Since the first report of the organoselenium compound, ebselen, as a potent inhibitor of the SARS-CoV-2 M^pro main protease by Z. Jin et al. (Nature, 2020), different OSe analogs have been developed and evaluated for their anti-COVID-19 activities. Herein, organoselenium-clubbed Schiff bases were synthesized in good yields (up to 87%) and characterized using different spectroscopic techniques. Their geometries were studied by DFT using the B3LYP/6–311 (d, p) approach. Ten FDA-approved drugs targeting COVID-19 were used as model pharmacophores to interpret the binding requirements of COVID-19 inhibitors. The antiviral efficiency of the novel organoselenium compounds was assessed by molecular docking against the 6LU7 protein to investigate their possible interactions. Our results showed that the COVID-19 primary protease bound to organoselenium ligands with high binding energy scores ranging from −8.19 to −7.33 Kcal/mol for 4c and 4a to −6.10 to −6.20 Kcal/mol for 6b and 6a. Furthermore, the docking data showed that 4c and 4a are good M^pro inhibitors. Moreover, the drug-likeness studies, including Lipinski’s rule and ADMET properties, were also assessed. Interestingly, the organoselenium candidates manifested solid pharmacokinetic qualities in the ADMET studies. Overall, the results demonstrated that the organoselenium-based Schiff bases might serve as possible drugs for the COVID-19 epidemic.

This study aimed to evaluate the antioxidant activity and total phenolic content (TPC) and total flavonoid content (TFC) of crude extracts obtained from three Asclepiadaceae species, namely, Calotropis procera L., Peruglaria tomentosa L., and Pentatropis spiralis (Forsk.) Decne. Both butanol and aq. methanol extracts of the three species showed the highest amount of phenol and flavonoid contents, which exhibited the greatest antioxidant activity in the scavenging of 2,2-diphenyl-2-picrylhydrazyl free radical (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS), ferrous chelating effect (FIC), and hydroxyl radical (HDR) assays. Phytochemical screening of the extracts revealed the presence of alkaloids, tannins, sponins, flavonoids, terpenoids, and glycosides. LC-MS analysis was carried out to identify the major compounds from each crude extract. A total of 12 phenolic compounds in the extracts of the 3 species were identified and quantified, including 9 flavonoids, 2 hydroxybenzoic acids, and 3 hydroxycinnamic acids. The current study also revealed a good correlation between total phenolic contents and the observed antioxidant activity of the crude extracts.

The novel seco-ursane-type triterpenoid 3β,11α-dihydroxy-17,22-seco-17(28), 12-ursadien-22-oic acid (1) was isolated for the first time from a natural source from two Salvia species growing wild in Jordan, Salvia palaestina Benth. and Salvia syrica L. In addition to compound 1, S. syriaca afforded a new sesquiterpene named syriacine (2). S. palaestina also afforded 15 other known compounds, 6 of which are isolated for the first time from the plant, and these include velutin, hyptadienic acid, cirsilineol, 2α,3β-dihydroxyurs-12-en-28-oic acid, 2α,3α-dihydroxy-24-nor-4(23),12-oleanan-28-oic acid, and 2α,3β,24-trihydroxyurs-12-en-28-oic acid. S. syriaca also afforded 16 other known compounds, 7 of which are isolated for the first time from the plant. These are 1α,3α-dihydroxyolean-9(11),12-diene, maslinic acid, 2α,3β,24-trihydroxyolean-12-en-28-oic acid, 11-oxo-oleanolic acid, 11-oxo-ursolic acid, poriferast-5-en-3,7-diol, and pectolinangenin.

A series of derivatives of trans-3-(2,4,6-trimethoxyphenyl)4,5-dihydroisoxazolo-4,5-bis[carbonyl-(4′phenyl)thiosemicarbazide (9) and of trans-3-(2,4,6-trimethoxyphenyl)-4,5-dihydro isoxazolo-4,5-bis(aroylcarbohydrazide) (10a–c) were synthesized from trans-3-(2,4,6-trimethoxyphenyl)-4,5-dihydro-4,5-bis(hydrazenocarbonyl)isoxazole (8). The structures of the compounds were elucidated by both elemental and spectral (IR, NMR, and MS) analysis. Compound 9 shows activity against some bacterial species. No antibacterial activities were observed for compounds 10a–c. The antioxidant activity of the new compounds has been screened. Compound 9 showed higher antioxidant activity using the DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2’-azino–bis(3-ethylbenzoline-6-sulfonic acid) diammonium salt methods.