Millettia dubia De Wild. (Fabaceae): Structural analysis of the oleanane-type glycosides and stimulation of the sweet taste receptors TAS1R2/TAS1R3.

From the root barks of a Central African tree Millettia dubia De Wild. (Fabaceae), ten previously undescribed oleanane-type glycosides were isolated by various chromatographic protocols. Their structures were elucidated by spectroscopic methods, mainly 2D NMR experiments and mass spectrometry, as mono- and bidesmosidic glycosides of mesembryanthemoidigenic acid, hederagenin and oleanolic acid. The stimulation of the sweet taste receptor TAS1R2/TAS1R3 by these glycosides was evaluated, and structure/activity relationships were proposed. Two of them showed an agonist effect on TAS1R2/TAS1R3.

Oleanane-type glycosides isolated from the trunk barks of the Central African tree Millettia laurentii.

Seven previously undescribed oleanane-type glycosides were isolated from the trunk barks of a Central African tree named Millettia laurentii De Wild (Fabaceae). After the extraction from the barks, the isolation and purification of these compounds were achieved using various solid/liquid chromatographic methods. Their structures were established mainly by 1D and 2D NMR (COSY, TOCSY, ROESY, HSQC, HMBC) and mass spectrometry (ESI-MS), as 3-O-ß-D-glucuronopyranosyl-(1 â†’ 2)-ß-D-glucuronopyranosylechinocystic acid, 3-O-ß-D-apiofuranosyl-(1 â†’ 3)-ß-D-glucuronopyranosyl-(1 â†’ 2)-ß-D-glucuronopyranosylechinocystic acid, 3-O-ß-D-apiofuranosyl-(1 â†’ 3)-ß-D-galactopyranosyl-(1 â†’ 2)-ß-D-glucuronopyranosylechinocystic acid, 3-O-ß-D-apiofuranosyl-(1 â†’ 3)-[ß-d-xylopyranosyl-(1 â†’ 2)]-ß-D-galactopyranosyl-(1 â†’ 2)-ß-D-glucuronopyranosylechinocystic acid, 3-O-ß-D-apiofuranosyl-(1 â†’ 3)-[α-L-arabinofuranosyl-(1 â†’ 2)]-ß-D-galactopyranosyl-(1 â†’ 2)-ß-D-glucuronopyranosylechinocystic acid, 3-O-α-L-arabinofuranosyl-(1 â†’ 2)-ß-D-galactopyranosyl-(1 â†’ 2)-ß-D-glucuronopyranosyloleanolic acid, 3-O-ß-D-apiofuranosyl-(1 â†’ 3)-[α-L-arabinofuranosyl-(1 â†’ 2)]-ß-D-galactopyranosyl-(1 â†’ 2)-ß-D-glucuronopyranosyloleanolic acid. In addition, the cytotoxicity of six glycosides among the isolated ones, was evaluated against 4 T1 cell line from a mouse mammary gland tissue, using MTS method.

Anti-phytopathogen terpenoid glycosides from the root bark of Chytranthus macrobotrys and Radlkofera calodendron.

Chytranthus macrobotrys and Radlkofera calodendron are two Sapindaceae characterized by a lack of phytochemical data. Both root barks from the two Sapindaceae species were processed by ethanol extraction followed by the isolation of their primary constituents by liquid chromatography. This process yielded four previously undescribed terpenoid glycosides together with eight known analogues. Extracts and isolated compounds from C. macrobotrys and R. calodendron were then screened for antimicrobial activity against fifteen phytopathogens. The biological screening also involved extracts and pure compounds from Blighia unijugata and Blighia welwitschii, two Sapindaceae previously studied by our group. Phytopathogens were chosen based on their economic impact on agriculture worldwide. The selection was composed primarily of fungal species including; Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Zymoseptoria tritici, Fusarium oxysporum, Botrytis cinerea, Pythium spp., Trichoderma spp. and Rhizoctonia solani. Furthermore, pure terpenoid glycosides were tested for the first time against wood-inhabiting phytopathogens such as; Phaeomoniella chlamydospora, Phaeoacremonium minimum, Fomitiporia mediterranea, Eutype lata and Xylella fastidiosa. Raw extracts exhibited different levels of activity dependent on the organism. Some pure compounds, including 3-O-α-L-arabinopyranosyl-(1 â†’ 4)-ß-D-xylopyranosyl-(1 â†’ 3)-α-L-rhamnopyranosyl-(1 â†’ 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 â†’ 2)-α-L-arabinopyranosylhederagenin (α-hederin), 3-O-ß-D-glucopyranosyl-(1 â†’ 3)-α-L-rhamnopyranosyl-(1 â†’ 2)-α-L-arabinopyranosylhederagenin (macranthoside A) and 3-O-α-L-arabinopyranosyl-(1 â†’ 3)-α-L-rhamnopyranosyl-(1 â†’ 2)-α-L-arabinopyranosylhederagenin (clemontanoside C), exhibited significant growth inhibitions on Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Fomitiporia mediterranea and Zymoseptoria tritici. Monodesmoside triterpene saponins, in particular, exhibited MIC (IC100) values as low as 25 µg/ml and IC50 values as low as 10 µg/ml against these phytopathogens. Structure-activity relationships, as well as plant-microbe interactions, were discussed.

A review on the phytopharmacological studies of the genus Polygala.

ETHNOPHARMACOLOGICAL RELEVANCE: The genus Polygala, the most representative genus of the Polygalaceae family, comprises more than 600 species from all over the world of which around 40 are distributed in China, some of them, being used in the Traditional Chinese Medicine system. AIM OF THE REVIEW: We intend to discuss the current knowledge about the traditional uses, and the newest phytochemical and pharmacological achievements with tentative elucidation of the mechanism of action on the genus Polygala covering the period 2013-2019 to provide a scientific support to the traditional uses, and to critically analyze the reported studies to obtain new insights for further researches. MATERIALS AND METHODS: The data were systematically collected from the scientific electronic data bases including SciFinder, Scopus, Elsevier, PubMed and Google Scholar. RESULTS: This literature overview reported several traditional uses of different species of Polygala, mainly against wounds, inflammation, cardiovascular and central nervous system disorders. P. altomontana, P caudata, P. flavescens, P. glomerata, P. japonica, P. molluginifolia, P. sibirica, P. tenuifolia are the main species which have been studied in the last few years. Phytochemical studies showed that they contain triterpene saponins, triterpenes, terpenoids, xanthones, flavonoids, coumarins, oligosaccharide esters, styryl-pyrones, benzophenones, and polysaccharides. Pharmacological in vitro and in vivo studies and proposal of the mechanisms of action indicated that pure constituents and extracts of Polygala ssp exhibited significant anti-inflammatory, neuroprotective, antiischemic, antidepressant, sedative, analgesic, antiatherosclerosis, antitumor and enzyme inhibitory properties. CONCLUSION: This review on traditional uses and phytopharmacological potential of the genus Polygala revealed updated insights which can be explored for further mechanism-based pharmacological activities and structure/activity relationships studies and a better comprehension of the development of Chinese medicine preparations. However some pharmacological studies showed several gaps such as incomplete methodologies and ambiguous findings. More high scientific quality preclinical studies with pharmacokinetic considerations will be required in the future to assess the traditional uses of some species of this genus. This might lead to efficacy and safety issues in clinical trials and to potential medicinal applications.

Triterpene glycosides from Blighia welwitschii and evaluation of their antibody recognition capacity in multiple sclerosis.

Multiple sclerosis (MS) in a multifactorial autoimmune disease in which reliable biomarkers are needed for therapeutic monitoring and diagnosis. Autoantibodies (autoAbs) are known biomarker candidates although their detection in biological fluids requires a thorough characterization of their associated antigens. Over the past twenty years, a reverse chemical-based approach aiming to screen putative autoantigens has underlined the role of glycans, in particular glucose, in MS. Despite the progress achieved, a lack of consensus regarding the nature of innate antigens as well as difficulties proposing new synthetic glucose-based structures have proved to be obstacles. Here is proposed a strategy to extend the current methodology to the field of natural glycosides, in order to dramatically increase the diversity of glycans that could be tested. Triterpene saponins from the Sapindaceace family represent an optimal starting material as their abundant description in the literature has revealed a prevalence of glucose-based oligosaccharides. Blighia welwitschii (Sapindaceae) was thus selected as a case study and twelve triterpene saponins were isolated and characterized. Their structures were elucidated on the basis of 1D and 2D NMR as well as mass spectrometry, revealing seven undescribed compounds. A selection of natural glycosides exhibiting various oligosaccharide moieties were then tested as antigens in enzyme-linked immunosorbent assay (ELISA) to recognize IgM antibodies (Abs) in MS patients' sera. Immunoassay results indicated a correlation between the glycan structures and their antibody recognition capacity, allowing the determination of structure-activity relationships that were coherent with previous studies. This approach might help to identify sugar epitopes putatively involved in MS pathogenesis, which remains poorly understood.

Meroterpenes from Dichrostachys cinerea inhibit protein farnesyl transferase activity.

Eighteen new meroterpene derivatives, dichrostachines A-R (1-18), have been isolated from the root and stem barks of Dichrostachys cinerea, and their structures determined by spectroscopic means and molecular modeling. From a biosynthetic standpoint these compounds arise from a Diels-Alder reaction between a labdane diene of the raimonol type and a flavonoid B-ring-derived quinone. The hypothesis was tested by the partial synthesis of similar compounds by simply mixing methyl communate and a synthetic flavonoid quinone. The hemisynthetic compounds were shown by NMR to have configurations different from those of the natural products, thus allowing a refinement of the biosynthesis hypothesis. Most of the compounds were assayed for their ability to inhibit the enzyme protein farnesyl transferase. The most active compounds exhibited IC50 and cytotoxicity values in the 1 microM range.

Hederagenin glycosides from the fruits of Blighia unijugata.

A phytochemical investigation of Blighia unijugata led to the isolation of eleven hederagenin glycosides. Among these compounds, six are previously undescribed, two are described in their native forms for the first time and three are known whereas firstly isolated from Blighia unijugata. The structure of the undescribed compounds was elucidated on the basis of 2D NMR and mass spectrometry analyses as 3-O-ß-D-xylopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-ß-D-xylopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-3-O-acetyl-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-ß-D-glucopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-ß-D-xylopyranosyl-(1 → 3)-ß-D-xylopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-ß-D-xylopyranosyl-(1 → 3)-ß-D-xylopyranosyl-(1 → 4)-3-O-acetyl-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-arabinopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin 28-O-ß-D-glucopyranosyl-(1 → 6)-ß-D-glucopyranosyl ester, 3-O-α-L-arabinopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin 28-O-ß-D-glucopyranosyl ester and 3-O-ß-D-xylopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin 28-O-ß-D-glucopyranosyl ester. These results revealed the existence of several conserved structural features that could be used as chemotaxonomic markers for the Blighia genus such as the glycosidic sequence 3-O-α-L-arabinopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl, the occurrence of 3-O-acetylated ß-D-glucopyranosyl units and the systematic presence of hederagenin as aglycone.

Terpenoid glycosides from the root's barks of Eriocoelum microspermum Radlk. ex Engl.

Eight undescribed triterpenoid saponins together with a known one, and two undescribed sesquiterpene glycosides were isolated from root's barks of Eriocoelum microspermum. Their structures were elucidated by spectroscopic methods including 1D and 2D experiments in combinaison with mass spectrometry as 3-O-α-L-rhamnopyranosyl-(1 → 3)-[α-L-rhamnopyranosyl-(1 → 2)]-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 3)-[ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)]-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 3)-[ß-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)]-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 4)-[α-L-rhamnopyranosyl-(1 → 2)]-α-L-arabinopyranosylhederagenin 28-O-ß-D-glucopyranosyl ester, 3-O-α-L-rhamnopyranosyl-(1 → 3)-ß-D-xylopyranosyl-(1 → 4)-ß-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-ß-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-ß-D-xylopyranosyl-(1 → 4)-α-L-arabinopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-ß-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)]-α-L-arabinopyranosylhederagenin, 1-O-{ß-D-xylopyranosyl-(1 → 3)-[α-L-rhamnopyranosyl-(1 → 2)]-ß-D-glucopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 6)}-[ß-D-xylopyranosyl-(1 → 3)]-[α-L-rhamnopyranosyl-(1 → 2)]-ß-D-glucopyranosyl-(2E,6E)-farnes-1-ol, 1-O-{ß-D-glucopyranosyl-(1 → 3)-[α-L-rhamnopyranosyl-(1 → 2)]-ß-D-glucopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 6)}-[ß-D-xylopyranosyl-(1 → 3)]-[α-L-rhamnopyranosyl-(1 → 2)]-ß-D-glucopyranosyl-(2E,6E)-farnes-1-ol. These results represent a contribution to the chemotaxonomy of the genus Eriocoelum highlighting farnesol glycosides as chemotaxonomic markers of the subfamily of Sapindoideae in the family of Sapindaceae.

Triterpenoid saponins from root bark of Zanha golungensis (Sapindaceae).

The chemical investigation of the methanolic extract from root bark of Zanha golungensis Hiern led to the isolation of five new and one known triterpenoid saponins. Their structures were elucidated by full analysis of their spectroscopic data and by partial hydrolysis. These glycosides contain zanhic acid as aglycone, a rare oleanane-type triterpenoid found in species belonging to Sapindaceae, Caryophyllaceae, Asteraceae, and Fabaceae. Two new saponins are esterified saponins by 3,3-dimethylacryloyl and 3-hydroxy-2-methyl-butanoyl residues located on the sugar part. The new compounds were named zanhasaponins D-H following previous isolation of similar compounds from Zanha africana.

Acylated oleanane-type saponins from Ganophyllum giganteum.

Five oleanane-type saponins, 3-O-ß-D-glucuronopyranosylzanhic acid 28-O-ß-D-xylopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-(4-O-acetyl)-ß-D-fucopyranosyl ester (1), 3-O-ß-D-glucopyranosylzanhic acid 28-O-ß-D-xylopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-(4-O-acetyl)-ß-D-fucopyranosyl ester (2), zanhic acid 28-O-ß-D-xylopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-(4-O-acetyl)-ß-D-fucopyranosyl ester (3), zanhic acid 28-O-α-L-rhamnopyranosyl-(1→2)-4-O-[(3'-hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyroyloxy]-ß-D-fucopyranosyl ester (4), medicagenic acid 28-O-α-L-rhamnopyranosyl-(1→2)-4-O-[(3'-hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyroyloxy]-ß-D-fucopyranosyl ester (5), were isolated from the root barks of Ganophyllum giganteum. Compounds 4 and 5 possessed an unusual substitution of the C-4 position of the ß-D-fucopyranosyl moiety by a C10 ester group formed by two symmetrical C5 nilic acid. From a chemotaxonomic point of view, their structures are in accordance with the previous saponins isolated from the Doratoxyleae tribe of the Sapindaceae family. Their cytotoxicity and anti-inflammatory activity were also evaluated.

Acylated triterpene saponins from the roots of Securidaca longepedunculata.

Four triterpene saponins, 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-[(6-O-acetyl)-beta-D-glucopyranosyl-(1-->3)]-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-galactopyranosyl-(1-->3)]-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, and 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-[alpha-L-arabinopyranosyl-(1-->4)]-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, were isolated from the roots of Securidaca longepedunculata, together with three known compounds. Their structures were established mainly by 2D NMR techniques and mass spectrometry.

Saponins from the roots of Nylandtia spinosa.

From the roots of Nylandtia spinosa, four new triterpene saponins, 3- O-beta- d-glucopyranosylpresenegenin 28- O-beta- d-galactopyranosyl-(1-->4)-[alpha- l-arabinopyranosyl-(1-->3)]-beta- d-xylopyranosyl-(1-->4)-[beta- d-apiofuranosyl-(1-->3)]-alpha- l-rhamnopyranosyl-(1-->2)-beta- d-fucopyranosyl ester ( 1), 3- O-beta- d-glucopyranosylpresenegenin 28- O-beta- d-galactopyranosyl-(1-->4)-[alpha- l-arabinopyranosyl-(1-->3)]-beta- d-xylopyranosyl-(1-->4)-alpha- l-rhamnopyranosyl-(1-->2)-beta- d-fucopyranosyl ester ( 2), 3- O-beta- d-glucopyranosylpresenegenin 28- O-beta- d-apiofuranosyl-(1-->4)-[beta- d-galactopyranosyl-(1-->2)]-beta- d-xylopyranosyl-(1-->4)-alpha- l-rhamnopyranosyl-(1-->2)-beta- d-fucopyranosyl ester ( 3), and 3- O-beta- d-glucopyranosylpresenegenin 28- O-beta- d-apiofuranosyl-(1-->3)-beta- d-xylopyranosyl-(1-->4)-alpha- l-rhamnopyranosyl-(1-->2)-beta- d-fucopyranosyl ester ( 4), were isolated, together with the known tenuifolin. Their structures were established mainly by 2D NMR techniques and mass spectrometry. Compounds 1- 4 were evaluated for cytotoxicity against HCT 116 and HT-29 human colon cancer cells, but were inactive (IC50 > 5 microg/mL).

Acylated triterpenoid saponins from the stem bark of Foetidia africana.

Nine new acylated triterpenoid saponins (4-12) were isolated from the stem bark of Foetidia africana. They all possess barringtogenol C as the aglycone, esterified by acetic and/or isovaleric acids. The sugar chain consists of up to three units: D-glucuronic acid (GlcUA) linked to C-3 of the aglycone and substituted by D-galactose (Gal) (at GlcUA C-2) and/or L-rhamnose (Rha) (at GlcUA C-4). The structures were established by acid and alkaline hydrolysis, by NMR experiments including (1)H-(1)H (COSY, HOHAHA, ROESY) and (1)H-(13)C (HSQC, HMBC) spectroscopy, and by mass spectrometry (ESIMS, ESIMS(n)).

Acylated preatroxigenin glycosides from Atroxima congolana.

Six new acylated bisdesmosidic preatroxigenin saponins named atroximasaponins E1, E2 (1, 2), F1, F2 (3, 4), and G1, G2 (5, 6) were isolated as three inseparable mixtures of the trans- and cis-p-methoxycinnamoyl derivatives, from the roots of Atroxima congolana. Their structures were established through extensive NMR spectroscopic analysis as 3-O-beta-D-glucopyranosylpreatroxigenin-28-O-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->3)]-[4-O-trans-p-methoxycinnamoyl]-beta-D-fucopyranoside (atroximasaponin E1, 1), and its cis-isomer, atroximasaponin E2 (2), 3-O-beta-D-glucopyranosylpreatroxigenin-28-O-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-[6-O-acetyl-beta-D-glucopyranosyl-(1-->3)]-[4-O-trans-p-methoxycinnamoyl]-beta-D-fucopyranoside (atroximasaponin F1, 3), and its cis-isomer, atroximasaponin F2 (4), 3-O-beta-D-glucopyranosylpreatroxigenin-28-O-beta-D-apiofuranosyl-(1-->3)-[alpha-l-rhamnopyranosyl-(1-->2)]-[4-O-trans-p-methoxycinnamoyl]-beta-D-fucopyranoside (atroximasaponin G1, 5), and its cis-isomer, atroximasaponin G2 (6), respectively.

Novel acylated triterpene glycosides from Muraltia heisteria.

Four new acylated triterpene glycosides (1-4) have been isolated as two inseparable mixtures of the trans- and cis-3,4,5-trimethoxycinnamoyl derivatives (1,2 and 3,4) from the roots of Muraltia heisteria. The structures of these compounds were elucidated by various 1D and 2D NMR techniques, including (1)H and (13)C, COSY, NOESY, HSQC, TOCSY, and HMBC experiments and FABMS. Compounds 3 and 4 were shown to be cytotoxic in a human colon cancer cell line but did not show any ability to potentiate in vitro cisplatin cytotoxicity.

Three new triterpene saponins from two species of Carpolobia.

Three new acetylated triterpene saponins 1-3 were isolated from the roots of Carpolobia alba and C. lutea. Their structures were established mainly by 2D NMR techniques as 3-O-beta-D-glucopyranosylpresenegenin-28-O-beta-D-galactopyranosyl-(1-->4)-[beta-D-xylopyranosyl-(1-->3)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-(3,4-di-O-acetyl)-beta-D-fucopyranosyl ester, 3-O-beta-D-glucopyranosylpresenegenin-28-O-beta-D-galactopyranosyl-(1-->4)-[alpha-L-arabinopyranosyl-(1-->3)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-(3,4-di-O-acetyl)-beta-D-fucopyranosyl ester, and 3-O-beta-D-glucopyranosylpresenegenin-28-O-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-(3,4-di-O-acetyl)-beta-D-fucopyranosyl ester, respectively.

Antiplasmodial activity of alkaloids from various strychnos species.

The in vitro antiplasmodial activities of 69 alkaloids from various Strychnos species were evaluated against chloroquine-resistant and chloroquine-sensitive lines of Plasmodium falciparum. The compounds, comprising mainly indolomonoterpenoid alkaloids, exhibited a wide range of biological potencies in the antiplasmodial assays. The most active alkaloids were also tested for cytotoxicity against HCT-116 colon cancer cells to determine their antiplasmodial selectivity. As a result of these studies, structure-activity relationships for these alkaloids have begun to emerge. Alkaloids presenting four types of bisindole skeleton exhibited potent and selective activities against Plasmodium. They were sungucine-type (IC(50) values ranging from 80 nM to 10 microM), longicaudatine-type (IC(50) values ranging from 0.5 to 10 microM), matopensine-type (IC(50) values ranging from 150 nM to 10 microM), and usambarine-type alkaloids. Within the last structural type, isostrychnopentamine (49) and ochrolifuanine A (46) were found to be active against chloroquine-sensitive and -resistant strains (IC(50) values of 100-150 and 100-500 nM, respectively), and dihydrousambarensine (51) exhibited a 30-fold higher activity against the chloroquine-resistant strain (IC(50) = 32 nM) than against the chloroquine-sensitive one.