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The chemical characterization of the extract of the aerial parts of Paronychia arabica afforded two oxetane containing lignans, paronychiarabicine A (1) and B (2), and one new megastigmane, paronychiarabicastigmane A (3), alongside a known lignan (4), eight known phenolic compounds (5–12), one known elemene sesquiterpene (13) and one steroid glycoside (14). The chemical structures of the isolated compounds were constructed based upon the HRMS, 1D, and 2D-NMR results. The absolute configurations were established via NOESY experiments as well as experimental and TDDFT-calculated electronic circular dichroism (ECD). Utilizing molecular docking, the binding scores and modes of compounds 1–3 towards the SARS-CoV-2 main protease (Mpro), papain-like protease (PLpro), and RNA-dependent RNA polymerase (RdRp) were revealed. Compound 3 exhibited a promising docking score (−9.8 kcal mol−1) against SARS-CoV-2 Mpro by forming seven hydrogen bonds inside the active site with the key amino acids. The reactome pathway enrichment analysis revealed a correlation between the inhibition of GSK3 and GSK3B genes (identified as the main targets of megastigmane treatment) and significant inhibition of SARS-CoV-1 viral replication in infected Vero E6 cells. Our results manifest a novel understanding of genes, proteins and corresponding pathways against SARS-CoV-2 infection and could facilitate the identification and characterization of novel therapeutic targets as treatments of SARS-CoV-2 infection.

Two sesquiterpenes, 8α-anisate-dauc-4-ene-3,9-dione (webiol anisate) (1) and 10α-acetoxy-6α-benzoate-jaeschkeanadiol (2) as well as, ten known analogues (3–10), and two sesquiterpene coumarins (11–12) were isolated from an organic root extract of Ferula vesceritensis (Fam. Apiaceae). Chemical structures were elucidated based on IR, 1D- and 2D-NMR and HRMS, spectroscopic analyses. With molecular overlap observed between two protease inhibitors that are being examined as anti-COVID-19 drugs, and sesquiterpenes isolated here, metabolite molecular docking calculations were made using the main protease (Mpro), which is required for viral multiplication as well as RNA-dependent RNA polymerase (RdRp). In silico binding-inhibition analysis predicted that select F. vesceritensis sesquiterpenes can bind to these enzymes required for viral replication. Structures of the isolated constituents were also consistent with the chemo-systematic grouping of F. vesceritensis secondary metabolites with other Ferula species.

The soft coral genus Sarcophyton contains the enzymatic machinery to synthesize a multitude of cembrene-type diterpenes. Herein, highly oxygenated cembrenoids, sarcoconvolutum A–E (1–5) were purified and characterized from an ethyl acetate extract of the red sea soft coral, Sarcophyton convolutum. Compounds were assemblies according to spectroscopic methods including FTIR, 1D- and 2D-NMR as well as HRMS. Metabolite cytotoxicity was tested against lung adenocarcinoma, cervical cancer, and oral-cavity carcinoma (A549, HeLa and HSC-2, respectively). The most cytotoxic compound, (4) was observed to be active against cell lines A549 and HSC-2 with IC50 values of 49.70 and 53.17 μM, respectively.

A solvent extract of the soft coral Sarcophyton ehrenbergi afforded cembrene diterpenoids, sarcoehrenbergilid D–F (1–3). Chemical structures were established by modern spectroscopic techniques with absolute stereochemistries determined by circular dichroism (CD) and time-dependent density functional theory electronic CD calculations (TDDFT-ECD). Cytotoxicity activities for 1–3 were evaluated against three human cancer cell lines: lung (A549), colon (Caco-2) and liver (HepG2).

The 80% aqueous methanol extract of Pentas lanceolata (Rubiaceae) was partitioned with n-hexane, ether, ethyl acetate extract, and n-butanol extract. The immunomodulatory role of the five extracts on humoral and cell-mediated immune response of viral vaccine in specific pathogen-free chicken vaccinated against Newcastle disease virus was carried out. The active fractions, n-butanol, was fractioned by silica-column chromatography and active sub-fraction were separated using reverse phase-high performance liquid chromatography. Two new iridoids, namely, 13R-methoxy-epi-gaertneroside 2 and 13S-methoxy-epi-gaertneroside 3, and three known, 13R-epi-gaertneroside 1, a mixture of E-uenfoside 4 and Z-uenfoside 5, were isolated from the active sub-fractions. Their chemical structures were achieved by the extensive 1D and 2D nuclear magnetic resonance (1H and 13C, correlation spectroscopy, heteronuclear multiple quantum correlation, and heteronuclear multiple bond correlation), IR as well as HREIMS spectral data. Stimulation of both seroresponses was observed, especially those of ethyl acetate extract, n-butanol extract, and compound 1. Remarkable effective increase of the antibody titers; lymphocyte and macrophage cells in blood were recorded. The study suggested that the possible role was played by P. lanceolata aerial parts n-butanol, ethyl acetate, and three iridoids 1, 4, and 5 in immunity (humoral and cellular) against Newcastle disease which is severely endangering out the poultry industry by causing economic losses.

Chemical investigation of the soft coral Lobophytum lobophytum collected from the Red Sea led to the isolation of a new compound gorgostan-5,25-dien-3β-ol (1), and two known compounds gorgosterol (2), and alismol (3). Structures were elucidated by employing extensive NMR and HR-ESI-MS experiments.

New sesquiterpenes tanacetolide A–C (1–3) were isolated from a Tanacetum sinaicum extract together with known compounds (4–10). The structures were elucidated on the basis of MS and NMR spectroscopic data. All the compounds were evaluated for the inhibition of inducible nitric oxide (NO) production in a mouse peritoneal macrophage system. Iso-seco-tanapartholide-3-O-methyl ether (4) produced potent inhibition of NO production (IC50 = 1.0 μM). At the protein expression level, 4 elicited concentration-dependant down-regulation of inducible nitric oxide synthase.

Two new sesquiterpene lactones 3R, 8R-dihydroxygermacr-4(15),9(10)-dien-6S,7S,11RH,12,6-olide (1) and 1R, 8S-dihydroxy-11R,13-dihydrobalchanin(2), together with two known compounds 11-epiartapshin (3) and 3'-hydroxygenkwanin (4), were isolated from Artemisia sieberi. Their structures were elucidated by 1D, 2D NMR, MS, and X-ray diffraction. Compound 4 inhibited Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus with Minimal inhibitory concentration values of 50 and 25 μg/disk, respectively. All the isolated compounds exhibited moderate antifungal activities.

A new 8-ionized hydroxylated 9,10-anthraquinone namely, 1-hydroxy-3-methyl-9,10-anthraquinone-6-O-β-D-glucopyranoside-8-olate (Rumpictuside A, 1) along with five known flavonoids, apigenin 7-O-β-D-glucoside (2), vitexin (3), quercetin 3-O-β-D-glucouronide (4), orientin (5), and isorientin (6) were isolated from Rumex pictus. The structures of isolated compounds were identified by the extensive spectroscopic techniques such as, UV, FT-IR, 1D, 2D NMR and HR-FAB-ESI-MS. The ionized hydroxyl group in the new anthraquinone (1) was rarely found for anthraquinone glycosides isolated from natural sources. All the isolated compounds were found inactive against influenza A virus infection. Compounds 2–6 exhibited significant antioxidant activity against DPPH and ABTS+. The alcoholic extract exhibited moderate activity while the new anthraquinone 1 showed the lowest activity against both assays.

Chemical investigations of the soft coral Sarcophyton trocheliophorum , has led to the isolation of six cembranoids, two of which are new, Trochelioid A (1) and B (2), and one, 16-oxosarcophytonin E (3) isolated from nature for the first time. Additionally, two have been isolated from S. trocheliophorum for the first time (4 and 6). Structures were elucidated by employing extensive NMR and HR-FAB-MS experimentation.

Three new cembrenoids, lobophylins F-H (1-3), along with three known ones, lobophylins A-C (4-6), were isolated from the ethyl acetate extract of the Taiwan water soft coral Lobophytum crassum. The structures of isolated cembrenoids were elucidated on the basis of extensive spectroscopic methods such as IR, 1D, 2D NMR and HR-ESI-MS.

The soft coral genus Sinularia is a rich source of bioactive metabolites containing a diverse array of chemical structures. A solvent extract of Sinularia polydactyla resulted in the isolation of three new casbane diterpenes: sinularcasbane M (1), sinularcasbane N (2) and sinularcasbane O (3); in addition, known metabolites (4–5) were isolated. Compounds were elucidated on the basis of spectroscopic analyses; the absolute configuration was confirmed by X-ray analysis.

Wild artichoke (Cynara cornigera), a thistle-like perennial belonging to the Asteraceae family, is native to the Mediterranean region, northwestern Africa, and the Canary Islands. While the pleasant, albeit bitter, taste of the leaves and flowers is attributed to the sesquiterpene lactones cynaropicrin and cynarin, a comprehensive phytochemical investigation still needs to be reported. In this study seven sesquiterpene lactones were isolated from an aqueous methanol plant extract, including a new halogenated metabolite (1), the naturally isolated compound sibthorpine (2), and five metabolites isolated for the first time from C. cornigera. Structures were established by spectroscopic methods, including HREIMS, (1 )H, (13 )C, DEPT, (1 )H-(1 )H COSY, HMQC, and HMBC-NMR experiments as well as by X-ray analysis. The isolated bioactive nutrients were analyzed for their antioxidant and metal chelating activity. Compound 1 exhibited a potent metal chelating activity as well as a high antioxidant capacity. Moreover, select compounds were effective as acetyl cholinesterase inhibitors presenting the possibility for such compounds to be examined for anti-neurodegenerative activity. A computational pharmacophore elucidation and docking study was performed to estimate the pharmacophoric features and binding conformation of isolated compounds in the acetyl cholinesterase active site.

Fractionation of methylene chloride extracts of the resin of Ferula vesceritensis and F. sinaica afforded three new sesquiterpene coumarins and a new glucose derivative. One of them was a sesquiterpene with a rare carbon skeleton. The structures of these compounds were determined by extensive NMR studies, including DEPT, COSY, NOE, HMQC, and HMBC.

Phytochemical studies of the aerial parts of Euphorbia rigida afforded three triterpenes: betulin (1), cycloart-23Z-ene-3, 25-diol (2) and cycloartan-3, 24, 25-triol (3), firstly isolated from this plant. The structures and relative stereochemistry were determined on the basis of extensive spectroscopic analyses, including 1D and 2D NMR experiments (1H NMR, 13C NMR, COSY, NOESY, HMQC and HMBC).