Enantiomeric neolignans from Picrasma quassioides exhibit distinctive cytotoxicity on hepatic carcinoma cells through ROS generation and apoptosis induction

Progress in the study of chemical composition, biological activity, and its metabolism of the Picrasma quassioides

Picrasma quassioides (D.Don) Benn is a member of the Simaroubaceae family, which has a long history of medicinal use in China, the composition of compounds is complex, mainly including alkaloids, lignin, triterpenoids, and other compounds. As a traditional Chinese medicine, P. quassioides has pharmacological effects such as anti-inflammatory, antipyretic, antiviral, blood pressure lowering and anticancer. Scholars at home and abroad have been studying P. quassioides for about 50 years. In the present review, the research status of the chemical composition, pharmacological activity and pharmacokinetics of P. quassioides was provided, as a reference for further developing the value of P. quassioides.

Aromatic glycosides and lignans glycosides with their acetylcholinesterase inhibitory activities from the leaves of Picrasma quassioides

In this study, eight new natural products were isolated from the leaves of Picrasma quassioides. Spectroscopic techniques were used for the elucidation of their planar structures. Their absolute configurations were elucidated on the basis of electron circular dichroism (ECD) techniques combined with the P/M helicity rule for the 2,3-dihydrobenzofuran chromophore, and saccharide hydrolysis. Cholinesterase inhibitors are often used as Alzheimer's disease inhibitors.Thus, acetylcholinesterase and butyrylcholinesterase inhibitory activity of these eight compounds were tested, and results showed that only compound 6 showed weakly acetylcholinesterase inhibitory activity. In particular, molecular docking was used to illustrate the bindings between compound 6 and the active sites of AChE.

Quassinoids from Picrasma chinensis with Insecticidal Activity against Adults and Larvae of Diaphorina citri Kuwayama and Neuroprotective Effect

Eleven new tetracyclic quassinoids, picrachinensin A-K (1-11), along with six known congeners, were isolated from the stems and leaves of Picrasma chinensis. Their structures were elucidated by integrated multiple spectroscopic techniques, single-crystal X-ray diffraction analysis, and electronic circular dichroism. Notably, compounds 3 and 4 are a pair of undescribed epimers, and 8 and 9 are unusual quassinoids with a hydroxymethyl group at C-13. Biologically, compound 7 exhibited insecticidal activity on both adults and larvae of Diaphorina citri Kuwayama even more effectively than the positive control (abamectin), with an LD₅₀ of 55.69 mg/L for adults and a corrected mortality rate of 30.42 ± 2.78% for larvae (100 mg/L). According to preliminary structure-activity relationship investigations, the hydroxymethyl at the C-13 position of quassinoids was beneficial for their insecticidal activity. In addition, compounds 1, 4, and 12 exhibited excellent neuroprotective effect against H₂O₂-induced oxidative injury on SH-SY5Y cells, with more potent activity than the positive control (Trolox), and all the compounds exhibited no cytotoxicity to SH-SY5Y and BV-2 cells at the indicated concentrations.

Cytotoxic cycloartane triterpenoid saponins from Actaea vaginata and their mechanism of action

A further phytochemical investigation of the whole plants of Actaea vaginata afforded two new cycloartane triterpenoid saponins, (20S*,24R*)-15α,16β-diacetoxy-20,24-epoxy-9,19-cyclolanostane-3β,25-diol-3-O-β-d-xylopyranoside (1) and (20S)-15β,16β -diacetoxy-18,20-epoxy-3β,25-diol-24-oxo-9,19-cyclolanostan-3-O-β-D-xylo-pyrano-syl-25-O-β-d-glucopyranoside (2), together with four known compounds (3-6). Their structures were established on the basis of extensive analysis of NMR and HRESIMS data as well as by comparison with the reported data in the literature. All the isolates were evaluated for their cytotoxic activities against human hepatocellular carcinoma HepG2 cell line. Compounds 1 and 2 exhibited weak cytotoxicity with IC₅₀ values of 36.10 and 27.39 μM, respectively. In addition, beesioside I (6) was found to significantly inhibit proliferation and induce apoptosis in HepG2 cells. A closer examination of underlying mechanism revealed that beesioside I could increase the levels of ROS and caspase-3 and promote phosphorylation of JNK in the JNK signaling pathway. Molecular modeling studies also shed further light on how beesioside I interacted with the key protein kinase.

Study on components with neuroinflammation inhibitory activities from Croton tiglium L. var. xiaopadou

An undescribed tigliane diterpenoid 12- O -tiglyl-13-acetyl-17- O -tiglyl-phorbol, together with thirty-three known components, were isolated from the stems of Croton tiglium L. var. xiaopadou (Euphorbiaceae). Their structures were established based on spectroscopic data and calculated ECD spectra. Their anti-neuroinflammatory effects were evaluated in LPS-induced BV-2 microglia. Thirteen tested compounds showed significant inhibitory activities, especially compounds 10 , 16 , 18 and 21 exhibited an inhibitory effect with IC 50 values in the range of 12.39 to 17.80 μM, which are comparable with that of the positive control (minocycline, IC 50 13.92 μM).

Natural Enantiomers: Occurrence, Biogenesis and Biological Properties

The knowledge that natural products (NPs) are potent and selective modulators of important biomacromolecules (e.g., DNA and proteins) has inspired some of the world's most successful pharmaceuticals and agrochemicals. Notwithstanding these successes and despite a growing number of reports on naturally occurring pairs of enantiomers, this area of NP science still remains largely unexplored, consistent with the adage "If you don't seek, you don't find". Statistically, a rapidly growing number of enantiomeric NPs have been reported in the last several years. The current review provides a comprehensive overview of recent records on natural enantiomers, with the aim of advancing awareness and providing a better understanding of the chemical diversity and biogenetic context, as well as the biological properties and therapeutic (drug discovery) potential, of enantiomeric NPs.

Bioassay-Guided Interpretation of Antimicrobial Compounds in Kumu, a TCM Preparation From Picrasma quassioides' Stem via UHPLC-Orbitrap-Ion Trap Mass Spectrometry Combined With Fragmentation and Retention Time Calculation

The stem of Picrasma quassioides (PQ) was recorded as a prominent traditional Chinese medicine, Kumu, which was effective for microbial infection, inflammation, fever, and dysentery, etc. At present, Kumu is widely used in China to develop different medicines, even as injection (Kumu zhusheye), for combating infections. However, the chemical basis of its antimicrobial activity has still not been elucidated. To examine the active chemicals, its stem was extracted to perform bioassay-guided purification against Staphylococcus aureus and Escherichia coli. In this study, two types of columns (normal and reverse-phase) were used for speedy bioassay-guided isolation from Kumu, and the active peaks were collected and identified via an UHPLC-Orbitrap-Ion Trap Mass Spectrometer, combined with MS Fragmenter and ChromGenius. For identification, the COCONUT Database (largest database of natural products) and a manually built PQ database were used, in combination with prediction and calculation of mass fragmentation and retention time to better infer their structures, especially for isomers. Moreover, three standards were analyzed under different conditions for developing and validating the MS method. A total of 25 active compounds were identified, including 24 alkaloids and 1 triterpenoid against S. aureus, whereas only β-carboline-1-carboxylic acid and picrasidine S were active against E. coli. Here, the good antimicrobial activity of 18 chemicals was reported for the first time. Furthermore, the spectrum of three abundant β-carbolines was assessed via their IC₅₀ and MBC against various human pathogens. All of them exhibited strong antimicrobial activities with good potential to be developed as antibiotics. This study clearly showed the antimicrobial chemical basis of Kumu, and the results demonstrated that HRMS coupled with MS Fragmenter and ChromGenius was a powerful tool for compound analysis, which can be used for other complex samples. Beta-carbolines reported here are important lead compounds in antibiotic discovery.

Dehydrocrenatidine inhibits head and neck cancer cells invasion and migration by modulating JNK1/2 and ERK1/2 pathway and decreases MMP-2 expression

Head and neck cancer is associated with poor prognosis because of its highly metastatic nature. For the better management of head and neck cancer patients, it is very important to diagnose the cancer at an early stage, as well as to prevent the rapid spread of cancer either through direct invasion or lymphatic metastasis. In present study, the effect of dehydrocrenatidine, which is a beta-carboline alkaloid found in the medicinal plant Picrasma quassioides, on human head and neck cancer metastasis was investigated. The study results revealed the treatment of FaDu, SCC9, and SCC47 cells with 5, 10, and 20 μM of dehydrocrenatidine significantly decreased the motility, migration, and invasion of head and neck cancer cells. Moreover, the dehydrocrenatidine treatment significantly decreased the expression of MMP-2 and phosphorylation of ERK1/2 and JNK1/2. Additional experiments revealed that the cotreatment of dehydrocrenatidine with either ERK1/2 or JNK1/2 inhibitor caused further reduction in cancer cell motility and migration compared to that in dehydrocrenatidine treatment alone. Moreover, similar trend was observed in case of ERK1/2 and JNK1/2 phosphorylation and MMP-2 expression after the cotreatment. Taken together, the mechanism by which dehydrocrenatidine can decrease the phosphorylation of ERK1/2 and JNK1/2, follow decrease the expression of MMP-2 and inhibits head and neck cancer cells invasion and migration. This present study identifies dehydrocrenatidine as a potent antimetastatic agent that can be used clinically to improve head and neck cancer prognosis.

Picrasma quassioides Extract Elevates the Cervical Cancer Cell Apoptosis Through ROS-Mitochondrial Axis Activated p38 MAPK Signaling Pathway

BACKGROUND/AIM

Picrasma quassioides (P. quassioides) is used in traditional Asian medicine widely for the treatment of anemopyretic cold, eczema, nausea, loss of appetite, diabetes mellitus, hypertension etc. In this study we aimed to understand the effect of P. quassioides ethanol extract on SiHa cervical cancer cell apoptosis.

MATERIALS AND METHODS

The P. quassioides extract-induced apoptosis was analyzed using the MTT assay, fluorescence microscopy, flow cytometry and western blotting.

RESULTS

P. quassioides extract induced cellular apoptosis by increasing the accumulation of cellular and mitochondrial reactive oxygen species (ROS) levels and inhibiting ATP synthesis. Pretreatment with N-Acetylcysteine (NAC), a classic antioxidant, decreased the intracellular ROS production and inhibited apoptosis. In addition, the P38 MAPK signaling pathway is a key in the apoptosis of SiHa cells induced by the P. quassioides extract.

CONCLUSION

The P. quassioides extract exerts its anti-cancer properties on SiHa cells through ROS-mitochondria axis and P38 MAPK signaling. Our data provide a new insight for P. quassioides as a therapeutic strategy for cervical cancer treatment.

Phytochemistry, Traditional Use and Pharmacological Activity of Picrasma quassioides: A Critical Reviews

Picrasma quassioides is a member of the Simaroubaceae family commonly grown in the regions of Asia, the Himalayas, and India and has been used as a traditional herbal medicine to treat various illnesses such as fever, gastric discomfort, and pediculosis. This study aims to critically review the presence of phytochemicals in P. quassioides and correlate their pharmacological activities with the significance of its use as traditional medicine. Data were collected by reviewing numerous scientific articles from several journal databases on the pharmacological activities of P. quassioides using certain keywords. As a result, approximately 94 phytochemicals extracted from P. quassioides were found to be associated with quassinoids, β-carbolines and canthinones. These molecules exhibited various pharmacological benefits such as anti-inflammatory, antioxidant, anti-cancer, anti-microbial, and anti-parasitic activities which help to treat different diseases. However, P. quassioides were also found to have several toxicity effects in high doses, although the evidence regarding these effects is limited in proving its safe use and efficacy as herbal medicine. Accordingly, while it can be concluded that P. quassioides may have many potential pharmacological benefits with more phytochemistry discoveries, further research is required to determine its real value in terms of quality, safety, and efficacy of use.

First Total Synthesis of (β-5)-(β-O-4) Dihydroxytrimer and Dihydrotrimer of Coniferyl Alcohol (G): Advanced Lignin Model Compounds

To investigate lignin degradation, scientists commonly use model compounds. Unfortunately, these models are most of the time simple β-O-4 dimers and do not sufficiently mimic the wide complexity of lignin structure (i.e., aliphatic side chains and robust C-C bonds). Herein, we present a methodology to access advanced lignin models through the first synthesis of two trimers of monolignol G—possessing side-chains and both robust β-5 bond and labile β-O-4 bond—via a chemo-enzymatic pathway. Key steps were (1) the C-C coupling via laccase-mediated oxidation, (2) the C-O coupling via a simple S_N2 between a phenolate and a bromoketoester, and (3) a modified Upjohn dihydroxylation or a palladium-catalyzed hydrogenation. (β-5)-(β-O-4) dihydroxytrimer and dihydrotrimer of coniferyl alcohol (G) were obtained in good global yield, 9 and 20%, respectively, over nine steps starting from ferulic acid.

Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances

Lignans and neolignans are plant secondary metabolites derived from the oxidative coupling of phenylpropanoids. Biological activity of these phenolic compounds ranges from antioxidant, antitumor (terminaloside P, IC₅₀ = 10 nM), anti-inflammatory, anti-neurodegenerative (schibitubin B, IC₅₀ = 3.2 nM) and antiviral (patentiflorin A, IC₅₀ = 14-23 nM) to antimicrobial. In addition, it was observed that several members of this group, namely enterolactone and its biochemical precursors also known as phytoestrogens, possess important protective properties. Most of these lignans and neolignans are presented in reasonable amounts in one's diet and thus the protection they provide against the colon and breast cancer, to name a few, is even more important to note. Similarly, neuroprotective properties were observed (schisanwilsonin G, IC₅₀ = 3.2 nM) These structural motives also serve as an important starting point in the development of anticancer drugs. Presumably the most famous members of this family, etoposide and teniposide, synthetic derivatives of podophyllotoxin, are used in the clinical treatment of lymphocytic leukemia, certain brain tumors, and lung tumors already for nearly 20 years. This review describes 413 lignans and neolignans which have been isolated between 2016 and mid-2018 being reported in more than 300 peer-reviewed articles. It covers their source, structure elucidation, and bioactivity. Within the review, the structure-based overview of compounds as well as the bioactivity-based overview of compounds are described.

Acylated Lignans Isolated from Brachanthemum gobicum and Their Trypanocidal Activity

Eight isovaleryllignans (1-4 and 8-11), three isovalerylphenylpropanoids (5-7), three known lignans (12-14), and four known compounds were isolated from an extract of the aerial part of Brachanthemum gobicum. The structures of the isolated compounds were elucidated based on NMR and MS data analyses. The enantiomers of compounds 1-3, 5, 8, and 9 were isolated using chiral-phase HPLC, and the absolute configurations of 1a/1b-3a/3b, 5a/5b, 8a/8b, and 9a/9b were elucidated from their optical rotations and ECD spectra; the other lignans were assumed to be racemic or scalemic by chiral-phase HPLC analyses and optical rotation data. Some of the acylated lignans (racemic mixtures) (1-4, 8, 9, and 12-14) exhibited moderate inhibitory activities against Trypanosoma congolense, the causative agent of nagana disease in animals.

Synthesis and antitumor activity of isolongifoleno[7,8-d]thiazolo[3,2-a]pyrimidine derivatives via enhancing ROS level

A series of novel isolongifoleno[7,8-d]thiazolo[3,2-a]pyrimidine derivatives (4a-4x) were synthesized from isolongifolanone according fragment-based design strategy, and their anticancer activity against human aortic smooth muscle cells (HASMC), human breast cancer (MCF-7) cells, human cervical cancer (HeLa) cells, and human liver cancer (HepG2) cells were investigated. Results of the anticancer activity illustrated that most of the compounds showed potent antitumor activity and compound 4i proved to be the most active derivative with IC₅₀ values of 0.33 ± 0.24 (for MCF-7 cells), 0.52 ± 0.13 (for HeLa cells), and 3.09 ± 0.11 μM (for HepG2 cells), respectively. Moreover, we assessed the effects of 4i on cell apoptosis, cell cycle distribution, mitochondrial membrane potential, and reactive oxygen species (ROS) generation. The results indicated that compound 4i altered mitochondrial membrane potential and produced ROS leading to cell apoptosis of MCF-7 cells in a dose-dependent manner, however, without affecting cell cycle progression. These findings suggested that 4i was an effective compound and provided a promising candidate for anticancer drugs.

Cytisine-Pterocarpan-Derived Compounds: Biomimetic Synthesis and Apoptosis-Inducing Activity in Human Breast Cancer Cells

Cytisine-pterocarpan derived compounds were biomimetically synthesized with (-)-cytisine and (-)-maackiain via a N,N-4-dimethyl-4-aminopyridine (DMAP)-mediated synthetic strategy in a mild manner. In the present study, tonkinensine B (4) was elaborated in good and high yields with the optimized reaction conditions. The in vitro cytotoxicity of compound 4 was evaluated against breast cancer cell lines and showed that 4 had a better cytotoxicity against MDA-MB-231 cells (IC₅₀ = 19.2 μM). Depending on the research on cytotoxicities of 4 against RAW 264.7 and BV2 cells, it was suggested that 4 produced low cytotoxic effects on the central nervous system. Further study indicated that 4 demonstrated cytotoxic activity against MDA-MB-231 cells and the cytotoxic activity was induced by apoptosis. The results implied that the apoptosis might be induced by mitochondrion-mediated apoptosis via regulating the ratio of Bax/Bcl-2 and promoting the release of cytochrome c from the mitochondrion to the cytoplasm in MDA-MB-231 cells.

Three New Iridoid Derivatives Have Been Isolated from the Stems of Neonauclea reticulata (Havil.) Merr. with Cytotoxic Activity on Hepatocellular Carcinoma Cells

Three new iridoids, namely neonanin A (1), neonanin B (2) and neoretinin A (3), as well as twelve known compounds, 6-hydroxy-7-methyl-1-oxo-4-carbomethoxyoctahydrocyclopenta[c]pyran (4), 4-epi-alyxialactone (5), loganetin (6), loganin (7), phenylcoumaran-α′-aldehyde (8), cleomiscosin A (9), ficusal (10), balanophonin (11), vanillic acid (12), p-coumaric acid (13), cis,trans-abscisic acid (14), and trans,trans-abscisic acid (15) were isolated from the stems of Neonauclea reticulata (Havil.) Merr. These new structures were determined by the detailed analysis of spectroscopic data and comparison with the data of known analogues. Compounds 1–13 were evaluated using an in-vitro MTT cytotoxic assay for hepatocellular carcinoma (HCC) cells, and the preliminary results showed that ficusal (10), balanophonin (11), and p-coumaric acid (13) exhibited moderate cytotoxic activity, with EC₅₀ values of 85.36 ± 4.36, 92.63 ± 1.41, and 29.18 ± 3.48 µg/mL against Hep3B cells, respectively.