Antioxidant activity and constituents of propolis collected in various areas of Korea

Propolis is a resinous substance collected by honeybees from various plant sources. The composition of propolis depends on time, vegetation, and the area of collection. This study examined the antioxidant activity of propolis from various areas of Korea: Chilgok, Cheongju, Geochang, Muju, Pocheon, and Sangju. Ethanol extracts of propolis (EEP) were prepared and evaluated for their antioxidant activity by beta-carotene bleaching, 1,1-diphenyl-2-picrylhydrazyl free radical scavenging, and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization assays. Furthermore, the major constituents in EEP were identified by high-performance liquid chromatography analysis with a photodiode array and mass spectrometric detection, and each component was quantitatively analyzed. EEP from Cheongju and Muju had relatively strong antioxidant activity accompanied by high total polyphenol contents. Propolis from Cheongju contained large amounts of antioxidative compounds, such as caffeic acid, kaempferol, and phenethyl caffeate. On the other hand, propolis from Pocheon had compounds not seen in propolis from other areas.     

Phosphate sorption characteristics of major soils in Okinawa,Japan

Abstract

Phosphate sorption isotherms were determined for 16 representative major soils developed from different parent materials on Okinawa. Phosphate sorption characteristics were satisfactorily described by the Langmuir equation, which was used to determine phosphorus (P) sorption maxima of the soils. Phosphate sorption maxima ranged from 630 to 2208 mg P kg^‐1 soil (mean 1,362 mg P kg^‐1). The standard P requirement (i.e., the amount of P required to attain 0.2 mg P L^‐1 equilibrium solution) followed the same trend as sorption maximum (r =0.94***), with values ranging from 132 to 1,020 mg P kg^‐1 soil (mean 615 mg P kg^‐1). This mean value corresponds to fertilizer addition of 923 kg P ha^‐1 indicating that the soils have high P fertilizer requirements. Results of simple linear regression analysis indicated that sorption maximum was significantly correlated with clay content, organic matter, oxalate iron (Fe), pyrophosphate Fe, DCB aluminum (Al), oxalate Al, and pyrophosphate Al, but not with DCB Fe, pH, or available P content. The best regression model for predicting sorption maximum was the combination of clay, organic matter, pyrophosphate Fe, and DCB Al which altogether explained 79% of the variance in sorption maximum. The equation obtained could offer a rapid estimation of P sorption in Okinawan soils.     

Antioxidant activity of citrus limonoids, flavonoids, and coumarins

A variety of in vitro models such as beta-carotene-linoleic acid, 1,1-diphenyl-2-picryl hydrazyl (DPPH), superoxide, and hamster low-density lipoprotein (LDL) were used to measure the antioxidant activity of 11 citrus bioactive compounds. The compounds tested included two limonoids, limonin (Lim) and limonin 17-beta-D-glucopyranoside (LG); eight flavonoids, apigenin (Api), scutellarein (Scu), kaempferol (Kae), rutin trihydrate (Rut), neohesperidin (Neh), neoeriocitrin (Nee), naringenin (Ngn), and naringin(Ng); and a coumarin (bergapten). The above compounds were tested at concentration of 10 microM in all four methods. It was found that Lim, LG, and Ber inhibited <7%, whereas Scu, Kae, and Rut inhibited 51.3%, 47.0%, and 44.4%, respectively, using the beta-carotene-linoleate model system. Lim, LG, Rut, Scu, Nee, and Kae showed 0.5% 0.25%, 32.2%, 18.3%, 17.2%, and 12.2%, respectively, free radical scavenging activity using the DPPH method. In the superoxide model, Lim, LG, and Ber inhibited the production of superoxide radicals by 2.5-10%, while the flavonoids such as Rut, Scu, Nee, and Neh inhibited superoxide formation by 64.1%, 52.1%, 48.3%, and 37.7%, respectively. However, LG did not inhibit LDL oxidation in the hamster LDL model. But, Lim and Ber offered some protection against LDL oxidation, increasing lag time to 345 min (3-fold) and 160 min (33% increase), respectively, while both Rut and Nee increased lag time to 2800 min (23-fold). Scu and Kae increased lag time to 2140 min (18-fold) and 1879 min (15.7-fold), respectively. In general, it seems that flavonoids, which contain a chromanol ring system, had stronger antioxidant activity as compared to limonoids and bergapten, which lack the hydroxy groups. The present study confirmed that several structural features were linked to the strong antioxidant activity of flavonoids. This is the first report on the antioxidant activity of limonin, limonin glucoside, and neoeriocitrin.     

Chemistry of the Urauchi River Water in Iriomote Island National Park, Okinawa, Japan

The chemical characteristics of the Urauchi River water in Iriomote Island National park, Okinawa, Japan have been studied. Concentrations of PO₄ ^3?, NO₂ ^?, and NH₄ ⁺ were barely detectable. We compared the concentration ratios of Mg²⁺/Na⁺, HCO₃ ^?/Na⁺, and Ca²⁺/Na⁺ in the Urauchi River to those of 60 large rivers in the world and indicated that the chemical composition of the river is most likely formed by the binary mixing of sea salt components and silicate rock weathering components. Although rock weathering in the catchments area is driven by both H₂CO₃ and H₂SO₄, the role of H₂CO₃ is dominant. The percentages of the concentration of each cation in the river water are almost the same as those of other rivers with drainage areas consisting of silicate rock and sandstone. Thus, the Urauchi River shows the typical chemical characteristics of a river in a silicate rock area that includes sandstone.     

Antioxidant capacity and lipophilic content of seaweeds collected from the Qingdao coastline

Lipophilic extracts from 16 species of seaweeds collected along the Qingdao coastline were screened and evaluated for their antioxidant activities (AA) using the beta-carotene-linoleate assay system. The diethyl ether soluble extracts of all selected seaweeds exhibited various degrees of antioxidative efficacy in each screen. The highest antioxidant capacities among the tested samples were observed for Rhodomela confervoides and Symphyocladia latiuscula and were comparable with that of the well-known antioxidant butylated hydroxytoluene and greater than that of propyl gallate. The lipophilic content of all 16 samples and the chemical composition of 4 selected seaweeds, R. confervoidesand S. latiuscula, which had higher AA, Laminaria japonica, which had intermediate AA, and Plocamium telfairiae, which had lower AA, were analyzed by gas chromatography and gas chromatography-mass spectrometry, respectively. Fatty acids and alkanes were found. The present data indicated an increase in antioxidative property with increasing content of unsaturated fatty acid. The result of this study suggests that seaweeds can be considered as a potential source for the extraction of lipophilic antioxidants, which might be used as dietary supplements or in production in the food industry. This is the first report on the antioxidant activities of lipophilic extracts from seaweeds.     

Limited survey of residual tetracyclines in tissues collected from diseased animals in Aichi Prefecture, Japan.

Tissues were collected to survey the actual conditions of tetracycline antibiotics (TCs) residues in slaughtered animals that did not pass inspection at slaughterhouses in Aichi Prefecture, Japan, because of the presence of disease symptoms. Tissues were analyzed by liquid chromatography. Among 271 samples, 49 (18.1%) were positive for oxytetracycline (OTC), 5 (1.8%) for chlortetracycline (CTC), and 5 (1.8%) for doxycycline (DC), respectively. One sample (cattle kidney) was positive for both OTC and DC. However, tetracycline was not detected in any samples. Percentage frequencies of TCs residues were 29.1% (37/127) and 15.2% (22/144) for cattle and hogs, respectively. Kidney samples showed higher incidence of TCs residues and 1.5-7 times higher residual concentrations than liver and miscellaneous samples.     

Antioxidant and prooxidant actions of prenylated and nonprenylated chalcones and flavanones in vitro

Prenylated flavonoids found in hops and beer, i.e., prenylchalcones and prenylflavanones, were examined for their ability to inhibit in vitro oxidation of human low-density lipoprotein (LDL). The oxidation of LDL was assessed by the formation of conjugated dienes and thiobarbituric acid-reactive substances (TBARS) and the loss of tryptophan fluorescence. At concentrations of 5 and 25 microM, all of the prenylchalcones tested inhibited the oxidation of LDL (50 microg protein/ml) induced by 2 microM copper sulfate. The prenylflavanones showed less antioxidant activity than the prenylchalcones, both at 5 and 25 microM. At 25 microM, the nonprenylated chalcone, chalconaringenin (CN), and the nonprenylated flavanone, naringenin (NG), exerted prooxidant effects on LDL oxidation, based on TBARS formation. Xanthohumol (XN), the major prenylchalcone in hops and beer, showed high antioxidant activity in inhibiting LDL oxidation, higher than alpha-tocopherol and the isoflavone genistein but lower than the flavonol quercetin. When combined, XN and alpha-tocopherol completely inhibited copper-mediated LDL oxidation. These findings suggest that prenylchalcones and prenylflavanones found in hops and beer protect human LDL from oxidation and that prenylation antagonizes the prooxidant effects of the chalcone, CN, and the flavanone, NG.     

Antioxidant activity of flavonoids isolated from young green barley leaves toward biological lipid samples

Natural plant flavonoids, saponarin/lutonarin=4.5/1, isolated from young green barley leaves were examined for their antioxidant activity using cod liver oil, omega-3 fatty acids, phospholipids, and blood plasma. The saponarin/lutonarin (S/L) mixture inhibited malonaldehyde (MA) formation from cod liver oil by 76.47+/-0.11% at a level of 1 micromol and 85.88+/-0.12% at a level of 8 micromol. The S/L mixture inhibited MA formation from the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) by 45.60+/-1.08 and 69.24+/-0.24%, respectively, at a level of 8 micromol. The S/L mixture inhibited MA formation from the phospholipids lecithin I and II by 43.08+/-0.72 and 69.16+/-2.92%, respectively, at a level of 8 micromol. It also inhibited MA formation from blood plasma by 62.20+/-0.11% at a level of 8 micromol. The antioxidant activities obtained from the S/L mixture were comparable to those obtained from alpha-tocopherol and butylated hydroxy toluene (BHT) in all lipids tested.     

Antioxidant activity of extracts, condensed tannin fractions, and pure flavonoids from Phaseolus vulgaris L. seed coat color genotypes

Twelve different seed coat color genotypes of Phaseolus vulgaris L. were extracted and pure flavonoids isolated from 10 of these. The seed coat methanol extracts, tannin fractions, and pure flavonoids all displayed antioxidant activity in a fluorescence-based liposome assay. The relatively high activity of the condensed tannin (proanthocyanidin) fractions indicates that these may play an important role in the overall activity of the extracts. This activity also indicates that although these polyphenols cause problems in digestibility, they may be important dietary supplements with beneficial health effects. The pure anthocyanins delphinidin 3-O-glucoside (1), petunidin 3-O-glucoside (2), and malvidin 3-O-glucoside (3) and the flavonol quercetin 3-O-glucoside (4) isolated from seed coats also had significantly higher antioxidant activity than the Fe(2+) control. The activity of kaempferol 3-O-glucoside (5) was not different from that of the Fe(2+) control. These findings suggest that variously colored dry beans may be an important source of dietary antioxidants.     

Photochemical Formation of Hydroxyl Radicals in Red Soil-Polluted Seawater on the North of Okinawa Island, Japan

Land development has caused runoff of red soil into the ocean on the north side of Okinawa Island, Japan. In an attempt to clarify the impacts of this “red soil pollution” on the oxidizing power of seawater, we studied the formation of hydroxyl radical (?OH), the most potent oxidant in the environment, in red soil-polluted waters using a 313-nm monochromatic light. ?OH was photochemically formed in the red soil-polluted water samples, and the formation rates of ?OH decreased as salinity increased, i.e., as red soil-polluted river water gets mixed with seawater. The photo-formation rates of ?OH showed good correlations with dissolved Fe concentrations (R ²?=?0.96) and [NO₂ ^?]?+?[NO₃ ^?] concentrations (R ²?=?0.87), while a negative and weak correlation was found with dissolved organic carbon concentrations (R?=??0.78). Theoretical calculation showed that direct photolysis of NO₃ ^?, Fe(OH)²⁺, and hydrogen peroxide all together accounted for less than 10% of the observed ?OH formation in the red soil-polluted waters. Comparison between filtered and unfiltered samples showed that red soil particles were not the main sources of ?OH, and the photolysis of NO₂ ^? could account for at most 78% of the observed ?OH formation rates. We found that the Fenton’s reaction (a reaction between Fe(II) and H₂O₂) could possibly account for the observed formation of ?OH in the red soil-polluted waters.     

Propolin G, a prenylflavanone, isolated from Taiwanese propolis, induces caspase-dependent apoptosis in brain cancer cells

We have previously shown that six propolins, A-F, could be isolated from Taiwanese propolis (TP) and that they exerted a broad spectrum of biological activities. Recently, we isolated a seventh compound, propolin G. Its chemical structure has been identified by NMR and fast atom bombardment-mass spectrometry spectra and was found to be identical to a known compound, nymphaeol C. We used high-performance liquid chromatography to determine the relative contents of propolins C, D, F, and G in TP collected in various seasons and regions and found them to be relatively higher in TPs collected from May to July than from September to October. In our present study, we were interested in the various biological activities of TP extract as well as in propolin G as a pure compound. We found that propolin G could efficiently induce apoptosis in brain cancer cell lines (glioma and glioblastoma). The apoptosis might have been through a mitochondrial- and caspase-dependent pathway. This result demonstrated that the TP collection season was more an important factor than the geographical region. Propolis has been suggested to possess a potent antioxidant activity. We further evaluated the antioxidant property of propolin G using DPPH (1,2-diphenyl-2-picryhydrazyl). Our results indicate that propolin G does possess free radical scavenging activity. We also evaluated the neuroprotective action of propolin G, TP, and BP (Brazilian propolis) extracts against oxidative stress in rat primary cortical neurons. Our data demonstrate that propolin G and TP extracts have a marked neuroprotective effect that is greater than BP extract. In conclusion, the isolation and characterization of propolin G from TP have demonstrated for the first time that this compound is a potent inducer of apoptosis in brain cancer cells and that this compound and TP extract exhibit a protective effect against oxidative stress in rat cortical neurons.     

Evaluation of the cytotoxicity, genotoxicity, mutagenicity, and antimutagenicity of propolis from Tucuman, Argentina

This study evaluates the toxic, genotoxic/mutagenic, and antimutagenic effects of propolis extract from Amaicha del Valle, Tucumán, Argentina. The cytotoxicity assays carried out with the lethality test of Artemia salina revealed that the LD50 was around 100 microg/mL. Propolis extracts showed no toxicity to Salmonella typhimurium TA98 and TA100 strains and Allium cepa at concentrations that have antibiotic and antioxidant activities. Otherwise, for the testing doses, neither genotoxicity nor mutagenicity was found in any sample. The propolis extracts were able to inhibit the mutagenesis of isoquinoline (IQ) and 4-nitro o-phenylenediamine (NPD) with ID50 values of 40 and 20 microg/plate, respectively. From this result, the studied propolis may be inferred to contain some chemical compounds capable of inhibiting the mutagenicity of direct-acting and indirect-acting mutagens. A compound isolated from Amaicha del Valle propolis, 2',4'-dihydroxychalcone, showed cytotoxic activity (LC50 values of 0.5 microg/mL) but was not genotoxic or mutagenic. Furthermore, this compound was able to inhibit the mutagenicity of IQ (ID50 values of 1 microg/plate) but was unable to inhibit the mutagenicity of NPD. Our results suggest a potential anticarcinogenic activity of Amaicha del Valle propolis and the chalcone isolated from it.     

Neuroprotective effects of xanthohumol, a prenylated flavonoid from hops (Humulus lupulus), in ischemic stroke of rats

Xanthohumol is the principal prenylated flavonoid in hops (Humulus lupulus L.), an ingredient of beer. Xanthohumol was found to be a potent chemopreventive agent; however, no data are available concerning its neuroprotective effects. In the present study, the neuroprotective activity and mechanisms of xanthohumol in rats with middle cerebral artery occlusion (MCAO)-induced cerebral ischemia were examined. Treatment with xanthohumol (0.2 and 0.4 mg/kg; intraperitoneally) 10 min before MCAO dose-dependently attenuated focal cerebral ischemia and improved neurobehavioral deficits in cerebral ischemic rats. Xanthohumol treatment produced a marked reduction in infarct size compared to that in control rats. MCAO-induced focal cerebral ischemia was associated with increases in hypoxia-inducible factor (HIF)-1α, tumor necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), and active caspase-3 protein expressions in ischemic regions. These expressions were obviously inhibited by treatment with xanthohumol. In addition, xanthohumol (3-70 μM) concentration-dependently inhibited platelet aggregation stimulated by collagen (1 μg/mL) in human platelet-rich plasma. An electron spin resonance (ESR) method was used to examine the scavenging activity of xanthohumol on free radicals which had formed. Xanthohumol (1.5 and 3 μM) markedly reduced the ESR signal intensity of hydroxyl radical (OH?) formation in the H?O?/NaOH/DMSO system. In conclusion, this study demonstrates for the first time that in addition to its originally being considered an agent preventing tumor growth, xanthohumol possesses potent neuroprotective activity. This activity is mediated, at least in part, by inhibition of inflammatory responses (i.e., HIF-1α, iNOS expression, and free radical formation), apoptosis (i.e., TNF-α, active caspase-3), and platelet activation, resulting in a reduction of infarct volume and improvement in neurobehavior in rats with cerebral ischemia. Therefore, this novel role of xanthohumol may represent high therapeutic potential for treatment or prevention of ischemia-reperfusion injury-related disorders.     

Mosquito-killing water molds isolated from soil samples collected in Taiwan

Mosquito-killing water molds were isolated from soils collected from various parts in Taiwan. The first-instar larvae of Aedes aegypti and Aedes albopictus were used as baits. A total of 453 soil samples were collected from Taipei, Ilan, Hualien, Taoyuan, Hsinchu, Miaoli, Taichung, Tainan, Nantou, Chiayi, Yunlin and Pintung. Four mosquito-killing Pythium spp. and one Saprolegnia sp. were isolated from the soil samples. Using zoospores of the Pythium spp. as inoculum to infect the first-instar larvae, scanning electron micrographs showed that most zoospores attached in the anal gill and a few attached between head and thorax. Thus, Pythium spp. is a potential biocontrol agent against first-instar larvae of A. aegypti and A. albopictus.     

Effect of caffeic acid phenethyl ester, an antioxidant from propolis, on inducing apoptosis in human leukemic HL-60 cells.

Caffeic acid phenethyl ester (CAPE) is an active component isolated from propolis. The aim of this study was to investigate the mechanism of CAPE-induced apoptosis in human leukemic HL-60 cells. It was found that CAPE entered HL-60 cells very quickly and then inhibited their survival in a concentration- and time-dependent manner. CAPE induced characteristic DNA fragmentation and morphological changes typical of apoptosis in these cells. Estimation of the apoptotic percentage showed a time-dependent increase after CAPE (6 microg/mL) treatment (up to 66.7 +/- 2.0% at 72 h). Treatment with CAPE caused rapid activation of caspase-3 after 4 h, down-regulation of Bcl-2 expression after 6 h, and up-regulation of Bax expression after 16 h. These results suggest that CAPE is a potent apoptosis-inducing agent; its action is accompanied by activation of caspase-3, down-regulation of Bcl-2, and up-regulation of Bax in human leukemic HL-60 cells.     

Propolin H from Taiwanese propolis induces G1 arrest in human lung carcinoma cells

Propolis, a natural product collected by honeybee, has been reported to exert a wide spectrum of biological functions. In this study, we have isolated a novel component, namely, propolin H, and investigated its effects in human carcinoma cells. Propolin H inhibited the proliferation of human lung carcinoma cell lines in MTT assay, and a significant G1 arrest was observed to occur in a dose-dependent manner at 24 h of exposure in H460 cells. After treatment with propolin H in H460 cells, the content of the CDK inhibitor p21Waf1/Cip1 protein increased in correlation with the elevation in p53 levels. Western blot analysis of G1 regulatory proteins further revealed a decrease in cyclin-dependent kinase 2 (CDK2) and CDK4 and an increase in cyclin E. The CDKs kinase activities assay showed that propolin H has inhibited CDK2 and CDK4 kinase activities. Accordingly, coimmunoprecipitations revealed an increased association of both CDK2 and CDK4 immunoreactive protein with the p21Waf1/Cip1 protein complex under propolin H-treated conditions. Additionally, we found that propolin H enhanced the expression of p21Waf1/Cip1 in p53-mutant and p53-null lung carcinoma cell lines, following the induction of G1 arrest. Together, these findings suggest that the induction of p21Waf1/Cip1 expression occurred through p53-dependent and -independent pathways in propolin H-treated cells. Propolin H exerts its significantly growth inhibitory effects and may have therapeutic applications.     

ECe prediction from EC1:5 in inland salt-affected soils collected from Khorat and Sakhon Nakhon basins,Thailand

ABSTRACT

We estimate the electrical conductivity of saturated soil paste extract (ECe) from electrical conductivity of a 1:5 soil-water dilution ratio (EC_1:5) in Northeastern Thailand. Soil samples of various textures and salinity collected from Sakhon Nakhon basin were used to develop multiple regression models, from which the linear model was chosen and was validated on soil samples from the Khorat basin. Comparison with previous models indicated that most linear models gave a good fit, but the non-linear models either over or underestimated the measured values. The models performed very well for low values of EC_e (<5 dS m^?1), while the prediction errors increased significantly for EC_e levels >35 dS m^?1. The present model performed well at various EC_e levels and can be used to predict salinity levels for soils weathered from salt deposits in sedimentary rocks with similar rock formation in countries like Malaysia, Vietnam, Cambodia, and Laos.