Rotenoids and flavonoids with anti-invasion of HT1080, anti-proliferation of U937, and differentiation-inducing activity in HL-60 from Erycibe expansa

Molecular-Oxygen-Mediated Multicomponent Oxidative Cyclization: Synthesis of Tertiary-Alcohol-Unit-Bearing N-Heterocycles via Transforming C-H to C-OH Bonds

We developed a molecular-oxygen-mediated multicomponent oxidative cyclization strategy to synthesize N-heterocycles containing tertiary alcohol units via the formation of key C-OH bonds and quaternary carbon centers. This formal [3 + 2 + 1] annulation offers a green and sustainable alternative for the de novo C-OH bond formation, using O2 as both the oxidant and oxygen source under metal- and catalyst-free conditions. Notably, continuous [1,5]-hydrogen transfer together with excess alcohols promotes the formation of C-OH-bearing products. Additionally, the generation of quaternary carbon centers inhibits the conversion of C-OH bonds to C═O bonds, thus stabilizing the desired products.

Control of Selectivity in FeCl3 -Catalyzed Aerobic Oxidation of Cycloketones

The FeCl₃ -catalyzed aerobic oxidation of ketones always gives rise to the α-C-C cleavage product, having challenges to afford hydroxyl keto compounds. Here we report an effective control of the main product from keto acid to α-hydroxyl ketone, by reducing the concentration of FeCl₃ catalyst, together with the use of DMSO as the solvent. In addition, mechanistic investigations suggested the same FeCl₃ -coordinated peroxide intermediate for both hydroxylation and C-C cleavage routes, and emphasize the role of DMSO as both ligand and reductant. This work provides a new approach for selective aerobic oxidation under Lewis acid catalysis.

Silyl-mediated photoredox-catalyzed radical–radical cross-coupling reaction of alkyl bromides and ketoesters

A strategy for cross-coupling between organic bromides and carbonyl compounds is developed by combining photocatalysis and halogen atom transfer using a photocatalyst and tris(trimethylsilyl)silane.

Conformational preferences in a series of α-hydroxy ketone derivatives: interplay of conformational energies and lattice cohesive energies

A detailed structural analysis of a series of α-hydroxy ketone derivatives in terms of lattice energies and conformational energies reveals the competing factors of inter- and intramolecular interactions that direct conformational preferences.

Natural Bioactive Cinnamoyltyramine Alkylamides and Co-Metabolites

Natural products are a vital source for agriculture, medicine, cosmetic and other fields. Among them alkylamides are a broad and expanding group found in at least 33 plant families. Frequently, they possess a simple carbon skeleton architecture but show broad structural variability and important properties such as immunomodulatory, antimicrobial, antiviral, larvicidal, insecticidal and antioxidant properties, amongst others. Despite to these several and promising biological activities, up to today, only two reviews have been published on natural alkylamides. One focuses on their potential pharmacology application and their distribution in the plant kingdom and the other one on the bioactive alkylamides specifically found in Annona spp. The present review is focused on the plant bioactive cinnamoyltyramine alkylamides, which are subject of several works reported in the literature. Furthermore, the co-metabolites isolated from the same natural sources and their biological activities are also reported.

The ethnopharmacology, phytochemistry, pharmacology and toxicology of the genus Erycibe (Convolvulaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Erycibe belongs to the Convolvulaceae family that contains approximately 70 species mainly distributed from tropical and subtropical Asia to north of Australia. Several Erycibe species are traditionally used in folk medicine for the treatment of various ailments, including rheumatic arthralgia, primary glaucoma, hepatopathies, and infectious and malignant diseases.

AIM OF THE REVIEW

This review aims to summarize comprehensive and updated information on traditional medicinal uses, phytochemistry, pharmacology, and toxicology of Erycibe species to provide a reference for the further research and application of the Erycibe genus.

MATERIALS AND METHODS

The scientific and extensive literatures between 1975 and 2020 were systematically gathered from scientific databases such as SciFinder Scholar, Science Direct, Web of Science, PubMed, Google Scholar, Scopus, Springer Link and China National Knowledge Infrastructure (CNKI), as well as Chinese herbal classic books, PhD and MSc theses, and several official websites.

RESULTS

Erycibe species have been used for the treatment of various rheumatoid diseases, glaucoma, a variety of hepatic diseases, infectious diseases and various malignancies in the traditional and local medicine. Since the 1970s, 153 compounds, including coumarins, quinic acid derivatives, flavonoids, alkaloids, lignans, and others have been isolated from five species of the Erycibe genus. Pharmacological studies have shown that these extracts and compounds from the Erycibe genus have extensive activities consistent with the traditional and local applications, such as anti-glaucoma, anti-arthritic, hepatoprotective and anti-cancer activities, as well as anti-inflammatory, anti-respiratory syncytial virus (RSV), and neuroprotective properties.

CONCLUSIONS

Although there are extensive data on the genus Erycibe, certain specific gaps still exist. For herbal preparations containing Erycibe species, clinical toxicological investigation is required for the safety of these herbal preparation therapies, as well as further investigations on pharmacokinetics and bioavailability for guideline for clinical application. Furthermore, more detailed pharmacological, toxicological and clinical researches are needed to assess the alternatives to Erycibe species. Systematic and comprehensive pre-clinical studies are similarly required to estimate the possibility of extracts and compounds from the genus Erycibe with bioactivity developing into new drugs.

Improvement of cytotoxicity of mitoxantrone and daunorubicin by candidone, tephrosin, and bavachinin

BACKGROUND

Flavonoids have been demonstrated to have the ability of sensitizing cancer cells to chemotherapy and inverse multidrug resistance via various mechanisms, such as modulating of pumps. The therapeutic effect of candidone, tephrosin, and bavachinin in treatment of cancer, particularly to overcome multidrug resistance (MDR) is largely unknown. The capacity of these agents in sensitization of MDR cells is investigated in the current work.

METHODS AND RESULTS

We analyzed the impact of candidone, tephrosin, and bavachinin, as chemosensitizer on cell cytotoxicity, P-gp and ABCG2 mRNA expression level on two multidrug resistant cells, ABCG2 overexpressing human epithelial breast cancer cell line (MCF7/MX), and P-gp overexpressing human gastric adenocarcinoma cell line (EPG85.257RDB). The inhibitory concentration of 50% (IC50) of daunorubicin in EPG85.257RDB cells in combination with IC10 of Bavachinin, Tephrosin, and Candidone were 6159 ± 948, 4186 ± 665, 730 ± 258 nM, and this data in MCF7/MX cell were 1773 ± 534, 7160 ± 405 and 3340 ± 622 nM respectively. These three flavonoids dose-dependently decreased the viability of MCF7/MX and EPG85.257RDB and significantly (p < 0.05) decreased IC50 of daunorubicin and mitoxantrone except Tephrosin in MCF7/MX cells. Candidone and Bavachinin were the most potent chemosensitizer in EPG85.257RDB and MCF7/MX cells respectively. Flavonoids did not reduce mRNA expression of P-gp and ABCG2 after 72 h treatment, except Candidone in EPG85.257RDB and Bavachinin in MCF7/MX cells.

CONCLUSIONS

This effect is not time-dependent, and flavonoids have their own patterns that are cell-dependent. In general, tephrosin, candidone, and bavachinin had the potential of sensitizing MDR cells to mitoxantrone and daunorubicin.

Chemical compositions, pharmacological activities, quality control studies of Erycibes plants, and the development of their substitutes

Erycibes are members of the Convolvulaceae family, including more than 10 species worldwide that are distributed in tropical Asia. Some Erycibes species have long been used as traditional remedies for rheumatoid arthritis, fever, hepatitis, and liver injury in China and Thailand. A total of 152 compounds from Erycibes plants have been isolated and identified, categorized as flavonoids, coumarins, quinic acid derivatives, lignans, and alkaloids. Coumarins are the characteristic and active constituents of this species, including scopoletin and scopolin. Modern pharmacological studies have shown that the extracts and bioactive components of Erycibes plants exhibit several biological activities, including antiinflammatory, analgesic, hepatoprotective, anti-gout, antitumor, antioxidation, and other therapeutic effects. However, in recent years, due to destructive exploitation and utilization, some Erycibes plants' natural resources have become rare or endangered. Developing substitutes is a strategy to alleviate the pressure on those endangered medicinal plant resources. To provide a scientific basis for the development and protection of those threatened Erycibes species, this review summarized the current status of the chemical compositions, pharmacological activities, quality control studies, and the development of substitutes for Erycibes plants. In particular, the rationale for use of Porana sinensis currently on the market is discussed.

1,5,7-Triazabicyclo[4.4.0]dec-5-ene Enhances Activity of Peroxide Intermediates in Phosphine-Free α-Hydroxylation of Ketones

The critical role of double hydrogen bonds was addressed for the aerobic α-hydroxylation of ketones catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), in the absence of either a metal catalyst or phosphine reductant. Experimental and theoretical investigations were performed to study the mechanism. In addition to initiating the reaction by proton abstraction, a more important role of TBD was revealed, that is, to enhance the oxidizing ability of peroxide intermediates, allowing DMSO to be used rather than commonly used phosphine reductants. Further characterizations with nuclear Overhauser effect spectroscopy (NOESY) confirmed the presence of double hydrogen bonds between TBD and the ketone, and kinetic studies suggested the attack of dioxygen on the TBD-enol adduct to be the rate-determining step. This work should encourage the application of TBD as a catalyst for oxidations.

Asymmetric Synthesis of Tertiary α -Hydroxyketones by Enantioselective Decarboxylative Chlorination and Subsequent Nucleophilic Substitution

Chiral tertiary α-hydroxyketones were synthesized with high enantiopurity by asymmetric decarboxylative chlorination and subsequent nucleophilic substitution. We recently reported the asymmetric decarboxylative chlorination of β-ketocarboxylic acids in the presence of a chiral primary amine catalyst to obtain α-chloroketones with high enantiopurity. Here, we found that nucleophilic substitution of the resulting α-chloroketones with tetrabutylammonium hydroxide yielded the corresponding α-hydroxyketones without loss of enantiopurity. The reaction proceeded smoothly even at a tertiary carbon. The proposed method would be useful for the preparation of chiral tertiary alcohols.

Development of a Cell-Based Assay for Identifying KCa3.1 Inhibitors Using Intestinal Epithelial Cell Lines

Inhibition of the K_Ca3.1 potassium channel has therapeutic potential in a variety of human diseases, including inflammation-associated disorders and cancers. However, K_Ca3.1 inhibitors with high therapeutic promise are currently not available. This study aimed to establish a screening assay for identifying inhibitors of K_Ca3.1 in native cells and from library compounds derived from natural products in Thailand. The screening platform was successfully developed based on a thallium flux assay in intestinal epithelial (T84) cells with a Z' factor of 0.52. The screening of 1352 compounds and functional validation using electrophysiological analyses identified 8 compounds as novel K_Ca3.1 inhibitors with IC₅₀ values ranging from 0.14 to 6.57 µM. These results indicate that the assay developed is of excellent quality for high-throughput screening and capable of identifying K_Ca3.1 inhibitors. This assay may be useful in identifying novel K_Ca3.1 inhibitors that may have therapeutic potential for inflammation-associated disorders and cancers.

Enhancing the Therapeutic Efficacy of Daunorubicin and Mitoxantrone with Bavachinin, Candidone, and Tephrosin

The capability of flavonoids in sensitizing cancer cells was demonstrated in numerous works to chemotherapy and converse multidrug resistance by modulating efflux pumps and apoptosis mechanisms. Three flavonoids, namely, bavachinin, tephrosin, and candidone, have been recently introduced to cancer treatment research presenting various activities, such as antibacterial, immunomodulatory, cell death, and anticancer. Less information exists regarding the therapeutic significance of these flavonoids in cancer treatment, especially in overcoming multidrug resistance (MDR). Here, we tempted to investigate the potency of these agents in reversing MDR by analyzing their effects as chemosensitizers on cell cytotoxicity, P-gp and ABCG2 protein expression levels, and their function on two multidrug-resistant cell lines, P-gp-overexpressing human gastric adenocarcinoma cell line (EPG85.257RDB) and ABCG2-overexpressing human epithelial breast cancer cell line (MCF7/MX). The inhibitory concentration of 10% (IC₁₀) of bavachinin, tephrosin, and candidone in EPG85.257RDB cells was 1588.7 ± 202.2, 264.8 ± 86.15, and 1338.6 ± 114.11 nM, respectively. Moreover, these values in MCF7/MX cell were 2406.4 ± 257.63, 38.8 ± 4.28, and 27.9 ± 5.59 nM, respectively. Expression levels of ABCG2 and P-gp were not significantly downregulated by these flavonoids. Maximum levels of daunorubicin and mitoxantrone accumulations and minimum rates of drug efflux in both cell lines were detected 48 hrs posttreatment with tephrosin and bavachinin, respectively. Chemosensitization to mitoxantrone and daunorubicin treatments was, respectively, achieved in MCF7/MX and EPG85.257RDB cells in response to IC₁₀ of bavachinin and tephrosin, independently. These effects did not follow time-dependent manner, and each flavonoid had its cell-dependent patterns. Overall, bavachinin, tephrosin, and candidone showed potency to sensitize MDR cells to daunorubicin and mitoxantrone and could be considered as attractive MDR modulators for cancer treatment. However, their action was time and cell specific.

A Pharmacological Overview of Alpinumisoflavone, a Natural Prenylated Isoflavonoid

Over the last decade, several studies demonstrated that prenylation of flavonoids enhances various biological activities as compared to the respective nonprenylated compounds. In line with this, the natural prenylated isoflavonoid alpinumisoflavone (AIF) has been explored for a number of biological and pharmacological effects (therapeutic potential). In this review, we summarize the current information on health-promoting properties of AIF. Reported data evidenced that AIF has a multitherapeutic potential with antiosteoporotic, antioxidant and anti-inflammatory, antimicrobial, anticancer, estrogenic and antiestrogenic, antidiabetic, and neuroprotective properties. However, research on these aspects of AIF is not sufficient and needs to be reevaluated using more appropriate methods and methodology. Further series of studies are needed to confirm these pharmacological effects, and this review should lay the basis for the design of respective investigations. Overall, despite the drawbacks of studies recorded, AIF exhibits a potential as drug candidate.

Anti-invasive Activity of Lawsonia inermis Branch and Its Potential Target Protein

The methanolic extract from the branch of Lawsonia inermis was found to inhibit the invasion of HT1080 cells strongly. The extract and its EtOAc- and 1-BuOH-soluble fractions strongly inhibited the enzyme activities and the secretions of MMPs from HT1080 cells. We, therefore, tried to examine and estimate the active constituents among the constituents isolated. However, there are no active compound among the isolated compounds. Next, we tried to identify the selective binding protein of whole constituents of their extracts. As a result, ribosomal protein S18 (RPs S18, human), 60S ribosomal protein L18 isoform 1 (60S RPs L18 i1, human) and eukaryotic elongation factor 2 (eEF2, human) were detected as their selective binding and potential target proteins. To confirm that the proteins are target proteins or not, we examined the effects of their proteins on synthesis of MMPs using siRNA method. With the treatment of siRNA for RPs S18, 60S RPs L18 i1 and eEF2 proteins, the MMP-2 protein synthesis were downregulated in HT1080 cells. MMP-9 productions were also downregulated with the treatment of siRNA for RPs S18 and eEF2. From the results, we reached a conclusion that the extract was considered to have the potential to inhibit the production of MMPs proteins via inhibition of RPs S18 and eEF2 proteins, leading to inhibit the invasion in HT1080 cells.

Concise Total Synthesis of (±)-Deguelin and (±)-Tephrosin Using a Vinyl Iodide as a Key Building Block

A concise and protecting-group-free total synthesis of the antiproliferative natural product (±)-deguelin (2) was accomplished in four steps and 62% overall yield from commercially available precursors. The key transformation employed a vinyl iodide as the pivotal building block to construct the 4-acylchromene substructure present in deguelin. Subsequent Cu₂O-mediated α-hydroxylation of deguelin (2) afforded tephrosin (3) in 90% yield.

Tephrosin attenuates sepsis induced acute lung injury in rats by impeding expression of ICAM-1 and MIP-2

Acute lung injury (ALI), a devastating form of respiratory infections, is characterized by increased edema, release of cytokines, weakened arterial oxygenation and infiltration of neutrophils and lymphocytes. The objective of the research envisaged was to reveal protective effects of tephrosin (TP) in ALI. In the present investigation, sepsis was triggered in rats by cecal ligation and puncture (CLP) method, and TP was administered intraperitonially. Five groups - Group A (control), Group B (Sham group) Group C (infected and untreated), and Group D and E (infected and treated with 25 and 50 mg/kg TP respectively) - of ten rats each, were used for the investigation. Evaluation parameters included measurement of arterial oxygenation, lung water content, protein determination, cytokine determination, neutrophil and lymphocyte count in the bronchoalveolar lavage fluid (BALF). As indicated by histopathological examination, the lung injury score was maximum in group C, but indicated reduction in group D and E. Intracellular adhesion molecule (ICAM)-1 and macrophage inflammatory protein-2 (MIP-2) are known to be important mediators responsible for ALI. Reduction in the ICAM-1 and MIP-2 expression was found to reduce after treatment with TP. In comparison to group D, group E reflected higher magnitude of ICAM-1 and MIP-2 suppression due to administration of higher TP dose. Compared to Group A and B, Group E indicated slightly higher expression of ICAM-1 and MIP-2. The research envisaged thus supports that TP attenuates ICAM-1 and MIP-2 expression in sepsis induced ALI rat model.

Ru-NHC Catalyzed Domino Reaction of Carbonyl Compounds and Alcohols: A Short Synthesis of Donaxaridine

Direct α-alkylation of amides and the synthesis of C3-alkylated 3-hydroxyindolin-2-one/2-substituted-2-hydroxy-3,4-dihydronaphthalen-1(2H)-one derivatives from 2-oxindole/1-teralone were reported using primary alcohols in the presence of Ru-NHC catalyst in a one pot condition under the borrowing hydrogen method. In the case of inert conditions, 2-oxindole/1-teralone exclusively forms the C3-alkylated product. Whereas, allowing this reaction mixture to occur under an air atmosphere predominantly forms C3-alkylated 3-hydroxyindolin-2-one via domino C-H alkylation and aerobic C-H hydroxylation. This Ru-NHC catalyst is easily accessible, air stable, and phosphine free. Using this method, synthesis of 2-oxindole based natural products such as Donaxaridine was accomplished.

Established Human Cell Lines as Models to Study Anti-leukemic Effects of Flavonoids

Despite the extensive work on pathological mechanisms and some recent advances in the treatment of different hematological malignancies, leukemia continues to present a significant challenge being frequently considered as incurable disease. Therefore, the development of novel therapeutic agents with high efficacy and low toxicity is urgently needed to improve the overall survival rate of patients. In this comprehensive review article, the current knowledge about the anticancer activities of flavonoids as plant secondary polyphenolic metabolites in the most commonly used human established leukemia cell lines (HL-60, NB4, KG1a, U937, THP-1, K562, Jurkat, CCRF- CEM, MOLT-3, and MOLT-4) is compiled, revealing clear anti-proliferative, pro-apoptotic, cell cycle arresting, and differentiation inducing effects for certain compounds. Considering the low toxicity of these substances in normal blood cells, the presented data show a great potential of flavonoids to be developed into novel anti-leukemia agents applicable also in the malignant cells resistant to the current conventional chemotherapeutic drugs.

Triterpenes with Anti-invasive Activity from Sclerotia of Inonotus obliquus

The methanolic extract [inhibition (%): 61.2±3.8 ( p<0.01) at 100 μg/mL] and its EtOAc-soluble fraction [inhibition (%): 82.5±1.7 ( p<0.01) at 100 μg/mL] from the sclerotia of Inonotus obliquus collected in Japan significantly inhibited invasion of human fibrosarcoma HT1080 cells through matrigel-coated filters. In addition, the methanolic extract significantly inhibited lung tumor formation fifteen days after injection of B16F10 melanoma cells in mice [inhibition (%) 66.1 ± 12.8 ( p < 0.05) at 500 mg/kg/d, p.o.]. Lanostane-type triterpenes were isolated as the common principal constituents from Japanese and Russian I. obliquus. Furthermore, we examine the inhibitory effects of the constituents on the invasion of HT 1080 cells. Interestingly, 3β-hydroxylanosta-8,24-dien-21-al [inhibition (%) 37.9 ± 3.0 ( p < 0.05) at 30 μM] significantly inhibited the invasion, and no cytotoxic effect at 30 μM was observed.

Bioactive constituents of Indigofera spicata

Four new flavanones, designated as (+)-5″-deacetylpurpurin (1), (+)-5-methoxypurpurin (2), (2S)-2,3-dihydrotephroglabrin (3), and (2S)-2,3-dihydrotephroapollin C (4), together with two known flavanones (5 and 6), three known rotenoids (7-9), and one known chalcone (10) were isolated from a chloroform-soluble partition of a methanol extract from the combined flowers, fruits, leaves, and twigs of Indigofera spicata, collected in Vietnam. The compounds were obtained by bioactivity-guided isolation using the HT-29 human colon cancer, 697 human acute lymphoblastic leukemia, and Raji human Burkitt's lymphoma cell lines. The structures of 1-4 were established by extensive 1D- and 2D-NMR experiments, and the absolute configurations were determined by the measurement of specific rotations and CD spectra. The cytotoxic activities of the isolated compounds were tested against the HT-29, 697, Raji, and CCD-112CoN human normal colon cells. Also, the quinone reductase induction activities of the isolates were determined using the Hepa 1c1c7 murine hepatoma cell line. In addition, cis-(6aβ,12aβ)-hydroxyrotenone (7) was evaluated in an in vivo hollow fiber bioassay using HT-29, MCF-7 human breast cancer, and MDA-MB-435 human melanoma cells.

Deguelin, a novel anti-tumorigenic agent targeting apoptosis, cell cycle arrest and anti-angiogenesis for cancer chemoprevention

Deguelin is a natural compound of the flavonoid family products isolated from Derris trifoliata Lour. or Mundulea sericea (Leguminosae). It exhibited significant anti-tumorigenesis and anti-proliferative activity in various types of cancer both in vitro and in vivo. Deguelin induced cell apoptosis by blocking anti-apoptotic pathways, such as PI3K-Akt, IKK-IκBα-NF-κB and AMPK-mTOR-survivin, while inhibiting tumor cell propagation and malignant transformation through p27-cyclinE-pRb-E2F1 cell cycle control and HIF-1α-VEGF anti-angiogenic pathways. In pre-clinical trials, deguelin markedly decreased the tumor incidence. These biological findings identified deguelin as a novel anti-tumorigenic agent targeting apoptosis, cell cycle arrest and anti-angiogenesis for cancer chemoprevention and chemotherapy.

The combination of tephrosin with 2-deoxy-D-glucose enhances the cytotoxicity via accelerating ATP depletion and blunting autophagy in human cancer cells

2-Deoxy-D-glucose (2-DG), a synthetic glucose analog that acts as a glycolytic inhibitor, is currently under clinical evaluation for targeting tumor cells. Tephrosin (TSN), a plant rotenoid, is known as an anticancer agent. In this study, we describe that the addition of TSN to 2-DG enhanced the cytotoxic activity of 2-DG against various types of cancer cells by accelerating ATP depletion and blunting autophagy. TSN increased the sensitivity of cancer cells to the cytotoxic effect of 2-DG. The combination of TSN and 2-DG induced acceleration of intracellular ATP depletion and the drastic activation of AMP-activated protein kinase (AMPK), which resulted in the inactivation of the mammalian target of rapamycin (mTOR) pathway. Of particular interest, TSN suppressed 2-DG-induced autophagy, a cell survival process in response to nutrient deprivation. We also showed that TSN inhibited 2-DG-induced activation of elongation factor-2 kinase (eEF-2K), which has been known to regulate 2-DG-induced autophagy. Inhibition of eEF-2K by RNA interference blunted 2-DG-induced autophagy and increased the sensitivity of cancer cells to the cytotoxic effect of 2-DG. The addition of TSN to 2-DG, however, did not enhance the cytotoxic activity of 2-DG by knockdown of eEF-2K, suggesting that inhibition of eEF-2K by tephrsoin could be a critical role in the potentiating effect of TSN on the cytotoxicity of 2-DG. Furthermore, we showed that the blunted autophagy and enhanced cytotoxicity of 2-DG was accompanied by the augmentation of apoptosis. These results show that TSN may be valuable for augmenting the therapeutic efficacy of 2-DG.

Synergistic Apoptosis-Inducing Antileukemic Effects of Arsenic Trioxide and Mucuna macrocarpa Stem Extract in Human Leukemic Cells via a Reactive Oxygen Species-Dependent Mechanism

The objective of this study was to examine the potential of enhancing the antileukemic activity of arsenic trioxide (ATO) by combining it with a folk remedy, crude methanolic extract of Mucuna macrocarpa (CMEMM). Human leukemia cells HL-60, Jurkat, and Molt-3 were treated with various doses of ATO, CMEMM, and combinations thereof for 24 and 48 h. Results indicated that the combination of 2.5 μM ATO and 50 μg/mL CMEMM synergistically inhibited cell proliferation in HL-60 and Jurkat cell lines. Apoptosis triggered by ATO/CMEMM treatment was confirmed by accumulation of cells in the sub-G₁ phase in cell cycle analyses, characteristic apoptotic nuclear fragmentation, and increased percentage of annexin V-positive apoptotic cells. Such combination treatments also led to elevation of reactive oxygen species (ROS). The antioxidants N-acetyl cysteine (NAC), butylated hydroxytoluene, and α-tocopherol prevented cells from ATO/CMEMM-induced apoptosis. The ATO/CMEMM-induced activation of caspase-3 and caspase-9 can be blocked by NAC. In summary, these results suggest that ATO/CMEMM combination treatment exerts synergistic apoptosis-inducing effects in human leukemic cells through a ROS-dependent mechanism and may provide a promising antileukemic approach in the future.

Invasion inhibitors of human fibrosarcoma HT 1080 cells from the rhizomes of Zingiber cassumunar: structures of phenylbutanoids, cassumunols

The methanolic extract and its EtOAc-soluble fraction from the rhizomes of Zingiber cassumunar inhibited invasion of human fibrosarcoma HT 1080 cells. From the EtOAc-soluble fraction, eight new phenylbutanoids, cassumunols A-H, were isolated together with 30 known constituents. The structures of new phenylbutanoids were elucidated on the basis of chemical and physicochemical evidence. Principal constituents were examined the inhibitory effects on the invasion of HT 1080 cells. Among them, phlain I and III, (E)-1-(3,4-dimethoxyphenyl)buta-1,3-diene, (E)-1-(2,4,5-trimethoxyphenyl)buta-1,3-diene, and (-)-β-sesquiphellandrene showed anti-invasion effects. Interestingly, (E)-1-(2,4,5-trimethoxyphenyl)buta-1,3-diene [inhibition (%) 46.8 ± 7.2 (p<0.05) at 30 µM] significantly inhibited the invasion, and only a weak cytotoxic effect was observed.

Pierreiones A-D, solid tumor selective pyranoisoflavones and other cytotoxic constituents from Antheroporum pierrei

Bioassay-guided fractionation of a solid tumor selective extract of the leaves and twigs of Antheroporum pierrei acquired from the U.S. National Cancer Institute extract repository afforded four new pyranoisoflavones, pierreiones A-D (1-4), together with rotenone (5), 12a-hydroxyrotenone (6), and tephrosin (7). The structures of all new compounds were determined on the basis of their spectroscopic data, and the absolute configuration of 1 was assigned with the help of (1)H NMR analysis of its Mosher's ester derivatives. Compounds 1 and 5-7 accounted for the majority of the biological activity in terms of either cytotoxicity and/or selective toxicity to solid tumor cell lines. Pierreiones A (1) and B (2) demonstrated solid tumor selectivity with minimal cytotoxicity, while pierreione C (3) exhibited no activity.

[Separation and preparation of two rotenoids from the roots of Derris by high-speed counter-current chromatography]

Two rotenoids (rotenone and deguelin) were successfully isolated and purified from the roots of Derris by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethylacetate-methanol-water (7: 0. 25:5:3, v/v/v/v) on a preparative scale. The lower phase was used as the mobile phase and the upper phase was used as the stationary phase. The revolution speed was 850 r/min, the detection wavelength was set at 254 nm and the flow rate was 2.0 mL/min. Under the optimized conditions, within 2.5 h, 6.4 mg of rotenone with the purity of 96.60% and 23.4 mg of deguelin with the purity of 97.87% were obtained from 50 mg of the crude extract of the roots of Derris in a one-step elution. The results indicate that the rotenone and deguelin with high purities can be obtained by HSCCC, and the established method can provide the basic experimental material for the intensive study of rotenoids.

In vitro and in vivo apoptosis-inducing antileukemic effects of Mucuna macrocarpa stem extract on HL-60 human leukemia cells

Mucuna macrocarpa Wallich (Leguminosae) is believed to hold blood circulation activating effects, and has been used as a folk remedy in Southeast Asia for the treatment of various hematologic and circulatory-related ailments. The objective of this study was to investigate whether crude methanolic extract of M macrocarpa (CMEMM) possessed antileukemic effects on HL-60, human leukemia cells. CMEMM was prepared from dried stems of this plant, and its apoptosis-inducing effects were investigated using HL-60 cells in vitro and in vivo. With treatment of 25 to 75 μg/mL CMEMM, the in vitro antiproliferative effect on HL-60 cells increased in a dose- and time-dependent manner during the 72-hour treatment period. The concentration of CMEMM that exhibited a 50% growth inhibition (IC(50)) for 72-hour exposure was 36.4 μg/mL. Apoptosis triggered by CMEMM in HL-60 cells was confirmed by the following observations: ( a) characteristic apoptotic nuclear fragmentation, (b) dose-dependent accumulation of sub-G(1) phase in cell cycle analyses, (c) increased percentages of annexin V-positive apoptotic cells, and (d) dose-dependent elevation of active caspase-3. Furthermore, an in vivo tumor growth suppression effect by CMEMM (500 mg/kg/d intraperitoneally) was observed in mouse xenografts. The results suggest that CMEMM exerts antileukemic effects via an apoptotic pathway in HL-60 cells, and could be a candidate for developing antileukemic agents in the future.

Differential chemosensitization of P-glycoprotein overexpressing K562/Adr cells by withaferin A and Siamois polyphenols

Background

Multidrug resistance (MDR) is a major obstacle in cancer treatment and is often the result of overexpression of the drug efflux protein, P-glycoprotein (P-gp), as a consequence of hyperactivation of NFκB, AP1 and Nrf2 transcription factors. In addition to effluxing chemotherapeutic drugs, P-gp also plays a specific role in blocking caspase-dependent apoptotic pathways. One feature that cytotoxic treatments of cancer have in common is activation of the transcription factor NFκB, which regulates inflammation, cell survival and P-gp expression and suppresses the apoptotic potential of chemotherapeutic agents. As such, NFκB inhibitors may promote apoptosis in cancer cells and could be used to overcome resistance to chemotherapeutic agents.

Results

Although the natural withanolide withaferin A and polyphenol quercetin, show comparable inhibition of NFκB target genes (involved in inflammation, angiogenesis, cell cycle, metastasis, anti-apoptosis and multidrug resistance) in doxorubicin-sensitive K562 and -resistant K562/Adr cells, only withaferin A can overcome attenuated caspase activation and apoptosis in K562/Adr cells, whereas quercetin-dependent caspase activation and apoptosis is delayed only. Interestingly, although withaferin A and quercetin treatments both decrease intracellular protein levels of Bcl2, Bim and P-Bad, only withaferin A decreases protein levels of cytoskeletal tubulin, concomitantly with potent PARP cleavage, caspase 3 activation and apoptosis, at least in part via a direct thiol oxidation mechanism.

Conclusions

This demonstrates that different classes of natural NFκB inhibitors can show different chemosensitizing effects in P-gp overexpressing cancer cells with impaired caspase activation and attenuated apoptosis.

B16 melanoma secretomes and in vitro invasiveness: syntenin as an invasion modulator

To characterize proteins involved in melanoma dissemination, protein profiles from B16F10 and B16Bl6 cells were compared, as only B16Bl6 cells give pulmonary metastases after subcutaneous graft. As B16F10 and B16Bl6 cells had the same invasive capacities in vitro, we wondered whether their extracellular content could be different and correlate with their metastatic properties. We have shown that B16F10 and B16Bl6 culture cell supernatants have different modulatory effects on HT1080 fibrosarcoma cell invasion in Matrigel-coated chambers. B16Bl6 supernatants significantly enhanced HT1080 in vitro invasion as compared with B16F10 ones, suggesting differences in their protein profiles. Indeed, proteomic analysis allowed the identification of 18 differential proteins. Among the proteins with a higher concentration in B16Bl6 supernanants, lactate dehydrogenase B, M2 pyruvate kinase, cathepsin D, and galectin 1 were involved in the melanoma aggressiveness signature. Interestingly, several Gag retroviral proteins, as well as syntenin, were found mainly in the B16F10 secretome. Although its intracellular form is known as an aggressive melanoma marker, we show for the first time that syntenin was actively secreted and could reduce the invasion process, probably by protein interactions in the B16 model.

Hepatoprotective constituents from the roots and stems of Erycibe hainanesis

Eleven new diglycosides, erycibosides A-K (1-11), four new chlorogenic acid derivatives (14-17), and a new bis-coumarin (18), together with 21 known compounds, have been isolated from an EtOH extract of the roots and stems of Erycibe hainanesis. Their structures were elucidated by means of spectroscopic methods and chemical evidence. Inhibitory activities of some of the compounds on d-galactosamine-induced cytotoxicity in WB-F344 rat hepatic epithelial stem-like cells were screened, and compounds 2, 6, 10, 18, and 32 showed potent hepatoprotective activities at concentrations of 1 x 10(-5) to 1 x 10(-4) M.

Tephrosin induces internalization and degradation of EGFR and ErbB2 in HT-29 human colon cancer cells

Inactivation of epidermal growth factor receptor (EGFR) family members are prime targets for cancer therapy. Here, we show that tephrosin, a natural rotenoid which has potent antitumor activities, induced internalization of EGFR and ErbB2, and thereby induced degradation of the receptors. Treatment of HT-29 cells with tephrosin inhibited both the ligand-induced and constitutive phosphorylation of EGFR, ErbB2 and ErbB3, and concomitantly suppressed the activation of the downstream signaling molecules such as Akt and Erk1/2 mitogen-activated protein kinase (MAPK). Tephrosin caused internalization of EGFR and ErbB2 into vehicles, which resulted in degradation of the receptors. This degradation was blocked by the lysosomal inhibitor, chloroquine. We also showed that tephrosin induced apoptosis. Tephrosin did not induce the proteolytic processing of caspase-3 and poly(ADP-ribose) polymerase (PARP), but did nuclear translocation of apoptosis-inducing factor (AIF), suggesting that tephrosin may induce caspase-independent apoptosis. These findings provide the first evidence that tephrosin could exert antitumor effects by inducing internalization and degradation of inactivated EGFR and ErbB2 in human colon cancer cells.

Nitric oxide inhibitory principles from Derris trifoliata stems

Nine rotenoids were isolated from the hexane and dichloromethane extracts of Derris trifoliata stems and were tested for nitric oxide (NO) inhibitory activity using RAW264.7 cells. The result indicated that 12a-hydroxyrotenone (7) possessed very potent NO inhibitory activity with an IC(50) value of 0.002 microM, followed by 1 (deguelin, IC(50)=0.008 microM), 9 (12a-hydroxyelliptone, IC(50)=0.010 microM) and 2 (alpha-toxicarol, IC(50)=0.013 microM), respectively. In addition, the DPPH scavenging activity of rotenoids was also investigated. It was found that 6a,12a-dehydrodeguelin (5) possessed the highest activity against DPPH with an IC(50) value of 7.4 microM, followed by deguelin (1, IC(50)=27.4 microM). All compounds did not show any cytotoxicity at their IC(50) values for NO inhibitory activity. Structure-activity relationships (SARs) of these rotenoids against NO release are as follows: (1) hydroxylation at C12a dramatically increased activity, (2) prenylation at furan ring increased activity markedly and (3) hydrogenation of a double bond at C6a-C12a conferred higher activity. For the DPPH radical scavenging effect, it was found that (1) introduction of a double bond at C6a-C12a increased activity and (2) hydroxylation of C11 at the D-ring decreased activity. As regards active compounds of Derris trifoliata stems, the isolated compounds are responsible for the NO inhibitory effect, especially 7, 1, 9 and 2, whereas 5 and 1 are those for the DPPH scavenging activity.

Structures of new monoterpenes from Thai herbal medicine Curcuma comosa

Three new monoterpenes, comosoxide A (1), comosoxide B (2), and comososide (3), were isolated from the methanolic extract of the rhizomes of Curcuma comosa cultivated in Thailand. Their structures were elucidated on the basis of chemical and physicochemical evidence.