Profiling the chlorogenic acids of sweet potato (Ipomoea batatas) from China

The leaves, stem and root of sweet potato cultivated in China have been analysed qualitatively for chlorogenic acids by structure-diagnostic LC–MS³. Chlorogenic acids were not detected in the root. Caffeoylquinic acids were quantitatively the major subgroup of chlorogenic acids detected in the stem and the only subgroup detected in the leaves. This subgroup was dominated by 5-caffeoylquinic acid. The stem also contained three feruloylquinic acids, 3,5- and 4,5-dicaffeoylquinic acid, and small amounts of at least four caffeoyl-feruloylquinic acids. This is the first report of feruloylquinic and caffeoyl-feruloylquinic acids from sweet potato. Two chemically unrelated and coeluting substances with the same molecular mass (M_r = 530) extracted from the Chinese sweet potato interfered with the characterisation of the caffeoyl-feruloylquinic acids. At least five caffeoyl-feruloylquinic acids were detected in the peel of sweet potato cultivated in Tanzania that lacked these interfering substances.     

Antioxidant and antibacterial activity of leaves of Etlingera species (Zingiberaceae) in Peninsular Malaysia

Methanolic extracts from fresh leaves of five Etlingera species were screened for total phenolic content (TPC), antioxidant activity (AOA), and antibacterial activity. Analysis of TPC was done using the Folin–Ciocalteu method. Evaluations of AOA included 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging ability, ferric-reducing antioxidant power (FRAP), ferrous-ion chelating (FIC) ability, and β-carotene bleaching (BCB) activity. Antibacterial activity was screened using the disc-diffusion method. Highest TPC, ascorbic acid equivalent antioxidant capacity (AEAC), and FRAP were found in leaves of E. elatior and E. rubrostriata. Leaves of E. maingayi, with the lowest TPC, AEAC, and FRAP, had the highest FIC ability and BCB activity. Ranking of TPC and AOA of different plant parts of E. elatior was in the order: leaves > inflorescences > rhizomes. Leaves of highland populations of Etlingera species displayed higher values of TPC and AEAC than those of lowland counterparts. Leaves of Etlingera species exhibited antibacterial activity against Gram-positive but not Gram-negative bacteria.     

Phenolic compounds from the edible seeds extract of Chinese Mei (Prunus mume Sieb. et Zucc) and their antimicrobial activity

Prunus mume seeds have been used as a healthy food and traditional drug in China. The present study investigated the phenolic compounds and antimicrobial activity of ethanolic extract from seeds of P. mume. Total phenolic content was determined as gallic acid equivalents by the Folin-Ciocalteu method. The antibacterial activity was measured by a filter paper disc method. Three chlorogenic acid isomers, namely, 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid and 4-O-caffeoylquinic acid, were identified from P. mume seeds for the first time. The contents of these isolated compounds were quantified by HPLC. Results showed that 3-O-caffeoylquinic acid was of the highest level in these three isomers. The ethanolic extract exhibited inhibition activity against bacteria and fungi obviously. The isolated phenolic compounds also exhibited inhibition activity against bacteria significantly, but showed weak or no inhibition activity against yeasts and mold. The results exhibited that the antimicrobial activity of P. mume seeds may be partly due to the phenolic compounds.     

Purification and partial characterization of polyphenol oxidase from the flower buds of Lonicera japonica Thunb.

The purification and partial enzymology characteristics of polyphenol oxidase from Lonicera japonica (LjPPO) were studied in this paper. The crude enzyme solution was purified in turn by ammonium sulfate, dialysis, and DEAE-cellulose ion-exchange chromatography after preliminary treatments. Purification resulted in 31-fold enrichment and its molecular weight was estimated to be ∼49 kDa exhibited on sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). The pH for optimal conditions of LjPPO was 7.5, and the temperature was 25 °C, in addition, the inhibitive effects of inhibitors were enhanced positively with increasing of the concentration. Moreover, crude enzyme solution showed diphenolase activity toward catechol, l-dopa and chlorogenic acid rather than monophenolase and triphenolase activity, and the best substrate was catechol because of the highest V_max/K_m value. However, the oxidation of diphenol related to browning significantly, so the data obtained in this research provided theoretical basis for the prevention of enzymatic browning of L. japonica during processing.     

Effects of gamma irradiation on color characteristics and biological activities of extracts of Lonicera japonica (Japanese honeysuckle) with methanol and acetone

Effects of gamma irradiation on the color characteristic and biological activities of methanol and acetone extracts of Lonicera japonica (Japanese honeysuckle) irradiated at 0, 10, 20, and 30 kGy were investigated. Hunter color L^*- and a^*-value increased by irradiation in a dose-dependent manner, resulting in it being lighter than the nonirradiated, while Hunter color b^*-values decreased by irradiation (P<0.05). The extracts from L. japonica showed an inhibition effect against tyrosinase, xanthine oxidase and the nitrite scavenging ability. Tyrosinase inhibition effect of L. japonica was higher in the irradiated sample than the nonirradiated, and the effect was increased by irradiation doses. The L. japonica extracts had a higher inhibitory effect against xanthine oxidase, and the effect was not changed by irradiation. Nitrite scavenging activity was the highest in L. japonica extract at pH 1.2. The difference between solvents used was not detected. Thus, gamma irradiation may have no influence on the biological activities of the L. japonica extracts except for the tyrosinase inhibition effect when irradiated up to 30 kGy.     

Screening and identification of the antibacterial bioactive compounds from Lonicera japonica Thunb. leaves

Our aim was to screen for antibacterial bioactive compounds from Lonicera japonica leaves. Staphylococcus aureus and Escherichia coli were used as the indicator bacteria. Bacteriostatic assay-guided extraction and stepwise partitioning of the samples yielded five compounds of interest. Antimicrobial activities of the compounds were determined using a disk diffusion assay. Extracts, fractions, and compounds from L. japonica leaves possessed considerable antibacterial activities against the tested bacterial strains and the most active fraction was attributed to J3B2, which primarily contained 3,5-di-O-caffeoylquinic acid and 4,5-di-O-caffeoylquinic acid. Meanwhile, five bacteriostatic constituents were isolated (3-O-caffeoylquinic acid, secoxyloganin, luteoloside, 3,5-di-O-caffeoylquinic acid and 4,5-di-O-caffeoylquinic acid), among which, secoxyloganin was isolated for the first time from leaves. The antibacterial activity of the compounds was in the order of 3,5-bis-O-caffeoyl quinic acid, 4,5-bis-O-caffeoylquinic acid, luteoloside > 3-O-caffeoylquinic acid > secoxyloganin. Our results suggested that the phenolic compounds might significantly contribute to antibacterial activity and were the most responsible for the bacteriostatic activity of L. japonica leaves.     

Antioxidative effects of leaves from Azadirachta species of different provenience

Twenty extracts of leaves from Azadirachta plants (Siamese neem tree of different provenience, neem tree and marrango tree), a traditional medicine, and frequently eaten in large amounts as parts of meals in Thailand, showed proportionality between total phenolics and radical-scavenging as measured, as reduction of Fremy’s salt by ESR-spectroscopy. Scavenging effect of extracts from the neem tree was significantly lower than those of the Siamese neem tree and the marrango tree. The ability of the extracts to trap carbon-centred 1-hydroxyethyl radicals indicates prooxidative activity for a very high concentration of extract. The extracts were found to be efficient scavengers of compounds known to initiate lipid oxidation, as demonstrated by rate constants (25 °C) for reaction with ferrylmyoglobin: k = (1.7 ± 0.3) × 10³ M⁻¹ s⁻¹ at pH 5.5 and k = (7.7 ± 1.4) × 10² M⁻¹ s⁻¹ at pH 7.4, respectively, and with riboflavin triplet-state: k = (1.30 ± 0.02) × 10⁹ M⁻¹ s⁻¹ at pH 7.4. The rate constants for deactivation of ferrylmyoglobin by the extracts were larger than the rate constant for deactivation by the pure phenolic compounds present in the extract, demonstrating synergistic effects. All extracts showed high efficiencies as chain-breaking antioxidants. This was indicated by lowering of oxygen consumption rates in a peroxidising lipid emulsion, suggesting a role as dietary antioxidants. Siamese neem tree leaf extracts were found to interact with α-tocopherol in peroxidising liposomes, resulting in synergistic effects.     

Kumquat (Fortunella japonica Swingle) juice: Flavonoid distribution and antioxidant properties

The flavonoids composition of kumquat (Fortunella japonica) crude juice, obtained from uripe and ripe fruits, were investigated by reverse-phase LC-DAD-ESI-ITMS analysis. Thirteen compounds (C- and O-glycosyl flavonoids) were identified. Acacetin 3,6-di-C-glucoside (1), vicenin-2 (2), lucenin-2 4′-methyl ether (3) narirutin 4′-O-glucoside (4) and apigenin 8-C-neohesperidoside (5) were identified for the first time in kumquat juice. Furthermore, we report on the remarkable antioxidant properties of crude juice, of selected flavonoids fractions and of the main component, phloretin 3′,5′-di-C-glucoside (6).     

Fumigant toxicity of essential oils from three Thai plants (Zingiberaceae) and their major compounds against Sitophilus zeamais, Tribolium castaneum and two parasitoids

Fumigant toxicity of essential oils from rhizomes of Alpinia conchigera, Zingiber zerumbet, Curcuma zedoaria and their major compounds; camphene, camphor, 1,8-cineole, α-humulene, isoborneol, α-pinene, β-pinene and terpinen-4-ol was investigated with adults of Sitophilus zeamais, Tribolium castaneum, Anisopteromalus calandrae and Trichogramma deion larvae. The last two insects are parasitoids commonly used to control stored-product weevils and moths. The trial was evaluated at 0, 37, 74, 148, 296, 444, 593 μL/L in air after 12, 24 and 48 h for S. zeamais, T. castaneum and A. calandrae, and 24 h for T. deion. Alpinia conchigera oils were toxic to S. zeamais, T. castaneum and T. deion, while the other two plant oils had low toxicity. Adults of S. zeamais and T. castaneum were more susceptible to A. conchigera oils than their eggs, larvae or pupae. Sitophilus zeamais adults (LC₅₀ 85 μL/L in air) were slightly more tolerant of A. conchigera oils than T. castaneum (LC₅₀ 73 μL/L in air) after 48 h exposure. Synthetic essential oils, a mixture of pure compounds in the same ratios of the extracted essential oils, were tested with S. zeamais and T. castaneum adults. Synthetic essential oils were more toxic than the extracted essential oils to both insects. Zingiber zerumbet oils (LC₅₀ 26 μL/L in air) and C. zedoaria oils (LC₅₀ 25 μL/L in air) were significantly more toxic to adults of A. calandrae than A. conchigera oils (LC₅₀ 37 μL/L in air) whereas T. deion larvae were more sensitive to A. conchigera oils (LC₅₀ 62 μL/L in air) than Z. zerumbet and C. zedoaria oils (LC₅₀ > 593 μL/L in air). Tribolium castaneum was more susceptible than S. zeamais to the eight pure compounds. Terpinen-4-ol was highly toxic to both insects.     

Analysis of chlorogenic acids in beverages prepared from Chinese health foods and investigation, in vitro, of effects on glucose absorption in cultured Caco-2 cells

The effects of aqueous extracts of Kuding tea (Ilex latifolia Thunb.) and the large-leaf form of Camellia sinensis var. sinensis), chrysanthemum (Dendranthema morifolium Ramat), honeysuckle flower (Lonicera japonica Thunb.), and purple sweet potato (Ipomoea batatas) stem on glucose absorption were investigated using Caco-2 cells. Glucose absorption by Caco-2 cells was significantly inhibited by aqueous extract of Kuding tea, chrysanthemum and purple sweet potato stem under both Na⁺-dependent conditions and Na⁺-free conditions indicating effects on SGLT1 and GLUT transporters. Analysis of the (poly)phenols in these aqueous extracts suggested that dicaffeoylquinic acids and flavanols may be particularly important in producing these effects. Kuding tea extract was the most effective, suggesting that this merits evaluation in a clinical study.     

Phytochemicals and antioxidant activity of different parts of bambangan (Mangifera pajang) and tarap (Artocarpus odoratissimus)

Mangifera pajang (family: Anacardiaceae; local name: bambangan) and Artocarpus odoratissimus (familiy: Moraceae; local name: tarap) are popular edible fruits in Sabah, Malaysia. The flesh, kernel and peel from M. pajang; seed and flesh from A. odoratissimus were analysed for total antioxidant activity, total polyphenol, total flavonoid and total anthocyanins contents. M. pajang kernel extract displayed the highest free radical scavenging and ferric reducing activities. Total phenolic content of the samples were in the range of 5.96–103.3 mg gallic acid equivalent/g. M. pajang kernel and M. pajang flesh contained the highest and lowest total flavonoid content with the values of 10.98 and 0.07 mg rutin equivalent/g, respectively. The antioxidant activities of extracts were significantly correlated with the total phenolic and flavonoid content (but not the anthocyanins content). The phytochemicals and antioxidant properties of M. pajang and A. odoratissimus, especially their by-products (kernel/seed), indicate that they may impart health benefits when consumed and should be regarded as a valuable source of antioxidant-rich nutraceuticals.     

Effects of extraction temperature on the phenolic and parthenolide contents,and colour of aqueous feverfew (Tanacetum parthenium) extracts

The aim of this study was to determine the effects of extraction temperature on the colour as well as on the phenolic and parthenolide content of feverfew (Tanacetum parthenium) aqueous extracts, with a view to incorporating the extracts into a beverage. Results showed that extraction temperatures of 20–70 °C yielded dark-coloured extracts with low total phenol and a relatively high total tannin concentration. However, increasing the temperature to 75 °C produced lighter-coloured extracts with a significantly higher concentration of total phenols, lower total tannin fraction and maximum extraction of parthenolide. Higher extraction temperatures (80–100 °C) yielded suitably pale extracts rich in total phenols, but with progressively higher total tannin to non-tannin ratio and lower parthenolide content. The compromise temperature of 80 °C was found to provide extracts rich in parthenolide content, phenolic content and with a desirable colour, suitable for incorporation into a functional beverage.     

Chicoric acid found in basil (Ocimum basilicum L.) leaves

This is the first report to identify the presence of chicoric acid (cichoric acid; also known as dicaffeoyltartaric acid, which is a caffeic acid derivatized with tartaric acid) in basil leaves. Rosmarinic acid, chicoric acid and caftaric acid (in the order of most abundant to least; all derivatives of caffeic acid) were identified in fresh basil leaves. Rosmarinic acid was the main phenolic compound found in both leaves and stems. Chicoric acid was not detected in sweet basil stems, although a small amount was present in Thai basil stems. Other cinnamic acid monomers, dimers and trimers were also found in minor quantities in both stems and leaves. Basil polyphenolic contents were determined by blanched methanol extraction, followed by HPLC/DAD analysis. The characterization of the polyphenolics found in the basil extracts were performed by HPLC/DAD/ESI–MS/MS and co-chromatographed with purchased standard. The influence of inoculation with an arbuscular mycorrhizal fungus (AMF), Glomus intraradices, on plant phenolic composition was studied on two basil cultivars,‘Genovese Italian’ and ‘Purple Petra’. Inoculation with AMF increased total anthocyanin concentration of ‘Purple Petra’ but did not alter polyphenolic content or profile of leaves and stems, of either cultivar, compared to non-inoculated plants. In the US diet, basil presents a more accessible source of chicoric acid than does Echinacea purpurea, in which it is the major phenolic compound.     

Lipid and fatty acid compositions differentiate between wild and cultured Japanese eel (Anguilla japonica)

The lipid profile and fatty acid composition of muscle, liver, and plasma lipoprotein were examined in wild and cultured Japanese eel (Anguilla japonica). Although, the muscle lipid levels of wild eels (11.6%) were less than those of cultured eels (13.1%), both eels were classified as typical fatty fish. Compared with the liver lipid composition of cultured eels, triacylglycerol (TG) level of the liver decreased in wild eels, whilst phosphatidylcholine and phosphatidylethanolamine levels of the liver increased in wild eels, reflecting the difference of liver lipid levels in both eels. Wild eels contained more cholesteryl ester (CE) and less TG, phospholipid, and free cholesterol in their plasma than cultured eels. The ratio of TG to CE decreased, whilst that of CE to total cholesterol increased in the plasma of wild eels. Different fatty acid compositions were found between wild and cultured eels. Compared with the fatty acid compositions of cultured eels, wild eels contained high percentages of 18:2, 18:3, and 20:4 and low percentages of 22:6, 20:1, and 20:5 in their muscle, liver, and plasma lipoprotein. The lipid profile and fatty acid composition seemed to be useful criteria for distinguishing between wild and cultured eels.     

Profiling of in vitro neurobiological effects and phenolic acids of selected endemic Salvia species

The ethyl acetate and methanol extracts from 16 Salvia L. species were screened for their inhibitory activity against acetylcholinesterase, butyrylcholinesterase, lipoxygenase, and tyrosinase; the enzymes linked to neurodegeneration. Their antioxidant activity was also tested using DPPH radical scavenging, metal-chelation, and ferric-reducing antioxidant power (FRAP) assays. Total flavonoid content of the extracts was determined by AlCl₃ reagent, while HPLC technique was applied for analysis of various phenolic acids in the extracts. The extracts exerted weak cholinesterase and tyrosinase inhibition, and remarkable inhibition against lipoxygenase (13.07 ± 2.73-74.21 ± 5.61%) at 100 μg ml⁻¹. The methanol extracts showed higher antioxidant activity in DPPH radical scavenging and FRAP assays. The extracts were analyzed for their gallic, protocateuchic, p-hydroxy-benzoic, vanillic, caffeic, chlorogenic, syringic, o- and p-coumaric, ferulic, rosmarinic, and tr-cinnamic acid contents and the methanol extract of Salvia ekimiana (153.50 mg 100 g⁻¹) was revealed to be the richest in terms of rosmarinic acid.     

Insecticidal activities of constituents identified in the essential oil from leaves of Chamaecyparis obtusa against Callosobruchus chinensis (L.) and Sitophilus oryzae (L.)

Analysis by gas chromatography-mass spectrometry led to the identification of 20 volatiles from the steam distilled oil of the leaves from Chamaecyparis obtusa Siebold et Zuccarni. Seven constituents of the oil were tested for contact and fumigant activity against adults of Callosobruchus chinensis (L.) and Sitophilus oryzae (L.). Responses varied with compound and dose rather than increasing exposure time beyond 1 or 2 days. In the impregnated-paper test with the constituents [bornyl acetate, (+)-limonene, myrcene, α-phellandrene, α-pinene, sabinene and terpinolene], at 0.1 mg/cm², bornyl acetate, α-phellandrene and terpinolene caused 97%, 97% and 87% mortality, respectively, against C. chinensis adults 1 day after treatment. At 0.05 mg/cm², moderate activity was achieved with bornyl acetate (56% mortality), α-phellandrene (75%) and terpinolene (55%). Against S. oryzae adults, at 0.26 mg/cm², terpinolene caused 93% mortality 2 days after treatment, whereas 80% mortality 4 days after treatment was observed with bornyl acetate and α-phellandrene. The toxicity of these compounds was significantly decreased at 0.18 mg/cm². In a fumigation test with S. oryzae adults, bornyl acetate and terpinolene were much more effective in sealed containers than in open ones, indicating that the insecticidal activity of these compounds was largely attributable to fumigant action. These naturally occurring materials derived from leaves of Chamaecyparis could be useful for managing populations of C. chinensis and S. oryzae.     

Extraction and physicochemical characterisation of polysaccharide gum from Yanang (Tiliacora triandra) leaves

Yanang (Tiliacora triandra) is a vegetable used in many cuisines of the northeast of Thailand and Lao People’s Democratic Republic. This paper reports the optimised extraction and some physicochemical characteristics of polysaccharide gum from Yanang leaves. The optimised extraction condition was at the leaf:water ratio of 1:6.6, 85 °C, and 100 min extraction time. The major monosaccharide constituent of Yanang gum was xylose, together with substantial amounts of other neutral sugars. The FT-IR spectra of Yanang gum were similar to that of xylan. Yanang gum exhibited shear-thinning flow behaviour and the extent of shear-thinning was concentration dependent. The mechanical spectra of Yanang gum at low concentration (0.5%) were typical of semi-diluted to concentrated solutions. However, with increasing concentration, the solution behaved like a weak gel.     

Heptadecanols from the leaves of Persea americana var. americana

From the leaves of Persea americana var. americana, eleven heptadecanol derivatives were identified. Their structures were elucidated on the basis of spectroscopic analyses. The absolute configurations were determined by chemical reaction, NOESY experiment and further comparison of the optical rotation value with the literature value. Additionally, the ratios of the contents of six heptadecanol derivatives in leaves, immature fruits, mature fruits and seeds of P. americana were estimated by LC-MS in multiple reaction monitoring (MRM) mode.     

Nitrosamine formation from different Catha edulis leaves extracts under simulated gastric condition

Nitrosamines are well-known carcinogenic and toxic compounds for humans and animals. The aim of this study was to investigate the possible formation of nitrosamine compounds from aqueous extracts of five different types of Catha edulis leaves using nitrite as a nitrosation agent, either in aqueous solution or under simulated normal fasting stomach conditions (at 37 °C and pH 2) for 1 h. Nitrosoephedrine was used as a reference compound in this study. Nitrosation of aqueous extracts of the different types of Catha edulis leaves with constant concentration of nitrite (14.4 mM) in aqueous solution showed total apparent nitrosamine compounds to be in the range 94–319 mg/100 g DM (dry matter) of CE (Catha edulis) leaves. In contrast, nitrosamines formed in simulated gastric fluid were much lower, in the range 23–79 mg/100 g DM of CE leaves. Based on the moderate formation of nitrosamines with the Sabri Catha edulis leaves, the latter was selected for investigating the effect of varying levels of nitrite in aqueous solution and simulated gastric juice. The nitrosation of aqueous extracts of Sabri Catha edulis with different levels of nitrite in aqueous solution yielded a dose-dependent amount of total apparent nitrosamine compounds, these being undetected at ?0.5 mM sodium nitrite in aqueous solution and ?1 mM in simulated gastric juice. This raises the question of whether the observed high incidence of esophageal and forestomach carcinomas in Yemen could be attributed to the formation of nitrosamines in vivo from the secondary amines present in Catha edulis leaves.     

Distribution of caffeic acid derivatives in Gundelia tournefortii L.

The caffeic acid derivatives including neochlorogenic acid (3-COA), cryptochlorogenic acid (4-CQA), chlorogenic acid (5-CQA) and caffeic acid (CA) have been characterised in Gundelia tournefortii using reference compounds, chemical, spectral evidences and chromatographic data. In addition, the total phenolic content and chlorogenic acid were measured in the leaf, hull-less seed, and skin extracts of this herb by the Folin–Ciocalteu reagent and high performance liquid chromatography (HPLC), respectively. The sample analysis was carried out on a C₁₈ column with 5% (v/v) aqueous acetic acid and methanol as the mobile phase, under gradient elution at ambient temperature, at 325 nm. The amount of chlorogenic acid in the leafs (at the flowering stage and after it) and hull-less seed were 984, 466 and 199 mg per 100 g dry plant sample and the total phenolic content in their dry extract were 128.4, 103.8 and 76.3 μg/mg as CGA equivalent, respectively.