Four new lignans from the leaves and stems of Schisandra propinqua var. sinensis

Lignans and sesquiterpenoids from the stems of Schisandra bicolor var. tuberculate

A pair of new tetrahydrofuran lignan enantiomers, (±)-schibiculatin A [(±)-1], a new enedione lignan, schibiculatin B (2), two new cadinane-type sesquiterpenoids, schibiculatins C (3) and D (4), along with two known seco-cadinane-type sesquiterpenoids (5 and 6) and seven known miscellaneous lignans (7-13) were isolated from the stems of Schisandra bicolor var. tuberculate. The structures of 1-4 were elucidated by comprehensive analysis of their spectroscopic data, quantum chemical calculations, as well as single-crystal X-ray diffraction. A few isolated compounds were tested for their protective activities against corticosterone-induced apoptosis in PC12 cells. Among them, compounds 5 and 6 showed moderate activities.

Plant-derived lignans as potential antiviral agents: a systematic review

Medicinal plants are one of the most important sources of antiviral agents and lead compounds. Lignans are a large class of natural compounds comprising two phenyl propane units. Many of them have demonstrated biological activities, and some of them have even been developed as therapeutic drugs. In this review, 630 lignans, including those obtained from medicinal plants and their chemical derivatives, were systematically reviewed for their antiviral activity and mechanism of action. The compounds discussed herein were published in articles between 1998 and 2020. The articles were identified using both database searches (e.g., Web of Science, Pub Med and Scifinder) using key words such as: antiviral activity, antiviral effects, lignans, HBV, HCV, HIV, HPV, HSV, JEV, SARS-CoV, RSV and influenza A virus, and directed searches of scholarly publisher's websites including ACS, Elsevier, Springer, Thieme, and Wiley. The compounds were classified on their structural characteristics as 1) arylnaphthalene lignans, 2) aryltetralin lignans, 3) dibenzylbutyrolactone lignans, 4) dibenzylbutane lignans, 5) tetrahydrofuranoid and tetrahydrofurofuranoid lignans, 6) benzofuran lignans, 7) neolignans, 8) dibenzocyclooctadiene lignans and homolignans, and 9) norlignans and other lignoids. Details on isolation and antiviral activities of the most active compounds within each class of lignan are discussed in detail, as are studies of synthetic lignans that provide structure-activity relationship information.

Bioactive tetrahydrofuran lignans from roots, stems, leaves and twigs of Anogeissus rivularis

Four previously undescribed tetrahydrofuran lignans, named anorisols A-D (1-4) and fourteen known compounds (5-18) were isolated from the roots, stems, leaves and twigs of Anogeissus rivularis. The chemical structures were elucidated on the basis of their spectroscopic data and by comparison with the literature data. The absolute configurations of 1-4 were established by comparison of the experimental ECD spectra with the calculated ECD spectra. Some isolated compounds were evaluated for their cytotoxic activity as well as anti-HIV-1 activity employing reverse transcriptase (RT) and syncytium reduction assays using the ^ΔTat/RevMC99 virus in 1A2 cell line systems. Compound 6 displayed the most potent activity in syncytium inhibition assay with effective concentration at 50% (EC₅₀) value of 13.3 μM (SI >3.0). In the reverse transcriptase assay, compound 1 exhibited moderate activity with IC₅₀ value of 213.9 μM.

Inhibitory effects of schisantherin F from Schisandra propinqua subsp. sinensis on human melanoma A375 cells through ROS-induced mitochondrial dysfunction and mitochondria-mediated apoptosis

Schisandra propinqua subsp. sinensis is a traditional medicinal plant used in Chinese folk medicine. Melanoma is the most dangerous form of skin cancer. To discover bioactive phytochemicals for preventing human melanoma, we have investigated the inhibitory effects of schisantherin F in Schisandra propinqua subsp. sinensis on human melanoma A375 cells and relevant mechanisms. The results showed that schisantherin F can inhibit A375 cells through inducing apoptosis. Further investigations have demonstrated schisantherin F attenuated the overproduction of ROS, depolarization of MMP, and mPTP opening. Meanwhile, schisantherin F inhibited the activity of Caspase-3 and up-stream Caspase-9, down-regulated Bcl-2 and up-regulated Bax. These findings propose the inhibitory mechanisms of schisantherin F in A375 cells include induction of mitochondrial dysfunction and mitochondria-mediated apoptosis.