In Vitro and In Vivo Anti-infective Potential of Thymol Against Early Childhood Caries Causing Dual Species Candida albicans and Streptococcus mutans

Early childhood caries (ECC), a severe form of caries due to cross-kingdom interaction of Candida albicans and Streptococcus mutans, is a serious childhood dental disease that affects majority of the children with poor background. The present study investigated the anti-infective potential of thymol against C. albicans and S. mutans dual species for the management of ECC. Thymol, a plant derivative of the monoterpene group, has been well known for its numerous biological activities. Thymol at 300 μg/ml concentration completely arrested growth and proliferation of dual species of C. albicans and S. mutans. Rapid killing efficacy of pathogens, within a span of 2 min, was observed in the time kill assay. In addition, at sub-inhibitory concentrations, thymol effectively diminished the biofilm formation and virulence of both C. albicans and S. mutans such as yeast-to-hyphal transition, hyphal-to-yeast transition, filamentation, and acidogenicity and acidurity, respectively, in single and dual species state. qPCR analysis was consistent with virulence assays. Also, through the invertebrate model system Galleria mellonella, in vivo toxicity and efficacy of the phytocompound was assessed, and it was found that no significant toxic effect was observed. Moreover, thymol was found to be proficient in diminishing the infection under single and dual state in in vivo condition. Overall, the results from the present study illustrate the anti-infective potential of thymol against the ECC-causing dual species, C. albicans and S. mutans, and the applicability of thymol in medicated dentifrice formulation.

A Comparative Study between Spanish and British SARS-CoV-2 Variants

The study of the interaction between the SARS-CoV-2 spike protein and the angiotensin-converting enzyme 2 (ACE2) receptor is key to understanding binding affinity and stability. In the present report, we sought to investigate the differences between two already sequenced genome variants (Spanish and British) of SARS-CoV-2. Methods: In silico model evaluating the homology, identity and similarity in the genome sequence and the structure and alignment of the predictive spike by computational docking methods. Results: The identity results between the Spanish and British variants of the Spike protein were 28.67%. This close correspondence in the results between the Spanish and British SARS-CoV-2 variants shows that they are very similar (99.99%). The alignment obtained results in four deletions. There were 23 nucleotide substitutions also predicted which could affect the functionality of the proteins produced from this sequence. The interaction between the binding receptor domain from the spike protein and the ACE2 receptor produces some of the mutations found and, therefore, the energy of this ligand varies. However, the estimated antigenicity of the British variant is higher than its Spanish counterpart. Conclusions: Our results indicate that minimal mutations could interfere in the infectivity of the virus due to changes in the fitness between host cell recognition and interaction proteins. In particular, the N501Y substitution, situated in the RBD of the spike of the British variant, might be the reason for its extraordinary infective potential.

​Dermal Response to Experimental Orfvirus (ORFV) Infection in Goats, Mice and Rabbit

Background: During a study on the outbreak of orf in goats, it was intended to study the disease transmissibility in different hosts from field samples and ascertain the infective potential of the agent in laboratory animals compared to goats. Methods: Cutaneous clinical materials from orf virus (ORFV) infected goats was used to experimentally infect naive goats, rabbits and mice and ascertain its infective potential and transmissibility in different hosts. The processed inoculum was applied topically to mimic a natural transmission through injured skin. Regular skin biopsies were taken that revealed characteristic macroscopic and microscopic lesions typical of orf. Result: Virus inoculum applied on abraded skin in goats successfully established the lesions of orf. A parallel inoculation in rabbit and mice could not successfully reproduce the disease in these unnatural hosts beyond a subtle vesicular stage on 3 dpi with subsequent healing by 7 dpi. The lesions in goats regressed spontaneously by 28 days post-infection (dpi). Intracytoplasmic inclusions were associated only in the vesicular stage. Immunopathological progression was observed by immunoperoxidase staining of CD4+ and CD8+ T-cells which were found to appear by day 5 in the dermis and became more abundant and distributed by day 8, but subsequently reduced in number by 15 dpi. CD4+ cells were found to be more numerous and widespread. Viral antigen in tissues could be demonstrated by 4 dpi by immunohistological methods that increased in signal intensity progressively and disappear by 28 dpi. Similarly, viral nucleic acid in the skin could be detected on day 8 dpi but not on 28 dpi by PCR. The present experiment depicts the ease of disease transmissibility through traumatized skin in the primary hosts, but establishment in unnatural hosts may not be readily achieved. The infection was self-limiting with possibly no virus latency as indicated by immunofluorescence and PCR studies.

Anti-infective Potential of Manzamine Alkaloids – A Review

Background: From time immemorial, natural products have been used for the treatment of various diseases. Various natural products, their semisynthetic derivatives, and synthetic analogs have been explored for their anti-infective properties. One such group of natural compounds that have been widely explored is manzamine alkaloids. Manzamine alkaloids are complex natural compounds consisting of a β-carboline nucleus attached to a pentacyclic ring system that was first isolated from a marine sponge during the 1980s. Objective: The review aims to provide a critical overview of the anti-infective potential of manzamine alkaloids. Method: A comprehensive and exhaustive review of the literature on manzamine alkaloids consisting of their isolation, anti-infective properties, and mechanism of action is presented. Results: Various manzamine alkaloids have been isolated and found to exhibit potent anti-infective activities like antibacterial, antimalarial, antiviral, antifungal, antileishmanial, among others. These manzamine alkaloids exhibit their anti-infective activity by inhibiting targets like GSK-3β and MtSK. Conclusion: This present review with structure-activity relationship study of manzamine alkaloids for their anti-infective activity will be useful for further development of semisynthetic manzamine analogs as potent anti-infective agents with better therapeutic potential and reduced toxicity.

Glycolytic inhibitor 2-Deoxy-D-glucose attenuates SARS-CoV-2 multiplication in host cells and weakens the infective potential of progeny virions

The COVID-19 pandemic is an ongoing public health emergency of international concern. Millions of people lost their lives to this pandemic. While a lot of efforts are being invested in vaccinating the population, there is also an emergent requirement to find potential therapeutics to effectively counter this fast mutating SARS-CoV-2 virus-induced pathogenicity. Virus-infected host cells switch their metabolism to a more glycolytic phenotype. This switch induced by the virus is needed for faster production of ATP and higher levels of glycolytic intermediates, which are required for anabolic processes such as fatty acid synthesis and nucleotide generation for new virion synthesis and packaging. In this study, we used 2-Deoxy-D-glucose (2-DG) to target and inhibit the metabolic reprogramming induced by SARS-CoV-2 infection. Our results showed that virus infection induces glucose influx and glycolysis resulting in selective high accumulation of the fluorescent glucose/2-DG analogue, 2-NBDG in these cells. Subsequently, 2-DG reduces the virus multiplication and alleviates the cells from infection-induced cytopathic effect (CPE) and cell death. Herein, we demonstrate that progeny virions produced from 2-DG treated cells are defective with compromised infectivity potential. Further, it was also observed that mannose inhibits 2-NBDG uptake at a very low concentration, suggesting that 2-DG uptake in virus-infected cells might be exploiting the specific mannose transporter or high-affinity glucose transporter, GLUT3, which was found to be increased on SARS-CoV-2 infection. In conclusion, our findings suggest that 2-DG effectively inhibits the SARS-CoV-2 multiplication and can be used as a treatment regimen. Based on these preliminary in-vitro findings this molecule reached clinical trial in COVID patients.

Anti-Infective and Antiviral Activity of Valinomycin and Its Analogues from a Sea Cucumber-Associated Bacterium, Streptomyces sp. SV 21

The manuscript investigated the isolation, characterization and anti-infective potential of valinomycin (3), streptodepsipeptide P11A (2), streptodepsipeptide P11B (1), and one novel valinomycin analogue, streptodepsipeptide SV21 (4), which were all produced by the Gram-positive strain Streptomycescavourensis SV 21. Although the exact molecular weight and major molecular fragments were recently reported for compound 4, its structure elucidation was not based on compound isolation and spectroscopic techniques. We successfully isolated and elucidated the structure based on the MS2 fragmentation pathways as well as 1H and 13C NMR spectra and found that the previously reported structure of compound 4 differs from our analysis. Our findings showed the importance of isolation and structure elucidation of bacterial compounds in the era of fast omics technologies. The here performed anti-infective assays showed moderate to potent activity against fungi, multi drug resistant (MDR) bacteria and infectivity of the Hepatitis C Virus (HCV). While compounds 2, 3 and 4 revealed potent antiviral activity, the observed minor cytotoxicity needs further investigation. Furthermore, the here performed anti-infective assays disclosed that the symmetry of the valinomycin molecule is most important for its bioactivity, a fact that has not been reported so far.

Superior anti-infective potential of eugenol–casein nanoparticles combined with polyethylene glycol against Colletotrichum musae infections

The aim of this study was to improve the stability of eugenol–casein nanoparticles (EL–CS-NPs) through polyethylene glycol (PEG) modification.