Abstract Phytochemical investigation of the stem bark of Diospyros longiflora yielded longiflorol ( 1 ), a new bergenin α - d -apioside, together with bergenin ( 2 ) and five known compounds: lupeol ( S1 ), betulin ( S2 ), betulinic acid ( S3 ), stigmasterol ( S4 ) and stigmasterol glucoside ( S5 ). Their structures were determined by one-dimensional (1D) and 2D nuclear magnetic resonance experiments along with electrospray ionization high-resolution mass spectrometry and extended density-functional theory calculations of chiroptical properties. Longiflorol ( 1 ) and bergenin ( 2 ) were evaluated for their DPPH (2,2-diphenyl-1-picrylhydrazyl) antioxidant activity, with the crude extract for comparison and ascorbic acid as standard. The results showed that the extract and 2 had good antioxidant activity, whereas 1 showed only moderate activity at high concentration (>2 mg mL −1 ).
Phytochemical investigation of leaves, barks and roots of Nauclea vanderguchtii led to the isolation of sixteen compounds, which includes one citric acid derivative (2), one alkaloid (16), one peptide derivative (3), and twelve triterpenes (1, 4 - 13). These compounds were identified as rotundanonic acid (1), 2-hydroxy-1,2,3-propanetricarboxylic acid 2-methyl ester (2), asperphenamate (3), lupeol (4), stigmasterol (5), betulin (6), betulenic acid (7), stigmasterol 3-O--D-glucopyranoside (8), quinovic acid 3-O--L-rhamnoside (9), -amyrin (10), 3-oxoquinovic acid (11), ursolic acid (12), hederagenin (13), rotundic acid (14), clethric acid (15), and naucleficine (16) by the analysis of their NMR spectroscopic data including 2D NMR spectra and by comparison of their spectroscopic data reported in the literature. Compounds 1 and 3 were isolated for the first time in the genus Nauclea, and compound 2 was isolated for the first time from the Rubiaceae family. Complete NMR assignations for 1 have been published for the first time.
. The study of the secondary metabolites of the chloroform extract of the stem wood of Erythrina sigmoidea afforded a new compound a -sophoradiol (1), and the known compounds: acetate of b -amyrin (2), acetate of oleanolic acid (3), n-isocosanyl-isocosanoate (4), and n-hexatetracontanol (5). Their structures were characterised by spectroscopic methods.
(Received February 12, 2001, revised July 3, 2001)
Bull.Chem.Soc.Ethiop. 2001, 15(2), 151-156
Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae) and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae) were assessed. The phytochemical studies led to the isolation of eight compounds (1–8) from Diospyros conocarpa and six compounds (6, 9–13) from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12) and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value < 10 μg/mL for crude extracts and < 1 μg/mL for pure compounds. The hexane/ethyl acetate (1:1) fraction of A.klaineanum root bark (AKERF1) and the hexane/ethyl acetate (1:1) fraction of A.klaineanum trunk bark (AKETF1) presented the strongest antiplasmodial activities with IC50 values of 0.4 and 4.4 μg/mL, respectively. Aridanin (4) and antrocarine A(11), as well as the crude extract of D.conocarpa roots (EDCR), AKERF1 and AKETF1 showed moderate trypanocidal effects. The crude extract of A.klaineanum root bark (AKER) and AKETF1 exhibited attractive activities on HIV-1 integrase with IC50 values of 1.96 and 24.04 μg/mL, respectively. The results provide baseline information on the use of A.klaineanum and D.conocarpa extracts, as well as certain components, as sources of new antiplasmodial, antitrypanosomal and anti-HIV drugs.
This study aimed for investigating chemical constituents and biological activities of Diospyros zenkeri (Gurke) F. White. 14 known secondary metabolites have been isolated from the leaves and the twigs of D. zenkeri such as 3-methoxy-7-methyljuglone (1), β-carotene (2), lupeol (3), mixture of β-sitosterol (4) and stigmasterol (5), betulin (6), ursolic acid (7), messagenin (8), 3β,28,30-lup-20(29)-ene triol (9), mixture of the glucosides of stigmasterol (10) and β-sitosterol (11), norbergenin (12), betulinic acid (13) and vanillic acid (14), respectively . The structures of the compounds were elucidated with the help of NMR and mass spectral studies. The compounds 8, 9 and 14 are reported for the first time from the genus Diospyros. The biological screening of all the isolates and the crude methanolic extracts have been carried out including antiproliferative activity, antioxidant potential and inhibitory activity against the enzymes lipoxygenase and urease, respectively. Compound 1 exhibited significant antiproliferative activity against two cancer cell lines CAL-27 (IC50=2.98 μM) and NCI-H460 (IC50=5.57 μM). Methanolic extracts of the leaves and twigs of D. zenkeri presented low antiproliferative activity against these two cancer cell lines. Compounds 1, 6, 8, 9, 12 and the crude extracts exhibited moderate antioxidant activity with IC50 values of 76.5 μM, 65.8 μM, 55.3 μM and 51.2 μM respectively compared to BHA (IC50=44.2 μM). Compounds 6, 8 and 9 showed moderate lipoxygenase inhibition activity with IC50 values of 58.5 μM, 52.8 μM and 58.8 μM, respectively compared to baicalein (IC50=22.6 μM).
Phytochemical investigation of the methanol extract of the dried ground aerial plants of Senecio manii gave two new compounds 4-methoxy6-(11-O-s-D-glucopyranosylstyryl)-α-pyrone (1) and 4-methoxy-6-(11-O-α-L-rhamnopyranosylstyryl)-α-pyrone (2) as well as the four known compounds, namely 4-methoxy-6-(11-hydroxystyryl)-α-pyrone (3), 4-methoxy-6-(12-hydroxystyryl)-α-pyrone (4), 4-methoxy-6-(12O-s-D-glucopyranosylstyryl)-α-pyrone (5) and α-amyrin. Their structures were established based on spectroscometric analysis. The styrylpyrone derivatives showed a significant antimicrobial activity.
Abstract The phytochemical study of the roots, leaves and twigs of Penianthus camerounensis Dekker (Menispermaceae) has led to the isolation and the characterization of 20 compounds. A ceramide, camerounamide ( 1 ), and a furoclerodanediterpenoid, camerounin ( 2 ), have not been described previously, while the compounds xylopic acid ( 3 ), syringaresinol ( 4 ), iso -propylmethylcyclohexa-1,4-diol ( 5 ), 1-(28-hydroxyoctacosanoyl)glycerol ( 6 ), scoparone ( 7 ), friedelin ( 8 ), friedelanol ( 9 ) and betulinic acid ( 10 ) are being reported for the first time from the genus Penianthus alongside 10 known compounds ( 11–20 ). Chemical structures were determined using 1D- and 2D-NMR spectroscopy, MS and chemical analysis. Their chemotaxonomic importance is discussed.
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