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From the root bark of Erythrina burttii three isoflav-3-enes, 7,4'-dihydroxy-2'-methoxy-6-(1",1"-dimethylallyl)isoflav-3-ene (trivial name, burttinol-A), 4'-hydroxy-2'-methoxy-2",2"-dimethylpyrano[5",6":8,7]isoflav-3-ene (trivial name, burttinol-B), 7,4'-dihydroxy-2'-methoxy-8-(3",3"-dimethylallyl)isoflav-3-ene (trivial name, burttinol-C), and 2-arylbenzofuran, 6,4'-dihydroxy-2'-methoxy-5-(1",1"-dimethylallyl)-2-arylbenzofuran (trivial name, burttinol-D) were isolated. In addition, the known compounds, abyssinone V-4'-methyl ether, bidwillol A, calopocarpin, erybraedin A, erythrabyssin II, isobavachalcone, phaseollidin and phaseollin were identified. The structures were determined on the basis of spectroscopic evidence. 相似文献
3.
The fruits of Myrsine africana afforded two new benzoquinone derivatives, methylvilangin and methylanhydrovilangin. On the other hand, from the fruits of Maesa lanceolata two more novel compounds; 2,5-dihydroxy-3-(nonadec-14-enyl)-benzoquinone and lanciaquinone were isolated. Their structural elucidation was achieved by spectroscopic measurements including 2D NMR experiments. 相似文献
4.
Xing Shun Song Chun Lan Tiao Kai Shi Wei Hua Mao Joshua Otieno Ogweno Yan Hong Zhou Jing Quan Yu 《Plant Growth Regulation》2006,49(1):85-93
In order to clarify the response of antioxidant systems in various cellular organelles to photo-oxidative stress, the activities
of superoxide dismutase (SOD) and enzymes of the ascorbate–glutathione (AsA-GSH) cycle were investigated in chloroplasts,
mitochondria and cytosol of cucumber leaves subjected to methyl viologen (MV) treatment. Photo-oxidation by MV resulted in
significant reductions in net photosynthetic rate (Pn) and increases in the ratio of the quantum efficiency of photosystem
II (PSII),
ΦPSII to that of the quantum efficiency of CO2 fixation (ΦCO2), followed by increased activities of SOD, and a general increase of AsA-GSH cycle enzymes in chloroplasts, mitochondria
and cytosol. These increases were however, most significant in chloroplasts. There were also significant increases in dehydroascorbate
(DHA), reduced glutathione (GSH), and oxidized glutathione (GSSG) except that the content of ascorbate (AsA) in chloroplasts
and cytosol was slightly decreased and little effected, respectively. However, GSSG in mitochondria and GSH in cytosol were
little influenced by the MV treatment. The activity of ascorbate oxidase (AO) in these organelles was independent of the MV
treatment while the activity of l-galactono-1,4- lactone dehydrogenase (GLDH) in mitochondria was slightly inhibited by MV treatment. These results indicate
that disturbance of electron transport in chloroplasts by MV influenced the metabolism of whole cell by a crosstalk signaling
system and that the AsA-GSH cycle played a primary role in sustaining the levels of AsA. 相似文献
5.
Ogweno Midiwo J. Yenesew A. Juma B.F. Derese S. Ayoo J.A. Aluoch A.O. Guchu S. 《Phytochemistry Reviews》2002,1(3):311-323
There are several described medicinal plants in Kenya from a flora of approximately 10,000 members. Strong cross-medical information
from the 42 ethnic groups points to the high potential of some of these species. The Myrsinaceae are well established ethno-anthelmintics
and anti-bacterials. They are harbingers of long alkyl side chain benzoquinones which clearly have a protective function from
their histochemical disposition. The main benzoquinone in the sub-family Myrsinodae is embelin while for the Maesodae it is
maesaquinone together with its 5-acetyl derivative; the distribution of these benzoquinones by their alkyl side chain length
or the presence/absence of a 6-methyl group is in accord with morphological sub-family de-limitation. The benzoquinones showed
anti-feedant, anti-microbial, phytotoxic, acaricidal, insecticidal and nematicidal activity. Many other benzoquinones of medium
and minor concentration were also isolated and characterised. Some plants belonging to the Polygonaceae which are widely used
as ethno-anthelmintics have been studied. The common anthelmintic anthraquinones were obtained from all five Rumex species
while the naphthalenic acetogenin derivative, nepodin was more selectively distributed. The leaf of Polygonum senegalense is up to 17% surface exudate; about thirteen non polar flavonoid derivatives (chalcones, dihydrochalcones, flavanones and
a flavone) have been isolated from it. From the internal aerial tissues of this plant, the major flavonoids were common flavonoids,
quercetin, kaempferol, luteolin and their glycosides. The only unique compound isolated from this plant was 2′-glucosyl-6′-hydroxy-4′-methoxydihydrochalcone
whose aglycone, uvangolatin is part of the exudate mixture. Other leaf exudate plants studied include the stomach-ache medicine,
Psiadia punctulata (Compositae) from which novel methylated flavonoids, kaurene and trachyloban diterpenes have been found.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Leonidah K. Omosa Jacob O. Midiwo Solomon Derese Abiy Yenesew Martin G. Peter Matthias Heydenreich 《Phytochemistry letters》2010,3(4):217-220
Phytochemical investigation of the leaf surface exudate of Dodonaea angustifolia L.f. yielded two new neo-clerodane diterpenes, neo-clerodan-3,13-dien-16,15:18,19-diolide (mkapwanin) and 15-methoxy-neo-clerodan-3,13-dien-16,15:18,19-diolide (15-methoxymkapwanin). In addition, ten known compounds were identified. The structures were determined on the basis of spectroscopic evidence. This additional chemical information could contribute towards solving the taxonomical controversy that exists between Dodonaea angustifolia and Dodonaea viscosa Jacq., which are morphologically similar. 相似文献
7.
7a-O-methyldeguelol, a modified rotenoid with an open ring-C, from the roots of Derris trifoliata 总被引:1,自引:0,他引:1
Yenesew A Mushibe EK Induli M Derese S Midiwo JO Kabaru JM Heydenreich M Koch A Peter MG 《Phytochemistry》2005,66(6):653-657
From the acetone extract of the roots of Derris trifoliata an isoflavonoid derivative, named 7a-O-methyldeguelol, a modified rotenoid with an open ring-C, representing a new sub-class of isoflavonoids (the sub-class is here named as rotenoloid), was isolated and characterised. In addition, the known rotenoids, rotenone, deguelin and alpha-toxicarol, were identified. The structures were determined on the basis of spectroscopic evidence. Rotenone and deguelin were identified as the larvicidal principles of the acetone extract of the roots of Derris trifoliata. 相似文献
8.
Joshua Otieno Ogweno Wen Hai Hu Xing Shun Song Kai Shi Wei Hua Mao Yan Hong Zhou Jing Quan Yu 《Plant Growth Regulation》2010,60(3):175-182
Detached leaves of tomato (Lycopersicon esculentum Mill.) experienced photoinhibition associated with sharp reductions in net photosynthetic rate (Pn), quantum efficiency of
PSII (ΦPSII) and photochemical quenching (qP) even though they were exposed to mild light intensity (400 μmol m−2 s−1 PPFD) at 28°C. Photoinhibition and the reduction in Pn, ΦPSII and qP, however, were significantly alleviated by 1 mg l−1 ABA, 0.1 mg l−1
N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) and 0.01 mg l−1 24-epibrassinolide (EBR). Higher concentrations, however, reduced the effects or even exacerbated the occurrence of photoinhibition.
Superoxide dismutase and ascorbate peroxidase activity in leaves increased with the increases in ABA concentration within
1–100 mg l−1, CPPU concentration within 0.1–10 mg l−1 and EBR concentration within 0.01–1.0 mg l−1. Catalase and guaiacol peroxidase activity also increased with the increase in EBR concentration but CPPU and ABA treatments
at higher concentrations caused a decrease. Malondialdehyde (MDA) content decreased with the increase in CPPU concentration.
ABA and EBR, however, decreased MDA concentration only at 1 and 0.01 mg l−1, respectively. In conclusion, detached leaves had increased sensitivity to PSII photoinhibition. Photoinhibition-induced
decrease in photosynthesis, however, was significantly alleviated by EBR, CPPU and ABA at a proper concentration. 相似文献
9.
K. M. Zhang X. M. Wang J. X. Cui J. O. Ogweno K. Shi Y. H. Zhou J. Q. Yu 《Biologia Plantarum》2011,55(2):361-364
To determine the effects of leaf colour on gas exchange and chlorophyll fluorescence, two genotypes of Begonia semperflorens with green leaves or red leaves were compared. The red leaves showed a high accumulation of anthocyanins and high absorbance
at 282 and 537 nm while the green leaves exhibited a higher net photosynthetic rate and lower thermal dissipation of light
energy. It seems likely that anthocyanins in the vacuoles restricted the absorption of green light to the chloroplasts, leading
to a decrease in the efficiency of excitation capture by open PS 2 centres, photochemical quenching and CO2 assimilation. 相似文献
10.
Joshua Otieno Ogweno Xing Shun Song Kai Shi Wen Hai Hu Wei Hua Mao Yan Hong Zhou Jing Quan Yu Salvador Nogués 《Journal of Plant Growth Regulation》2008,27(1):49-57
To investigate the effects of exogenously applied brassinosteroids on the thermotolerance of plants, leaf CO2 assimilation, chlorophyll fluorescence parameters, and antioxidant enzyme metabolism were examined in tomato (Lycopersicon esculentum Mill. cv. 9021) plants with or without 24-epibrassinolide (EBR) application. Tomato plants were exposed to 40/30°C for 8
days and then returned to optimal conditions for 4 days. High temperature significantly decreased the net photosynthetic rate
(P
n), stomatal conductance (G
s), and maximum carboxylation rate of Rubisco (V
cmax), the maximum potential rate of electron transport contributed to ribulose-1,5-bisphosphate (RuBP), as well as the relative
quantum efficiency of PSII photochemistry (ФPSII), photochemical quenching (q
P), and increased nonphotochemical quenching (NPQ). However, only slight reversible photoinhibition occurred during heat stress.
Interestingly, EBR pretreatment significantly alleviated high-temperature-induced inhibition of photosynthesis. The activities
of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPOD), and catalase
(CAT) increased during heat treatments, and these increases proved to be more significant in EBR-treated plants. EBR application
also reduced total hydrogen peroxide (H2O2) and malonaldehyde (MDA) contents, while significantly increasing shoot weight following heat stress. It was concluded that
EBR could alleviate the detrimental effects of high temperatures on plant growth by increasing carboxylation efficiency and
enhancing antioxidant enzyme systems in leaves. 相似文献