and 6.06±0.41 mg TAE.g-1) for the methanol, N-hexane and ethyl acetate extracts respectively. The DPPH radical scavenging assay results displayed gradual increase in percentage inhibition from the lowest to the highest concentration across all the standard groups, a similar trend was observed with the extracts, the ethyl acetate extract showed highest percentage inhibition amongst the other extracts. All the extracts showed high reducing power ability. The nitric oxide scavenging ability of the extracts showed constant increase with increase in concentration. Helianthus annus, it could be a good source of antimicrobial and antioxidant especially in a world where resistance to antibiotic has increasingly become a global concern.

In Vitro Screening to Identify Anti-Toxoplasma Compounds and In Silico Modeling for Bioactivities and Toxicity

Toxoplasmosis, which affects more than a billion people worldwide, is a common parasitic infection caused by the obligate intracellular parasite, Toxoplasmagondii. Current treatment strategies have several limitations, including unwanted side effects and poor efficacy. Therefore, newer therapies are needed for toxoplasmosis. Drug repurposing and screening of a vast array of natural and/or synthetic compounds is a viable option for antiparasitic drug discovery. In this study, we screened 62 compounds comprising natural products (NPs) and FDA-approved (FDA) drugs, to identify the hit compounds that suppress the growth of T. gondii. To determine the parasite inhibitory potential of the compounds, host mammalian cells were infected with a transgenic T. gondii strain, and the viability of the parasite was evaluated by luminescence. Of the 62 compounds, tubericidin, sulfuretin, peruvoside, resveratrol, narasin and diacetoxyscirpenol of the natural product isolates, as well as bortezonib, 10-Hydroxycamtothecin, mebendazole, niflumic acid, clindamycin HCl, mecamylamine, chloroquine, mitomycin C, fenbendazole, daunorubicin, atropine, and cerivastatin of FDA molecules were identified as "hits" with ≥ 40 percent anti-parasite action. Additionally, mitomycin C, radicicol, naringenin, gitoxigenin, menadione, botulin, genistin, homobutein, and gelsemin HCl of the natural product isolates, as well as lomofungin, cyclocytidine, prazosin HCl, cerivastatin, camptothecin, flufenamic acid, atropine, daunorubicin, and fenbendazole of the FDA compounds exhibited cytotoxic activity, reducing the host viability by ≥ 30 percent. Our findings not only support the prospects of drug repurposing, but also indicate that screening a vast array of molecules may provide viable sources of alternative therapies for parasitic infection.