PubMed Health⌕ Search

Biomedical subjects

A Kijjoa

Publications and source records attributed to A Kijjoa.

14 recordsLinked to original sources
PubMed2005

Naturally-occurring xanthones: recent developments.

A literature survey covering the report of naturally occurring xanthones from January 2000 to December 2004, with 219 references, is presented in this review. Among 515 xanthones reported in this period, 278 were new natural xanthones. These xanthones have been identified from 20 families of higher plants (122 species in 44 genera), fungi (19 species) and lichens (3 species). The structural formulas of 368 identified xanthones, their distribution and a brief mention of their biological properties are also included.

Fungi↗
PubMed2003

Inhibition of lymphocyte proliferation by prenylated flavones: artelastin as a potent inhibitor.

Eight natural prenylated flavones, previously isolated from Artocarpus elasticus, were evaluated for their effect on the mitogenic response of human lymphocytes to PHA. They all exhibited a dose-dependent suppression effect. An interesting relationship was observed between their antiproliferative activity and their chemical structure. Indeed, the most potent flavones possessed a 3,3-dymethylallyl group (prenyl) at C-8, such as artelastin, which exhibited the highest antiproliferative activity. Studies of the mechanism underlying its effect revealed that artelastin had an irreversible inhibitory effect on the PHA-induced lymphocyte proliferation and could affect the course of the ongoing mitogenic response either at the initial induction phase or at the late phase of proliferation. This prenylated flavone was also shown to be a potent inhibitor of both T- and B-lymphocyte mitogen induced proliferation although B-mitogenic response was the more sensitive one. Artelastin did not affect either the basal levels of the early marker of activation CD69 on non-stimulated splenocytes or its expression on ConA- or LPS-stimulated splenocytes. However, it decreased the production of IFN-gamma, IL-2, IL-4 and IL-10 in ConA-stimulated splenocytes. Furthermore, artelastin had no effect on apoptosis of splenocytes.

Animals↗
PubMed2001

Naturally occurring 1,2,8-trimethoxyxanthone and biphenyl ether intermediates leading to 1,2-dimethoxyxanthone.

In order to study structure-activity relationships, a series of mono-, di- and trioxygenated xanthones has been synthesized and the structures of methyl 2-(3,4-dimethoxyphenoxy)benzoate, C(16)H(16)O(5), 2-(3,4-dimethoxyphenoxy)benzoic acid, C(15)H(14)O(5), 1,2-dimethoxy-9H-xanthen-9-one, C(15)H(12)O(4), and 1,2,8-trimethoxy-9H-xanthen-9-one, C(16)H(14)O(5), have been determined. The first two compounds both assume skew conformations, the dihedral angles between the two phenyl rings being 80.04 (8) and 83.0 (1) degrees, respectively. The latter two compounds are essentially planar and their methoxy substituents assume orientations consistent with minimum steric interactions.

Biphenyl Compounds↗
PubMed2001

Artelastocarpin and carpelastofuran, two new flavones, and cytotoxicities of prenyl flavonoids from Artocarpus elasticus against three cancer cell lines.

Further study of one of the fractions from the wood of Artocarpus elasticus furnished two new prenylated flavonoids artelastocarpin and carpelastofuran as well as ethyl 2,4-dihydroxybenzoate. The two flavonoids and the prenylated flavonoids artelastin, artelastochromene, artelasticin, artocarpesin, and cyclocommunin isolated earlier from this species were tested for cytotoxicity in vitro against three human cell lines. All seven flavonoids were active, the cytotoxic effect varying from strong to moderate and with artelastin showing the most potent activity.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Xanthones from Calophyllum teysmannii var. inophylloide.

Further study of the wood of Calophyllum teysmannii Miq. var. inophylloide yielded xanthones 7-hydroxy-1,2,8-trimethoxyxanthone, 6-hydroxy-1,2,5-trimethoxyxanthone, and 2-carbomethoxy-6-methoxyxanthone in addition to 3,8-dihydroxy-1,2,4-trimethoxyxanthone, 3-hydroxy-2,4-dimethoxyxanthone, 1,7-dihydroxy-3-methoxyanthone (gentisin) and 2-hydroxyxanthone.

Molecular Structure↗
PubMed2000

Xanthones from Calophyllum teysmannii var. inophylloide.

Further study of the wood of Calophyllum teysmannii Miq. var. inophylloide from Thailand yielded the xanthones 1,2,8-trimethoxyxanthone, 6-hydroxy-1,2,5,7-tetramethoxyxanthone and 3-(3'-carboxybutyl)-4-methoxyxanthone (teysmannic acid) in addition to scriblitifolic acid, 1,7-dihydroxyxanthone and the benzoic acid derivative leiocarpic acid.

Magnetic Resonance Spectroscopy↗
PubMed1996

Inhibition of inflammatory responses by a series of novel dolabrane derivatives.

Four dolabrane derivatives isolated from Endospermum diadenum have been studied for their inhibitory effects on murine models of inflammation and human neutrophil functions in vitro. After topical application, akendo 1, akendo 2 and akendo 3 potently inhibited the mouse ear oedema induced by 12-O-tetradecanoylphorbol acetate (TPA) with a striking effect on myeloperoxidase levels. After oral administration, akendo 2 and akendo 3 inhibited mouse paw oedema induced by carrageenan, with a significant reduction in myeloperoxidase levels. In contrast to indomethacin, they did not modify the prostaglandin E2 content of the inflammed paw. None of the compounds affected superoxide generation by human neutrophils. On the contrary, they inhibited degranulation induced by different stimuli. The most effective compounds were akendo 2 and akendo 3, which also inhibited myeloperoxidase activity. All compounds were weak inhibitors of leukotriene B4 synthesis and release by human neutrophils, whereas only akendo 3 decreased 5-lipoxygenase activity. Cyclo-oxygenase-1 from human platelets was inhibited mainly by akendo 2 and akendo 3, although with a low potency. The latter compound also reduced weakly the synthesis of prostaglandin E2 by cyclo-oxygenase-2. The anti-inflammatory activity of these dolabrane derivatives was not related to arachidonic acid mobilization or metabolism.

Animals↗
PubMed1993

HIV-1 gp120 and NMDA induce protein kinase C translocation differentially in rat primary neuronal cultures.

Exposure of rat cortical neurons to the human immunodeficiency virus type 1 (HIV-1) coat protein gp120 in vitro causes a rise in the intracellular Ca2+ level and a subsequent translocation of protein kinase C (PKC) from the cytosol to the membrane. Such a translocation persists for at least 2 h, but only in cultures with media not depleted of endogenous glutamate. Enzymatic degradation of glutamate in the medium by the enzyme glutamate-pyruvate transaminase (GPT) abolishes the long-lasting effect of gp120 on the association state of PKC; under this incubation condition the translocation period is < 1 h. Memantine and the ganglioside GM1 prevent N-methyl D-aspartate receptor-mediated long-term translocation of PKC and gp120-mediated neurotoxicity (in the absence of GPT); they have no effect on short-term translocation of PKC. We suggest that gp120-caused neuronal death involves an indirect sensitization step of the NMDA receptors, which ultimately induces neuronal death.

Animals↗
PubMed1991

Constituents of Knema laurina and Knema tenuinervia ssp. setosa.

Extraction of the stem bark of KNEMA LAURINA Warb. and KNEMA TENUINERVIA W. J. J. O. de Wilde ssp. SETOSA de Wilde furnished 3-(12-phenyl-8 Z-dodecenyl)-phenol and 3-(8 Z-pentadecenyl)-phenol together with 8-hydroxy-6-methoxy-3- N-pentylisocoumarin, respectively. 2-Carboxy-3-(12-phenyldodecyl)-phenol) and 2,4-dihydroxy-6-(10-phenyldecyl)-acetophenone were common to both extracts.

Journal Article↗
PubMed1981

Ocotea quixos, American cinnamon.

Among the three South American Lauraceae with cinnamon odours, Ocotea quixos Lam. is distinguished with the richest historical legacy. Cinnamaldehyde, its odoriferous principle, occurs besides o-methoxycinnamaldehyde, cinnamic acid and methyl cinnamate in the fruit calyx. In contradistinction, 1-nitro-2-phenylethane is responsible for the cinnamon odour of bark and leaves of Aniba canelilla (H..B.K.) Mez and Ocotea pretiosa (Nees) Mez.

Cinnamomum zeylanicum↗