A new flavanone glycoside isolated from Tournefortia sibirica

Two new triterpenoid saponins and two new goodyerosides isolated from the whole plant of Tournefortia sibirica

Two new triterpenoid saponins (oleanolic acid 2β-hydroxyl-3-O-β-D-glucuronopyranoside-6'-O-buthyl ester (1) and oleanolic acid 2β-hydroxyl-3-O-[β-D-glucuronopyranosyl-6'-O-methylester]-28-O-β-D-glucopyranoside (2)) and two new goodyerosides (4-methylenefuran-2(5H)-one (6'-O-vanilloyl)-β-D-glucopyranoside (3), 3-hydroxy-2(5H)-furanone, 4-(6'-O-vanilloyl)-β-D-glucopyranoside (4)), together with seven known compounds (5-11) were isolated from the whole plant of Tournefortia sibirica L. The chemical structures of the compounds were determined by spectroscopic analysis (1D and 2D NMR) and HR-ESI-MS. Compounds 1, 6 and 9 showed significant cytotoxicity towards A549, SK-Hep1 and HeLa cells, with IC50 values ranging from 1.68 ± 0.09 to 6.87 ± 0.13 μM.

Flavonoids and phenols from the stems of Ephedra equisetina

Twelve undescribed compounds, including five flavonoids and seven phenols, were isolated from the stems of Ephedra equisetina Bunge. Their structures were elucidated by spectroscopic methods, including NMR spectroscopy and HRESIMS analysis. Their absolute configurations were elucidated by comparing their experimental and calculated ECD spectra. In the in vitro bioactive assay, all compounds were tested for their anti-asthmatic activities by releasing β-Hex in C48/80-induced RBL-2H3 cells. The β-Hex release rates of compounds 3, 8, 10, and 11 were 0.8502 ± 0.0231, 0.8802 ± 0.0805, 0.7850 ± 0.0593, and 0.8361 ± 0.0728, respectively, suggesting that compounds 3, 8, 10, and 11 have potential anti-asthmatic activities.

Two new stilbene glucosides and a new benzoic acid derivative from Tournefortia sibirica

Two new stilbene glucosides, trans-3,5-dihydroxy-4-methoxystilbene 3-O-β-D-glucopyranoside (1), cis-3,5-dihydroxy-4-methoxystilbene 3-O-β-D-glucopyranoside (2), one new benzoic acid derivative, cis-4-hydroxy-3-hydroxymethyl-2-butenyl benzoate 4-O-β-D-glucopyranoside (3), and four known compounds (4 - 7) were isolated from Tournefortia sibirica L. The structures of these compounds were elucidated on the basis of spectral data. Anti-inflammatory effects of compounds (1 - 7) were evaluated in terms of inhibition on production of NO, TNF-α and IL-6 in LPS-induced RAW 264.7 cells. Compounds 1, 2 and 5 - 7 could inhibit the levels of NO, TNF-α and IL-6 in LPS-induced RAW264.7 cells with IC₅₀ values ranging from 40.96 to 88.76 µM.

Anin silicoperception for newly isolated flavonoids from peach fruit as privileged avenue for a countermeasure outbreak of COVID-19

3′-Hydroxy-4′-methoxy-chroman-7-O-β-d-glucopyranoside 4 was first isolated from a natural source, together with three known compounds, the ferulic acid heptyl ester 1, naringenin 2, and 4,2′,4′-trihydroxy-6′-methoxychalcone-4′-O-β-d-glucopyranoside 3, which were isolated from peach [Prunus persica (L.) Batsch] fruits. These compounds were subjected to different virtual screening strategies in order to examine their activity to combat the COVID-19 outbreak. The study design composed of some major aspects: (a) docking with main protease (M^pro), (b) docking with spike protein, (c) 3D shape similarity study (Rapid Overlay Chemical Similarity-ROCS) to the clinically used drugs in COVID-19 patients, and finally, (d) the rule of five and the estimated pre-ADMT properties of the separated flavonoids. Docking study with M^pro of SARS-CoV-2 (PDB ID:6LU7, and 6Y2F) showed that compound 3, its aglycone part, and compound 4 have a strong binding mode to a protease receptor with key amino acids, especially Gln:166AA, and having a similar docking pose to co-crystalized ligands. Docking with the spike protein of SARS-CoV-2 illustrated that compounds 3 and 4 have a good binding affinity to PDB ID:6VSB through the formation of HBs with Asp:467A and Asn:422A. According to ROCS analysis, compounds 1, 3, and 4 displayed high similarities to drugs that prevent SARS-Co2 entry to the lung cells or block the inflammatory storm causing lung injury. Compounds 3 and 4 are good candidates for drug development especially because they showed predicted activity against SARS-CoV-2 through different mechanisms either by preventing genome replication or by blocking inflammatory storm that trigger lung injury. These compounds were isolated from peach fruit, and the study supports data and continues with the recommendation of peach fruits in controlling and managing COVID-19 cases.

3′-Hydroxy-4′-methoxy-chroman-7-O-β-d-glucopyranoside 4, together with three known compounds, ferulic acid heptyl ester 1, naringenin 2, and 4,2′,4′-trihydroxy-6′-methoxychalcone-4′-O-β-d-glucopyranoside 3, was isolated from peach fruits.

Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances

Lignans and neolignans are plant secondary metabolites derived from the oxidative coupling of phenylpropanoids. Biological activity of these phenolic compounds ranges from antioxidant, antitumor (terminaloside P, IC₅₀ = 10 nM), anti-inflammatory, anti-neurodegenerative (schibitubin B, IC₅₀ = 3.2 nM) and antiviral (patentiflorin A, IC₅₀ = 14-23 nM) to antimicrobial. In addition, it was observed that several members of this group, namely enterolactone and its biochemical precursors also known as phytoestrogens, possess important protective properties. Most of these lignans and neolignans are presented in reasonable amounts in one's diet and thus the protection they provide against the colon and breast cancer, to name a few, is even more important to note. Similarly, neuroprotective properties were observed (schisanwilsonin G, IC₅₀ = 3.2 nM) These structural motives also serve as an important starting point in the development of anticancer drugs. Presumably the most famous members of this family, etoposide and teniposide, synthetic derivatives of podophyllotoxin, are used in the clinical treatment of lymphocytic leukemia, certain brain tumors, and lung tumors already for nearly 20 years. This review describes 413 lignans and neolignans which have been isolated between 2016 and mid-2018 being reported in more than 300 peer-reviewed articles. It covers their source, structure elucidation, and bioactivity. Within the review, the structure-based overview of compounds as well as the bioactivity-based overview of compounds are described.