l-Arginine Improves Solubility and ANTI SARS-CoV-2 Mpro Activity of Rutin but Not the Antiviral Activity in Cells

The COVID-19 pandemic outbreak prompts an urgent need for efficient therapeutics, and repurposing of known drugs has been extensively used in an attempt to get to anti-SARS-CoV-2 agents in the shortest possible time. The glycoside rutin shows manifold pharmacological activities and, despite its use being limited by its poor solubility in water, it is the active principle of many pharmaceutical preparations. We herein report our in silico and experimental investigations of rutin as a SARS-CoV-2 Mpro inhibitor and of its water solubility improvement obtained by mixing it with l-arginine. Tests of the rutin/l-arginine mixture in a cellular model of SARS-CoV-2 infection highlighted that the mixture still suffers from unfavorable pharmacokinetic properties, but nonetheless, the results of this study suggest that rutin might be a good starting point for hit optimization.

Labdanes and sucrose esters from Physalis sordida

Eight new compounds, labdanes 2-4, homoergostane 10, and sucrose esters 12-15, were isolated from aerial parts of Physalis sordida together with several known compounds. Structures of the new compounds were elucidated using spectroscopic evidence and chemical transformations. The structure of 10 was confirmed by X-ray crystallographic analysis of its methyl ester. Anti-inflammatory activity of compounds 1, 2, 4, 5, and 12-15 was evaluated using the TPA-induced mouse ear edema test. Compounds 12 (IC(50) 0.26 mumol/ear) and 15 (IC(50) 0.24 mumol/ear) showed anti-inflammatory activity similar to that of indomethacin (IC(50) 0.24 mumol/ear).

Quadranosides I-V, new triterpene glucosides from the seeds of Combretum quadrangulare

Five new triterpene glucosides, quadranosides I-V (1-5), have been isolated from a MeOH extract of the seeds of Combretum quadrangulare, together with 13 known compounds. The structures of compounds 1-5 were elucidated on the basis of spectroscopic analysis. Among the new triterpene glucosides, three compounds (1, 2, 5) showed significant hepatoprotective effects against D-galactosamine (D-GalN)/tumor necrosis factor-alpha (TNF-alpha)-induced cell death in primary cultured mouse hepatocytes.

The identification of Combretum gums which are not permitted food additives, II

Combretum gums, readily available at low prices in East and West Africa, may be offered for sale as 'gum arabic'. Vigilance is necessary to detect such misrepresentations because Combretum gums differ greatly from gum arabic (Acacia senegal (L.) Willd.) in terms of quality, solution properties and value. Moreover, because there is no toxicological evidence for their safety in use, Combretum gums are not included in any of the international lists of permitted food additives. Food manufacturers and regulatory authorities therefore require data that characterize Combretum gums so that their use in foodstuffs can be prevented. This paper presents such data for the gums from a further six Combretum species. All of these have negative optical rotations similar to that of food grade gum arabic. It is no longer sufficient, therefore, to rely solely on an optical rotation measurement to confirm the identity of gum arabic. The additional analyses necessary to differentiate between Combretum gums and gum arabic are discussed.