Eckart Eich

Antiplasmodial activity of naphthoquinones and one anthraquinone from Stereospermum kunthianum.

A lipophilic extract of the root bark of Stereospermum kunthianum revealed antiplasmodial activity in vitro. Bioassay-guided fractionation led to the isolation of four novel naphthoquinones (sterekunthals A and B, pyranokunthones A and B) and one novel anthraquinone (anthrakunthone) together with the known naphthoquinone pinnatal. The structures of the novel compounds were determined by comprehensive analyses of their 1D and 2D NMR data. The antiplasmodial activities and toxicity against the endothelial cell line ECV-304 of the isolated compounds have been assessed.

In vitro antiplasmodial activity of Central American medicinal plants

Summary The in vitro antiplasmodial activities of 14 plant species traditionally used in Central America for the treatment of malaria or fever were evaluated. Lipophilic extracts of Piper hispidum, Siparuna andina, S. pauciflora, S. tonduziana, and Xylopia cf. frutescens, proved to be active against both a chloroquine‐sensitive and a resistant strain of Plasmodium falciparum. IC50 values ranged between 3.0 μg/ml and 21.9 μg/ml; however, moderate cytotoxicity of active extracts was observed. Bioactivity‐guided fractionation of Piper hispidum yielded 2′,4,6′‐trihydroxy‐4′‐methoxydihydrochalcone (asebogenin) as an active compound.

In Vitro Antiplasmodial Investigation Of Medicinal Plants From El Salvador

In vitro antiplasmodial activities of extracts from Albizia saman, Fabaceae, Calea tenuifolia (C. zacatechichi), Asteraceae, Hymenaea courbaril, Fabaceae, Jatropha curcas, Euphorbiaceae, Momordica charantia, Cucurbitaceae, and Moringa oleifera, Moringaceae were evaluated. From the lipophilic extract of C. tenuifolia five active flavones were obtained. 4′,5- Dihydroxy-7-methoxyflavone [genkwanin] and 5-hydroxy-4′,7-dimethoxyflavone [apigenin 4′,7-dimethylether] exhibited the strongest antiplasmodial activity against a chloroquine-sensitive strain (poW) and a chloroquine-resistant strain (Dd2) of Plasmodium falciparum (IC50 values: 17.1 - 28.5 μm). Furthermore octadeca-9,12-dienoic acid [linoleic acid] {IC50 values of 21.8 μm (poW) and 31.1 μm (Dd2)} and octadeca-9,12,15-trienoic acid (α-linolenic acid) were isolated

DIFFERENTIAL IN VITRO ANTI-HIV ACTIVITY OF NATURAL LIGNANS

Abstract Two naturally occurring lignanolides, isolated from the tropical climbing shrub Ipomoea cairica, (-)-arctigen in and (-)-trachelogen in , were found to inhibit strongly replication of human immunodeficiency virus type 1 (HIV-1; strain HTLV-III B) in vitro. At a concentration of 0.5 (μм , (-)-arctigenin and (-)-trachelogenin inhibited the expression of HIV-1 proteins p 17 and p24 by 80 -90 % and 60 -70 % , respectively. The reverse transcriptase activity in the culture fluids was reduced by 80 -90 % when the cells (HTLV-III B/H 9) were cultivated in the presence of 0.5 μм (-)-arctigen in or 1 μм (-)-trachelogenin . At the same concentrations, the formation of syncytia in the HTLV-III B/H 9-Jurkat cell system was inhibited by the compounds by more than 80%. A series of other lignan type compounds displayed no anti-HIV activity. Studying the molecular mechanism of action of (-)-arctigenin and (-)-trachelogenin we found that both compounds are efficient inhibitors of the nuclear matrix-associated DNA topoisomerase II activity, particularly of the enzyme from HIV -1-infected cells. Our results suggest that both compounds prevent the increase of topoisomerase II activity, involved in virus replication, after infection of cells with HIV -1.

Herbal Remedies Traditionally Used Against Malaria in Ghana: Bioassay-Guided Fractionation of Microglossa pyrifolia (Asteraceae)

Different extracts from 11 West African plants traditionally used against malaria in Ghana were tested against both the chloroquine-sensitive strain PoW and the chloroquine-resistant clone Dd2 of Plasmodium falciparum. Due to the promising in vitro activity of the lipophilic extract [IC50: 10.5 μg/ml (PoW); 13.1 μg/ml (Dd2)], Microglossa pyrifolia (Lam.) Kuntze (Asteraceae) was chosen for further phytochemical investigation. From active fractions 13 compounds were isolated; their structures were established on the basis of spectroscopic methods. 1-Acetyl-6E-geranylgeraniol-19-oic acid and sinapyl diangelate represent new natural compounds. The two diterpenes E-phytol [IC50: 8.5 μм (PoW); 11.5 μм (Dd2)], and 6Egeranylgeraniol- 19-oic acid [IC50: 12.9 μм (PoW); 15.6 μм (Dd2)] proved to be the most active constituents in our test system.

Flavonoid sulfates from the Convolvulaceae

Abstract A novel flavonoid, quercetin 7-methyl ether-3,3′-disulfate ( 5 ), was obtained from the roots of Argyreia mollis , together with the known compounds quercetin 7-methyl ether-3-sulfate ( 4 ) and kaempferol 7-methyl ether-3-sulfate ( 2 ). Two further new flavonoid sulfates, quercetin 3,7-dimethyl ether-4′-sulfate ( 6 ) and quercetin 3′,4′,7-trimethyl ether-3-sulfate ( 8 ), were isolated from the aerial vegetative parts of Ipomoea regnellii , together with the known compound kaempferol 4′,7-dimethyl ether-3-sulfate ( 3 ). This is the first report on sulfated flavonoids in the Convolvulaceae family and, furthermore, the presence of flavonoids in A. capitata , A. mollis , I. reticulata and I. regnellii is reported for the first time.

Distribution and taxonomic significance of calystegines in the convolvulaceae

Abstract The GC-MS analysis of 65 convolvulaceous species from many, predominantly tropical provenances, belonging to 22 genera (9 tribes), revealed the occurrence of one to five calystegines in 30 species belonging to 15 genera (8 tribes). This indicates the chemotaxonomic significance of these glycosidase inhibiting polyhydroxy-nortropanes for the Convolvulaceae.

Occurrence of loline alkaloids in Argyreia mollis (Convolvulaceae)

Abstract N -Formylloline was isolated from roots of Argyreia mollis . This is the first identification of a 1-aminopyrrolizidine alkaloid (loline alkaloid) in a species of the Convolvulaceae. Lolines are only known from the genus Adenocarpus (Fabaceae) and certain grasses (e. g. Festuca ) infected with endophytic fungi. A GC–MS analysis revealed N -formylloline to be present in roots and aerial vegetative plant parts. It is accompanied by three congeners (i. e. loline, N -methylloline and N -propionylnorloline) and simple pyrrolidine alkaloids such as hygrine and its derivatives as well as tropan-3β-ol. Lolines could not be detected in Argyreia capitata , A. hookeri , A. nervosa and numerous species of 14 other convolvulaceous genera.

Pyrrolizidine alkaloids of Ipomoea hederifolia and related species

Abstract The common necine base of the novel pyrrolizidine alkaloids (ipangulines) isolated recently from Ipomoea hederifolia is not turneforcidine but its 1β-epimer, platynecine. Three novel ipangulines were isolated from the aerial parts of I. hederifolia and identified as 9- O -[2-hydroxy-3-(2-acetoxy)-2-methylbutyryl]-7- O -salicyloylplatynecine (ipanguline B 2 ), 9- O -[2-hydroxy-3-(2-methylbutyryloxy)-2-methylbutyryl]-platynecine (ipanguline D 10 ) and 9- O -salicyloylplatynecine (ipanguline D 11 ). Comprehensive GC-mass spectrometric analysis also revealed a great variety of >38 platynecine monoesters and diesters. They are classified as ipangulines A (diesters with one phenylacetic acid moiety), ipangulines B (diesters with one salicylic acid moiety), ipangulines C (diesters with two aliphatic moieties) and ipangulines D (either 7- or 9-monoesters). In shoot tips and young leaves, total ipangulines concentrations are up to 0.45% (on dry wt basis). The ipangulines are stored as tertiary alkaloids and not as N -oxides. Seeds of different provenance showed similar alkaloid patterns. Taxonomically related species, such as I. neei and I. × perigrenium , also contain platynecine esters in their vegetative tissues.

Ipangulines, the first pyrrolizidine alkaloids from the convolvulaceae

Abstract Four novel pyrrolizidine alkaloids were isolated from Ipomoea hederifolia. It could be shown by spectroscopic methods that the compounds represent two pairs of isomeric turneforcidine diesters with either erythro- or threo-2,3-dihydroxy-2-methyl-butyric acid as the acyl moiety at C-9 OH. One pair (ipanguline A/isoipanguline A) is characterized by phenylacetic acid as the second acyl component (at C-7 OH), the other (ipanguline B/isoipanguline B) includes a salicylic acid moiety in this position. The distribution pattern shows the occurrence of the A compounds in the seeds and of the B compounds in the roots, respectively, with all four alkaloids in the aerial parts.