Pentacylic triterpenes from <i>Lavandula coronopifolia</i>: structure related inhibitory activity on α-glucosidase

Ten pentacyclic triterpenes (1-10) were isolated from Lavandula coronopifolia. We evaluated their α-glucosidase inhibitory activity, and found that the aglycones, 1, 2, 3, 4, 7 and 10 showed superior IC50 values to the positive control. In order to explain the structural requirements for α-glucosidase inhibitory activity, eleven derivatives were prepared, including one new compound, 2-formyl-(A)1–19α-hydroxy-1-norursane-2, 12-dien-28-oic acid 10c. The results demonstrated that a free hydroxyl at ring-A and a free carboxylic group at position 28 are key structural features for the α-glucosidase inhibitory activity, also that an ursane skeleton is optimum for the activity. Additionally, enzyme kinetic analysis of pomolic acid 2, the most potent compound, revealed that it inhibited α-glucosidase in a mixed-type manner. The molecular docking simulation validated this type of inhibition and highlighted the role of the C-3 hydroxyl and C-28 carboxylic groups in interaction with the enzyme in silico.</p

Acylated Preatroxigenin Glycosides from <i>Atroxima </i><i>c</i><i>ongolana</i>

Six new acylated bisdesmosidic preatroxigenin saponins named atroximasaponins E1, E2 (1, 2), F1, F2 (3, 4), and G1, G2 (5, 6) were isolated as three inseparable mixtures of the trans- and cis-p-methoxycinnamoyl derivatives, from the roots of Atroxima congolana. Their structures were established through extensive NMR spectroscopic analysis as 3-O-β-d-glucopyranosylpreatroxigenin-28-O-β-d-xylopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→3)]-[4-O-trans-p-methoxycinnamoyl]-β-d-fucopyranoside (atroximasaponin E1, 1), and its cis-isomer, atroximasaponin E2 (2), 3-O-β-d-glucopyranosylpreatroxigenin-28-O-β-d-xylopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→2)-[6-O-acetyl-β-d-glucopyranosyl-(1→3)]-[4-O-trans-p-methoxycinnamoyl]-β-d-fucopyranoside (atroximasaponin F1, 3), and its cis-isomer, atroximasaponin F2 (4), 3-O-β-d-glucopyranosylpreatroxigenin-28-O-β-d-apiofuranosyl-(1→3)-[α-l-rhamnopyranosyl-(1→2)]-[4-O-trans-p-methoxycinnamoyl]-β-d-fucopyranoside (atroximasaponin G1, 5), and its cis-isomer, atroximasaponin G2 (6), respectively

(−)-Axinyssene: A Novel Cytotoxic Diterpene from a Japanese Marine Sponge <i>Axinyssa </i>sp

A novel diterpene, (−)-axinyssene, was isolated from the Japanese marine sponge Axinyssa sp. The structure of (−)-axinyssene was determined on the basis of spectroscopic and synthetic evidence to be 1-methyl-4-[(4E)-5‘,9‘-dimethyl-1‘-methylene-4‘,8‘-decadienyl]-(4S)-cyclohexene. (−)- and (+)-axinyssene showed mild cytotoxicity against acute promyelocytic leukemia, HL-60 cells

Amphimelibiosides A−F, Six New Ceramide Dihexosides Isolated from a Japanese Marine Sponge <i>Amphimedon</i> sp.

Six new ceramide dihexosides, amphimelibiosides A−F (1−6), were isolated from a Japanese marine sponge Amphimedon sp. The structure of amphimelibioside C (3), which is a major component of amphimelibiosides, was determined by 2D NMR techniques, chemical degradation, and a semisynthetic method to be 1-O-[β-d-glucopyranosyl-(1→6)-α-d-galactopyranosyl]-(2S,3S,4R,6E)-2-[(2‘R)-2-hydroxydocosanoyl]-2-amino-6-octadecene-1,3,4-triol. The structures of the other constituents were elucidated by a combination of mass spectra, 1H NMR, and GC−MS analysis

Eryngium creticum L.: Chemical Characterization, SARS-CoV‑2 Inhibitory Activity, and <i>In Silico</i> Study

Phytochemical investigation of Eryngium creticum L. has resulted in isolation of five compounds, including four compounds that are reported from the plant for the first time. Compound 1 was identified as (E)-rosmarinic acid, meanwhile, compound 2 was isolated as an (E/Z)-rosmarinic acid mixture. Interestingly, the E/Z-isomeric mixture was about 4 times as active as the single E-isomer toward the severe acute respiratory syndrome coronavirus 2 3-chymotrypsin-like protease (3CLpro), IC50 = 6.062 and 25.75 μM, respectively. Utilizing combined molecular docking and molecular dynamics (MD) techniques, the binding affinities and features of the isolated compounds were evaluated against 3CLpro. Compound 2Z demonstrated a higher binding affinity for 3CLpro than 2E, with docking scores of −8.9 and −8.5 kcal/mol and MM-GBSA/150 ns MD binding energies of −26.5 and −22.1 kcal/mol, respectively. This justifies the superior activity of the E/Z-isomeric mixture versus the single E-isomer. Structural and energetic analyses revealed the stability of 2Z and 2E compared to the reference HIV-1 protease inhibitor, lopinavir. Besides, DFT calculations demonstrated the more energetic stability of 2E compared to 2Z, which justifies the difficulty in isolating the Z-isomer in a pure form, where it readily isomerizes to the E-isomer

Synthesis of 12‑<i>O</i>‑Mono- and Diglycosyl-oxystearates, a New Class of Agonists for the C‑type Lectin Receptor Mincle

Fifteen glycosyl-oxystearates were synthesized by Crich’s 4,6-benzylidene and Köening–Knorr strategies. Assessment of structure–activity relationships using macrophage-inducible C-type lectin (Mincle) receptor cells expressing nuclear factor of activated T cells (NFAT)-green fluorescent protein (GFP) revealed that four dimannopyranosyl-oxystearate analogues were Mincle agonists and that 12-O-(2-O-α-d-mannopyranosyl)-α-d-mannopyranosyl-oxystearate was as an activator of both mouse and human Mincle

Isolation and identification of new anthraquinones from <i>Rhamnus alaternus</i> L and evaluation of their free radical scavenging activity

<p>From the butanolic and the ethyl acetate extracts of <i>Rhamnus alaternus</i> L root bark and leaves, three new anthraquinone glycosides, alaternosides A-C (1,4,6,8 tetrahydroxy-3 methyl anthraquinone 1-O-ß-D-glucopyranosyl-4,6-di-O-α-L-rhamnopyranoside (<b>1</b>); 1,2,6,8 tetrahydroxy-3 methyl anthraquinone 8-O-ß-D-glucopyranoside <b>(2</b>) and 1, 6 dihydroxy-3 methyl 6 [2′-Me (heptoxy)] anthraquinone <b>(3</b>)) were isolated and elucidated together with the two known anthraquinone glycosides, Physcion-8-O-rutinoside (<b>4</b>) and emodin-6-O-α-L-rhamnoside (<b>5)</b> as well as with the known kaempferol-7-methylether (<b>6</b>), β-sitosterol (<b>7</b>) and β-sitosterol-3-O-glycoside (8). Their chemical structures were elucidated using spectroscopic methods (1D-, 2D-NMR and FAB-MS). Free radical scavenging activity of the isolated compounds was evaluated by their ability to scavenge DPPH^. free radicals. Compounds (<b>3</b>), (<b>4</b>) and (<b>6</b>) showed the highest activity with IC₅₀ values of 9.46, 27.68 and 2.35 μg/mL, respectively.</p

Supporting information - Supplemental material for Triterpenoid Saponins From the Stem Bark of <i>Pentaclethra eetveldeana</i>

Supplemental material, Supporting information for Triterpenoid Saponins From the Stem Bark of Pentaclethra eetveldeana by David Pertuit, Mpuza Kapundu, Anne-Claire Mitaine-Offer, Tomofumi Miyamoto, Chiaki Tanaka, Clément Delaude, and Marie-Aleth Lacaille-Dubois in Natural Product Communications</p

Steroidal Saponins from <i>Chlorophytum orchidastrum</i>

Six new spirostane-type saponins (1−6), named orchidastrosides A−F, and chloromaloside D were isolated from an ethanol extract of the roots of Chlorophytum orchidastrum. The saponins have neotigogenin or neogitogenin as the aglycon and oligosaccharidic chains possessing seven to nine sugar units. Their structures were elucidated mainly by 2D NMR spectroscopic analyses (COSY, TOCSY, NOESY, HSQC, and HMBC) and FABMS and HRESIMS. Compounds 1−6 were tested for cytotoxicity against two human colon cancer cell lines, HCT 116 and HT-29

Structure, Synthesis, and Biological Activity of a C‑20 Bisacetylenic Alcohol from a Marine Sponge <i>Callyspongia</i> sp.

An optically inactive C-20 bisacetylenic alcohol, (4<i>E</i>,16<i>E</i>)-icosa-4,16-diene-1,19-diyne-3,18-diol, was isolated from a marine sponge <i>Callyspongia</i> sp. as a result of screening of antilymphangiogenic agents from marine invertebrates. An optical resolution using chiral-phase HPLC gave each enantiomer, (−)-<b>1</b> and (+)-<b>2</b>. Because the natural and synthetic enantiomers <b>1</b> and <b>2</b> showed different biological properties, we investigated the structure–activity relationships of bisacetylenic alcohols using 11 synthetic derivatives, and it is clarified that the essential structural unit for antiproliferative activity is the “1-yn-3-ol” on both termini and that there is a minimum chain length that connects the “1-yn-3-ol” moieties