Letter to the editor in response to article: "Clinical considerations for patients with diabetes in times of COVID-19 epidemic (Gupta et al.)

Screening of α-Glucosidase Inhibitors in Cichorium glandulosum Boiss. et Huet Extracts and Study of Interaction Mechanisms

Cichorium glandulosum Boiss. et Huet (CGB) extract has an α-glucosidase inhibitory effect (IC50 = 59.34 ± 0.07 μg/mL, positive control drug acarbose IC50 = 126.1 ± 0.02 μg/mL), but the precise enzyme inhibitors implicated in this process are not known. The screening of α-glucosidase inhibitors in CGB extracts was conducted by bioaffinity ultrafiltration, and six potential inhibitors (quercetin, lactucin, 3-O-methylquercetin, hyperoside, lactucopicrin, and isochlorogenic acid B) were screened as the precise inhibitors. The binding rate calculations and evaluation of enzyme inhibitory effects showed that lactucin and lactucopicrin exhibited the greatest inhibitory activities. Next, the inhibiting effects of the active components of CGB, lactucin and lactucopicrin, on α-glucosidase and their mechanisms were investigated through α-glucosidase activity assay, enzyme kinetics, multispectral analysis, and molecular docking simulation. The findings demonstrated that lactucin (IC50 = 52.76 ± 0.21 μM) and lactucopicrin (IC50 = 17.71 ± 0.64 μM) exhibited more inhibitory effects on α-glucosidase in comparison to acarbose (positive drug, IC50 = 195.2 ± 0.30 μM). Enzyme kinetic research revealed that lactucin inhibits α-glucosidase through a noncompetitive inhibition mechanism, while lactucopicrin inhibits it through a competitive inhibition mechanism. The fluorescence results suggested that lactucin and lactucopicrin effectively reduce the fluorescence of α-glucosidase by creating lactucin-α-glucosidase and lactucopicrin-α-glucosidase complexes through static quenching. Furthermore, the circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR) analyses revealed that the interaction between lactucin or lactucopicrin and α-glucosidase resulted in a modification of the α-glucosidase's conformation. The findings from molecular docking and molecular dynamics simulations offer further confirmation that lactucopicrin has a robust binding affinity for certain residues located within the active cavity of α-glucosidase. Furthermore, it has a greater affinity for α-glucosidase compared to lactucin. The results validate the suppressive impact of lactucin and lactucopicrin on α-glucosidase and elucidate their underlying processes. Additionally, they serve as a foundation for the structural alteration of sesquiterpene derived from CGB, with the intention of using it for the management of diabetic mellitus.

Innate Immunity in Children and the Role of ACE2 Expression in SARS-CoV-2 Infection

COVID-19 (Coronavirus Disease 2019) is an emerging viral disease caused by the coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), which leads to severe respiratory infections in humans. The first reports came in December 2019 from the city of Wuhan in the province of Hubei in China. It was immediately clear that children developed a milder disease than adults. The reasons for the milder course of the disease were attributed to several factors: innate immunity, difference in ACE2 (angiotensin-converting enzyme II) receptor expression, and previous infections with other common coronaviruses (CovH). This literature review aims to summarize aspects of innate immunity by focusing on the role of ACE2 expression and viral infections in children in modulating the antibody response to SARS-CoV-2 infection. This review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles deemed potentially eligible were considered, including those dealing with COVID-19 in children and providing more up-to-date and significant data in terms of epidemiology, prognosis, course, and symptoms, focusing on the etiopathogenesis of SARS-CoV-2 disease in children. The bibliographic search was conducted using the search engines PubMed and Scopus. The following search terms were entered in PubMed and Scopus: COVID-19 AND ACE2 AND Children; COVID-19 AND Immunity innate AND children. The search identified 857 records, and 18 studies were applicable based on inclusion and exclusion criteria that addressed the issues of COVID-19 concerning the role of ACE2 expression in children. The scientific literature agrees that children develop milder COVID-19 disease than adults. Milder symptomatology could be attributed to innate immunity or previous CovH virus infections, while it is not yet fully understood how the differential expression of ACE2 in children could contribute to milder disease.