α-Glucosidase Inhibitory Phytochemical Components of Chinese Endemic Plant Whitfordiodendron filipes var. tomentosum.

Whitfordiodendron filipes var. tomentosum is an endemic plant in China. There have been no chemical or pharmacological studies of this plant reported before. In the current research, eight triterpenes and two steroids were obtained. Their structures were established by the analysis of NMR data and comparison with those reported in the literature. These ten structurally diverse compounds comprised five distinct carbon frameworks with different functionalities. The chemotaxonomic significance of these secondary metabolites was discussed, disclosing the common components between the variant W. filipes var. tomentosum and the species W. filipe. Evaluation of α-glucosidase inhibitory activities of these isolates disclosed that compounds 1, 2, 4, and 6 exhibited significant α-glucosidase inhibitory activities (IC50 = 16.6-19.2 µM), which were close in value to the positive control acarbose (IC50 = 11.5 µM). Moreover, the binding modes between the biologically active compounds 1, 2, 4, and 6 and the α-glucosidase protein were preliminarily studied using molecular docking. This study not only showed the chemical and biological profile of the plant W. filipes var. tomentosum but also revealed that these components could be developed as hypoglycemic lead compounds.

Genus Litophyton: A Hidden Treasure Trove of Structurally Unique and Diversely Bioactive Secondary Metabolites.

Marine soft corals are prolific sources of various natural products that have served as a wealthy reservoir of diverse chemical scaffolds with potential as new drug leads. The genus Litophyton contains almost 100 species but only a small proportion of them has been chemically investigated, which calls for more attentions from global researchers. In the current work, 175 secondary metabolites have been discussed, drawing from published data spanning almost five decades, up to July 2023. The studied species of the genus Litophyton resided in various tropical and temperate regions and encompassed a broad range of biologically active natural products including terpenes, steroids, nitrogen-containing metabolites, lipids, and other metabolites. A wide spectrum of pharmacological effects of these compounds had been evaluated, such as cytotoxic, antiviral, antibacterial, antifungal, anti-malarial, antifeedant, anti-inflammatory, molluscicidal, PTP1B inhibitory, insect growth inhibitory, and neuroprotective activities. This review aims to offer an up-to-date survey of the literature and provide a comprehensive understanding of the chemical structures, taxonomical distributions, and biological activities of the reported metabolites from the title genus whenever available.

Extending the Record of Terpenes from Soft Coral Sarcophyton mililatensis.

In the present study, a new polyoxygenated cembranoid named sarcomililatol H (1) as well as six known terpenes 2-7 with different skeletons were isolated from South China Sea soft coral Sarcophyton mililatensis. Based on the comprehensive analyses of 1D and 2D NMR spectroscopic data, the structure of the new compound 1 was established. This new cembranoid was characterized by the presence of the rarely encountered tetrahydropyran ring with the ether linkage across C-2 and C-12. By applying the time-dependent density functional theory electronic circular dichroism (TDDFT ECD) approach, the absolute configuration of sarcomililatol H (1) was determined. All of the isolates were subjected to the anti-inflammatory and anti-tumor bioassays. However, none of them was active in these evaluations. Additionally, the preliminary virtual screening of inhibitory against SARS-CoV-2 by molecular docking showed that diterpene 1 could be regarded as a SARS-CoV-2 main protease (Mpro ) inhibitor (binding energy: -7.63 kcal/mol). The discovery of these terpenes has expanded the chemical diversity and complexity of terpenes from the species S. mililatensis.

Cembrane Diterpenes Possessing Nonaromatic Oxacycles from the Hainan Soft Coral Sarcophyton mililatensis.

Documents on the chemical composition of the soft coral Sarcophyton mililatensis are sparse. The present investigation of the Hainan soft coral S. mililatensis resulted in the discovery of six new cembrane diterpenes, sarcoxacyclols A-F (1-6) and four known analogs (7-10). Their structures were elucidated by extensive spectroscopic analysis along with a comparison with the data in current literature. The nonaromatic oxacycles in their structures were the rarely found tetrahydrofuran ether across C-1 and C-12 and tetrahydropyran ether across C-1 and C-11, respectively. Moreover, the absolute configuration of compound 4 was established unambiguously by X-ray diffraction analysis using Ga Kα radiation (λ = 1.34139 Å). Based on the biogenetical consideration, the absolute configurations of other five new compounds were tentatively assumed. Assessment of the bioactivity for these secondary metabolites revealed that compound 1 exhibited significant tumor necrosis factor (TNF)-α inhibitory activity (IC50 = 9.5 µmol/L), similar to the positive control dexamethasone (IC50 = 8.7 µmol/L), but no obvious cytotoxicity towards RAW264.7 cells (CC50 > 50 µmol/L). The preliminary molecular docking suggested the crucial roles of the hydroxyl and acetoxyl groups in the computational prediction of the binding mode between the diterpene and the protein.

Mililatensols A-C, New Records of Sarsolenane and Capnosane Diterpenes from Soft Coral Sarcophyton mililatensis.

Three unusual diterpenes with rare sarsolenane and capnosane skeletons, namely mililatensols A-C (1-3), were isolated from the South China Sea soft coral Sarcophyton mililatensis, leading to the first record of sarsolenane and capnosane diterpenes from the title animal. The structures of compounds 1-3 were established by extensive spectroscopic analysis and comparison with the literature data. Moreover, the absolute configuration of 2 was determined by TDDFT ECD calculations. In an in vitro bioassay, none of the isolated compounds showed obvious anti-inflammatory activity on LPS-induced TNF-α release in RAW264.7 macrophages. In the preliminary virtual screening of inhibitory potential against SARS-CoV-2 by molecular docking, the results showed these three diterpenes were potential SARS-CoV-2 Mpro inhibitors.