Naturally Available Flavonoid Aglycones as Potential Antiviral Drug Candidates against SARS-CoV-2.

Flavonoids are important secondary plant metabolites that have been studied for a long time for their therapeutic potential in inflammatory diseases because of their cytokine-modulatory effects. Five flavonoid aglycones were isolated and identified from the hydrolyzed aqueous methanol extracts of Anastatica hierochuntica L., Citrus reticulata Blanco, and Kickxia aegyptiaca (L.) Nabelek. They were identified as taxifolin (1), pectolinarigenin (2), tangeretin (3), gardenin B (4), and hispidulin (5). These structures were elucidated based on chromatographic and spectral analysis. In this study, molecular docking studies were carried out for the isolated and identified compounds against SARS-CoV-2 main protease (Mpro) compared to the co-crystallized inhibitor of SARS-CoV-2 Mpro (α-ketoamide inhibitor (KI), IC50 = 66.72 µg/mL) as a reference standard. Moreover, in vitro screening against SARS-CoV-2 was evaluated. Compounds 2 and 3 showed the highest virus inhibition with IC50 12.4 and 2.5 µg/mL, respectively. Our findings recommend further advanced in vitro and in vivo studies of the examined isolated flavonoids, especially pectolinarigenin (2), tangeretin (3), and gardenin B (4), either alone or in combination with each other to identify a promising lead to target SARS-CoV-2 effectively. This is the first report of the activity of these compounds against SARS-CoV-2.

Morphological, phytochemical and anti-hyperglycemic evaluation of Brachychiton populneus

Abstract Brachychiton populneus (Schott & Endl.) R.Br., Malvaceae, is one of five Brachychiton species cultivated in Egypt. Little information was found concerning the morphological, phytochemical and biological investigations of B. populneus. Morphological investigations of B. populneus were performed on fresh and dried leaves. Air-dried, ground leafy branches were extracted with 70% methanol/water yielding B. populneus extract. Seventeen flavonoids were isolated and identified using different chromatographic and spectroscopic techniques; eleven of them were reported for the first time from this plant. Potential activity of B. populneus extract against alloxan inducing oxidative stress and diabetes in male rats was preliminary investigated (four groups of ten rats /group). B. populneus extract (500 mg/kg bw i.p.) exhibited significant acute anti-hyperglycemic activity with blood glucose levels of 227.3 and 157.6 mg/dl after 4 and 24 h, respectively, compared to alloxan and standard Diamicron (5 mg/kg bw p.o.) groups, as well as to a normoglycemic control group at p < 0.05. The extract reverted the body weight values of the alloxan-induced diabetic rats to that of control animals after 24 h. In addition, B. populneus extract counteracted the effect of the oxidative stress induced by alloxan causing significantly increase in the glutathione content level (2.35 mmol/l) and relative decrease in the malondialdehyde level (21.31 nmol/l) and nitric oxide content (1.98 µmol/l) in serum after 24 h of treatment compared to alloxan-induced diabetic rats (1.01 mmol/l, 118.9 nmol/l, 4.69 µmol/l, respectively) and to normoglycemic control at p < 0.05. These effects appear to be related to the flavonoid principles. The intergeneric relationship of the genus Brachychiton and other related genera assessed well-supported differentiation between them. Furthermore, a significant dissimilarity was observed at interspecific level.