Pharmacoinformatic study of inhibitory potentials of selected flavonoids against papain-like protease and 3-chymotrypsin-like protease of SARS-CoV-2

Background

Inhibition of papain-like protease (PLpro) and 3-chymotrypsin-like protease (3CLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is projected to terminate its replication. Hence, these proteases represent viable therapeutic targets.

Methods

Sixty-one flavonoids with reported activities against other RNA viruses were selected and docked in PLpro and 3CLpro. Flavonoids with better binding energies compared to reference inhibitors (lopinavir and ritonavir) in their interaction with PLpro and 3CLpro were selected for drug-likeness and ADMET analysis. The best representative flavonoid for each protease from the ADMET filtering analysis was subjected to molecular dynamics simulations (MDS) and clustering analysis of the trajectory files.

Results

Licorice, ugonin M, procyanidin, silymarin, and gallocatechin gallate had better binding energies (-11.8, -10.1, -9.8, -9.7 and -9.6 kcal/mol respectively) with PLpro compared to lopinavir and ritonavir (-9.1 and -8.5 kcal/mol respectively). Also, isonymphaeol B, baicalin, abyssinone II, tomentin A, and apigetrin had better binding energies (-8.7, -8.3, -8.2, -8.1, and -8.1 kcal/mol respectively) with 3CLpro compared to lopinavir and ritonavir (-7.3 and -7.1 kcal/mol respectively). These flavonoids interacted with the proteases via hydrogen and non-hydrogen bonding. Of these flavonoids, silymarin and isonymphaeol B demonstrated most favourable combination of attributes in terms of binding energies, compliance with Lipinski rule for drug-likeness and favourable pharmacokinetics in silico. These two flavonoids exhibited appreciable degree of structural stability, maintaining strong interaction with residues in the different representative clusters selected during the MDS run.

Conclusion

Silymarin and isonymphaeol B are proposed for further studies as compounds with potential activities against SARS-CoV-2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40816-022-00347-y.

• Flavonoids displayed varying affinities for PLpro and 3CLpro of SARS-CoV-2

• They interacted via hydrogen and non-hydrogen bonds; nine and twenty-seven flavonoids had better binding affinities for PLpro and 3CLpro respectively than lopinavir and ritonavir

• Silymarin and isonymphaeol B demonstrated most favourable combination of attributes in terms of binding energies, compliance with Lipinski rule for drug-likeness and favourable pharmacokinetics.

• Silymarin and isonymphaeol B exhibited appreciable degree of structural stability, maintaining strong interaction with residues in the different representative clusters selected during the MDS run.

Spectrum of pulmonary fungal pathogens, associated risk factors, and anti-fungal susceptibility pattern among persons with presumptive tuberculosis at Gombe, Nigeria

Background

Pulmonary mycosis (PM) poses a great diagnostic challenge due to the lack of pathognomonic and radiological features, especially in the absence of mycology laboratory tests. This study was aimed to isolate, phenotypically identify, determine the prevalence of pulmonary fungal pathogens and antifungal susceptibility pattern of isolates of presumptive tuberculosis (PTB) patients attending Federal Teaching Hospital (FTH) Gombe, Nigeria.

Methods

After ethical approval, three consecutive early morning sputa were collected from 216 participants with presumptive of PTB attending FTH Gombe, between May 2, 2017 and May 30, 2018. Samples were processed using standard mycological staining, microscopy, sugar biochemistry, and antifungal susceptibility test protocols. Sociodemographic variables and risk factors of pulmonary fungal infection were assessed through structured questionnaires. Pulmonary fungal infection was defined by the positive culture in at least two sputa. PTB was defined by Genexpert^® nested polymerase chain reaction.

Results

Of the 216 participants, 19.9% had PTB and 73.6% had pulmonary fungal pathogens. Among the isolated pulmonary fungal pathogens, Aspergillus fumigatus made the highest occurrence, while 6.5% had PTB-fungal co-infection. No significant association existed between the prevalence of PM with age and sex of participants (P < 0.05). Cigarette smoking (adjusted odds ratio [aOR] = 15.9 [95% confidence interval (CI): 0.9-268.8]), prolong antibiotic use (aOR = 77.9 [95% CI: 4.7-1283]) and possession of domestic pet (aOR = 77.9 [95% CI: 4.7-1283]) were significant risk factors of PM (P < 0.05). Penicillium citrinum, Mucor spp. and Aspergillus flavus are more susceptible to voriconazole, and Candida albicans was found to be more susceptible to Nystatin. Of the 159 fungal isolates, 92.5% were resistant to fluconazole.

Conclusion

Findings from this study revealed high level pulmonary fungal pathogens, especially among PTB patients. A majority of fungal isolates were resistant to fluconazole. It's recommended that persons should do away with or minimize risk factors for pulmonary fungal pathogens identified in this study.

Asymptomatic Rotavirus infections among children in Maiduguri, Borno state, Northeast, Nigeria

Background:

Rotavirus remains one of the main causative agents of gastroenteritis in young children. This happens, especially in countries (e.g., Nigeria) that have not yet introduced the vaccine into the national immunization program. A significant prevalence of Rotavirus infection both in children and adults without major symptoms has earlier been reported. This study aimed at defining the prevalence of asymptomatic Rotavirus infection from apparently healthy children in Maiduguri, Borno State, Northeastern Nigeria.

Methods:

A total of 269 stool samples were randomly collected from apparently healthy children <15 years of age from July 2017 to June 2018. All samples were screened using a commercially available enzyme-linked immunosorbent assay kit for the presence of Rotavirus antigen. The Rotavirus-positive samples were further subjected to polyacrylamide gel electrophoresis (PAGE) to determine their RNA electropherotypes.

Results:

A total of 59 stool samples (19.9%) were Rotavirus positive with peaks observed in the cold dry season, among male children, and 6–10 years of age group. A total of 50 randomly selected Rotavirus-positive samples were subjected to PAGE, and none of the samples showed either long or short profiles.

Conclusion:

This study shows that Rotavirus can be shed into environments without any signs and symptoms. In view of this, the Rotavirus vaccine should be considered a priority and be introduced in the existing national immunization program in Nigeria, particularly in Borno State.

Relevance of moldy fungi as agents of chronic lower respiratory tract infection in patients seen in Maiduguri, Nigeria

BACKGROUND

In Maiduguri, Nigeria in the 1990's, we had available to us only the direct Acid Fast Bacilli (AFB) smear method to diagnose tuberculosis (TB), and no facility for TB culture. Because the clinical and radiologic manifestations of lower respiratory tract (LRT) fungal infections are difficult to differentiate from those of LRT TB, it was not clear how many of the direct AFB smear negative patients had fungal infections, or were true negatives for TB.

OBJECTIVE

To assess sputum samples from patients with suspected lower respiratory tract infection for non-candidal fungal isolates as well as Mycobacterium tuberculosis.

METHODS

Smears of sputum samples were examined microscopically for fungal hyphae and AFB. Sputum samples were also plated onto different fungal culture media. Isolation data were correlated with clinical and radiological data, to determine their clinical significance.

RESULTS

Of the 274 patients seen, 41(15%) had positive sputum for AFB, while 61(22.3%) had positive sputum for fungal isolates. The most common fungal isolates were Aspergillus spp (42.9%), Scopulariopsis (14.3%), Chrysosporium (8.9%), Penicillium (7.1%), Fusarium (7.1%) and Acremonium (5.4%). No patient with mold isolate had cavitary lung disease, while 62.5% of TB patients had cavitary disease. Extensive disease (54.2%) and abnormal chest x-ray (91.7 %) were characteristic of patients with TB but very rare in patients with fungal infection.

CONCLUSION

We therefore conclude that serious lower respiratory tract fungal infection was rare and that extensive or cavitary disease was usually due to pulmonary TB. The clinical diagnosis of TB under defined conditions, as in our setting, still has great utility.

An ethnobotanical survey of Bauchi State herbal plants and their antimicrobial activity

A survey of medicinal plants used locally in the treatment of various diseases was carried out in Bauchi State-Nigeria. A total of 84 medicinal plants were listed. Preliminary antimicrobial activity of the aqueous extracts of the plants was investigated. The results indicated that out of 84 plants, 75 exhibited antimicrobial activity against one or more of the test organisms at a concentration of 200 mg/ml. The extracts were found to show potentially interesting activity against Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli.

Infraglottic and bronchial infections

Concerns over infraglottic and bronchial infections have been a source of anxiety and lost sleep for many children, parents, and physicians. The annual incidence of lower respiratory tract infections in children younger than 6 years old exceeds 5 million in the United States. Despite the frequency of these infections, the often common and nonspecific clinical symptomatology, variable severity, and changing epidemiology over time all have contributed to our understanding and misunderstanding of these disorders.

Performance of normal and disabled Nigerian students on a selective attention task

To determine to what extent disabled students may be selected and integrated into the regular schools in Nigeria, normal and blind students were compared for differences in selective attention in a task involving letters and numbers. It was predicted that, because of the sociocultural stigma attached to blindness, normal students (n = 21) would perform better than blind students (n = 21). The hypothesis was substantiated.

Cultural determinations on the auditory split-span technique of selective attention

Cultural differences in selective attention among Ibo and Yoruba adolescents of Nigeria were examined with the auditory split-span technique. It was predicted that Yoruba would perform better than Ibo in a task involving auditory discrimination of digits alternated with letters. A group of 200 16-year-old boys and girls was randomly drawn from four secondary schools of both ethnic groups to represent a wide range of socioenconomic environments. Factorial analysis and analysis of variance showed no significant differences and did not substantiate the hypothesis. Theoretical implications of the findings were elaborated.