A Laurane Sesquiterpene and Rearranged Derivatives from the Chinese Red Alga <i>Laurencia </i><i>o</i><i>kamurai</i> Yamada

One new laurane sesquiterpenoid, 3β-hydroxyaplysin (2), and two novel rearranged sesquiterpenes, laurokamurenes A (3) and B (4), together with three known related compounds, 3α-hydroxydebromoaplysin (1), debromoaplysin (6), and laurinterol (7), have been isolated from the Chinese red alga Laurencia okamurai. Their structures, including relative stereochemistry, were determined on the basis of detailed interpretation of 2D NMR spectra and comparison with related known compounds

<i>Iso</i>-ximaonanolobatin G, a minor new cembrane-type diterpenoid from the South China Sea soft coral <i>Sinularia nanolobata</i>

A new cembrane-type diterpenoid, named iso-ximaonanolobatin G (1), and one known related one, namely ximaonanolobatin G (2), along with four known steroids, were isolated from the South China Sea soft coral Sinularia nanolobata. Their full structures were elucidated by extensive spectroscopic analysis, quantum mechanical (QM)-NMR methods, and by the comparison of the spectroscopic data with those reported in the literature.</p

Nanjiols A−C, New Steroids from the Chinese Soft Coral <i>Nephthea </i><i>b</i><i>ayeri</i>

Three new polyoxygenated steroids, nanjiol A (1), B (2), and C (3), were isolated from an East China Sea soft coral Nephthea bayeri, and their structures were characterized by spectroscopic methods and comparison with known compounds. The new molecules were structurally related to (20S)-cholesta-1,4-diene-18,20-diol-3-one (4), a typical metabolite from the black coral Antipathes subpinnata

Synthesis, spectral characterization, and antituberculosis activity of thiazino[3,2-<i>A</i>]benzimidazole derivatives

<p>A series of novel thiazino[3,2-a]benzimidazole derivatives synthesized by cyclization of (R)-2-(chloromethyl)oxirane with benzimidazole-2-thiol followed by reacted with benzyl bromides in high yield under milder conditions. The molecular structures of all compounds were confirmed by ¹H and ¹³C NMR spectroscopy and Mass spectrometry. The absolute configuration of the compounds was confirmed by X-ray diffraction analysis. All the synthesized compounds were evaluated in vitro for their antituberculosis activity.</p> <p></p

A new 5α,8α-epidioxysterol with immunosuppressive activity from the South China Sea soft coral <i>Sinularia</i> sp.

A new 5α,8α-epidioxysterol, namely yalongsterol A (1), along with two known related steroids 5α,8α-epidioxy-24-methyl-cholesta-6,24(28)-dien-3β-ol (2) and (22E,24S)-5α,8α-epidioxy-24-methyl-cholesta-6,22-dien-3β-ol (3), were isolated from the South China Sea soft coral Sinularia sp. Their structures were established by extensive spectroscopic analyses and comparisons of the spectral data with those reported in the literature. In bioassay, compounds 1–3 showed moderate immunosuppressive activities against T and/or B lymphocyte cells with IC50 values ranging from 19.30 to 59.49 μM, and low cytotoxicity on murine splenocytes with CC50 values ranging from 40.88 to 62.29 μM. </p

Sesquiterpenes from the Hainan Sponge <i>Dysidea septosa</i>

Five new sesquiterpenes, named lingshuiolides A (1) and B (2), lingshuiperoxide (6), isodysetherin (10), and spirolingshuiolide (12), along with several known related analogues (7−9, 11, and 13−15), were isolated from the Hainan marine sponge Dysidea septosa. The structures of new compounds 1, 2, 6, 10, and 12 were determined by detailed analysis of 1D and 2D NMR spectra and by comparison with related model compounds. The absolute configuration of lingshuiolide B (2) was established by using the modified Mosher’s method. Spirolingshuiolide (12) represents the first example of a sesquiterpene with a rearranged drimane skeleton. Compounds 7−9 and 15 exhibited significant inhibitory activity against human protein tyrosine phosphatase 1B (hPTP1B), an enzyme involved in the regulation of insulin signaling. In particular, 15 showed the most potent effect, with an IC50 value of 1.9 μg/mL

Paracaseolide A, First α-Alkylbutenolide Dimer with an Unusual Tetraquinane Oxa-Cage Bislactone Skeleton from Chinese Mangrove <i>Sonneratia paracaseolaris</i>

A novel α-alkylbutenolide dimer, paracaseolide A (2), characterized by an unusual tetraquinane oxa-cage bislactone skeleton bearing two linear alkyl chains, was isolated from the mangrove plant Sonneratia paracaseolaris. The structure of 2 was elucidated by extensive spectroscopic analysis. A plausible retrosynthetic pathway for paracaseolide A (2) was proposed. Compound 2 exhibited significant inhibitory activity against dual specificity phosphatase CDC25B, a key enzyme for cell cycle progression, with an IC50 value of 6.44 μM

Biscembranoids Formed from an α,β-Unsaturated γ‑Lactone Ring as a Dienophile: Structure Revision and Establishment of Their Absolute Configurations Using Theoretical Calculations of Electronic Circular Dichroism Spectra

Four new biscembranoids, bislatumlides C–F (1–4), were isolated from the Hainan soft coral Sarcophyton latum. Their structures were elucidated by detailed analysis of spectroscopic data and by comparison with reported data of related derivatives, leading to the structure revision of co-occurring bislatumlides A (5) and B (6) at the C-21 configuration. The absolute configurations of bislatumlides C and E (1 and 3) were determined by TDDFT calculations of their solution ECD spectra, allowing the configurational assignment of the related bislatumlides D and F (2 and 4) and A and B (5 and 6) as well. Bislatumlides A–F (1–6) represent the only biscembranoids formed by the undescribed coupling pattern of Diels–Alder cycloaddition between the Δ1(2) double bond involving an α,β-unsaturated γ-lactone ring as a dienophile group and a trisubstituted conjugated Δ21(34)/Δ35(36)-butadiene moiety. An endo-cycloaddition gave 1, 2, 5, and 6, whereas an exo-cycloaddition produced 3 and 4. This is the first report of exo-addition dicembranoids from marine sources and from nature. Bislatumlides C and E (1, 3) could be used as ECD reference compounds in the determination of absolute configuration for related derivatives

Hyrtiosins F and G, two new scalarane sesterterpenes from the South China sea sponge <i>Hyrtios erecta</i>

Two new scalarane sesterterpenes, hyrtiosins F and G (1 and 2), along with two known related compounds, hyrtiosin D and sesterstatin 6 (3 and 4), were isolated from the Hainan marine sponge Hyrtios erecta. The structures of new compounds 1 and 2 were determined by detailed analysis of 1D and 2D NMR spectra and by comparison of the spectroscopic data with those reported in the literatures.</p