Bioactivity guided isolation of anticancer constituents from leaves of Alnus sieboldiana (Betulaceae)

Cloning of three Alnus sieboldiana type III polyketide synthases and formation of polyketides in recombinant Escherichia coli using cinnamic acid analogs as substrates

Alnus sieboldiana is an actinorhizal plant that coexists with the nitrogen-fixing actinomycete Frankia via nodules. It produces a variety of polyketides, including flavonoids, stilbenoids, and diarylheptanoids. These compounds have beneficial biological activities. Plant polyketides are produced by type III polyketide synthases (PKSIII). In this study, three A. sieboldiana PKSIIIs (AsPKSIII1, AsPKSIII2, and AsPKSIII3) predicted from next-generation sequencing analysis of A. sieboldiana seedling RNA were amplified and cloned. Phylogenetic tree analysis classified AsPKSIII2 and AsPKSIII3 into the chalcone synthase (CHS) group, whereas AsPKSIII1 was not classified into this group. We attempted to produce polyketides by adding cinnamic acid analogs to the culture medium of Escherichia coli, in which the respective PKSIII gene and the acetyl-CoA carboxylase (ACC) and 4-coumarate: CoA ligase (4CL) genes were simultaneously recombined. AsPKSIII1 is an enzyme that condensed only one molecule of malonyl-CoA to cinnamoyl-CoAs. In contrast, AsPKSIII2 and AsPKSIII3 produced chalcones as shown in a phylogenetic tree analysis, but also produced triketide pyrone. The ratio of these products differed between the two enzymes. We determined the gene and amino acid sequences as well as the substrate specificities of the two enzymes involved in flavonoid production and one enzyme potentially involved in diarylheptanoid production in A. sieboldiana.

Galangin: A food-derived flavonoid with therapeutic potential against a wide spectrum of diseases

Galangin is an important flavonoid with natural activity, that is abundant in galangal and propolis. Currently, various biological activities of galangin have been disclosed, including anti-inflammation, antibacterial effect, anti-oxidative stress and aging, anti-fibrosis, and antihypertensive effect. Based on the above bioactivities, more and more attention has been paid to the role of galangin in neurodegenerative diseases, rheumatoid arthritis, osteoarthritis, osteoporosis, skin diseases, and cancer. In this paper, the natural sources, pharmacokinetics, bioactivities, and therapeutic potential of galangin against various diseases were systematically reviewed by collecting and summarizing relevant literature. In addition, the molecular mechanism and new preparation of galangin in the treatment of related diseases are also discussed, to broaden the application prospect and provide reference for its clinical application. Furthermore, it should be noted that current toxicity and clinical studies of galangin are insufficient, and more evidence is needed to support its possibility as a functional food.

Cloning and characterization of NADPH-dependent double-bond reductases from Alnus sieboldiana that recognize linear diarylheptanoids as substrates

Diarylheptanoids are secondary metabolites of plants that comprise a C6-C7-C6 scaffold. They can be broadly classified into linear-type and cyclic-type diarylheptanoids based on their chemical structures. Actinorhizal trees, such as Casuarina, Alnus, and Myrica, which form nodule symbiosis with actinomycetes Frankia, produce cyclic diarylheptanoids (CDHs); in Alnus sieboldiana Matsum. in particular, we have reported that the addition of CDHs leads to an increase in the number of nodules. However, the information available on the biosynthesis of CDHs is scarce. A greater number of plants CDHs (including those isolated from actinorhizal trees) with a saturated heptane chain have been isolated compared with linear, non-cyclic diarylheptanoids. To identify the genes involved in the synthesis of these compounds, genes with significant sequence similarity to existing plant double-bond reductases were screened in A. sieboldiana. This report describes the isolation and characterization of two A. sieboldiana double-bond reductases (AsDBR1 and AsDBR2) that catalyze the NADPH-dependent reduction of bisdemethoxycurcumin and curcumin. The optimum pH for the two enzymes was 5.0. The apparent Km values for bisdemethoxycurcumin and NADPH were 4.24 and 3.53 μM in the case of AsDBR1, and 2.55 and 2.13 μM for AsDBR2. The kcat value was 9.4-fold higher for AsDBR1 vs. AsDBR2 when using the bisdemethoxycurcumin substrate. Interestingly, the two AsDBRs failed to reduce the phenylpropanoid monomer.

Pharmacological activities and therapeutic potential of galangin, a promising natural flavone, in age-related diseases

BACKGROUND

The extension of average life expectancy and the aggravation of population aging have become the inevitable trend of human development. In an aging society, various problems related to medical care for the elderly have become increasingly prominent. However, most of the age-related diseases have the characteristics of multiple diseases at the same time, prone to complications, and atypical clinical manifestations, which bring great difficulties to its treatment. Galangin (3,5,7-trihydroxyflavone) is a natural active compound extracted from the root of Alpinia officinarum Hance (Zingiberaceae). Recently, many studies have shown that galangin has potential advantages in the treatment of neurodegenerative diseases and cardiovascular and cerebrovascular diseases, which are common in the elderly. In addition, it also showed that galangin had prospective activities in the treatment of tumor, diabetes, liver injury, asthma and arthritis.

PURPOSE

This review aims to systematically summarize and discuss the effects and the underlying mechanism of galangin in the treatment of age-related diseases.

METHODS

We searched PubMed, SciFinder, Web of Science and CNKI literature database resources, combined with the keywords "galangin", "neurodegenerative disease", "tumor", "diabetes", "pharmacological activity", "drug combination", "pharmacokinetics", "drug delivery system" and "safety", and comprehensively reviewed the pharmacological activities and mechanism of galangin in treating age-related diseases.

RESULTS

According to the previous studies on galangin, the anti-neurodegenerative activity, cardiovascular and cerebrovascular protective activity, anti-tumor activity, anti-diabetes activity, anti-arthritis activity, hepatoprotective activity and antiasthmatic activity of galangin were discussed, and the related mechanisms were classified and summarized in detail. In addition, the drug combination, pharmacokinetics, drug delivery system and safety of galangin were furtherly discussed.

CONCLUSIONS

This review will provide reference for galangin in the treatment of age-related diseases. Meanwhile, further experimental research and long-term clinical trials are needed to determine the therapeutic safety and efficacy of galangin.

Methyl Gallate Suppresses Tumor Development by Increasing Activation of Caspase3 and Disrupting Tumor Angiogenesis in Melanoma

Methyl gallate is a phenolic compound mainly found in medicinal plants. It has been reported to its anticancer activity in various tumors. In this study, we aimed to demonstrate the antitumor effect of methyl gallate in the melanoma mouse model and B16F10 cells. Our results showed that methyl gallate decreased cell viability and induced apoptosis by increasing the expression of cleaved caspase3 in B16F10 cells and prevented cell migration and tube formation in human umbilical vein endothelial cells. In B16F10 cell-inoculated mice, methyl gallate not only decreased tumor volume by 30% but also significantly reduced tumor vessel density and pericyte coverage. Moreover, methyl gallate diminished by close to 50% the expression of cytokeratin and LYVE-1 in mouse right inguinal lymph nodes, indicating that methyl gallate could suppress metastasis. In conclusion, this study suggests that methyl gallate inhibits tumor development by inducing apoptosis and blocking tumor angiogenesis and metastasis and might be considered a therapeutic agent for melanoma.

Feature-Based Molecular Networking-An Exciting Tool to Spot Species of the Genus Cortinarius with Hidden Photosensitizers

Fungi have developed a wide array of defense strategies to overcome mechanical injuries and pathogen infections. Recently, photoactivity has been discovered by showing that pigments isolated from Cortinarius uliginosus produce singlet oxygen under irradiation. To test if this phenomenon is limited to dermocyboid Cortinarii, six colourful Cortinarius species belonging to different classical subgenera (i.e., Dermocybe, Leprocybe, Myxacium, Phlegmacium, and Telamonia) were investigated. Fungal extracts were explored by the combination of in vitro photobiological methods, UHPLC coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS2), feature-based molecular networking (FBMN), and metabolite dereplication techniques. The fungi C. rubrophyllus (Dermocybe) and C. xanthophyllus (Phlegmacium) exhibited promising photobiological activity in a low concentration range (1-7 µg/mL). Using UHPLC-HRMS2-based metabolomic tools, the underlying photoactive principle was investigated. Several monomeric and dimeric anthraquinones were annotated as compounds responsible for the photoactivity. Furthermore, the results showed that light-induced activity is not restricted to a single subgenus, but rather is a trait of Cortinarius species of different phylogenetic lineages and is linked to the presence of fungal anthraquinones. This study highlights the genus Cortinarius as a promising source for novel photopharmaceuticals. Additionally, we showed that putative dereplication of natural photosensitizers can be done by FBMN.

Natural products isolation studies of the paleoendemic plant species Nothofagus gunnii and Nothofagus cunninghamii

The first natural product isolation studies of Nothofagus gunnii (Hook.f.) Oerst and Nothofagus cunninghamii (Hook.f.) Oerst have been undertaken. A previously unreported stilbene derivative, pinosylvin monoacetate, was isolated from the leaves of N. gunnii, in addition to 14 known compounds; including the flavonoids galangin, pinobanksin, catechin and quercetin; sesquiterpenoids such as, ilicol and (+)-β-costol acetate; 2,4-dihydroxy-6-methoxychalcone and pinosylvin. Four known flavonoid natural products, catechin, quercetin, ayanin, and avicularin were isolated from the leaves of N. cunninghamii. This study reveals that N. gunnii is a rich source of flavonoid, chalcone and stilbene compounds, while primarily hydroxyflavonoid compounds are found in N. cunninghamii. The isolated phytochemicals are consistent with the evolutionary relationships suggested to exist among Nothofagus species.

Review On Documented Medicinal Plants Used For The Treatment Of Cancer

Background:

Cancer is a frightful disease and it is the second leading cause of death worldwide. Naturally derived compounds are gaining interest of research workers as they have less toxic side effects as compared to currently used treatments such as chemotherapy. Plants are the pool of chemical compounds which provides a promising future for research on cancer.

Objective:

This review paper provides updated information gathered on medicinal plants and isolated phytoconstituents used as anticancer agents and summarises the plant extracts and their isolated chemical constituents exhibiting anticancer potential on clinical trials.

Methods:

An extensive bibliographic investigation was carried out by analysing worldwide established scientific databases like SCOPUS, PUBMED, SCIELO, ScienceDirect, Springerlink, Web of Science, Wiley, SciFinder and Google Scholar etc. In next few decades, herbal medicine may become a new epoch of medical system.

Results:

Many researches are going on medicinal plants for the treatment of cancer but it is a time to increase further experimental studies on plant extracts and their chemical constituents to find out their mechanism of action at molecular level.

Conclusion:

The article may help many researchers to start off further experimentation that might lead to the drugs for the cancer treatment.

Chemical constituents of the antiulcer purified fractions of Lindera reflexa Hemsl. and its quantitative analysis

The root of Lindera reflexa Hemsl. (LR) is a folk Chinses herbal medicine that has been used to treat gastritis and peptic ulcers. In this study, three new stilbenes (1-3) and two known flavonoids (4 and 5) were isolated from the antiulcer purified fractions of LR. The chemical structures of the isolated compounds were characterized comprehensively based on the basis of extensive spectroscopic data. Absolute configurations of compounds 1, 2, and 3 were determined by ECD calculations. The cytotoxic activities of compounds 1-5 were evaluated by MTT assay. Compound 4 showed the strongest inhibitory effect on the proliferation of tumor cells lines MGC803 and SMMC-7721, with IC₅₀ values of 2.65 and 4.13 μM, respectively. The quantitative analysis of 12 compounds of the antiulcer purified fractions of LR were carried out by using the reversed-phase high-performance liquid chromatography (HPLC) method. Within the test range, all calibration curves showed good linearity (R² > 0.9993). The LOD, LOQ, specificity, precision, and accuracy of the method were verified. Therefore, the present study may provide a valuable method for quality control the antiulcer purified fractions of LR.

Activation of JNK and p38 in MCF-7 Cells and the In Vitro Anticancer Activity of Alnus hirsuta Extract

JNK and p38 are important mitogen-activated protein kinases (MAPKs) that respond to stress stimuli. The stress-activated MAPKs associated with apoptotic cell death play vital roles in mammalian cells. Alnus hirsuta, which contains abundant diarylheptanoids derivatives, is a valuable medicinal plant. The CHCl3 extract (AHC) containing platyphyllenone (1) and platyphyllone (3) as main compounds showed in vitro anticancer effects. We report the biological activities of A. hirsuta extract associated with the regulation of apoptosis and JNK and p38 in MCF-7 breast cancer cells. Levels of phospho-JNK and phospho-p38 by AHC treatment were evaluated by enzyme-linked immunosorbent assay (ELISA). ROS production, apoptotic effect, and DNA contents of the cells were measured by flow cytometry. The two diarylheptanoids 1 and 3 and the AHC extract exhibited cytotoxic effects on MCF-7 cells in MTT assay, with IC50 values of 18.1, 46.9, 260.0 μg/mL, respectively. AHC induced ROS generation and elevated the endogenous levels of phospho-JNK and phospho-p38. AHC resulted in apoptosis and cell cycle arrest. We suggest that the antitumor effect of A. hirsuta extract is achieved by apoptosis promotion and cell cycle arrest mediated by the activation of JNK and p38 signaling pathway via ROS generation.

Untargeted Metabolomics Toward Systematic Characterization of Antioxidant Compounds in Betulaceae Family Plant Extracts

Plant species have traditionally been revered for their unparalleled pharmacognostic applications. We outline a non-iterative multi-parallel metabolomic-cum-bioassay-guided methodology toward the functional characterization of ethanol extracts from the Betulaceae family plants (n = 10). We performed mass spectrometry (MS)-based multivariate analyses and bioassay-guided (ABTS antioxidant activity and cytoprotective effects against H₂O₂-induced cell damage) analyses of SPE fractions. A clearly distinct metabolomic pattern coupled with significantly higher bioactivities was observed for 40% methanol SPE eluate. Further, the 40% SPE eluate was subjected to preparative high-performance liquid chromatography (prep-HPLC) analysis, yielding 72 sub-fractions (1 min⁻¹), with the highest antioxidant activities observed for the 15 min and 31 min sub-fractions. We simultaneously performed hyphenated-MS-based metabolite characterization of bioactive components for both the 40% methanol SPE fraction and its prep-HPLC sub-fraction (15 min and 31 min). Altogether, 19 candidate metabolites were mainly observed to contribute toward the observed bioactivities. In particular, ethyl gallate was mainly observed to affect the antioxidant activities of SPE and prep-HPLC fractions of Alnus firma extracts. We propose an integrated metabolomic-cum-bioassay-guided approach for the expeditious selection and characterization of discriminant metabolites with desired phenotypes or bioactivities.

Pharmacokinetics and Tissue Distribution Study of Pinosylvin in Rats by Ultra-High-Performance Liquid Chromatography Coupled with Linear Trap Quadrupole Orbitrap Mass Spectrometry

Pinosylvin is a potential anti-inflammatory and antioxidant compound and the major effective medicinal ingredient in the root of Lindera reflexa Hemsl. However, few investigations have been conducted regarding the pharmacokinetics, excretion, characteristics of tissue distribution, and major metabolites of pinosylvin in rats after oral administration. To better understand the behavior and mechanisms of action underlying the activity of pinosylvin in vivo, we established a simple, sensitive, and reliable ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for quantifying pinosylvin in rat plasma, urine, feces, and various tissues (including heart, liver, spleen, lung, kidneys, large intestine, small intestine, and stomach). Noncompartmental pharmacokinetic parameters indicated that pinosylvin is rapidly distributed and taken up by tissues. The time to peak (maximum) concentration (T_max) was 0.137 h, and the apparent elimination half-life (t_1/2) was 1.347±0.01 h. The results of the tissue distribution study suggest that pinosylvin is widely distributed to various tissues; the highest concentration was observed after 10 min in the stomach, followed by the heart, lung, spleen, and kidneys. Results of the excretion study suggest that a small amount of pinosylvin is excreted from the urine and feces in the parent form; the 73 h accumulative excretion ratios of urine and feces were 0.82% and 0.11%, respectively. It is likely that pinosylvin is mostly metabolized in vivo. Nine metabolites were found, and the main metabolic pathways of pinosylvin in rats included glucuronidation, hydroxylation, and methylation. Four metabolites had higher concentrations in the stomach, suggesting that the stomach is a potential target organ of pinosylvin. In conclusion, the present study may provide a material basis for studying the pharmacological action of pinosylvin and provides meaningful information for the clinical treatment of chronic gastritis and gastric ulcers using Radix Linderae Reflexae.

The Genus Alnus, A Comprehensive Outline of Its Chemical Constituents and Biological Activities

The genus Alnus (Betulaceae) is comprised of more than 40 species. Many species of this genus have a long history of use in folk medicines. Phytochemical investigations have revealed the presence of diarylheptanoids, polyphenols, flavonoids, terpenoids, steroids and other compounds. Diarylheptanoids, natural products with a 1,7-diphenylheptane structural skeleton, are the dominant constituents in the genus, whose anticancer effect has been brought into focus. Pure compounds and crude extracts from the genus exhibit a wide spectrum of pharmacological activities both in vitro and in vivo. This paper compiles 273 naturally occurring compounds from the genus Alnus along with their structures and pharmacological activities, as reported in 138 references.

Constituents of Fermented Male Flowers of Alnus sieboldiana (Betulaceae)

Fractionation of the ethyl acetate crude extract of the fermented male flowers of Alnus sieboldiana resulted in the isolation of two diarylheptanoids and six flavonoids. Yashabushidiol A, yashabushidiol B and naringenin were known constituents of the male flowers of A. sieboldiana while kaempferol, quercetin, pinocembrin dimethyl ether, 5,7-dimethoxy-3-hydroxyflavanone and 5,7-dimethoxy-3-hydroxyflavone were isolated for first time from the fermented male flowers of A. sieboldiana. The isolated compounds were characterized using NMR and HRMS and compared with available literature.

Phytochemical and biological studies on Alnus glutinosa subsp. glutinosa, A. orientalis var. orientalis and A. orientalis var. pubescens leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Alnus species have been used for the treatment of rheumatism, hemorrhoids and for wound healing in folk medicine.

MATERIALS AND METHODS

Aqueous and methanol extracts of A. glutinosa (L.) Gaertner subsp. glutinosa, A. orientalis Decne. var. orientalis and A. orientalis var. pubescens Dippel leaves were evaluated for their wound healing, anti-inflammatory and antioxidant activities. In vivo wound models of linear incision and circular excision were performed. "Inhibition of acetic acid-induced capillary permeability", "carrageenan-induced hind paw edema" and T"PA-induced ear edema" assays were applied to determine the anti-inflammatory effects. For the antioxidant activity assessment, DPPH and ABTS radicals scavenging effect, reducing power and denaturation of nonspecific hydroxyl radical-targeted 2-deoxyribose were used. In vitro inhibitory effects on enzymes hyaluronidase, collagenase and elastase were evaluated. The methanol extract of the leaves of A. glutinosa subsp. glutinosa (MB), the most potent extract, was fractionated by bioassay-guided fractionation technique. The structure of the isolated compound was determined as shikimic acid by using NMR and IR analyses.

RESULTS

MB increased the wound tension by 42.79% value and provided a contraction by 51.58%. Wound tension, contraction capacity and tissue hydroxyproline levels were increased with the application of the fraction EtOAc: MeOH (Fr. D), subfraction D_27-38 and shikimic acid. In the "inhibition of acetic acid-induced capillary permeability" assay, MB, Fr. D, subfraction D_27-38 and shikimic acid inhibited the permeability with significant inhibition values of 30.22%, 32.46%, 38.24% and 27.19%, respectively. In carrageenan-induced hind paw edema model, MB displayed 29.1% inhibition. Likewise, Fr. D, subfraction D_27-38, and shikimic acid were found to exhibit remarkable anti-inflammatory and antioxidant effects. Shikimic acid exhibited significant inhibitory effect (38.24%) on the hyaluronidase enzyme.

CONCLUSIONS

This is the first and unique study that investigates wound healing, anti-inflammatory and antioxidant effects of some Alnus taxons growing in Turkey. According to the results, shikimic acid was found to be the major compound responsible from the activity.

Bioactivity-guided isolation of antioxidant and anti-hepatocarcinoma constituents from Veronica ciliata

Background

Veronica ciliata Fisch., widely distributed in western China, has been traditionally used in Tibetan Medicine as a treatment for hepatitis, cholecystitis, rheumatism, and urticaria. However, V. ciliata Fisch. has not been subjected to detailed chemical constitution analysis and the bioactive studies were restricted to its crude extracts. It is necessary to investigate the active chemical components of these extracts and identify their biological effects.

Results

Four iridoid glycosides, (veronicoside, cataposide, amphicoside, and verminoside) were isolated from the ethyl acetate fraction. Among these compounds, veronicoside and verminoside were isolated for the first time from this plant. These compounds exhibited strong antioxidant activity and inhibitory activity on HepG2 cell proliferation. The antioxidant activity of verminoside was equal to Vc. Cataposide, amphicoside and verminoside had stronger anti-hepatocarcinoma activity than 5-fluorouracil.

Conclusions

Four iridoid glycosides,(veronicoside, cataposide, amphicoside and verminoside) were isolated from the extract of V. ciliata Fisch. using bioassay-guided screening.Among these compounds, veronicoside and verminoside were isolated for the first time from this plant. The above results indicated that these compounds were the active chemical components responsible for the antioxidant and anti-hepatocarcinoma properties of V. ciliata Fisch. The underlying mechanism of their bioactivity is worthy of further investigation.

Comparative Study of the Volatile Components of Fresh and Fermented Flowers of Alnus sieboldiana (Betulaceae)

Analysis of the volatile components present in the fresh male and female flowers and young leaves shows that 2-phenylethanol is the major component in all these three organs, which play a significant role in the strong resinous aromatic odor. The male flowers contained styrene as a second major compound. The level of styrene does not affect the male flowers odor concentration. The level of β-phenylethyl cinnamate and trans-methyl cinnamate in the fermented male flowers decreased as the fermentation time increased. This was due to the Penicillium enzymatic action on the fermented male flowers.

In vitro antioxidant and antiproliferative activities of methanolic plant part extracts of Theobroma cacao

The aims of this study were to determine the antioxidant and antiproliferative activity of the following Theobroma cacao plant part methanolic extracts: leaf, bark, husk, fermented and unfermented shell, pith, root, and cherelle. Antioxidant activity was determined using 2,2-diphenyl-2-picrylhydrazyl (DPPH), thiobarbituric acid-reactive substances (TBARS), and Folin-Ciocalteu assays; the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium (MTT) assay was used to determine antiproliferative activity. The root extract had the highest antioxidant activity; its median effective dose (EC50) was 358.3±7.0 µg/mL and total phenolic content was 22.0±1.1 g GAE/100 g extract as compared to the other methanolic plant part extracts. Only the cherelle extract demonstrated 10.4%±1.1% inhibition activity in the lipid peroxidation assay. The MTT assay revealed that the leaf extract had the highest antiproliferative activity against MCF-7 cells [median inhibitory concentration (IC50)=41.4±3.3 µg/mL]. Given the overall high IC50 for the normal liver cell line WRL-68, this study indicates that T. cacao methanolic extracts have a cytotoxic effect in cancer cells, but not in normal cells. Planned future investigations will involve the purification, identification, determination of the mechanisms of action, and molecular assay of T. cacao plant extracts.

Cytotoxicity of dietary flavonoids on different human cancer types

Flavonoids are ubiquitous in nature. They are also in food, providing an essential link between diet and prevention of chronic diseases including cancer. Anticancer effects of these polyphenols depend on several factors: Their chemical structure and concentration, and also on the type of cancer. Malignant cells from different tissues reveal somewhat different sensitivity toward flavonoids and, therefore, the preferences of the most common dietary flavonoids to various human cancer types are analyzed in this review. While luteolin and kaempferol can be considered as promising candidate agents for treatment of gastric and ovarian cancers, respectively, apigenin, chrysin, and luteolin have good perspectives as potent antitumor agents for cervical cancer; cells from main sites of flavonoid metabolism (colon and liver) reveal rather large fluctuations in anticancer activity probably due to exposure to various metabolites with different activities. Anticancer effect of flavonoids toward blood cancer cells depend on their myeloid, lymphoid, or erythroid origin; cytotoxic effects of flavonoids on breast and prostate cancer cells are highly related to the expression of hormone receptors. Different flavonoids are often preferentially present in certain food items, and knowledge about the malignant tissue-specific anticancer effects of flavonoids could be purposely applied both in chemoprevention as well as in cancer treatment.

Anti-proliferative and apoptotic activities of constituents of chloroform extract of Juglans regia leaves

OBJECTIVES

To evaluate anti-proliferative as well as apoptotic activities of compounds identified in chloroform extract of Juglans regia leaves, on human breast and oral cancer cell lines (MCF-7 and BHY).

MATERIALS AND METHODS

Column chromatography, MTT assay, flowcytometry and western blotting have all been used in the study.

RESULTS

Bioassay-guided fractionation of chloroform extract of J. regia afforded isolation of 5-hydroxy-3,7,4'-trimethoxyflavone [1], lupeol [2], daucosterol [3], 4-hydroxy-α-tetralone [4], β-sitosterol [5], 5,7- dihydroxy-3,4'-dimethoxyflavone [6] and regiolone [7]. Structures of the compounds were established on the basis of spectroscopic analyses [Nuclear magnetic resonance (NMR) and mass]. All compounds inhibited proliferation of MCF-7 (human breast adenocarcinoma) and BHY (human oral squamous carcinoma) cells in a concentration-dependent manner. Compounds 6 and 7 had potent cytotoxic effects on both MCF-7 and BHY cells (IC50 21-51 μm), yet were not toxic to normal cells. MCF-7 growth inhibition was attributed to apoptosis; population of apoptotic cells increased from 1.12% in controls to 5.64 and 8.1% after 48-h treatment with compounds 6 and 7, indicating their potential at inducing early and late apoptosis. The caspase cascade was not activated, as indicated by only insignificant cleavage of caspase-3.

CONCLUSIONS

Our results suggest that compounds 6 and 7 can induce apoptosis in MCF-7 cells through the caspase-3 independent pathway.

Site-specific anticancer effects of dietary flavonoid quercetin

Food-derived flavonoid quercetin, widely distributed in onions, apples, and tea, is able to inhibit growth of various cancer cells indicating that this compound can be considered as a good candidate for anticancer therapy. Although the exact mechanism of this action is not thoroughly understood, behaving as antioxidant and/or prooxidant as well as modulating different intracellular signalling cascades may all play a certain role. Such inhibitory activity of quercetin has been shown to depend first of all on cell lines and cancer types; however, no comprehensive site-specific analysis of this effect has been published. In this review article, cytotoxicity constants of quercetin measured in various human malignant cell lines of different origin were compiled from literature and a clear cancer selective action was demonstrated. The most sensitive malignant sites for quercetin revealed to be cancers of blood, brain, lung, uterine, and salivary gland as well as melanoma whereas cytotoxic activity was higher in more aggressive cells compared to the slowly growing cells showing that the most harmful cells for the organism are probably targeted. More research is needed to overcome the issues of poor water solubility and relatively low bioavailability of quercetin as the major obstacles limiting its clinical use.

Suppression of Src/ERK and GSK-3/β-catenin signaling by pinosylvin inhibits the growth of human colorectal cancer cells

Pinosylvin, a naturally occurring trans-stilbenoid mainly found in Pinus species, has exhibited a potential cancer chemopreventive activity. However, the growth inhibitory activity against cancer cells and the underlying molecular mechanisms remain to be elucidated. Therefore, the anti-proliferative activity of pinosylvin was investigated in human colorectal HCT 116 cancer cells. Pinosylvin inhibited the proliferation of HCT 116 cells by arresting transition of cell cycle from G1 to S phase along with the downregulation of cyclin D1, cyclin E, cyclin A, cyclin dependent kinase 2 (CDK2), CDK4, c-Myc, and retinoblastoma protein (pRb), and the upregulation of p21(WAF1/CIP1) and p53. Pinosylvin was also found to attenuate the activation of proteins involved in focal adhesion kinase (FAK)/c-Src/extracellular signal-regulated kinase (ERK) signaling, and phosphoinositide 3-kinase (PI3K)/Akt/ glycogen synthase kinase 3β (GSK-3β) signaling pathway. Subsequently, pinosylvin suppressed the nuclear translocation of β-catenin, one of downstream molecules of PI3K/Akt/GSK-3β signaling, and these events led to the sequential downregulation of β-catenin-mediated transcription of target genes including BMP4, ID2, survivin, cyclin D1, MMP7, and c-Myc. These findings demonstrate that the anti-proliferative activity of pinosylvin might be associated with the cell cycle arrest and downregulation of cell proliferation regulating signaling pathways in human colorectal cancer cells.

Natural stilbenoids: distribution in the plant kingdom and chemotaxonomic interest in Vitaceae

Stilbenoids, a family of polyphenols known for the complexity of their structure and for their diverse biological activities, occur with a limited but heterogeneous distribution in the plant kingdom. The most prominent stilbene containing plant family, the Vitaceae, represented by the famous wine producing grape vines Vitis vinifera L., is one of the richest sources of novel stilbenes currently known, together with other families, such as Dipterocarpaceae, Gnetaceae and Fabaceae. This review focuses on the distribution of stilbenes and 2-arylbenzofuran derivatives in the plant kingdom, the chemical structure of stilbenes in the Vitaceae family and their taxonomic implication.

HPLC Quantitative Analysis of Main Stilbenes and Flavones in Different Parts ofMatteuccia struthiopteris

A simple and accurate HPLC-UV method was developed for the simultaneous quantitative analysis of main stilbenes and flavones in different parts (fronds, rhizomes, and frond bases) ofM. struthiopteris. The chromatographic separation was performed on a Kromasil C18 column (4.6 mm × 250 mm, 5 μm) with the mobile phase of MeOH-H2O (including 0.1% phosphoric acid) using a gradient elution at the flow rate of 1.0 mL min−1and UV detection at 295 nm. The method was validated by specificity, linearity, accuracy (recovery), and precision tests (repeatability, intra- and interday). For all the six compounds, the linear regression coefficients ranged from 0.9958 to 0.9998 within the test ranges; intra- and interday precisions were<2% and the mean recoveries ranged from 98.09 to 103.56%. The amount of these compounds in the frond bases was almost the same as in the rhizomes but much higher than that in the fronds. The results indicate that the HPLC method developed was appropriate for the analysis of the six compounds in different parts (fronds, rhizomes, and frond bases) ofM. struthiopteris.

Cytotoxicity effects of various Juglans regia (walnut) leaf extracts in human cancer cell lines

CONTEXT

Currently, natural products have been shown to present interesting biological and pharmacological activities and are used as chemotherapeutic agents. Plants have historically been used in treating cancer and are recognized for their ability to produce secondary metabolites. Juglans regia L. (Juglandaceae) has medicinal applications to treat a wide range of diseases such as cancer.

OBJECTIVE

The current study was designed to evaluate the antiproliferative activity of total extract as well as several fractions from the leaves of J. regia.The total phenolics, flavonoids, and condensed tannins content of these extracts were also determined to obtain further information on the correlation between the contents of phenolic compounds and antiproliferative effects as well as the leaf developmental stages.

MATERIALS AND METHODS

Antiproliferative activity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and flow cytometry methods against human oral cancer, breast adenocarcinoma and colon adenocarcinoma cell lines. The total phenolics, flavonoids, and condensed tannins were determined by Folin-Ciocalteu, aluminum chloride and butanol-HCl colorimetric methods.

RESULTS

Our present study has shown that chloroform fraction has the lowest IC(50) values (0.36-0.81 mg/mL) and also induces cell cycle arrest (G0\G1 phase) after a 24 h treatment. The colorimetric methods showed the highest amount of total phenolics, flavonoids, and condensed tannins in the methanol fraction (120.28 ± 2.32, 59.44 ± 0.87, 227.00 ± 4.91 mg/g of dry weight of extract).

DISCUSSION AND CONCLUSION

The results obtained herein indicate that walnut chloroform fraction may contain effective compounds which can be used as a chemotherapeutic agent.

The natural stilbenoid pinosylvin and activated neutrophils: effects on oxidative burst, protein kinase C, apoptosis and efficiency in adjuvant arthritis

AIM

To investigate the effects of the naturally occurring stilbenoid pinosylvin on neutrophil activity in vitro and in experimental arthritis, and to examine whether protein kinase C (PKC) activation served as an assumed target of pinosylvin action.

METHODS

Fresh human blood neutrophils were isolated. The oxidative burst of neutrophils was evaluated on the basis of enhanced chemiluminescence. Neutrophil viability was evaluated with flow cytometry, and PKC phosphorylation was assessed by Western blotting analysis. Adjuvant arthritis was induced in Lewis rats with heat-killed Mycobacterium butyricum, and the animals were administered with pinosylvin (30 mg/kg, po) daily for 21 d after arthritis induction.

RESULTS

In isolated human neutrophils, pinosylvin (10 and 100 μmol/L) significantly decreased the formation of oxidants, both extra- and intracellularly, and effectively inhibited PKC activation stimulated by phorbol myristate acetate (0.05 μmol/L). The inhibition was not due to neutrophil damage or increased apoptosis. In arthritic rats, the number of neutrophils in blood was dramatically increased, and whole blood chemiluminescence (spontaneous and PMA-stimulated) was markedly enhanced. Pinosylvin administration decreased the number of neutrophils (from 69 671 ± 5588/μL to 51 293 ± 3947/μL, P=0.0198) and significantly reduced the amount of reactive oxygen species in blood.

CONCLUSION

Pinosylvin is an effective inhibitor of neutrophil activity, and is potentially useful as a complementary medicine in states associated with persistent inflammation.