Phytochemistry (v.70, #9)

Chemistry and biological activity of azoprenylated secondary metabolites by Salvatore Genovese; Massimo Curini; Francesco Epifano (1082-1091).
N-Prenyl natural products represent a family of rare secondary metabolites. Although few structures have been isolated and characterized, these alkaloids display interesting and valuable biological properties, mainly as anti-microbial, anti-viral, anti-inflammatory and anti-cancer agents. In this comprehensive review the structures are divided by chemical categories, with an indication of their natural sources and biological activities described. N-Prenyl secondary metabolites (isopentenylazo-, geranylazo-, farnesylazo- and their biosynthetic derivatives) represent a family of extremely rare natural products. Only in recent years have these alkaloids been recognized as interesting and valuable biologically active secondary metabolites. To date about 35 alkaloids have been isolated from plants mainly belonging to the Rutaceae family, and from fungi, bacteria, and/or obtained by chemical synthesis. These metabolites comprise anthranilic acid derivatives, diazepinones, and indole, and xanthine alkaloids. Many of the isolated prenylazo secondary metabolites and their semisynthetic derivatives are shown to exert valuable in vitro and in vivo anti-cancer, anti-inflammatory, anti-bacterial, anti-viral, and anti-fungal effects. The aim of this comprehensive review is to examine the different types of prenylazo natural products from a chemical, phytochemical and biological perspective.
Keywords: Alkaloids; Biological activity; Biosynthesis; Chemical synthesis; Microbial secondary metabolites; Prenylazo secondary metabolites; Rutaceae;

Berberine bridge enzyme catalyzes the six electron oxidation of (S)-reticuline to dehydroscoulerine by Andreas Winkler; Martin Puhl; Hansjörg Weber; Toni M. Kutchan; Karl Gruber; Peter Macheroux (1092-1097).
Under physiological conditions berberine bridge enzyme catalyzes the oxidation of (S)-reticuline to (S)-scoulerine. With a lower rate of conversion (S)-scoulerine serves as a substrate for further oxidation to the protoberberine alkaloid dehydroscoulerine.Berberine bridge enzyme catalyzes the stereospecific oxidation and carbon–carbon bond formation of (S)-reticuline to (S)-scoulerine. In addition to this type of reactivity the enzyme can further oxidize (S)-scoulerine to the deeply red protoberberine alkaloid dehydroscoulerine albeit with a much lower rate of conversion. In the course of the four electron oxidation, no dihydroprotoberberine species intermediate was detectable suggesting that the second oxidation step leading to aromatization proceeds at a much faster rate. Performing the reaction in the presence of oxygen and under anoxic conditions did not affect the kinetics of the overall reaction suggesting no strict requirement for oxygen in the oxidation of the unstable dihydroprotoberberine intermediate. In addition to the kinetic characterization of this reaction we also present a structure of the enzyme in complex with the fully oxidized product. Combined with information available for the binding modes of (S)-reticuline and (S)-scoulerine a possible mechanism for the additional oxidation is presented. This is compared to previous reports of enzymes ((S)-tetrahydroprotoberberine oxidase and canadine oxidase) showing a similar type of reactivity in different plant species.
Keywords: Eschscholzia californica; Protoberberine alkaloids; Berberine bridge enzyme; (S)-Tetrahydroprotoberberine oxidase; (S)-Reticuline; (S)-Scoulerine; Dehydroscoulerine;

Organoselenides from Nicotiana tabacum genetically modified to accumulate selenium by Adam J. Matich; Marian J. McKenzie; David A. Brummell; Daryl D. Rowan (1098-1106).
Four organoselenides, 2-(methylseleno)acetaldehyde, 2,2-bis(methylseleno)acetaldehyde, 4-(methylseleno)-(2E)-nonenal, and 4-(methylseleno)-(2E,6Z)-nonadienal, were identified in leaf extracts of tobacco (Nicotiana tabacum) that was genetically modified to overexpress genes for selenium accumulation, and treated with inorganic selenium. Nicotiana tabacum L. (tobacco) plants were transformed to overexpress a selenocysteine methyltransferase gene from the selenium hyperaccumulator Astragalus bisulcatus (Hook.) A. Gray (two-grooved milkvetch), and an ATP-sulfurylase gene from Brassica oleracea L. var. italica (broccoli). Solvent extraction of leaves harvested from plants treated with selenate revealed five selenium-containing compounds, of which four were identified by chemical synthesis as 2-(methylseleno)acetaldehyde, 2,2-bis(methylseleno)acetaldehyde, 4-(methylseleno)-(2E)-nonenal, and 4-(methylseleno)-(2E,6Z)-nonadienal. These four compounds have not previously been reported in nature.
Keywords: Nicotiana tabacum; Tobacco; Selenium; Volatiles; Methylselenocysteine; Selenocysteine methyltransferase; ATP-sulfurylase;

Gene expression changes related to the production of phenolic compounds in potato tubers grown under drought stress by Christelle M. André; Roland Schafleitner; Sylvain Legay; Isabelle Lefèvre; Carlos A. Alvarado Aliaga; Giannina Nomberto; Lucien Hoffmann; Jean-François Hausman; Yvan Larondelle; Danièle Evers (1107-1116).
The expression of 13 genes involved in the biosynthesis of polyphenols in potato tubers were investigated using real-time RT-PCR. Five cultivars presenting contrasting polyphenolic profiles were analysed and compared both under control and drought conditions. The expression of eight genes was coordinated and truly reflected at the metabolite level, providing important information on key genes, which could be exploited for the development of potato varieties with enhanced health benefits.Polyphenols represent a large family of plant secondary metabolites implicated in the prevention of various diseases such as cancers and cardiovascular diseases. The potato is a significant source of polyphenols in the human diet. In this study, we examined the expression of thirteen genes involved in the biosynthesis of polyphenols in potato tubers using real-time RT-PCR. A selection of five field grown native Andean cultivars, presenting contrasting polyphenol profiles, was used. Moreover, we investigated the expression of the genes after a drought exposure. We concluded that the diverse polyphenolic profiles are correlated to variations in gene expression profiles. The drought-induced variations of the gene expression was highly cultivar-specific. In the three anthocyanin-containing cultivars, gene expression was coordinated and reflected at the metabolite level supporting a hypothesis that regulation of gene expression plays an essential role in the potato polyphenol production. We proposed that the altered sucrose flux induced by the drought stress is partly responsible for the changes in gene expression. This study provides information on key polyphenol biosynthetic and regulatory genes, which could be useful in the development of potato varieties with enhanced health and nutritional benefits.
Keywords: Potato; Andean tuber; Solanum tuberosum; Antioxidant; Polyphenols; Chlorogenic acid; Gene expression; Real-time RT-PCR; PAL; Phenylpropanoid; Drought; Genotype;

Characterization of glycolytic initial metabolites and enzyme activities in developing sunflower (Helianthus annuus L.) seeds by M. Adrián Troncoso-Ponce; Nicholas J. Kruger; George Ratcliffe; Rafael Garcés; Enrique Martínez-Force (1117-1122).
Glycolytic pathway in sunflower seeds has been characterized during storage lipid synthesis. An incomplete glycolytic route was found in plastids pointing to phosphoenolpyruvate as candidate carbon source for lipid biosynthesis.Unlike other oilseeds (e.g. Arabidopsis), developing sunflower seeds do not accumulate a lot of starch and they rely on the sucrose that comes from the mother plant to synthesise lipid precursors. Between 10 and 25 days after flowering (DAF), when sunflower seeds form and complete the main period of storage lipid synthesis, the sucrose content of seeds is relatively constant. By contrast, the glucose and fructose content falls from day 20 after flowering and it is always lower than that of sucrose, with glucose being the minor sugar at the end of the seed formation. By studying the apparent kinetic parameters and the activity of glycolytic enzymes in vitro, it is evident that all the components of the glycolytic pathway are present in the crude seed extract. However, in isolated plastids important enzymatic activities are missing, such as the glyceraldehyde-3-phosphate dehydrogenase, involved in the conversion of glyceraldehyde 3-phosphate into 1,3-biphospho-glycerate, or the enolase that converts 2-phosphoglycerate into phosphoenolpyruvate. Hence, phosphoenolpyruvate or one of its derivatives, like pyruvate and malate from the cytosol, may be the primary carbon sources for lipid biosynthesis. Accordingly, the glucose-6-P imported into the plastid is likely to be used in the pentose phosphate pathway to produce the reducing power for lipid biosynthesis in the form of NADPH. Data from crude seed extracts indicate that enolase activity increased during seed formation, from 16 days after flowering, and that this activity was well correlated with the period of storage lipid synthesis. In addition, while the presence of some glycolytic enzymes increased during lipid synthesis, others decreased, remained constant, or displayed irregular temporal behaviour.
Keywords: Helianthus annuus; Glycolysis; Seeds; Plastids; Fatty acids; Storage lipids;

Localization of enzymes of artemisinin biosynthesis to the apical cells of glandular secretory trichomes of Artemisia annua L. by Mikael E. Olsson; Linda M. Olofsson; Ann-Louise Lindahl; Anneli Lundgren; Maria Brodelius; Peter E. Brodelius (1123-1128).
The initial enzymes of artemisinin biosynthesis, i.e. amorpha-4,11-diene synthase, amorpha-4,11-diene hydroxylase and artemisinic aldehyde Δ11(13) reductase are expressed in apical cells of glandular trichomes of Artemisia annua. No expression of these ezymes is observed in the photosynthetic sub-apical cells. Artemisinin appears to be biosynthesized exclusively in apical cells.A method based on the laser microdissection pressure catapulting technique has been developed for isolation of whole intact cells. Using a modified tissue preparation method, one outer pair of apical cells and two pairs of sub-apical, chloroplast-containing cells, were isolated from glandular secretory trichomes of Artemisia annua. A. annua is the source of the widely used antimalarial drug artemisinin. The biosynthesis of artemisinin has been proposed to be located to the glandular trichomes. The first committed steps in the conversion of FPP to artemisinin are conducted by amorpha-4,11-diene synthase, amorpha-4,11-diene hydroxylase, a cytochrome P450 monooxygenase (CYP71AV1) and artemisinic aldehyde Δ11(13) reductase. The expression of the three biosynthetic enzymes in the different cell types has been studied. In addition, the expression of farnesyldiphosphate synthase producing the precursor of artemisinin has been investigated. Our experiments showed expression of farnesyldiphosphate synthase in apical and sub-apical cells as well as in mesophyl cells while the three enzymes involved in artemisinin biosynthesis were expressed only in the apical cells. Elongation factor 1α was used as control and it was expressed in all cell types. We conclude that artemisinin biosynthesis is taking place in the two outer apical cells while the two pairs of chloroplast-containing cells have other functions in the overall metabolism of glandular trichomes.
Keywords: Amorpha-4,11-diene synthase; Apical cells; Artemisia annua; Artemisinin biosynthesis; Immunogold labeling; Laser microdissection pressure catapulting; Mesophyl cells; Glandular secretory trichomes; Silver enhancement; Sub-apical cells;

1-Methylindolyl-3-acetaldoxime and 1′-methylindolyl-3′-acetothiohydroxamic acid are transformed to 1′-methylglucobrassicin but not to phytoalexins.Although several biosynthetic intermediates in pathways to cruciferous phytoalexins and phytoanticipins are common, questions regarding the introduction of substituents at N-1 of the indole moiety remain unanswered. Toward this end, we investigated the potential incorporations of several perdeuterated d- and l-1′-methoxytryptophans, d- and l-tryptophans and other indol-3-yl derivatives into pertinent phytoalexins and phytoanticipins (indolyl glucosinolates) produced in rutabaga (Brassica napus L. ssp. rapifera) roots. In addition, we probed the potential transformations of quasi-natural compounds, these being analogues of biosynthetic intermediates that might lead to “quasi-natural” products (products similar to natural products but not produced under natural conditions). No detectable incorporations of deuterium labeled 1′-methoxytryptophans into phytoalexins or glucobrassicin were detected. l-tryptophan was incorporated in a higher percentage than d-tryptophan into both phytoalexins and phytoanticipins. However, in the case of the phytoalexin rapalexin A, both d- and l-tryptophan were incorporated to the same extent. Furthermore, the transformations of both 1′-methylindolyl-3′-acetaldoxime and 1′-methylindolyl-3′-acetothiohydroxamic acid (quasi-natural products) into 1′-methylglucobrassicin but not into phytoalexins suggested that post-aldoxime enzymes in the biosynthetic pathway of indolyl glucosinolates are not substrate-specific. Hence, it would appear that the 1-methoxy substituent of the indole moiety is introduced downstream from tryptophan and that the post-aldoxime enzymes of the glucosinolate pathway are different from the enzymes of the phytoalexin pathway. A higher substrate specificity of some enzymes of the phytoalexin pathway might explain the relatively lower structural diversity among phytoalexins than among glucosinolates.
Keywords: Brassica napus L. ssp. rapifera; Brassicaceae; Rutabaga; Brassinin; Crucifer; Glucobrassicin; Indolyl-3-acetaldoxime; Indolyl-3-acetothiohydroxamic acid; Indolyl glucosinolate; Rapalexin A; Rutalexin; Phytoalexin; 1′-Methoxytryptophan;

Molecular and biochemical evolution of maize terpene synthase 10, an enzyme of indirect defense by Tobias G. Köllner; Jonathan Gershenzon; Jörg Degenhardt (1139-1145).
The maize terpene synthase TPS10 forms volatile terpenes with an important function in plant defense. Identification and functional characterization of apparent orthologs in related species indicate the conservation of this defense trait and elucidates structure–function relationships of the TPS10 active site.Maize plants attacked by lepidopteran larvae emit a volatile mixture that consists mostly of the sesquiterpene olefins, (E)-α-bergamotene and (E)-β-farnesene. These volatiles are produced by the herbivore-induced terpene synthase TPS10 and attract natural enemies to the damaged plants. A survey of volatiles in maize lines and species of teosinte showed that the TPS10 products (E)-α-bergamotene and (E)-β-farnesene are consistently induced by herbivory, indicating that release of TPS10 volatiles is a defense trait conserved among maize and its wild relatives. Sequence comparison of TPS10 from maize and its apparent orthologs from four teosinte species demonstrated stabilizing selection on this defense trait. The teosinte volatiles and the enzymatic activity of the apparent TPS10 orthologs were not completely uniform but varied in the ratio of (E)-α-bergamotene to (E)-β-farnesene products formed. We identified a single amino acid in the active center which determines the ratio of (E)-α-bergamotene to (E)-β-farnesene and has changed during the evolution of maize and teosinte species. Feeding experiments with the substrate (Z,E)-farnesyl diphosphate revealed that this amino acid controls the rate of isomerization of the (E,E)-farnesyl carbocation intermediate to the (Z,E)-configuration.
Keywords: Zea mays; Teosinte; Sesquiterpene synthase; Terpene synthase reaction mechanism; β-Farnesene; α-Bergamotene; Molecular modeling; Site-directed mutagenesis;

Morphological, chemical and genetic differentiation of two subspecies of Cistus creticus L. (C. creticus subsp. eriocephalus and C. creticus subsp. corsicus) by Julien Paolini; Alessandra Falchi; Yann Quilichini; Jean-Marie Desjobert; Marie-Cecile De Cian; Laurent Varesi; Jean Costa (1146-1160).
Differentiation of two subspecies of Cistus creticus L. (C. creticus subsp. eriocephalus and C. creticus subsp. corsicus) from Corsica and Sardinia Islands using morphological characteristics (leaf trichome), essential oil production, volatile fraction composition (HS-SPME) and genetic data (inter-simple sequence repeat). Cistus creticus L., an aromatic species from the Mediterranean area, contains various diterpenes bearing the labdane skeleton. The production of essential oil from this species has potential economic value, but so far, it has not been optimized. In order to contribute to a better knowledge of this species and to its differentiation, the morphological characters, volatile chemical composition and genetic data of two subspecies (C. creticus subsp. eriocephalus and C. creticus subsp. corsicus) were investigated. The leaf trichomes were studied using scanning electron microscopy. The chemical composition of Corsican essential oil (C. creticus subsp. corsicus) has been reported using GC, GC/MS and 13C NMR; the main constituents were oxygenated labdane diterpenes (33.9%) such as 13-epi-manoyl oxide (18.5%). Using plant material (54 samples) collected from 18 geographically distinct areas of the islands of Corsica and Sardinia, the basis of variation in the headspace solid-phase microextraction volatile fraction and an inter-simple sequence repeat genetic analysis were also examined. It was shown that the two subspecies of C. creticus differed in morphology, essential oil production, volatile fraction composition and genetic data.
Keywords: Cistus creticus; SEM; Labdane diterpene; GC/MS; HS-SPME; ISSR; Statistical analysis;

Isopimarane diterpenoids from Aeollanthus rydingianus and their antimicrobial activity by Patricia Rijo; Maria Fátima Simões; Aida Duarte; Benjamín Rodríguez (1161-1165).
The diterpenoids 19-acetoxy-7,15-isopimaradien-3β-ol (4) and 7,15-isopimaradien-19-ol (5), two of the six isopimaranes isolated from the plant, showed significant antimicrobial activity against Staphylococcus aureus and Enterococcus hirae.Four acyloxy-isopimarane derivatives along with two known isopimarane diterpenoids, the flavone cirsimaritin and the sterols β-sitosterol and stigmasterol were isolated from the aerial parts of Aeollanthus rydingianus. The structures of the compounds were established on the basis of spectroscopic analysis and chemical evidence. The isolated substances were screened for antimicrobial activity against Gram-positive and Gram-negative bacteria and a yeast strain. 19-Acetoxy-7,15-isopimaradien-3β-ol and 7,15-isopimaradien-19-ol showed minimum inhibitory concentration (MIC) values of 3.90–15.62 μg/ml for Staphylococcus aureus and of 7.81 μg/ml for Enterococcus hirae.
Keywords: Aeollanthus rydingianus; Labiatae; Aerial parts; Isopimarane diterpenoids; Acyloxy-isopimarane derivatives; Antibacterial activity;

Oleanane-type triterpene oligoglycosides with pancreatic lipase inhibitory activity from the pericarps of Sapindus rarak by Toshio Morikawa; Yuanyuan Xie; Yasunobu Asao; Masaki Okamoto; Chihiro Yamashita; Osamu Muraoka; Hisashi Matsuda; Yutana Pongpiriyadacha; Dan Yuan; Masayuki Yoshikawa (1166-1172).
Oleanane-type triterpene oligoglycosides, rarasaponins I–III (13) and raraoside A (4) were isolated from the pericarps of Sapindus rarak DC. Among them, rarasaponins I (1, IC50  = 131 μM) and II (2, 172 μM), and raraoside A (4, 151 μM) inhibited pancreatic lipase activity.The methanolic extract from the pericarps of Sapindus rarak DC. was found to show pancreatic lipase inhibitory activity (IC50  = ca. 614 μg/mL). From the extract, oleanane-type triterpene oligoglycosides, rarasaponins I–III (13), and raraoside A (4), were isolated together with 13 known saponins and four known sesquiterpene glycosides. Among them, several saponin constituents including rarasaponins I (1, IC50  = 131 μM) and II (2, 172 μM), and raraoside A (4, 151 μM) inhibited pancreatic lipase activity, which were stronger than that of theasaponin E1 (270 μM).
Keywords: Sapindus rarak; Sapindaceae; Thai natural medicine; Oleanane-type triterpene oligoglycoside; Pancreatic lipase inhibitor;

Neural cell protective compounds isolated from Phoenix hanceana var. formosana by Yi-Pei Lin; Tai-Yuan Chen; Hsiang-Wen Tseng; Mei-Hsien Lee; Shui-Tein Chen (1173-1181).
Phoenix hanceana var. formosana is a plant endemic to Taiwan and has been shown to have potential medicinal properties. Here we use a bioassay system to identify specific bioactive compounds from plant extracts. In the bioassay, isovitexin, luteolin-7-O-β-d-glucopyranoside, and (+)-catechin were identified as potential compounds capable of protecting PC12 cells from 6-OHDA-induced apoptotic neurotoxicity.A platform for screening drugs for their ability to protect neuronal cells against cytotoxicity was developed. Nerve growth factor (NGF) differentiates PC12 cells into nerves, and these differentiated PC12 cells enter apoptosis when challenged with 6-hydroxydopamine (6-OHDA). A screening spectrophotometer was used to assay cytotoxicity in these cells; pretreatment with test samples allowed identification of compounds that protected against this neuronal cytotoxicity. The 95% ethanol extract of Phoenix hanceana Naudin var. formosana Beccari. (PH) showed potential neuroprotective activity in these assays. The PH ethanol extract was further fractionated by sequential partitioning with n-hexane, ethyl acetate (EtOAc), n-butanol (n-BuOH), and water. Subsequent rounds of assaying resulted in the isolation of ten constituents, and their structures were characterized by various spectroscopic techniques and identified by comparison with previous data as: isoorientin (1), isovitexin (2), veronicastroside (3), luteolin-7-O-β-d-glucopyranoside (4), isoquercitrin (5), tricin-7-neohesperidoside (6), tricin-7-O-β-d-gluco-pyranoside (7), (+)-catechin (8), (−)-epicatechin (9), and orientin 7-O-β-d-glucopyranoside (10). Among these compounds, isovitexin (2), luteolin-7-O-β-d-glucopyranoside (4) and (+)-catechin (8) showed significant neuroprotective activity in cell viability (WST-8 reduction), anti-apoptosis (Annexin V-FITC/propidium iodide double-labeled flow cytometry), and cellular ROS scavenging assays (besides isovitexin (2)), as well as a decreased caspase-8 activity in 6-OHDA-induced PC12 cells. Hence, isovitexin (2), luteolin-7-O-β-d-glucopyranoside (4), and (+)-catechin (8) protected PC12 cells from 6-OHDA-induced apoptotic neurotoxicity.
Keywords: Phoenix hanceana var. formosana; Palmae; 6-Hydroxydopamine; Neuroprotective activity; Isovitexin; Luteolin-7-O-β-d-glucopyranoside; (+)-Catechin; Antiapoptosis; Cellular ROS scavenging assay;

Four tetracyclic oxindole alkaloids and a taberpsychine derivative from a Malayan Tabernaemontana by Kuan-Hon Lim; Kooi-Mow Sim; Guan-Huat Tan; Toh-Seok Kam (1182-1186).
Four tetracyclic oxindole alkaloids, 7(R)- and 7(S)-geissoschizol oxindole (1 and 2), 7(R),16(R)- and 7(S),16(R)–19(E)-isositsirikine oxindole (3 and 4), in addition to a taberpsychine derivative, N(4)-demethyltaberpsychine (5), were isolated from the Malayan Tabernaemontana corymbosa and the structures were established using NMR and MS analysis.Four tetracyclic oxindole alkaloids, 7(R)- and 7(S)-geissoschizol oxindole (1 and 2), 7(R),16(R)- and 7(S),16(R)–19(E)-isositsirikine oxindole (3 and 4), in addition to a taberpsychine derivative, N(4)-demethyltaberpsychine (5), were isolated from the Malayan Tabernaemontana corymbosa and the structures were established using NMR and MS analysis.
Keywords: Oxindole alkaloids; Tabernaemontana; NMR; Plants;

Essential oil secretory cavities embedded in Eucalyptus leaves contain two non-volatile glucose monoterpene esters, cuniloside B and froggattiside A, in high proportions relative to the essential oils.The essential oils extracted from the embedded foliar secretory cavities of many Eucalyptus species are of economic value as pharmaceuticals and fragrance additives. Recent studies have indicated that Eucalyptus secretory cavities may not be exclusively involved in the biosynthesis and storage of essential oils. Therefore, we selected three species upon which to perform an examination of the contents of foliar secretory cavities: Eucalyptus froggattii, E. polybractea and E. globulus. This paper describes the isolation and structural characterization of two non-volatile glucose monoterpene esters, which we have named cuniloside B and froggattiside A, from within the secretory cavities of these species, and shows the presence of these compounds in solvent extracts of the leaves from two other species of Eucalyptus. Both compounds were found in high proportions relative to the essential oils extracted from the leaves. We propose that many other carbohydrate monoterpene esters previously isolated from bulk leaf extracts of various Eucalyptus species may also be localized within the non-volatile fraction of foliar secretory cavities.
Keywords: Eucalyptus froggattii; Eucalyptus polybractea; Myrtaceae; Kamarooka mallee; Blue mallee; Gland; Metabolomics; Monoterpene ester; Oleuropeic acid; Terpene;

Cytotoxic 16-β-[(d-xylopyranosyl)oxy]oxohexadecanyl triterpene glycosides from a Malagasy plant, Physena sessiliflora by Masaki Inoue; Kazuhiro Ohtani; Ryoji Kasai; Mayu Okukubo; Marta Andriantsiferana; Kazuo Yamasaki; Tohru Koike (1195-1202).
Eight triterpene glycosides were isolated from the leaves of Physena sessiliflora, and their structures were elucidated based on analysis of spectroscopic data. Among these compounds, the 16-β-[(d-xylopyranosyl)oxy]oxohexadecanyl triterpene glycoside, Physenoside S7, exhibited the strongest cytotoxic activity in the brine shrimp lethality assay.Brine shrimp lethality assay-guided separation of the MeOH extract of leaves of Physena sessiliflora, which is endemic to Madagascar, afforded eight triterpene glycosides, Physenoside S1–4 and 16-β-[(d-xylopyranosyl)oxy]oxohexadecanyl homologues, Physenoside S5–8. Structural elucidation of these compounds was based on both spectroscopic analyses and chemical properties. Physenoside S7 and S8 have significant cytotoxic activities in the brine shrimp lethality assay.
Keywords: Physena sessiliflora; Capparidaceae; Physenaceae; Physenoside; Triterpene glycoside; Cytotoxicity; 16-Hydroxy-oxohexadecanoic acid;