5-deoxystansioside,an iridoid glucoside from Tecoma stans

In addition to plantarenaloside and stansioside, a new iridoid glucoside with a formyl group at C-4 has been isolated from Tecoma stans. The new glucoside was shown to be 5-deoxystansioside by ¹³C NMR and ¹H NMR spectroscopy.     

Indolic compounds in the leaves of Tecoma stans

Indole, tryptophan, tryptamine and skatole were isolated from the leaves of Tecoma stans. Anthranilic acid was also identified in its free form, in contrast to its glucoside, in Jasminum grandiflorum. The presence of both indole and anthranilic acid in the leaves of Tecoma stans indicates that they are the true substrate and product of indole oxygenase from the leaves of Tecoma stans.     

Anti-proliferative constituents from Selaginella pulvinata

Two new compounds, (S)-(−)-N-[2-(3-Hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl)-ethyl]-acetamide (1) and 6-formyl-5-isopropyl-3-hydroxymethyl-7-methyl-1H-indene (2), were isolated from the leaves of Selaginella pulvinata. Their structures were determined by spectroscopic methods. Additionally, compound 1 could inhibit the growth of SK-mel-110 cells and induce cell apoptosis in vitro through up-regulating the expression of inhibitor of growth family member 4.     

Purification and Characterization of a New Indole Oxygenase from the Leaves of Tecoma stans L

A new indole oxygenase from the leaves of Tecoma stans was isolated and purified to homogenity. The purified enzyme system catalyzes the conversion of indole to anthranilic acid. It is optimally active at pH 5.2 and 30°C. Two moles of oxygen are consumed and one mole of anthranilic acid is formed for every mole of indole oxidized. Dialysis resulted in complete loss of the activity. The inactive enzyme could be reactivated by the addition of concentrated dialysate. The enzyme is not inhibited by copper-specific chelators, non-heme iron chelators or atebrin. It is not a cuproflavoprotein, unlike the other indole oxygenases and oxidases.     

Role of phenolics and boron in reproductive success in seasonally transient sterile Tecoma stans L

Quantitative and qualitative analysis of phenolics and boron in stigma of transient sterile Tecoma stans L. during seedless (May-July), partially seedbearing (August-November, April) and seedbearing periods (December-March) was made. UV absorption profile of stigmatic exudates indicated the presence of simple phenolics. Total phenolics were higher in stigma during seedless period. Thin layer chromatographic analysis of stigmatic extracts exhibited only three principal spots. Mass spectrophotometry showed the presence of derivatives of cinnamic acid, namely, caffeic acid in these spots. Quantity of boron in stigma during seedless period was lowest but the difference with other periods was not significant. It was suggested that the accumulation of higher quantity of caffeic acid in the stigma during seedless period due to high temperature (40 degrees-45 degrees C) could lead to inhibition of pollen germination in vivo, thereby rendering the plants seedless. This was confirmed by inhibition of in vitro pollen germination in the basal medium containing higher quantity of caffeic acid.     

Bee diversity in Tecoma stans (L.) Kunth (Bignoniaceae): importance for pollination and fruit production

Tecoma stans (L.) Kunth is an exotic plant in Brazil, commonly distributed in urban areas, which is considered an invasive species in crop and pasture areas. In this study, the floral biology and the behavior of bees in flowers of T. stans from three urban areas in southeastern Brazil were investigated. In all study sites, T. stans was an important food resource to the Apoidea to 48 species of bees. Centris tarsata Smith and Exomalopsis fulvofasciata Smith (Hymenoptera: Apidae) were the effective pollinators more abundant, while Scaptotrigona depilis Moure (Hymenoptera: Apidae) was the more frequent robber species. The most part of T. stans visitors (87.5%) exploited exclusively nectar, which varied in sugar concentration depending on the day period and flower phase. In all flower stages, higher averages of nectar concentration (26.4% to 32.7%) occurred from 10 am to 2 pm. The presence of osmophore in the petals and protandry were detected. In two urban areas the number of visitors varied significantly during the day. The greatest abundance of pollinators occurred when pollen availability was higher and flowers showed receptive stigma, which could be contributing to the reproductive success of T. stans. The results indicate that the production of fruits increased in plants that received a higher number of effective pollinators.     

New isolations of iridoids from Tecoma and Skytanthus

Abstract

Isolation and structural determinations of iridoid glucosides from Tecoma arequipensis (Sprague) Sandw. and Skytanthus acutus Meyen are reported. The two species are characterized by the co-occurrence of iridoid glucosides and monoterpene alkaloids.     

Development of an efficient micropropagation system for Tecoma stans (L.) Juss. ex Kunth using thidiazuron and effects on phytochemical constitution

The present study was designed to investigate the stimulatory effects of different doses (0.1 to 2.5 μM) of thidiazuron (TDZ) on in vitro shoot induction and proliferation of mature nodal explants of Tecoma stans. Of the tested concentrations, 2.0 μM TDZ proved to be optimal for maximum regeneration (91%) with a mean shoot number of 5.6 ± 0.67, and length of 2.38 ± 0.08 cm, after 4 wk of incubation. To determine the negative effects of prolonged TDZ exposure, after 4 wk of incubation at optimized level of TDZ, the cultures were transferred to a secondary medium either lacking plant growth regulators or supplemented with benzyladenine (BA) alone, or in combination with different auxins (indole-3-acetic acid, indole-3-butyric acid, or α-naphthalene acetic acid; NAA). Among the tested concentrations, 2.5 μM BA in combination with 0.5 μM NAA yielded the maximum mean shoot number (16.60 ± 0.40), and average shoot length (4.76 ± 0.15 cm) after 4 wk of culture. The best rhizogenesis (93%) was achieved on ½ MS medium containing 1.5 μM NAA, with a mean root number of 7.60 ± 0.40 and length of 4.11 ± 0.23 cm, after 4 wk of incubation. The micropropagated plantlets were successfully acclimatized and hardened off in Soilrite™ with a 90% survival rate. The plantlets grew well with normal growth, flowering and showed, by gas chromatography–mass spectroscopy, an increase in the number of bioactive compounds compared with the donor plant. This is the first report on T. stans in vitro regeneration using TDZ.

     

Isolation of antioxidant constituents from Combretum apiculatum subsp. apiculatum

Species of the family Combretaceae are used extensively in traditional medicine against inflammation and infections, and although antibacterial activity has been reported in non-polar extracts, further rationale for the widespread use of the Combretaceae is expected to exist. Methanol extracts of leaves of ten different Combretum species were evaluated for antioxidant activity by spraying TLC chromatograms of each leaf extract with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Compounds with antioxidant activity were detected by bleaching of the purple DPPH colour. Leaf extracts of Combretum apiculatum subsp. apiculatum had the most antioxidant compounds. This species was consequently selected for phytochemical investigation. A DPPH assay-directed fractionation of the leaf extracts of C. apiculatum led to the isolation of four antioxidant compounds from the ethyl acetate and butanol soluble fractions. The structures of the compounds were determined by spectroscopic analyses (¹H-NMR, ¹³C-NMR and MS) and identified as: cardamonin (1), pinocembrin (2), quercetrin (3) and kaempferol (4). In a quantitative antioxidant assay, the more polar fractions (ethyl acetate and butanol) obtained by solvent–solvent fractionation had the highest antioxidant activity among the solvent fractions obtained from C. apiculatum, with EC₅₀ values of 3.91 ± 0.02 and 2.44 ± 0.02 μg/ml respectively. Of the four isolated compounds, quercetrin (4) and kaempferol (3) had the strongest antioxidant activity, with EC₅₀ values of 11.81 ± 85 and 47.36 ± 0.03 μM respectively. Cardamonin (1) and pinocembrin (2) did not demonstrate strong activity. L-ascorbic acid was used as standard antioxidant agent (EC₅₀ = 13.37 ± 0.20 μM or 2.35 μg/ml). The cytotoxicity of cardamonin and pinocembrin was evaluated on Vero kidney cells using the MTT (3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide) assay with berberine as positive control. At concentrations higher than 50 μg/ml of cardamonin or pinocembrin, the cells were not viable. Cardamonin was more toxic (LC₅₀ = 1.97 μg/ml) than pinocembrin (LC₅₀ = 29.47 μg/ml) and even the positive control, berberine (LC₅₀ = 12.35 μg/ml).     

A new mode of ring cleavage of 2,3-dihydroxybenzoic acid in Tecoma stans (L.). Partial purification and properties of 2,3-dihydroxybenzoate 2,3-oxygenase.

2,3-Dihydroxybenzoic acid has been shown to be oxidized via the 3-oxoadipate pathway in the leaves of Tecoma stans. The formation of 2-carboxy-cis,cis-muconic acid, a muconolactone, 3-oxoadipic acid and carbon dioxide during its metabolism has been demonstrated using an extract of Tecoma leaves. The first reaction of the pathway, viz., the conversion of 2,3-dihydroxybenzoate to 2-carboxy-cis,cis-muconic acid has been shown to be catalysed by an enzyme designated as 2,3-dihydroxybenzoate 2,3-oxygenase. The enzyme has been partially purified and a few of its properties studied. The enzyme is very labile with a half-life of 3--4 h. It is maximally active with 2,3-dihydroxybenzoate as the substrate and does not exhibit any activity with catechol, 4-methyl catechol, 3,4-dihydroxybenzoic acid, etc. However, 2,3-dihydroxy-p-toluate and 2,3-dihydroxy-p-cumate are also oxidized by the enzyme by about 38% and 28% respectively, compared to 2,3-dihydroxybenzoate. Sulfhydryl reagents inhibit the enzyme reaction and the inhibition can be prevented by preincubation of the enzyme with the substrate. Substrate also affords protection to the enzyme against thermal inactivation. Sulfhydryl compounds strongly inhibit the reaction and the inhibition cannot be prevented by preincubation of the enzyme with its substrates. Data on the effect of metal ions as well as metal chelating agents suggest that copper is the metal cofactor of the enzyme. Evidence is presented which suggests that iron may not be participating in the overall catalytic mechanism.     

Naphthoquinone and flavonoid constituents from the carnivorous plant Nepenthes mirabilis and their anti-osteoporotic and antioxidant activities

The methanolic extract of Nepenthes mirabilis (Nepenthaceae) showed significant in vitro antioxidant (peroxyl radical-scavenging and reducing effects) and anti-osteoporotic (pre-osteoclastic RAW 264.7 cells) activities. Phytochemical investigation of chloroform and ethyl acetate partitions of N. mirabilis branches and leaves allowed to isolate 13 compounds (1–13), including two new naphthoquinones, nepenthones F (1) and G (2), together with 11 known compounds. The structures of the isolated compounds were established mainly by extensive analysis of the 1D and 2D NMR, as well as HRMS data. The isolated compounds also were further evaluated for in vitro antioxidant and anti-osteoclast activities. Among them, compounds 10 and 11 showed potent antioxidant effects. While compounds 4 and 12 showed significant inhibition on receptor activation for nuclear factor κB ligand (RANκL)-induced osteoclast formation in murine bone-marrow macrophages.     

红豆树叶挥发油化学成分及其抗氧化和抑菌活性研究

为探究红豆树叶挥发油的化学组成及其生物活性,本研究首次采用水蒸气蒸馏法提取红豆树叶挥发油,并通过气相色谱-质谱联用技术(GC-MS)分析其化学成分,结合DPPH和ABTS法及抑菌圈法,评价其体外抗氧化和抑菌活性。结果表明,从红豆树叶挥发油中共检测出化合物36个,占挥发油总量的90.50%;挥发油主要成分为1,4-二十烷二烯(25.72%)、1,19-二十烷二烯(10.85%)、2,6-二叔丁基对甲酚(10.14%)、邻苯二甲酸正丁基异丁基酯(9.75%)、(Z,Z)-6,9-二十烷二烯(7.60%)、(E,E)-α-金合欢烯(7.51%)、叶醇(4.74%)和2-异丙烯基-5-甲基-6-庚烯-1-醇(4.04%)。红豆树叶挥发油对DPPH自由基和ABTS自由基清除作用的半数有效量(ED₅₀)分别为0.27、0.14 mg/mL,且抗氧化活性与挥发油浓度呈量效相关。红豆树叶挥发油浓度为7.1 mg/mL时,其对枯草芽孢杆菌(Bacillus subtilis)、金黄色葡萄球菌(Staphylococcus aureus)、绿脓杆菌(Pseudomonas aeruginosa)和大肠杆菌(Escherichia coli)的抑菌圈分别为11.29、9.88、10.85和11.03 mm。本研究为红豆树叶资源的综合开发利用提供了理论基础。     

Phenolic constituents from the lichen Parmotrema stuppeum (Nyl.) Hale and their antioxidant activity

Lichen, Parmotrema stuppeum (P. stuppeum) was successively extracted with benzene and acetone. Both the extracts were fractionated on 1% oxalic acid impregnated silica gel column to obtain four phenolic compounds. The structures of compounds were identified by 1H and 13C NMR spectra as methyl orsenillate, orsenillic acid, atranorin and lecanoric acid respectively. Antioxidant activity of benzene extract, acetone extract and isolated compounds were evaluated in a beta-carotene-linoleate model system. The pure compounds showed moderate antioxidant activity. This is the first report on the isolation and characterisation of compounds from the lichen P. stuppeum as well as on their antioxidant activity.     

Isolation of 6-epimonomelittoside from Tecoma heptaphylla and its conversion into monomelittoside

The isolation of a new iridoid glucoside, 6-epimonomelittoside, from Tecoma heptaphylla is reported. The structure and configuration were establish     

Volatile constituents of glutathione--ribose model system and its antioxidant activity

Summary.  Reaction between glutathione and ribose was carried out to study the volatiles formed via Maillard reaction and their antioxidant activity as well as their role in inhibition of LDL oxidation. The simultaneous distillation – extraction technique was used for trapping the volatile components followed by GC – MS analysis. Thirty six compounds were identified with the predominance of carbonyls and sulfur – containing compounds in the volatiles of this model system. Sensory evaluation was performed for the model system product according to the International Standard Methods (ISO). The results showed a high decrease in roasted and burnt attributes and remarkable increase in the like – boiled and roasted meat attributes. The sensory results of the model system product were confirmed by the presence of high concentrations of some volatile compounds having meat – like aroma such as 2-methyl-3-furanthiol and 2-furylmethanethiol. The radical scavenging activity of glutathione – ribose model system was quantified spectrophotometrically, using DPPH radical. The activity of the model system product was found to be slightly lower than that of gallic acid and BHA, but it was much higher than that of cinnamic acid (200 ppm. for each). A highly antioxidative activity was recorded by the model system product during the inhibition of LDL – oxidation in comparison with L-ascorbic acid as well as reduced glutathione (as a concentration of 0.5 μmol/L, for each) which may be due to the presence of some compounds such as 2-furylmethanethiol, 2-acetyl thiazole, 4-hydroxy-5-methyl-3(2H)-furanone. Received October 15, 2001 Accepted April 3, 2002 Published online September 4, 2002 Authors' address:  Khaled Farouk El-massry, Flavour and Aromatic Chemistry Department, National Research Center, Tahrir st., Dokki, Cairo, Egypt, Fax: 002 02 337 0 931, E-mail: kfarouk@yahoo.com     

Biology and host range of the leafminer,Pseudonapomyza sp. (Diptera: Agromyzidae), a potential biological control agent for Tecoma stans (Bignoniaceae) in South Africa

Tecoma stans (Bignoniaceae), is an evergreen shrub that has a wide natural distribution in the tropical and subtropical parts of the western hemisphere. This shrub is native to Mexico and the southern regions of the USA. This weed is widely distributed in South Africa and neighbouring countries. As part of the biological control initiative, a leafmining fly, Pseudonapomyza sp. (Diptera: Agromyzidae), was imported into South Africa, and was subsequently studied as a potential biological control agent for T. stans. During no-choice tests involving 46 plant species in 16 families, Pseudonapomyza sp. only oviposited and developed on T. stans. Neither oviposition nor larval development was recorded on the closely related and indigenous plant species. When six plant species in the Bignoniaceae family were exposed to Pseudonapomyza sp. during multi-choice tests, oviposition and larval development only occurred on T. stans. It was concluded that Pseudonapomyza sp. was sufficiently host-specific to be released against T. stans in South Africa. Pseudonapomyza sp. also displayed very promising biological attributes that could enhance its effectiveness to control T. stans.     

Isolation of phenolic constituents and characterization of antioxidant markers from sunflower (Helianthus annuus) seed extract

A new compound, benzyl alcohol β-d-apiofuranosyl-(1→6)-β-d-(4-O-caffeoyl) glucopyranoside (1), was isolated from the seed of sunflower (Helianthus annuus), together with eight known phenolic compounds: caffeic acid (2), methyl caffeoate (3), chlorogenic acid (4), 4-O-caffeoylquinic acid (5), 3-O-caffeoylquinic acid (6), methyl chlorogenate (7), 3,5-di-O-caffeoylquinic acid (8), and eriodictyol 5-O-β-d-glucoside (9). Their structures were elucidated on the basis of spectroscopic methods and chemical evidence. The antioxidative effect of the phenolic constituents from the sunflower seeds was also evaluated based on the oxygen-radical absorbance capacity (ORAC), and the fraction containing caffeic acid derivatives showed a high antioxidant potency.     

Flavonoid constituents,cytotoxic and antioxidant activities of Gleditsia triacanthos L. leaves

Gleditsia triacanthos L. is a deciduous tree belonging to the family Fabaceae. It possesses important biological activities as anti-mutagenic, anticancer, cytotoxic and treating rheumatoid arthritis. The total ethanol extract (EtOHE) and successive extracts (petroleum ether, chloroform, ethyl acetate, and aqueous ethanol) were prepared from the leaves. Eight flavone glycosides and two flavone aglycones named vicenin-I (1), vitexin (2), isovitexin (3), orientin (4), isoorientin (5), luteolin-7-O-ß-glucopyranoside (6), luteolin-7-O-ß-galactopyranoside (7), apigenin-7-O-ß-glucopyranoside (8), luteolin (9) and apigenin (10) were isolated from the aqueous ethanol extract of G. triacanthos L. leaves. Potent cytotoxic activity of the EtOHE extract was observed against the liver (IC₅₀ = 1.68 μg), breast (IC₅₀ = 0.74 μg), cervix (IC₅₀ = 1.28 μg), larynx (IC₅₀ = 0.67 μg) and colon (IC₅₀ = 2.50 μg) cancer cell lines. Cytotoxic activity of compounds 2, 4, 6 and 8 against, the liver, breast and colon cancer cell lines was also proved. Evaluation of the in-vivo antioxidant activity of the EtOHE and successive extracts revealed that the highest activity was exhibited by 100 mg of EtOHE (97.89% potency) as compared with vitamin E (100% potency). Compound 6 showed 91.8% free radical scavenging activity.