Cytotoxic polyphenolic compounds from Lespedeza bicolor stem bark

Lespedeza bicolor root extract exerts anti-TNBC potential by regulating FAK-related signalling pathways

Lespedeza bicolor is a shrub plant that has been widely distributed in East Asia. The methanol extract from its LBR has been shown to exhibit anticancer and anti-bacterial effects. However, its anticancer efficacy in TNBC remains uncertain. This work aimed to study the anti-TNBC effect of LBR ethanol extract and its underlying mechanism. LBR triggered the cell death in TNBC through inhibiting cell proliferation, S-phase cell arrest, and induction of apoptosis. RNA-seq analysis revealed that the genes altered by LBR treatment were predominantly enriched in the cell adhesion. Notably, LBR inhibited phosphorylation and distribution of FAK. Furthermore, LBR demonstrated significant anticancer activity in xenograft tumors in mice through inhibiting cancer cell growth and inducing apoptosis. This work demonstrated the anticancer efficiency of LBR in TNBC without causing significant adverse effect, which providing a foundation for developing LBR based chemotherapeutic agents for breast cancer therapy.

Seven new secondary metabolites isolated from roots of Lespedeza bicolor

Chemical investigation of a methanol extract obtained from the roots of Lespedeza bicolor identified one new pterocarpene (1), three new pterocarpans (2-4), and three new arylbenzofurans (5-7), and two known compounds (8 and 9). Their structures were determined by interpretations obtained from combined UV, NMR, and HRTOFMS spectroscopic data. Furthermore, the absolute configurations of compounds 2 and 3 were established by the combination of electronic circular dichroism (ECD) calculations and NMR calculations with DP4+ probability analysis. All isolated compounds (1-9) were evaluated for cytotoxicity against the human lung carcinoma cell line A549 and the human hepatoma cell line Huh-7. Compound 4 showed antiproliferative activity against A549 cell line with IC50 value of 24.9 μM. Furthermore, compound 9 exhibited cytotoxicity against Huh-7 cell line with IC50 value of 68.7 μM.

Neuroprotective and Antiherpetic Properties of Polyphenolic Compounds from Maackia amurensis Heartwood

In this study, we isolated a new isoflavanostilbene maackiapicevestitol (1) as a mixture of two stable conformers 1a and 1b as well as five previously known dimeric and monomeric stilbens: piceatannol (2), maackin (3), scirpusin A (4), maackiasine (5), and maackolin (6) from M. amurensis heartwood, using column chromatography on polyamide, silicagel, and C-18. The structures of these compounds were elucidated by NMR, HR-MS, and CD techniques. Maksar® obtained from M. amurensis heartwood and polyphenolics 1–6 possessed moderate anti-HSV-1 activity in cytopathic effect (CPE) inhibition and RT-PCR assays. A model of PQ-induced neurotoxicity was used to study the neuroprotective potential of polyphenolic compounds from M. amurensis. Maksar® showed the highest neuroprotective activity and increased cell viability by 18% at a concentration of 10 μg/mL. Maackolin (6) also effectively increased the viability of PQ-treated Neuro-2a cells and the value of mitochondrial membrane potential at concentrations up to 10 μΜ. Maksar® and compounds 1–6 possessed higher FRAP and DPPH-scavenging effects than quercetin. However, only compounds 1 and 4 at concentrations of 10 μM as well as Maksar® (10 μg/mL) statistically significantly reduced the level of intracellular ROS in PQ-treated Neuro-2a cells.

Polyphenolic Compounds from Lespedeza bicolor Protect Neuronal Cells from Oxidative Stress

Pterocarpans and related polyphenolics are known as promising neuroprotective agents. We used models of rotenone-, paraquat-, and 6-hydroxydopamine-induced neurotoxicity to study the neuroprotective activity of polyphenolic compounds from Lespedeza bicolor and their effects on mitochondrial membrane potential. We isolated 11 polyphenolic compounds: a novel coumestan lespebicoumestan A (10) and a novel stilbenoid 5’-isoprenylbicoloketon (11) as well as three previously known pterocarpans, two pterocarpens, one coumestan, one stilbenoid, and a dimeric flavonoid. Pterocarpans 3 and 6, stilbenoid 5, and dimeric flavonoid 8 significantly increased the percentage of living cells after treatment with paraquat (PQ), but only pterocarpan 6 slightly decreased the ROS level in PQ-treated cells. Pterocarpan 3 and stilbenoid 5 were shown to effectively increase mitochondrial membrane potential in PQ-treated cells. We showed that pterocarpans 2 and 3, containing a 3’-methyl-3’-isohexenylpyran ring; pterocarpens 4 and 9, with a double bond between C-6a and C-11a; and coumestan 10 significantly increased the percentage of living cells by decreasing ROS levels in 6-OHDA-treated cells, which is in accordance with their rather high activity in DPPH^• and FRAP tests. Compounds 9 and 10 effectively increased the percentage of living cells after treatment with rotenone but did not significantly decrease ROS levels.

Biologically active polyphenolic compounds from Lespedeza bicolor

We investigated the ability of six prenylated prerocarpans, stilbenoid, and a new dimeric flavonoid, lespebicolin B, from stem bark as well as two 3-O-rutinosides and a mixture of 3-O-β-D-glucosides of quercetin and kaempferol from flowers of Lespedeza bicolor to inhibit HSV-1 replication in Vero cells. Pretreatment of HSV-1 with polyphenolic compounds (direct virucidal effect) showed that pterocarpans lespedezol A₂ (1), (6aR,11aR)-6a,11a-dihydrolespedezol A₂ (2), (6aR,11aR)-2-isoprenyldihydrolespedezol A₂ (4), and (6aR,11aR,3'R)-dihydrolespedezol A₃ (5) significantly inhibited viral replication, with a selective index (SI) ≥10. Compound 4 possessed the lowest 50% - inhibiting concentration (IC₅₀) and the highest SI values (2.6 μM and 27.9, respectively) in this test. (6aR,11aR)-2-Isoprenyldihydrolespedezol A₂ (4) also had a moderate effect under simultaneous treatment of Vero cells with the tested compound and virus (IC₅₀ and SI values were 5.86 μM and 12.4, respectively). 3-O-rutinosides of quercetin and kaempferol and a mixture of 3-O-β-D-glucosides of quercetin and kaempferol (10 and 12) also showed significant virucidal activity, with SI values of 12.5, 14.6, and 98.2, respectively, and IC₅₀ values of 8.6, 12.2, and 3.6, respectively. We also performed a quantitative structure-activity relationship (QSAR) analysis of data on the virucidal activity of polyphenolics with 4 < pIC₅₀ < 6. It was found that the virucidal activity of these compounds depended on both the structure of the aromatic part and the conformation of geranyl and isoprenyl side chains of their molecules. These findings are correlated with the largest value of the principal moment of inertia (pmi) descriptor describing the geometry of molecules.

Polyphenolic Compounds from Lespedeza Bicolor Root Bark Inhibit Progression of Human Prostate Cancer Cells via Induction of Apoptosis and Cell Cycle Arrest

From a root bark of Lespedeza bicolor Turch we isolated two new (7 and 8) and six previously known compounds (1–6) belonging to the group of prenylated polyphenols. Their structures were elucidated using mass spectrometry, nuclear magnetic resonance and circular dichroism spectroscopy. These natural compounds selectively inhibited human drug-resistant prostate cancer in vitro. Prenylated pterocarpans 1–3 prevented the cell cycle progression of human cancer cells in S-phase. This was accompanied by a reduced expression of mRNA corresponding to several human cyclin-dependent kinases (CDKs). In contrast, compounds 4–8 induced a G1-phase cell cycle arrest without any pronounced effect on CDKs mRNA expression. Interestingly, a non-substituted hydroxy group at C-8 of ring D of the pterocarpan skeleton of compounds 1–3 seems to be important for the CDKs inhibitory activity.

Antiproliferative Pterocarpans and Coumestans from Lespedeza bicolor

Chromatographic purification of a methanol extract of the roots of Lespedeza bicolor led to the isolation of four new pterocarpans (1-4), two new coumestans (6 and 7), two new arylbenzofurans (8 and 9), and the known pterocarpan 1-methoxyerythrabyssin II (5). Their structures were identified using NMR spectroscopy, UV spectroscopy, and mass spectrometry. Cytotoxicity assays showed that compounds 1-9 exerted antiproliferative effects on blood cancer cells. Of these compounds, 1 and 6 induced mitochondrial depolarization and induced apoptosis in Jurkat cells. These compounds promoted cell death by inducing cell-cycle arrest at the G1 stage, reducing levels of BCL2, and increasing cleavage of PARP-1. These findings indicate that 1 and 6 are possible lead compounds for the treatment of human leukemia cells via intracellular signaling.