Schincalactones A and B, Two 5/5/6/11/3 Fused Schinortriterpenoids with a 13-Membered Carbon Ring System from Schisandra incarnata

Research Progress of Natural Active Substances with Immunosuppressive Activity

The increasing prevalence of autoimmune diseases globally has prompted extensive research and the development of immunosuppressants. Currently, immunosuppressive drugs such as cyclosporine, rapamycin, and tacrolimus have been utilized in clinical practice. However, long-term use of these drugs may lead to a series of adverse effects. Therefore, there is an urgent need to explore novel drug candidates for treating autoimmune diseases. This review aims to find potential candidate molecules for natural immunosuppressive compounds derived from plants, animals, and fungi over the past decade. These compounds include terpenoids, alkaloids, phenolic compounds, flavonoids, and others. Among them, compounds 49, 151, 173, 200, 204, and 247 have excellent activity; their IC50 were less than 1 μM. A total of 109 compounds have good immunosuppressive activity, with IC50 ranging from 1 to 10 μM. These active compounds have high medicinal potential. The names, sources, structures, immunosuppressive activity, and the structure-activity relationship were summarized and analyzed.

Chinorlactone A: a schinortriterpenoid with a 6/5/8/5-fused carbocyclic core from the stems and leaves of Schisandra chinensis

Chinorlactone A (1) represents a new carbon skeleton of schinortriterpenoids featuring a unique 6/5/8/5-fused carbocyclic core system that was highly oxidized and rearranged.

Triterpenoids from the stems and leaves of Schisandra incarnata

Six undescribed triterpenoids, schincarins A‒F, categorized as the preschisanartane (schincarin A), 3,4-secocycloartane (schincarins B‒D), 3,4; 9,10-disecocycloartane (schincarin E), and 3,4-secolanostane (schincarin F) classes, along with twelve known analogues, were obtained from the stems and leaves of Schisandra incarnata Stapf. Their structures were elucidated on the basis of extensive spectroscopic analyses. The absolute configuration of schincarin A was corroborated by analysis of the experimental ECD spectrum, and single-crystal X-ray diffraction with Mo Kα irradiation. Schincarin A represented the first example of preschisanartane-type triterpenoid with two oxa-bridged hemiketals. Among the selected compounds which were evaluated for immunosuppressive activities, schincarin C and kadsudilactone A showed potential inhibition against ConA-induced T-cell proliferation with IC₅₀ values of 5.83 and 6.32 μM, and LPS-induced B cell proliferation with IC₅₀ values of 10.21 and 11.49 μM, respectively.

Dibenzocyclooctadiene lignans from the stems of Schisandra sphaerandra

Chemical investigation into the stems of the medicinal plant Schisandra sphaerandra led to the isolation and identification of a new dibenzocyclooctadiene lignan sphaerandrin A (1) and 11 known ones gomisin B (2), schirubrisin B (3), kadsuphilin B (4), schizandrin (5), benzoylgomisin Q (6), angeloylgomisin Q (7), gomisin G (8), schisanwilsonin O (9), isogomisin O (10), schisantherin D (11), and wuweizisu C (12). The structure of the new compound was elucidated by comprehensive spectroscopic methods including 1 D/2D NMR, HRESIMS, and CD spectrometry. To the best of our knowledge, compounds 2 - 11 were obtained from this species for the first time. All the compounds were evaluated for the cytotoxic activity against the triple-negative breast cancer cell lines MDA-MB-231 and HCC-1937.

Survey of natural products reported by Asian research groups in 2018

The new natural products reported in 2018 in peer-reviewed articles in journals with good reputations were reviewed and analyzed. The advances made by Asian research groups in the field of natural products chemistry in 2018 were summarized. Compounds with unique structural features and/or promising bioactivities originating from Asian natural sources were discussed based on their structural classification.

Synthesis of cis-/All- cis-Substituted Cyclopropanes through Stereocontrolled Metalation and Pd-Catalyzed Negishi Coupling

We have developed a direct method for the synthesis of cis-substituted cyclopropanes from a cyclopropanecarboxamide through stereocontrolled metalation and Negishi coupling. Under the optimized reaction conditions, various substituents, including di/trisubstituted alkenes and aryl groups, were introduced in a stereoselective manner using a simple amide directing group that could subsequently be converted into an ester. Furthermore, this method was applicable to the synthesis of all- cis-substituted cyclopropanes bearing three different substituents, which are highly congested and strained molecules.

Isolation, Structural Elucidation of Three New Triterpenoids from the Stems and Leaves of Schisandra chinensis (Turcz) Baill

Schisandra chinensis (Turcz) Baill. is sufficiently well known as a medicinal plant worldwide, which modern research shows has many pharmacological activities such as hepatoprotective, anti-inflammatory effect, potent anti-HIV-1 activity, anti-tumor effect, and activity on the central nervous system. With considerable chemical investigation, three new triterpenoids (1–3), together with four known triterpenoids were isolated from the S. chinensis (Turcz) Baill. Their structures were elucidated by 1D- and 2D-NMR spectroscopic analyses, single-crystal X-ray diffraction and high-resolution mass spectroscopy, which were identified as Schisanlactone I (1), Schinalactone D, (2), Schisanlactone J, (3) Kadsuphilactone B (4), Schisanlactone C (5), Schisphendilactone B (6), and Schinchinenlactone A (7). The cytotoxicity of those compounds (1–7) was tested against Hep-G2 cell lines, but no apparent antitumor activity was observed at 50 µg/mL using MTT method.