Lasianosides F-I: A New Iridoid and Three New Bis-Iridoid Glycosides from the Leaves of Lasianthus verticillatus (Lour.) Merr.

A series of iridoid glycosides were isolated from the leaves of Lasianthus verticillatus (Lour.) Merr., belonging to family Rubiaceae. A new iridoid glycoside, lasianoside F (1), and three new bis-iridoid glycosides, lasianosides G-I (2-4), together with four known compounds (5-8) were isolated. The structures were established by spectroscopic methods, including 1D and 2D NMR experiments (1H, 13C, DEPT, COSY, HSQC, HMBC, and NOESY) in combination with HR-ESI-MS and CD spectra.

Lasianosides A-E: New Iridoid Glucosides from the Leaves of Lasianthus verticillatus (Lour.) Merr. and Their Antioxidant Activity.

The genus Lasianthus (Rubiaceae) consists of approximately 180 species, of which the greatest species diversity is found in tropical Asia. Some of the Lasianthus species have been used in folk medicine to treat tinnitus, arthritis, fever, and bleeding. Lasianthus verticillatus (Lour.) Merr. (Syn. Lasianthus trichophlebus auct. non Hemsl.) is a shrub, branchlets terete about 1.5-3 m in height. This paper studies the chemical composition of the leaves of L. verticillatus for the first time, which resulted in the isolation of five undescribed iridoid glucosides, lasianosides A-E (1-5), together with three known compounds (6-8). The undescribed structures of isolated compounds (1-5) were characterized by physical and spectroscopic data analyses, including one-dimensional (1D) and two-dimensional (2D) NMR, IR, UV, and high-resolution electrospray ionization mass spectra (HR-ESI-MS). Furthermore, the electronic circular dichroism data determined the absolute configurations of the new compounds. The free radical scavenging properties of isolated compounds was assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and their cytotoxicity was assessed toward human lung cancer cell line A549 by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Among the isolated compounds, 3 and 4 displayed potent radical scavenging activities with IC50 values of 30.2 ± 1.8 and 32.0 ± 1.2 µM, which were comparable to that of Trolox (29.2 ± 0.39 µM), respectively, while 5 possessed moderate activity with an IC50 value of 46.4 ± 2.3 µM. None of the isolated compounds exerted cytotoxicity against human cell line A549. As a result, lasianosides C, D, and E have the potential to be non-toxic safe antioxidant agents.

Crotocascarins I-K: Crotofolane-Type Diterpenoids, Crotocascarin γ, Isocrotofolane Glucoside and Phenolic Glycoside from the Leaves of Croton cascarilloides.

From the 1-BuOH-soluble fraction of a methanol (MeOH) extract of the leaves of Croton cascarilloides, crotofolanes: crotocascarins I-K, nor-crotofolane: crotocascarin γ, isocrotofolane glucoside and phenolic glycoside were isolated by a combination of various separation techniques. Their structures were elucidated mainly from the NMR spectroscopic evidence. The structure of crotocascarin K was first elucidated by spectroscopic analysis and then was confirmed by X-ray crystallographic analysis. Its absolute structure was finally determined by the modified Mosher's method. Isocrotofolane glucoside was found to possess a new skeleton, however, its absolute structure remains to be determined.

Nitrile-containing phenolic glucosides from the leaves of Glochidion acuminatum.

From the EtOAc-soluble fraction of a MeOH extract of the leaves of Glochidion acuminatum, six new compounds along with five known ones were isolated. The structures of the new compounds were elucidated to be two gallates, a p-hydroxybenzoate and an (S)-2-(4-hydroxycyclohex-1-en-1-yl)acetate of a nitrile-containing phenolic glucoside, methyl 2-(2-hydroxyphenyl)acetate ß-D-glucopyranoside, and (S)-methyl 2-[4-sulfooxycyclohex-1-en-1-yl]acetate on the basis of spectroscopic evidence.

Schoepfiajasmins A-H: C-glycosyl dihydrochalcones, dihydrochalcone glycoside, C-glucosyl flavanones, flavanone glycoside and flavone glycoside from the branches of Schoepfia jasminodora.

From the branches of Schoepfia jasminodora collected in Okinawa, three new dihydrochalcone C-glycosides, one dihydrochalcone di-O-glucopyranoside, two flavanone C-glycosides, one flavanone O-glycoside and one flavone O-glycoside were isolated. Their structures were elucidated by extensive study of one- and two-dimensional NMR spectroscopic data.

Eight new diterpenoids and two new nor-diterpenoids from the stems of Croton cascarilloides.

From the stems of Croton cascarilloides, eight new diterpenoids, named crotocascarins A-H (1-8), having a crotofolane skeleton were isolated along with two new nor-diterpenoids (9 and 10), named crotocascarins α and ß, derived through rearrangement of the crotofolane skeleton. The structures of these compounds were elucidated by means of extensive one- and two-dimensional NMR spectroscopic analyses. The absolute structures of the diterpene moiety were determined by application of the circular dichroism (CD) rule for the γ-lactone ring. The relative structures of the two crotofolanes (1 and 2) and one rearranged compound (9) were confirmed by X-ray crystallographic analyses. Compounds 1, 2 and 9 possessed 2-methylbutyric acid in their molecules, the absolute configuration of which was found to be 2S by comparison of its HPLC behavior with that of an authentic sample. Therefore, the absolute structures of these crotocascarins (1, 2 and 9) were unambiguously determined. The absolute structures of crotofolanes are reported for the first time in this paper.

Tareciliosides N-S: further cycloartane saponins from the leaves of Tarenna gracilipes, and cytotoxicity of saponins and triterpenes.

Six cycloartane glycosides, named tareciliosides N-S, and a known iridoid glucoside, ixoroside, were isolated in further extensive studies on the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Tarenna gracilipes. From the EtOAc-soluble fraction, three known triterpenes were isolated. Their toxicities toward A549 and Leishmania major trypanosome protozoa were assayed. Triterpenes were selectively active in the two organisms.

Microtropins A-I: 6'-O-(2″S,3″R)-2″-ethyl-2″,3″-dihydroxybutyrates of aliphatic alcohol ß-D-glucopyranosides from the branches of Microtropis japonica.

From the branches of Microtropis japonica (Celastraceae), nine aliphatic glucosides, named microtropins A-I, were isolated. The 6-position of glucose was esterified with (2S,3R)-2-ethyl-2,3-dihydroxybutyric acid. Microtropins A-D contained a rare natured product nitrile functional group in their aglycones. The absolute structures of the (2S,3R)-2-ethyl-2,3-dihydroxybutyric acid moiety and aglycone of microtropin A were determined by an X-ray crystallographic method.

Glucosylated sesquiterpene alcohols from Fraxinus griffithii.

Phytochemical investigation of the leaves of Fraxinus griffithii has led to the isolation of two new glucosylated acyclic sesquiterpene alcohols, griffithosides D (1) and E (2), along with iridoid and secoiridoid glycosides. The molecular structures of these compounds were elucidated using NMR, MS and other spectroscopic techniques, as well as comparison with literature data. The isolated compounds were tested for radical-scavenging activity and cytotoxicity against A549 human lung adenocarcinoma cells and Leishmania major parasites.

Three new aliphatic glycosides from the leaves of Antidesma japonicum Sieb. et Zucc.

From the 1-BuOH-soluble fraction of an MeOH extract of leaves of Antidesma japonicum, three new aliphatic glycosides, α-L-arabinofuranosyl-(1 → 6)-ß-D-glucopyranosides of (6R,9R)-megastigma-4,7-dien-9-ol-3-one, (Z)-hex-3-en-1-ol, and methyl 2-hydroxy-2-(1'-hydroxyethyl)pentanoate 1'-O-ß-D-glucopyranoside, were isolated, along with seven known compounds.

Annonamine, a new aporphine alkaloid from the leaves of Annona muricata.

Atypical Parkinsonism in the Caribbean Island Guadeloupe is thought to be associated with the consumption of plants of the Annonaceae family, especially Annona muricata (soursop). In this study, a new aporphine alkaloid named annonamine (1) was isolated from the leaves of A. muricata L. together with four known benzylisoquinoline alkaloids (2-5). The structures of the isolated compounds were elucidated by the spectroscopic method.

A new iridoid glycoside and NO production inhibitory activity of compounds isolated from Russelia equisetiformis.

From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Russelia equisetiformis, one new iridoid glucoside was isolated along with 24 known compounds, comprising iridoids and iridoid glucosides, phenyl propane glucosides, phenyl ethanoids, lignan glucosides, and flavonoid glucosides. The structure of the new compound was elucidated to be 10-O-cinnamoyl sinuatol. Of the 25 compounds isolated, rehmaglutin B exhibited moderate inhibitory activity toward NO production, which was not associated with cytotoxicity.

Myrseguinosides A-E, five new glycosides from the fruits of Myrsine seguinii.

Chemical investigation of the 1-BuOH soluble fraction of the dried fruits of Myrsine seguinii (Myrsinaceae) led to the isolation of five new glycosides, named myrseguinosides A-E (1-5), together with eight known compounds (6-13). The absolute structures of the new glycosides were elucidated by spectroscopic and chemical analyses to be a monoterpene glucoside (1), two flavonol glycosides (2, 3), and two oleanane-type triterpene saponins (4, 5). Myrseguinosides B (2), D (4), and E (5) exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and growth inhibitory activity toward human cancer cells, respectively.

Tareciliosides H-M: further cycloartane glycosides from leaves of Tarenna gracilipes.

From the 1-BuOH-soluble fraction of a MeOH extract of leaves of Tarenna gracilipes, collected in Okinawa, six further new cycloartane glycosides, named tareciliosides H-M (1-6), were isolated. Their structures were established through a combination of spectroscopic analyses.

Gallates of isoorientin and (2S)-1,2-propanediol glucoside from the leaves of Schoepfia jasminodora.

From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Schoepfia jasminodora collected from Okinawa Island, two new galloyl esters and 15 known compounds were isolated. The structures of the new compounds were elucidated by spectroscopic analysis to be isoorientin 4″-O-gallate and (2S)-1,2-propanediol 1-O-ß-D: -glucopyranoside 6'-O-gallate. The compounds possessing galloyl or cathechol moieties showed equal radical scavenging activity.

Tricalysionoside A, a megastigmane gentiobioside, sulfatricalysines A-F, and tricalysiosides X-Z, ent-kaurane glucosides, from the leaves of Tricalysia dubia.

Further isolation work on the water-soluble fraction of a MeOH extract of Tricalysia dubia afforded one new megastigmane gentiobioside, named tricalysionoside A (1), and three sulfates, named sulfatricalysines A-C (2-4). Extensive isolation work on the 1-BuOH-soluble fraction of a MeOH extract of T. dubia yielded sulfatricalysines D-F (5-7) and three new ent-kaurane glucosides, named tricalysiosides X-Z (8-10). The structures of the new compounds were elucidated by analyses of one- and two-dimensional NMR spectroscopic data. The absolute stereochemistry of tricalysionoside A (1) was established by modified Mosher's method.

Prenylated flavonoid glucoside and two aliphatic alcohol glycosides from the leaves of Euodia meliaefolia (Hance) Benth.

A new prenylated flavonoid (1) and two new aliphatic glycosides (2, 3) have been isolated from leaves of Euodia meliaefolia (Hance) Benth., together with three known compounds, (2R,3R)-5,7,4'-trihydroxy-8-(3-methylbut-2-enyl)dihydroflavonol 7-O-ß-D: -glucopyranoside (phellamurin) (4), (2R,3R)-dihydroquercetin 3'-O-ß-D: -glucopyranoside (5), and (7R,8S)-dihydrodiconiferyl alcohol 4-O-ß-D: -glucopyranoside (6). Their structures were determined on the basis of the results of spectroscopic analysis.

A glycerol α-D-glucuronide and a megastigmane glycoside from the leaves of Guettarda speciosa L.

From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Guettarda speciosa L., two new compounds (1, 2) were isolated together with six known compounds. Spectroscopic analysis of 1 and 2 established their structures to be derivatives of a glycerol α-glucuronide and a megastigmane glycoside, respectively. HPLC analysis of the hydrolyzate of 1 confirmed the presence of D-glucuronic acid in the structure, and the modified Mosher's method established the absolute structure of 2.

Flavonol glycosides from the leaves of Indigofera zollingeriana.

Two new flavonol glycosides were isolated from the 1-butanol (1-BuOH)-soluble fraction of a methanol (MeOH) extract of the leaves of Indigofera zollingeriana, along with four flavonol glycosides and three known megastigmane glucosides. The structures of the new compounds were elucidated by spectroscopic analyses as kaempferol 3-O-ß-D-(2"-O-ß-D-apiofuranosyl)glucopyranoside 7-O-α-L-rhamnopyranoside and 3-O-ß-D-(2"-O-ß-D-apiofuranosyl, 6"-O-α-L-rhamnopyranosyl)glucopyranoside 7-O-α-L-rhamnopyranoside.

Crotonionosides A-G: megastigmane glycosides from leaves of Croton cascarilloides Räuschel.

From the 1-BuOH-soluble fraction of a MeOH extract of leaves of Croton cascarilloides, collected in Okinawa, Japan, seven megastigmane glycosides, named crotonionosides A-G, were isolated together with three known megastigmane glucosides, dendranthemosides A and B, and citroside A. This structures were elucidated by a combination of spectroscopic analyses, HPLC analyses, and application of the modified Mosher's method.