Cytotoxic and apoptotic effects of constituents from Millettia pachycarpa Benth

Total synthesis of isoflavonoids

Covering: 2012 to 2024Isoflavonoids are phenolic compounds with wide structural diversity and a plethora of biological activities. Owing to their structural variation and potential health-promoting and other benefits, they have been targeted for synthesis. Herein, we review the synthesis of natural isoflavonoids belonging to different classes that include isoflavones, isoflavanones, isoflavans, isoflavenes, pterocarpans, rotenoids, coumaronochromones, and coumestans. The synthetic methodologies employed and advancements in synthetic strategies are highlighted.

Isoflavone Derivatives as Potential Anticancer Agents: Synthesis and Bioactivity Studies

Isoflavones are phenolic natural compounds with a C6C3C6 framework. They possess a plethora of biological activities that are associated with putative benefits to human health. In particular, the cancer chemopreventive and chemotherapeutic potential of isoflavones has attracted the interest of researchers. Several isoflavone derivatives have been synthesised and probed for their anticancer activities. The isoflavone analogues are mainly synthesised by molecular hybridisation and other strategies that enable diversification through early or late-stage functionalisation of A-, B- and C-rings of the isoflavones. This has resulted in the discovery of isoflavone analogues with improved antiproliferative activities against several cancer cells and different mechanisms of action. In this review, the synthesis of isoflavone derivatives and their anticancer activity studies are discussed.

A review on Millepachine and its derivatives as potential multitarget anticancer agents

Chalcones have a long history of being used for many medical purposes. These are the most prestigious scaffolds in medicine. The potential of Millepachine and its derivatives to treat various malignancies has been demonstrated in this review. The anticancer effects of Millepachine and its derivatives on ovarian cancer, hepatocellular carcinoma, breast, liver, colon, cervical, prostate, stomach, and gliomas are highlighted in the current review. Several genes that are crucial in reducing the severity of the disease have been altered by these substances. They mainly work by preventing tubulin polymerizing. They also exhibit apoptosis and cell cycle arrest at the G2/M phase. Additionally, these compounds inhibit invasion and migration and have antiproliferative effects. Preclinical studies have shown that Millepachine and its derivatives offer exceptional potential for treating a number of cancers. These results need to be confirmed in clinical research in order to develop viable cancer therapies.

Natural Phosphodiesterase-4 Inhibitors with Potential Anti-Inflammatory Activities from Millettia dielsiana

The results of in silico screening of the 50 isolated compounds from Millettia dielsiana against the target proteins PDE4 (PDE4A, PDE4B, and PDE4D) showed binding affinity ranges from -5.81 to -11.56, -5.27 to -13.01, and -5.80 to -12.12 kcal mol-1, respectively, with median values of -8.83, -8.84, and -8.645 kcal mol-1, respectively. Among these compounds, Millesianin F was identified as the most promising PDE4A inhibitor due to its strongest binding affinity with the target protein PDE4A. (-11.56 kcal mol-1). This was followed by the compound 5,7,4'-trihydroxyisoflavone 7-O-β-d-apiofuranosyl-(1→6)-β-d-glucopyranoside (D50) with the binding affinity value of -11.35 kcal mol-1. For the target protein PDE4B, compound D50 exhibited the strongest binding affinity value of -13.01 kcal mol-1, while showing poorer inhibition ability for PDE4D. The 100 ns MD simulation examination (radius of gyration, Solvent Accessible Surface Area (SASA), Root-Mean-Square Deviation (RMSD), Root-Mean-Square Fluctuation (RMSF), and hydrogen bonding) was carried out to examine the overall stability and binding efficiency of the protein-ligand complex between compounds (Millesianin F, Millesianin G, Claclrastin-7-O-β-d-glucopyranoside, 7-hydroxy-4',6 dimethoxyisoflavone-7-O-β-d-apiofuranosyl-(1→6)-β-d-glucopyranoside, 7-hydroxy-4',8-dimethoxyisoflavone 7-O-β-d-apiofuranosyl-(1→6)-β-d-glucopyranoside, Odoratin-7-O-β-d-glucopyranoside, and 5,7,4'-trihydroxyisoflavone 7-O-β-d-apiofuranosyl-(1→6)-β-d-glucopyranoside) and PDE4 (A, B) subtype proteins. Compound D50 has shown strong anti-inflammatory activity, as evidenced by experimental results. It effectively inhibits PDE4B and PDE4D, with IC50 values of 6.56 ± 0.7 µM and 11.74 ± 1.3 µM, respectively. Additionally, it reduces NO production, with an IC50 value of 5.40 ± 0.9 µM. Based on these findings, it is promising and considered a potential novel anti-inflammatory drug for future development.

Novel Indole-Containing Hybrids Derived from Millepachine: Synthesis, Biological Evaluation and Antitumor Mechanism Study

Millepachine, a bioactive natural product isolated from the seeds of Millettia pachycarpa, is reported to display potential antitumor activity. In this study, novel indole-containing hybrids derived from millepachine were designed, synthesized and evaluated for their antitumor activities. Among all the compounds, compound 14b exhibited the most potent cytotoxic activity against five kinds of human cancer cell lines, with IC₅₀ values ranging from 0.022 to 0.074 μM, making it almost 100 times more active than millepachine. Valuable structure-activity relationships (SARs) were obtained. Furthermore, the mechanism studies showed that compound 14b induced cell-cycle arrest at the G2/M phase by inhibiting tubulin polymerization and further induced cell apoptosis through reactive oxygen species (ROS) accumulation and mitochondrial membrane potential (MMP) collapse. In addition, the low cytotoxicity toward normal human cells and equivalent sensitivity towards drug-resistant cells of compound 14b highlighted its potential for the development of antitumor drugs.

Efforts in Bioprospecting Research: A Survey of Novel Anticancer Phytochemicals Reported in the Last Decade

Bioprospecting natural products to find prominent agents for medical application is an area of scientific endeavor that has produced many clinically used bioactive compounds, including anticancer agents. These compounds come from plants, microorganisms, and marine life. They are so-called secondary metabolites that are important for a species to survive in the hostile environment of its respective ecosystem. The kingdom of Plantae has been an important source of traditional medicine in the past and is also enormously used today as an exquisite reservoir for detecting novel bioactive compounds that are potent against hard-to-treat maladies such as cancer. Cancer therapies, especially chemotherapies, are fraught with many factors that are difficult to manage, such as drug resistance, adverse side effects, less selectivity, complexity, etc. Here, we report the results of an exploration of the databases of PubMed, Science Direct, and Google Scholar for bioactive anticancer phytochemicals published between 2010 and 2020. Our report is restricted to new compounds with strong-to-moderate bioactivity potential for which mass spectroscopic structural data are available. Each of the phytochemicals reported in this review was assigned to chemical classes with peculiar anticancer properties. In our survey, we found anticancer phytochemicals that are reported to have selective toxicity against cancer cells, to sensitize MDR cancer cells, and to have multitarget effects in several signaling pathways. Surprisingly, many of these compounds have limited follow-up studies. Detailed investigations into the synthesis of more functional derivatives, chemical genetics, and the clinical relevance of these compounds are required to achieve safer chemotherapy.

Millettia isoflavonoids: a comprehensive review of structural diversity, extraction, isolation, and pharmacological properties

There are approximately 260 known species in the genus Millettia, many of which are used in traditional medicine to treat human and other animal ailments in various parts of the world. Being in the Leguminosae (Fabaceae) family, Millettia species are rich sources of isoflavonoids. In the past three decades alone, several isoflavonoids originating from Millettia have been isolated, and their pharmacological activities have been evaluated against major diseases, such as cancer, inflammation, and diabetes. Despite such extensive research, no recent and comprehensive review of the phytochemistry and pharmacology of Millettia isoflavonoids is available. Furthermore, the structural diversity of isoflavonoids in Millettia species has rarely been reported. In this review, we comprehensively summarized the structural diversity of Millettia isoflavonoids, the methods used for their extraction and isolation protocols, and their pharmacological properties. According to the literature, 154 structurally diverse isoflavonoids were isolated and reported from the various tissues of nine well-known Millettia species. Prenylated isoflavonoids and rotenoids were the most dominant subclasses of isoflavonoids reported. Other subclasses of reported isoflavonoids include isoflavans, aglycone isoflavones, glycosylated isoflavones, geranylated isoflavonoids, phenylcoumarins, pterocarpans and coumaronochromenes. Although some isolated molecules showed promising pharmacological properties, such as anticancer, anti-inflammatory, estrogenic, and antibacterial activities, others remained untested. In general, this review highlights the potential of Millettia isoflavonoids and could improve their utilization in drug discovery and medicinal use processes.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11101-022-09845-w.

Antidiabetic and Cytotoxic Activities of Rotenoids and Isoflavonoids Isolated from Millettia pachycarpa Benth

A phytochemical investigation of the root and leaf extracts of Millettia pachycarpa Benth resulted in the isolation and identification of 16 compounds, including six rotenoids (1-6) and 10 prenylated isoflavonoids (7-16). Compound 4 was isolated as a scalemic mixture, which was resolved by chiral HPLC to afford (-)-(6aS,12aS)-12a-hydroxy-α-toxicarol (4) and (+)-(6aR,12aR)-12a-hydroxy-α-toxicarol (4). (+)-(6aR,12aR)-Millettiapachycarpin (3) and (-)-(6aS,12aS)-12a-hydroxy-α-toxicarol (4) were isolated as new compounds. The absolute configuration of (-)-(6R)-pachycarotenoid (2), (+)-(6aR,12aR)-millettiapachycarpin (3), (-)-(6aS,12aS)-4 and (+)-(6aR,12aR)-12a-hydroxy-α-toxicarol (4), (+)-(6aS,12aS)-(5), and (-)-(6aS,12aS,2″R)-sumatrol (6) were identified by electronic circular dichroism (ECD) data. (-)-(6aS,12aS,2″R)-Sumatrol (6) was also confirmed by X-ray diffraction analysis using Cu-Kα radiation. Antidiabetic activities, including α-glucosidase and α-amylase inhibitory activities, and cytotoxicities against lung cancer A549, colorectal cancer SW480, and leukemic K562 cells of some isolated compounds were evaluated. Of these, isolupalbigenin (11) exhibited the highest α-glucosidase inhibitory activity, with an IC₅₀ value of 11.3 ± 0.2 μM, whereas the scalemic mixture of 12a-hydroxy-α-toxicarol (4) displayed the best α-amylase inhibitory activity, with an IC₅₀ value of 106.9 ± 0.2 μM. Euchrenone b10 (15) exhibited the highest cytotoxicity against lung cancer A549, colorectal cancer SW480, and leukemic K562 cells, with IC₅₀ values of 40.3, 39.1, and 15.1 μM, respectively. In addition, molecular docking simulations of α-glucosidase inhibition of the active compounds were studied.

Recent advance on carbamate-based cholinesterase inhibitors as potential multifunctional agents against Alzheimer's disease

Alzheimer's disease (AD), as the fourth leading cause of death among the elderly worldwide, has brought enormous challenge to the society. Due to its extremely complex pathogeneses, the development of multi-target directed ligands (MTDLs) becomes the major strategy for combating AD. Carbamate moiety, as an essential building block in the development of MTDLs, exhibits structural similarity to neurotransmitter acetylcholine (ACh) and has piqued extensive attention in discovering multifunctional cholinesterase inhibitors. To date, numerous preclinical studies demonstrate that carbamate-based cholinesterase inhibitors can prominently increase the level of ACh and improve cognition impairments and behavioral deficits, providing a privileged strategy for the treatment of AD. Based on the recent research focus on the novel cholinesterase inhibitors with multiple biofunctions, this review aims at summarizing and discussing the most recent studies excavating the potential carbamate-based MTDLs with cholinesterase inhibition efficacy, to accelerate the pace of pleiotropic cholinesterase inhibitors for coping AD.

Molecular interactions at the colchicine binding site in tubulin: An X-ray crystallography perspective

Tubulin is an important cancer drug target. Compounds that bind at the colchicine site in tubulin have attracted significant interest as they are generally less affected by multidrug resistance than other potential drugs. Modeling is useful in understanding the interactions between tubulin and colchicine binding site inhibitors (CBSIs), but because the colchicine binding site contains two flexible loops whose conformations are highly ligand-dependent, modeling has its limitations. X-ray crystallography provides experimental pictures of tubulin-ligand interactions at this challenging colchicine site. Since 2004, when the first X-ray structure of tubulin in complex with N-deacetyl-N-(2-mercaptoacetyl)-colchicine (DAMA-colchicine) was published, many X-ray crystal structures have been reported for tubulin complexes involving the colchicine binding site. In this review, we summarize the crystal structures of tubulin in complexes with various CBSIs, aiming to facilitate the discovery of new generations of tubulin inhibitors.

A review on synthetic chalcone derivatives as tubulin polymerisation inhibitors

Microtubules play an important role in the process of cell mitosis and can form a spindle in the mitotic prophase of the cell, which can pull chromosomes to the ends of the cell and then divide into two daughter cells to complete the process of mitosis. Tubulin inhibitors suppress cell proliferation by inhibiting microtubule dynamics and disrupting microtubule homeostasis. Thereby inducing a cell cycle arrest at the G2/M phase and interfering with the mitotic process. It has been found that a variety of chalcone derivatives can bind to microtubule proteins and disrupt the dynamic balance of microtubules, inhibit the proliferation of tumour cells, and exert anti-tumour effects. Consequently, a great number of studies have been conducted on chalcone derivatives targeting microtubule proteins. In this review, synthetic or natural chalcone microtubule inhibitors in recent years are described, along with their structure-activity relationship (SAR) for anticancer activity.

MIL-1, a novel antitumor agent derived from natural product millepachine, acts as tubulin polymerization inhibitor for the treatment of hepatocellular carcinoma

Natural products are a large source of clinically effective antitumor drugs. Millepachine, a natural product derived from leguminous plants, was reported to display antitumor activity. In this study, the novel compound, (1H-indol-5-yl) (5-methoxy-2,2-dimethyl-2H-chromen-8-yl)methanone (MIL-1), was designed and synthesized by fusing millepachine and indole rings. MIL-1 exerted much better antitumor activity than millepachine, manifesting as a 24- to 201-fold increase in vitro cytotoxicity and a 2.4-fold increase in in vivo antitumor activity in hepatocellular cell lines-derived models. The immunofluorescence and HPLC detection revealed that MIL-1 was a potent microtubule targeting agent by interfering with the equilibrium of tubulin-microtubule dynamics and irreversibly binding to tubulin. MIL-1 displayed remarkable antitumor activity with an IC50 of 31-207 nM towards various human cancer cell lines derived from various organs and tissues, and it exerted no evidence of toxicity against normal cells. Mechanistic studies showed that MIL-1 arrested the cell cycle at G2/M phase and induced apoptosis by activating caspase-3 activity and reactive oxygen species (ROS) accumulation. Moreover, the superior antitumor effect of MIL-1 is worthy of further detailed study for the treatment of hepatocellular carcinoma (HCC).

Recent advances in research of colchicine binding site inhibitors and their interaction modes with tubulin

Microtubules have been a concerning target of cancer chemotherapeutics for decades, and several tubulin-targeted agents, such as paclitaxel, vincristine and vinorelbine, have been approved. The colchicine binding site is one of the primary targets on microtubules and possesses advantages compared with other tubulin-targeted agents, such as inhibitors of tumor vessels and overcoming P-glycoprotein overexpression-mediated multidrug resistance. This study reviews and summarizes colchicine binding site inhibitors reported in recent years with structural studies via the crystal structures of complexes or computer simulations to discover new lead compounds. We are attempting to resolve the challenge of colchicine site agent research.

DBU-promoted ring-opening reactions of multi-substituted donor–acceptor cyclopropanes: access to functionalized chalcones with a quaternary carbon group

A strategy to synthesize highly stereoselective chalcones with alkylcyanoacetate subunits via DBU-promoted ring-opening reactions of multi-substituted D–A cyclopropanes has been developed without the requirement of a transition metal catalyst and extra solvent.

Diverse flavonoids from the roots of Millettia brandisiana

The phytochemical investigation for the constituents of the roots of Millettia brandisiana, using bioassay guided fractionation, resulted in the isolation of five previously undescribed (namely brandisianones A-E) and twenty-six known flavonoids. Their chemical structures were determined using a combination of NMR, MS, IR, optical rotation and CD analysis, as well as comparison with the literature data. The crude extract as well as the isolated compounds were evaluated in various biological assays for their cytotoxicity against a panel of human cancer cell lines, potential inhibitory activity against aromatase, and antioxidant property using the oxygen radical absorbance capacity (ORAC) with an aim to search for leads and develop them to drug candidates in our drug discovery effort, we identified three bioactive flavonoids from M. brandisiana which could be further developed into a potential chemopreventive (antiaromatase) agent against breast cancer.

The effect and mechanism of millepachine-disrupted spindle assembly in tumor cells

Millepachine (MIL) is a bioactive natural product that shows great potential for cancer treatment. Previous studies showed that MIL was a novel cancer drug candidate with a special structure. To provide reference for the research and development of MIL, we further investigated the mechanism of MIL inducing G2/M arrest and found MIL disrupted spindle assembly in tumor cells. In this study, we investigated the disrupting spindle assembly effects of MIL with a focus on its potential mechanism of action. First, we indicated that MIL did not inhibit microtubule polymerization from the results of in-vivo microtubule nucleation assay and microtubule polymerization in-vitro assay but delayed this process by inhibiting the production of ATP in tumor cells. Thereafter, we investigated the effect of MIL on the mitotic spindle. We found that MIL induced multipolar spindles by inhibiting the activity of Eg5 and inhibited mitotic spindle formation and chromatin condensation by the activation of the spindle assembly checkpoint (SAC) in tumor cells. These results established a novel function of MIL in regulating the assembly of mitotic spindle. As Eg5 and SAC are antitumor targets, effect of MIL on the Eg5 protein and SAC activation hinted that MIL has novel application in the development of antitumor drugs.

Millepachine showed novel antitumor effects in cisplatin-resistant human ovarian cancer through inhibiting drug efflux function of ATP-binding cassette transporters

Millepachine (MIL), a bioactive natural chalcone from Chinese herbal medicine Millettia pachycarpa Benth, exhibits strong antitumor effects against many human cancer cells both in vitro and in vivo. In this study, we found that MIL significantly inhibited the proliferation of cisplatin-resistant A2780CP cells via inducing obvious G2/M arrest and apoptosis and down-regulating the activity of topoisomerase II protein. We further found that the mechanism by which MIL showed good antitumor effects in cisplatin-resistant human ovarian cancer was associated with inhibiting the expression of ATP-binding cassette transporters in cisplatin-resistant A2780CP cells. Importantly, MIL did not only significantly inhibit the tumor growth in cisplatin-sensitive A2780S xenograft model, with an inhibitory rate of 73.21%, but also inhibited the tumor growth in the cisplatin-resistant A2780CP xenograft model, with an inhibitory rate of 65.68% (p < 0.001 vs. control; p < 0.001 vs. DDP). In addition, MIL did not induce acquired drug resistance in A2780S tumor-bearing mice with an inhibitory rate of 60.03%. The promising in vitro and in vivo performance indicated that MIL exhibited potential significance for drug research and development.

The compound millepachine and its derivatives inhibit tubulin polymerization by irreversibly binding to the colchicine-binding site in β-tubulin

Inhibitors that bind to the paclitaxel- or vinblastine-binding sites of tubulin have been part of the pharmacopoeia of anticancer therapy for decades. However, tubulin inhibitors that bind to the colchicine-binding site are not used in clinical cancer therapy, because of their low therapeutic index. To address multidrug resistance to many conventional tubulin-binding agents, numerous efforts have attempted to clinically develop inhibitors that bind the colchicine-binding site. Previously, we have found that millepachine (MIL), a natural chalcone-type small molecule extracted from the plant Millettia pachycarpa, and its two derivatives (MDs) SKLB028 and SKLB050 have potential antitumor activities both in vitro and in vivo However, their cellular targets and mechanisms are unclear. Here, biochemical and cellular experiments revealed that the MDs directly and irreversibly bind β-tubulin. X-ray crystallography of the tubulin-MD structures disclosed that the MDs bind at the tubulin intradimer interface and to the same site as colchicine and that their binding mode is similar to that of colchicine. Of note, MDs inhibited tubulin polymerization and caused G₂/M cell-cycle arrest. Comprehensive analysis further revealed that free MIL exhibits an s-cis conformation, whereas MIL in the colchicine-binding site in tubulin adopts an s-trans conformation. Moreover, introducing an α-methyl to MDs to increase the proportion of s-trans conformations augmented MDs' tubulin inhibition activity. Our study uncovers a new class of chalcone-type tubulin inhibitors that bind the colchicine-binding site in β-tubulin and suggests that the s-trans conformation of these compounds may make them more active anticancer agents.

Endophytic fungus Pseudofusicoccum stromaticum produces cyclopeptides and plant-related bioactive rotenoids

In the present study, we integrated liquid chromatography high-resolution mass spectrometry (LC-HRMS) and high-throughput DNA sequencing for prospecting cytotoxic specialized metabolites from Pseudofusicoccum stromaticum, an endophytic fungus associated to the medicinal plant Myracrodruon urundeuva. LC-HRMS profiling allowed identifying putatively eleven compounds in the ethyl acetate extract from P. stromaticum broth. Additionally, a chemical fractionation guided by cytotoxicity combined with spectrometric analysis resulted in the isolation of three compounds: the cyclopeptide cyclo-l-Phe-d-Leu-l-Leu-l-Leu-l-lle along with the known rotenoids rotenolone and tephrosin. MTT assay showed that tephrosin (IC₅₀ 0.51 μg mL⁻¹) has strong cytotoxic effect and may be pointed out as the compound responsible for the antiproliferative activity of P. stromaticum. Next Generation Sequencing (NGS) and genome mining of P. stromaticum draft genome revealed 56 contigs codifying specialized metabolites biosynthesis-related enzymes. Nearly half of such genes (44.6%) could be mapped to orphan Biosynthetic Gene Clusters (BGCs) of related plant pathogens belonging to family Botryosphaeriaceae. Also, screening for rotenoids biosynthetic enzymes led to characterization of a putative chalcone isomerase-like (CHI-like) protein. This is the first report of rotenoids biosynthesized by a fungus, unveiling a unique ability of P. stromaticum.

Pseudofusicoccum stromaticum produces cyclopeptides and plant-related rotenoids, which are responsible for its antiproliferative effect.

Synthesis, biological evaluation and molecular docking studies of a new series of chalcones containing naphthalene moiety as anticancer agents

A series of chalcones containing naphthalene moiety 4a-4p have been synthesized, characterized by ¹H NMR and ¹³C NMR and evaluated for their in vitro anticancer activity. The majority of the screened compounds displayed potent anticancer activity against both HCT116 and HepG2 human cancer cell lines. Among the series, compound 4h with a diethylamino group at the para position of the phenyl ring exhibited the most potent anticancer activity against HCT116 and HepG2 cell lines with IC₅₀ values of 1.20 ± 0.07 and 1.02 ± 0.04 μM, respectively. The preliminary structure-activity relationship has been summarized. Tubulin polymerization experiments indicated that 4h effectively inhibited tubulin polymerization and flow cytometric assay revealed that 4h arrests HepG2 cells at the G2/M phase in a dose-dependent manner. Furthermore, molecular docking studies suggested that 4h binds to the colchicine binding site of tubulin.

A New Flavonol Glycoside from Millettia pachycarpa

Eight compounds (1-8), including a new flavonol glycoside (1), were isolated from Millettia pachycarpa. Their structures were elucidated based on combination of spectroscopic methods and comparing with data in literatures. Three of them (2, 6 and 8) were obtained from this genus for the first time. Meanwhile, this is also the first time compound 5 has been found from nature. Biological evaluation of all isolates against two cholinesterases (ChEs) is also described.

Isoflavones and Rotenoids from the Leaves of Millettia oblata ssp. teitensis

A new isoflavone, 8-prenylmilldrone (1), and four new rotenoids, oblarotenoids A-D (2-5), along with nine known compounds (6-14), were isolated from the CH₂Cl₂/CH₃OH (1:1) extract of the leaves of Millettia oblata ssp. teitensis by chromatographic separation. The purified compounds were identified by NMR spectroscopic and mass spectrometric analyses, whereas the absolute configurations of the rotenoids were established on the basis of chiroptical data and in some cases by single-crystal X-ray crystallography. Maximaisoflavone J (11) and oblarotenoid C (4) showed weak activity against the human breast cancer cell line MDA-MB-231 with IC₅₀ values of 33.3 and 93.8 μM, respectively.

Separation of flavonoids from Millettia griffithii with high-performance counter-current chromatography guided by anti-inflammatory activity

Millettia griffithii is a unique Chinese plant located in the southern part of Yunnan Province. Up to now, there is no report about its phytochemical or related bioactivity research. In our previous study, the n-hexane crude extract of Millettia griffithii revealed significant anti-inflammatory activity at 100 μg/mL, inspiring us to explore the anti-inflammatory constituents. Four fractions (I, II, III, and A) were fractionated from n-hexane crude extract by high-performance counter-current chromatography with solvent system composed of n-hexane/ethyl acetate/methanol/water (8:9:8:9, v/v) and then were investigated for the potent anti-inflammatory activity. Fraction A, with the most potent inhibitory activity was further separated to give another four fractions (IV, V, VI, and B) with solvent system composed of n-hexane/ethyl acetate/methanol/water (8:4:8:4, v/v). Compound V and fraction B exhibited remarkable anti-inflammatory activity with nitric oxide inhibitory rate of 80 and 65%, which was worth further fractionation. Then, three fractions (VII, VIII, and IX) were separated from fraction B with a solvent system composed of n-hexane/ethyl acetate/methanol/water (8:1:8:1, v/v), with compound VIII demonstrating the most potent inhibitory activity (80%). Finally, the IC50 values of compound V and VIII were tested as 38.2 and 14.9 μM. The structures were identified by electrospray ionization mass spectrometry and(1)H and (13)C NMR spectroscopy.

Mirabijalone E: a novel rotenoid from Mirabilis himalaica inhibited A549 cell growth in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

The roots of Mirabilis himalaica have been used in Tibetan folk medicine for treatment of uterine cancer, nephritis edematous, renal calculus and arthrodynia. In our previous work, the ethanol extract of roots had shown potent cytotoxicity against human cancer cells. However, no information is available on the antitumor effect of Mirabilis himalaica. The aim of the present study was to investigate the active constituents guided by bioassay and evaluate the related antitumor efficacy in vitro and in vivo.

MATERIALS AND METHODS

The active subextract (ethyl acetate) was subjected to successive chemical separation using a combination of silica gel, LH-20 chromatography and semi-preparative HPLC. The structures were determined by spectroscopic analysis techniques such as nuclear magnetic resonance (NMR) and mass spectrometry. Three human cancer cell lines, A549, HepG2 and HeLa were used for in vitro cytotoxicity evaluation of all isolated compounds by MTT-assay. Then, the potent and novel compound mirabijalone E was employed to the mechanism study againstA549 cells. BrdU immunofluorescence, soft agar assay and cell cycle analysis were employed to detect the cell proliferation effects. Annexin V-FITC/PI staining assay was used for examining apoptotic effects. Expression levels of apoptosis-related proteins were determined by western blot assay. in vivo tumorigenic assay was used to evaluate the xenograft tumor growth treated with mirabijalone E.

RESULTS

One new rotenoid compound, mirabijalone E, together with eight known rotenoids was isolated from Mirabilis himalaica. Mirabijalone E, 9-O-methyl-inone B, boeravinone C and boeravinone H exhibited cytotoxicity against A 549 and HeLa cells. Further study on mirabijalone E was carried out in vitro and in vivo. Mirabijalone E inhibited A549 cells growth in a time and dose-dependent manner, which arrested cell cycle in S phase. Mechanistically, mirabijalone E treatment resulted in the increase of Bax expression level, the decrease of Bcl-2 level and the activation of caspase-3, which suggested the activation of apoptosis cascades. Consequently, the xenograft treated with mirabijalone E showed markedly suppressed tumor growth.

CONCLUSIONS

The result suggested that mirabijalone E, together with active compounds, 9-O-methyl-4-hydroxyboeravinone B, boeravinone C and boeravinone H could be a promising candidate for cancer therapy.

Design, synthesis and biological evaluation of a series of pyrano chalcone derivatives containing indole moiety as novel anti-tubulin agents

A new series of pyrano chalcone derivatives containing indole moiety (3-42, 49a-49r) were synthesized and evaluated for their antiproliferative activities. Among all the compounds, compound 49b with a propionyloxy group at the 4-position of the left phenyl ring and N-methyl-5-indoly on the right ring displayed the most potent cytotoxic activity against all tested cancer cell lines including multidrug resistant phenotype, which inhibits cancer cell growth with IC50 values ranging from 0.22 to 1.80μM. Furthermore, 49b significantly induced cell cycle arrest in G2/M phase and inhibited the polymerization of tubulin. Molecular docking analysis demonstrated the interaction of 49b at the colchicine binding site of tubulin. In experiments in vivo, 49b exerted potent anticancer activity in HepG2 human liver carcinoma in BALB/c nude mice. These results indicated these compounds are promising inhibitors of tubulin polymerization for the potential treatment of cancer.

An update on antitumor activity of naturally occurring chalcones

Chalcones, which have characteristic 1,3-diaryl-2-propen-1-one skeleton, are mainly produced in roots, rhizomes, heartwood, leaves, and seeds of genera Angelica, Sophora, Glycyrrhiza, Humulus, Scutellaria, Parartocarpus, Ficus, Dorstenia, Morus, Artocarpus, and so forth. They have become of interest in the research and development of natural antitumor agents over the past decades due to their broad range of mechanisms including anti-initiation, induction of apoptosis, antiproliferation, antimetastasis, antiangiogenesis, and so forth. This review summarizes the studies on the antitumor activity of naturally occurring chalcones and their underlying mechanisms in detail during the past decades.