Eriocitrin Inhibits Angiogenesis by Targeting VEGFR2-Mediated PI3K/AKT/mTOR Signaling Pathways.

Eriocitrin, a flavanone found in peppermint and citrus fruits, is known to possess many physiological activities. However, the anti-angiogenic effects of eriocitrin are yet to be fully elucidated. Therefore, the objective of this research was to explore the anti-angiogenic effects of eriocitrin both in vitro and in vivo as well as its underlying mechanism. Anti-angiogenic effects of eriocitrin were evaluated utilizing in vitro models of angiogenesis, including inhibition of tube formation, and induction of apoptosis in human umbilical vein endothelial cells (HUVECs). A chorioallantoic membrane (CAM) assay in chick embryos was also performed to evaluate the in vivo effects of eriocitrin on angiogenesis. Results showed significant eriocitrin effects on proliferation, tube formation, migration, and apoptosis in HUVECs. Furthermore, in vivo analysis revealed that eriocitrin significantly suppressed the formation of new blood vessels. In particular, it regulated MAPK/ERK signaling pathway and VEGFR2, inhibited the downstream PI3K/AKT/mTOR signaling pathway, and activated apoptosis signals such as caspase cascades. In HUVECs, the expression of matrix metalloproteinases (MMP-2 and MMP-9) exhibited an inhibitory effect on angiogenesis through the suppression of the signaling pathway. Therefore, eriocitrin presents potential for development into an antiangiogenic therapeutic agent.

Probiotic microbes: Are their anti-melanogenicity and longevity promoting activities closely linked through the major "pathogenic" kinase PAK1?

PAK1-deficient mutant of C. elegans lives 60% longer than the wild-type. Interestingly, PAK1-deficient mutant of melanocytes produces less melanin (only a half compared with the wild-type) in the presence of either serum (PDGF) or α-MSH (alpha-melanocyte stimulating hormone). These observations indicate that the major "pathogenic" kinase PAK1 is responsible for both shortening the healthy lifespan, and PDGF/α-MSH-dependent melanogenesis. For screening of PAK1-blocking probiotic bacteria or their products, their anti-melanogenic as well as longevity promoting properties were examined. Recently it was found that C. elegans fed with Lactobacillus rhamnosus in Xinjiang cheese lives 40% longer than the worm fed with the standard E. coli. Interestingly, a Chinese traditional medicine called "ChiBai" fermented with the Lactobacillus rhamnosus also inhibited the α-MSH-induced melanogenesis, and this bacteria itself produces butyric acid that blocks the oncogenic HDAC (histone deacetylase)-PAK1 signaling pathway. These findings strongly suggest, if not proven, that anti-melanogenic activity of Lactobacillus and many other probiotic bacteria might serve as a reliable indicator for their longevity promoting activity. In this context, a popular Japanese Lactobacillus-fermented milk drink called "Calpis", developed a century ago, and recently proven to inhibit the melanogenesis by suppressing the PAK1-dependent tyrosinase gene expression, may potentially prolong our healthy lifespan.

Chemical Profiles of Korean Bee Pollens and Their Catechol-O-methyltransferase Inhibitory Activities.

Bee pollen is an apicultural product collected by honeybees from flower stamens and is consumed to help maintain a healthy diet. In this study, the chemical profiles of 11 Korean bee pollens were investigated using molecular networking analysis. This analysis elucidated the presence of two major clusters, hydroxycinnamoyl acid amides (HCAAs, molecular network 1 (MN1)) and flavonoid glycosides (MN2), in the bee pollen samples. The inhibitory properties of the bee pollens and the isolated HCAAs toward human catechol-O-methyltransferase (COMT), a key neurotransmitter involved in Parkinson's disease and depression, were determined. N1,N5,N10-(E)-tricaffeoylspermidine ((E,E,E)-1) exhibited the highest activity of the four compounds isolated, with an IC50 value 16 µM, and inhibited COMT competitively. Quantitative analysis of HCAAs showed that the amounts of N1,N10-dicaffeoyl-N5-p-coumaroylspermidine (2) and N10-caffeoyl-N1,N5-di-p-coumaroylspermidine (3) contributed to the observed differences in the COMT inhibitory activities of Korean bee pollens. This study may lead to the prevention and treatment of Parkinson's disease and depression using bee pollens.

Promotion effect of the propolis from Jeju Island, Korea, on NGF secretion in human glioblastoma cells.

Propolis is a resinous mixture of substances collected and processed from various botanical sources by honeybees (Apis mellifera). We previously found that propolis collected on Jeju Island, located off the southern coast of Korea, originates from a single plant, Angelica keiskei KOIDZUMI (Ashitaba). A. keiskei has been well-studied as a health food and has been reported to promote nerve growth factor (NGF) production. Propolis formed from the resin of A. keiskei is expected to have a similar promotional effect on NGF production. NGF is a potential pharmacological agent for Alzheimer's disease. In this study, the effects of an ethanolic extract of propolis from Jeju Island (EEPJ) on NGF secretion and cell viability in T98G human glioblastoma cells were evaluated. Ethanolic extracts of propolis from Brazil (Baccharis type) and from Uruguay (Populus type) were also studied for comparison. We found that EEPJ significantly increased NGF secretion in the cells in a concentration-dependent manner. Furthermore, the effects of 27 compounds previously isolated from EEPJ were also evaluated. Several compounds were found to have a promotion effect on NGF secretion, and the structure-activity relationships of the compounds were considered relative to their promotional effect on NGF biosynthesis. The promotional effect of EEPJ is a characteristic biological activity that is not present with other propolis types, so the propolis from Jeju Island may have potential applications as a therapeutic candidate for Alzheimer's disease.

Anti-Neuroinflammatory Property of Phlorotannins from Ecklonia cava on Aß25-35-Induced Damage in PC12 Cells.

Alzheimer disease (AD) is a neurodegenerative disorder characterized by excessive accumulation of amyloid-beta peptide (Aß) and progressive loss of neurons. Therefore, the inhibition of Aß-induced neurotoxicity is a potential therapeutic approach for the treatment of AD. Ecklonia cava is an edible brown seaweed, which has been recognized as a rich source of bioactive derivatives, mainly phlorotannins. In this study, phlorotannins including eckol, dieckol, 8,8'-bieckol were used as potential neuroprotective candidates for their anti-apoptotic and anti-inflammatory effects against Aß25-35-induced damage in PC12 cells. Among the tested compounds, dieckol showed the highest effect in both suppressing intracellular oxidative stress and mitochondrial dysfunction and activation of caspase family. Three phlorotannins were found to inhibit TNF-α, IL-1ß and PGE2 production at the protein levels. These result showed that the anti-inflammatory properties of our compounds are related to the down-regulation of proinflammatory enzymes, iNOS and COX-2, through the negative regulation of the NF-κB pathway in Aß25-35-stimulated PC12 cells. Especially, dieckol showed the strong anti-inflammatory effects via suppression of p38, ERK and JNK. However, 8,8'-bieckol markedly decreased the phosphorylation of p38 and JNK and eckol suppressed the activation of p38. Therefore, the results of this study indicated that dieckol from E. cava might be applied as a drug candidate for the development of new generation therapeutic agents against AD.

Shear stress induces noncanonical autophagy in intestinal epithelial monolayers.

Flow of fluids through the gut, such as milk from a neonatal diet, generates a shear stress on the unilaminar epithelium lining the lumen. We report that exposure to physiological levels of fluid shear stress leads to the formation of large vacuoles, containing extracellular contents within polarizing intestinal epithelial cell monolayers. These observations lead to two questions: how can cells lacking primary cilia transduce shear stress, and what molecular pathways support the formation of vacuoles that can exceed 80% of the cell volume? We find that shear forces are sensed by actin-rich microvilli that eventually generate the apical brush border, providing evidence that these structures possess mechanosensing ability. Importantly, we identified the molecular pathway that regulates large vacuole formation downstream from mechanostimulation to involve central components of the autophagy pathway, including ATG5 and LC3, but not Beclin. Together our results establish a novel link between the actin-rich microvilli, the macroscopic transport of fluids across cells, and the noncanonical autophagy pathway in organized epithelial monolayers.

From bench (laboratory) to bed (hospital/home): How to explore effective natural and synthetic PAK1-blockers/longevity-promoters for cancer therapy.

PAK family kinases are RAC/CDC42-activated kinases that were first found in a soil amoeba 4 decades ago, and 2 decades later, were discovered in mammals as well. Since then at least 6 members of this family have been identified in mammals. One of them called PAK1 has been best studied so far, mainly because it is essential not only for malignant cell growth and metastasis, but also for many other diseases/disorders such as diabetes (type 2), AD (Alzheimer's disease), hypertension, and a variety of inflammatory or infectious diseases, which definitely shorten our lifespan. Moreover, PAK1-deficient mutant of C. elegans lives longer than the wild-type by 60%, clearly indicating that PAK1 is not only an oncogenic but also ageing kinase. Thus, in theory, both anti-oncogenic and longevity-promoting activities are among the "intrinsic" properties or criteria of "clinically useful" PAK1-blockers. There are a variety of PAK1-blocking natural products such as propolis and curcumin which indeed extend the healthy lifespan of small animals such as C. elegans by inducing the autophagy. Recently, we managed to synthesize a series of potent water-soluble and highly cell-permeable triazolyl esters of COOH-bearing PAK1-blockers such as Ketorolac, ARC (artepillin C) and CA (caffeic acid) via "Click Chemistry" that boosts their anti-cancer activity over 500-fold, mainly by increasing their cell-permeability, and one of them called 15K indeed extends the lifespan of C. elegans. In this mini-review we shall discuss both synthetic and natural PAK1-blockers, some of which would be potentially useful for cancer therapy with least side effect (rather promoting the longevity as well).

Both triazolyl ester of ketorolac (15K) and YM155 inhibit the embryonic angiogenesis in ovo (fertilized eggs) via their common PAK1-survivin/VEGF signaling pathway.

15 K is 1,2, 3-triazolyl ester of ketorolac, an old pain-killer, that blocks PAK1 by its R-form and inhibits COX-2 by its S-form. Mainly due to a robust increase in cell-permeability, 15K is over 500 times more potent than ketorolac in both anti-cancer and anti-PAK1 activities in cell culture with IC50 around 24 nM. However, 15K has no anti-AKT activity. Angiogenesis requires at least the kinase PAK1, and perhaps the kinase AKT as well, and is essential for a robust growth of solid tumors. Thus, in this study, we examined the potential antiangiogenic activity of 15K both in ovo and cell culture, prior to its in vivo (xenograft) anti-cancer activity test. The IC50 of 15K against the embryonic angiogenesis in ovo in CAM (chorioallantoic membrane) assay is around 1 nmol/egg. Surprizingly, however, 15K failed to inhibit the tube formation of HUVECs (human umbilical vein endothelial cells) in cell culture even at high as 150 µM. In an attempt to solve this mystery, we tested both in ovo as well as HUVECs-based anti-angiogenic activity of a potent survivin-suppressor called YM155, which blocks PAK1, in addition to AKT. YM155 is slightly more potent than 15K in CAM assay with IC50 around 0.5 nmol/egg, and apparenty inhibits the tube formation of HUVECs with IC50 around 18 nM. According to a few previous findings with the direct PAK1-inhibitor frondoside A (FRA), the tube formation of HUVECs depends solely on PAK1. Thus, the failure of 15K to affect their tube formation is most likely due to their drug (15K)-resistance. Furthermore, unlike FRA, YM155 killed HUVECs with IC50 around 18 nM, clearly indicating that AKT is essential for survival of HUVECs, instead of their tube formation.

Involvement of miR-Let7A in inflammatory response and cell survival/apoptosis regulated by resveratrol in THP-1 macrophage.

BACKGROUND/OBJECTIVES: Resveratrol, a natural polyphenol, has multiple functions in cellular responses including apoptosis, survival, and differentiation. It also participates in the regulation of inflammatory response and oxidative stress. MicroRNA-Let-7A (miR-Let7A), known as a tumor suppressor miRNA, was recently reported to play a crucial role in both inflammation and apoptosis. Therefore, we examined involvement of miR-Let7A in the modulation of inflammation and cell survival/apoptosis regulated by resveratrol. MATERIALS/METHODS: mRNA expression of pro-/anti-inflammatory cytokines and sirtuin 1 (SIRT1), and protein expression of apoptosis signal-regulating kinase 1 (ASK1), p-ASK1, and caspase-3 and cleaved caspase-3 were measured, and cell viability and Hoechst/PI staining for apoptosis were observed in Lipopolysaccharide (LPS)-stimulated human THP-1 macrophages with the treatment of resveratrol and/or miR-Let7A overexpression. RESULTS: Pre-treatment with resveratrol (25-200 µM) resulted in significant recovery of the reduced cell viabilities under LPS-induced inflammatory condition and in markedly increased expression of miR-Let7A in non-stimulated or LPS-stimulated cells. Increased mRNA levels of tumor necrosis factor-α and interleukin (IL)-6 induced by LPS were significantly attenuated, and decreased levels of IL-10 and brain-derived neurotrophic factor were significantly restored by resveratrol and miR-Let7A overexpression, respectively, or in combination. Decreased expression of IL-4 mRNA by LPS stimulation was also significantly increased by miR-Let7A overexpression co-treated with resveratrol. In addition, decreased SIRT1 mRNA levels, and increased p-ASK1 levels and PI-positive cells by LPS stimulation were significantly restored by resveratrol and miR-Let7A overexpression, respectively, or in combination. CONCLUSIONS: miR-Let7A may be involved in the inflammatory response and cell survival/apoptosis modulated by resveratrol in human THP-1 macrophages.

In Vitro and In Vivo Antiangiogenic Activity of Crowberry (Empetrum nigrum var. japonicum).

Crowberry, Empetrum nigrum var. japonicum, is widely used in folk medicine and grows naturally in Korea. Although some constituents and biological activity of Korean crowberry have been examined, there is little detailed information available. In this study, we investigated the effects of ethanol extracts of crowberry (EECB) on the inhibition of angiogenesis, both in vitro and in vivo. The effects of EECB were tested on in vitro models of angiogenesis, that is, tube formation and proliferation of human umbilical vein endothelial cells (HUVECs). EECB exhibited significant inhibitory effects on tube formation of HUVECs in a concentration-dependent manner. In addition, crowberry significantly suppressed the proliferation of HUVECs in a concentration-dependent manner. Furthermore, strong antiangiogenic activity of EECB samples was observed in the in vivo assay using chick embryo chorioallantoic membrane (CAM). These results indicate that crowberry may have potential applications in the prevention and treatment of angiogenesis-dependent human diseases.

Fasting Glucose is a Useful Indicator for Cerebrovascular Risk in Non-Diabetic Koreans: Association With Oxidative Stress and Inflammation.

Diabetes and impaired fasting glucose are associated with incidence of cerebro-/cardio-vascular diseases. This study hypothesized that fasting glycemic status may reflect cerebrovascular risk in non-diabetic Koreans. Fasting glycemic status, lipid profiles, oxidative stress, and inflammation markers were measured in non-diabetic subjects (healthy controls, n = 112 and stroke n = 41). Systolic blood pressure, fasting glucose, glycated hemoglobin (HbA1C), triglycerides, high sensitivity C-reactive protein (hs-CPR), interleukin-6, and tumor necrosis factor-alpha were higher, and high density lipoprotein (HDL)-cholesterols were lower in patients with stroke than healthy controls. Fasting glucose positively correlated with hs-CRP, interleukin-6, tumor necrosis factor-alpha, oxidized low density lipoprotein (LDL) and malondialdehyde. The significances continued or at least turned to a trend after adjustments for confounding factors. Multiple regression analyses revealed that fasting glucose was mainly associated with cerebrovascular risk (ß'-coefficient = 0.284, p < 0.0001) together with age, systolic blood pressure, total cholesterol, hs-CRP, body mass index, dietary poly unsaturated fatty acid/saturated fatty acid (PUFA/SFA), and HbA1C (r(2) = 0.634, p = 0.044). The subjects were subdivided by their fasting glucose levels [normal fasting glucose: 70-99 mg/dL, n = 91 [NFG-control] and n = 27 [NFG-stroke]; higher fasting glucose: 100-125 mg/dL, n = 21 [HFG-control] and n = 14 [HFG-stroke]). In both controls and stroke patients, HFG groups show higher triglyceride, total- and LDL-cholesterol and lower HDL-cholesterol than NFG groups. Control-HFG group showed significantly higher levels of oxidative stress and inflammation than control-NFG group. Stroke-HFG group also showed significantly higher inflammatory levels than stroke-NFG group, moreover the highest among the groups. Additionally, stroke-NFG group consumed higher PUFA/SFA than stroke-HFG group. Fasting glucose may be a useful indicator for cerebrovascular risk in non-diabetic individuals which may be mediated by oxidative stress and inflammation status.

Apigenin Suppresses Angiogenesis by Inhibiting Tube Formation and Inducing Apoptosis.

Apigenin has been reported to exert angiogenic and anticancer activities in vitro. The mechanism of inhibition of angiogenesis by apigenin, however, has not been well-established. In this study, we investigated whether apigenin not only inhibited tube formation but also induced apoptosis in human umbilical vein endothelial cells (HUVECs). Furthermore, strong antiangiogenic activity of apigenin was observed in the in vivo assay using chick embryo chorioallantoic membrane (CAM). We also analyzed changes in survival signals and the apoptotic pathway through Western blotting. The results indicate that apigenin exerts its antiangiogenic effects through induction of endothelial apoptosis.

Anthocyanin Profile and Antioxidant Activity of Various Berries Cultivated in Korea.

This study examined the anthocyanin composition and antioxidant activity of various berries cultivated in Korea: blueberry, crowberry, Korean black raspberry, mulberry, and strawberry. The anthocyanins in berries were identified by high-performance liquid chromatography (HPLC) analysis, and each component was quantitatively analyzed. Furthermore, the antioxidant activity of berries was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolorization, oxygen radical absorbance capacity (ORAC), and ferric ion reducing antioxidant (FRAP) assays. The results revealed that the total content of anthocyanins in crowberry was 35.1 mg/g of extract, which was higher than that in the other four major berry species (1.9-27.7 mg/g of extract). Nineteen anthocyanins were identified in the various berries. The major anthocyanins of crowberry were cyanidin-3-galactoside and delphinidin-3-galactoside, and those from Korean black raspberry were cyanidin-3-rutinoside and cyanidin-3-sambubioside-5-rhamnoside. These two berries also had relatively strong antioxidant activity accompanied by high total polyphenol contents. Thus, consumption of crowberry and Korean black raspberry may be beneficial in reducing the risk of developing lifestyle-related chronic diseases because of their strong antioxidant activity.

Neuroprotective effect of loganin against Aß25-35-induced injury via the NF-κB-dependent signaling pathway in PC12 cells.

Amyloid-beta (Aß) protein, the main constituent of senile plaques, is believed to play a pivotal role in the pathogenesis of Alzheimer's disease (AD). AD is closely associated with inflammatory reactions which are considered to be responses to Aß deposition. The present study investigated the effect of loganin on Aß25-35-induced inflammatory damage and the underlying molecular mechanism of its neuroprotective action. Loganin predominantly prevented Aß25-35-stimulated cell death through suppressing ROS generation, and attenuating apoptosis by inhibiting caspase-3 activity and regulating cell cycle. Furthermore, loganin suppressed the level of TNF-α and protein expression of iNOS and COX-2 in Aß25-35-injured PC12 cells. These inhibitions appeared to correlate with the suppression of NF-κB activation by loganin, as pre-treating cells with loganin blocked the translocation of NF-κB into the nuclear compartment and degradation of the inhibitory subunit IκB. Loganin substantially inhibited phosphorylation of MAPKs including ERK1/2, p38 and JNK, which are closely related to regulation of NF-κB activation. Taken together, the results implied that loganin attenuated neuroinflammatory responses through the inactivation of NF-κB by NF-κB dependent inflammatory pathways and phosphorylation of MAPK in Aß25-35-induced PC12 cells.

Korean propolis suppresses angiogenesis through inhibition of tube formation and endothelial cell proliferation.

Propolis, a sticky material that honeybees collect from living plants, has been used for its pharmaceutical properties since ancient times. In this study, we examined the effects of ethanol extracts of Korean propolis (EEKP) from various geographic regions on the inhibition of angiogenesis, both in vitro and in vivo. The effects of EEKP were tested on in vitro models of angiogenesis, that is, tube formation and proliferation of human umbilical vein endothelial cells (HUVECs). All EEKP samples exhibited significant inhibitory effects on tube formation of HUVECs in a concentration-dependent manner (6.25-25 microg/mL). In addition, two EEKP samples, prepared from Uijeongbu and Pyoseon propolis, significantly suppressed the proliferation of HUVECs in a concentration-dependent manner (3.13-25 microg/mL). Furthermore, in an in vivo angiogenesis assay using the chick embryo chorioallantoic membrane (CAM) system, we found that the two EEKP samples significantly reduced the number of newly formed vessels. These results indicate that Korean propolis may have potential applications in the prevention and treatment of angiogenesis-related diseases such as cancer.

Identification of the phenolic compounds contributing to antibacterial activity in ethanol extracts of Brazilian red propolis.

The purpose of this study is to identify the quantity and antibacterial activity of the individual phenolic compounds in Brazilian red propolis. Quantitative analysis of the 12 phenolic compounds in Brazilian red propolis was carried out using reversed-phase high-performance liquid chromatography. The main phenolic compounds in Brazilian red propolis were found to be (3S)-vestitol (1), (3S)-neovestitol (2) and (6aS,11aS)-medicarpin (4) with quantities of 72.9, 66.9 and 30.8 mg g of ethanol extracts(- 1), respectively. Moreover, the antibacterial activities of each compound against Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa were evaluated by measuring the minimum inhibitory concentrations. In particular, compound 4 exhibited the most potent antibacterial activity among all the assayed compounds against selected bacteria, indicating that 4 is the most active compound in Brazilian red propolis extracts. Thus, Brazilian red propolis may be used as food additives and pharmaceuticals to protect against bacteria.

Component analysis of propolis collected on Jeju Island, Korea.

A study of propolis from Jeju Island, located off the southern tip of Korea, led to the isolation and identification of eight chalcones: (±)-(E)-4'-methoxy-4,2'-dihydroxy-3'-(2″,3″-dihydroxy-3″-methylbutyl)-chalcone, (E,E,E)-4,2',4'-trihydroxy-3'-(7″-hydroxy-3″,7″-dimethyloct-2″,5″-dienyl)-chalcone, (±)-(E,E)-4,2',4'-trihydroxy-3'-(5″-hydroxy-3″,7″-dimethyloct-2″,6″-dienyl)-chalcone, (±)-(E)-4'-methoxy-4,3″,4″-trihydroxy-2″,2″-dimethyldihydropyrano-(2',3')-chalcone, (±)-(E)-4'-methoxy-4,3″-dihydroxy-2″-(1″'-hydroxyisopropyl)-dihydrofurano-(2',3')-chalcone, (-)-(E)-4,4'-dihydroxy-2″-(1″'-hydroxy-1″',5″'-dimethylhex-4″'-enyl)-dihydrofurano-(2',3')-chalcone, (+)-(E)-4,2'-dihydroxy-2″-methyl-2″-(3″',4″'-dihydroxy-4″'-methylpentanyl)-2H-pyrano-(3',4')-chalcone and (-)-(E)-4,2'-dihydroxy-2″-methyl-2″-(3″',4″'-dihydroxy-4″'-methylpentanyl)-2H-pyrano-(3',4')-chalcone. Nineteen other known compounds were also isolated. Their structures were determined by spectroscopic analyses and comparison with literature data. The propolis from Jeju Island contained compounds not present in propolis from other regions.

Identification of the plant origin of propolis from Jeju Island, Korea, by observation of honeybee behavior and phytochemical analysis.

Propolis collected on Jeju Island, Korea, contains characteristic components not present in propolis from other regions. Hence, the plant origin of the propolis from Jeju Island can be expected to be a novel plant. To identify the plant origin of this propolis, first we observed honeybee behavior, and found them collecting the resin from Angelica keiskei. Then comparative analyses of chemical and biological properties of the resin from the plant and propolis from hives of nearby apiaries were performed. Alcoholic extracts showed entirely identical HPLC profiles and closely similar antioxidant activities. These results indicate that A. keiskei is the plant origin of the propolis from Jeju Island, Korea.

Brazilian Propolis Suppresses Angiogenesis by Inducing Apoptosis in Tube-Forming Endothelial Cells through Inactivation of Survival Signal ERK1/2.

We recently reported that propolis suppresses tumor-induced angiogenesis through tube formation inhibition and apoptosis induction in endothelial cells. However, molecular mechanisms underlying such angiogenesis suppression by propolis have not been fully elucidated. The aim of this study was to investigate the effects of ethanol extract of Brazilian propolis (EEBP) on two major survival signals, extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt, and to elucidate whether changes in these signals were actually involved in antiangiogenic effects of the propolis. Detection by western blotting revealed that EEBP suppressed phosphorylation of ERK1/2, but not that of Akt. Pharmacological inhibition by U0126 demonstrated that ERK1/2 inactivation alone was enough to inhibit tube formation and induce apoptosis. It was also shown that EEBP and U0126 similarly induced activation of caspase-3 and cleavage of poly ADP-ribose polymerase (PARP) and lamin A/C, all of which are molecular markers of apoptosis. These results indicate that inhibition of survival signal ERK1/2, and subsequent induction of apoptosis, is a critical mechanism of angiogenesis suppression by EEBP.

Radical-scavenging activity and phenolic constituents of propolis from different regions of Argentina.

Propolis is a resinous substance collected by honeybees from various plant sources. The composition of propolis depends on the type of vegetation and the area of collection. We examined the radical-scavenging activity of propolis from the following regions of Argentina: Mendoza, Rio Negro, La Pampa, and Entre Rios. Ethanol extracts of propolis (EEP) were prepared and their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities were evaluated. Furthermore, the major constituents in EEP were identified by HPLC with photodiode array (PDA) detection, and each component was quantitatively analysed. Almost all of the propolis samples, except La Pampa, had radical-scavenging activity. Propolis with strong radical-scavenging activity contained large amounts of antioxidative compounds, such as caffeic acid, ferulic acid and caffeic acid phenethyl ester.