Two pentacyclic triterpenes from Rubia cordifolia

Rubicoumaric acid and rubifolic acid isolated from Rubia cordifolia have been shown to be 30-hydroxy-3β-p-hydroxycoumaryloxy-urs-12-ene-28-oic acid and 3β,30-dihydroxy-urs-12-ene-28-oic acid(30-hydroxyursolic acid) respectively on the basis of ¹H NMR, ¹³C NMR and mass spectral and chemical evidence.     

3-Oxo-friedelan-20α-OIC acid from gymnosporia emarginata

3-Oxo-friedelan-20α-oic acid, named as maytenonic (polpunonic) acid, has been isolated along with β-amyrin and sitosterol from Gymnosporia emarginata. ¹H and ¹³C NMR signals have been assigned for the structure. X-ray analysis of the single crystal confirmed that the carboxylic acid is α-oriented at C-20 and the D/E rings of this D:A-friedo-oleanane are in chair-chair conformation. ¹³C NMR data of the present compound also enabled the assignment of the C-20α- and β-methyl carbons in friedelin.     

Ovosäure,ein neues tridepsid aus der flechte Parmelia substygia

The structure of ovoic acid, a new tridepside from the lichen Parmelia substygia Ras. has been elucidated as 2′-O-methylgyrophoric acid by ¹³C and ¹H NMR, by UV spectroscopy and by hydrolysis to orsellinic and isoeverninic acids.     

Absolute configuration of ceriporic acids, the iron redox-silencing metabolites produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora

Ceriporic acids are a class of alk(en)ylitaconic acids produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora. The unique function of alkylitaconic acid is the redox silencing of the Fenton reaction system by inhibiting reduction of Fe³⁺. Ceriporic acids have an asymmetric centre at carbon-3, but absolute configuration has not been determined. We have isolated a series of ceriporic acids from the cultures of C. subvermispora, and measured their NMR spectra using a chiral shift reagent. In comparison with NMR spectra of (R)-(−)- and (S)-(+)-methylsuccinic acid and those of natural and chemically synthesized racemic mixtures of ceriporic acids, we have determined the absolute configuration of ceriporic acids as (R)-3-tetradecylitaconic acid (ceriporic acid A), (R)-3-hexadecylitaconic acid (ceriporic acid B) and (R,Z)-2-(hexadec-7-enyl)-3-itaconic acid (ceriporic acid C). We herein discuss their stereoselective biosynthetic pathway and the structural diversity of fungal secondary metabolites.     

3-Chlordivaricatsäure,ein neues depsid aus Thelomma-arten

The structure of 3-chlorodivaricatic acid, a new depside from the lichen Thelomma mammosum was elucidated by ¹H NMR, ¹³C NMR, mass and UV spectroscopy. The synthesis of 5-chlorodivaricatic acid is described.     

Sulphate ester of trans-4-hydroxypipecolic acid in seeds of Peltophorum

An acidic compound isolated from seed of the legume Peltophorum africanum has been characterised on the basis of FAB-MS, EIMS, ¹³C and ¹H NMR as trans-4-hydroxypipecolic acid-4-sulphate. This is the first naturally occurring sulphate ester of a non-protein amino acid to be described. The possible systematic significance of the distribution of the ester within Peltophorum and related genera is considered.     

Structures of verbascoside and orobanchoside,caffeic acid sugar esters from Orobanche rapum-genistae

The complete structural elucidation of the two caffeic acid sugar esters verbascoside and orobanchoside, has been realized by ¹H and ¹³C NMR studies. It has been demonstrated that verbascoside is β-(3′,4′-dihydroxyphenyl)ethyl-O-α-L-rhamnopyranosyl(1→3)-β-D-(4-O-caffeoyl)-glucopyranoside, and orobanchoside is β-hydroxy-β-(3′,4′-dihydroxyphenyl)-ethyl-O-α-L-rhamnopyranosyl(1→2)-β-D-(4-O-caffeoyl)-glucopyranoside.     

A diterpenoid from Elaeoselinum foetidum

A new diterpene acid has been isolated from the roots of Elaeoselinum foetidum. Its structure was established as ent-7α-senecioxy-15α-hydroxy-atis-16-en-19-oic acid by ¹H NMR and ¹³C NMR spectroscopic studies of its methyl ester derivative and confirmed by correlation with a margotianin derivative.     

Structure des acides isomuronique et neuropogolique,nouveaux acides aliphatiques du lichen Neuropogon trachycarpus

The structures of two new aliphatic acids, isomuronic and neuropogolic acid, from the lichen Neuropogon trachycarpus, were established by spectroscopic (MS, ¹H and ¹³C NMR) and chemical evidence. Circular dichroism data allowed the configuration of isomuronic acid to be assigned as 2R.     

Myrianthic acid: a triterpene acid from the rootwood of Myrianthus arboreus

Arjunolic acid and a new triterpene acid, myrianthic acid, were isolated from the rootwood of Myrianthus arboreus. The structures of the two compounds were elucidated by IR, ¹H NMR and mass spectroscopy.     

Synthesis and cytotoxic activity of the N-acetylglucosamine-bearing triterpenoid saponins

Fourteen ursolic acid and oleanolic acid saponins with N-acetyl-β-d-glucosamine, and (1→4)-linked and (1→6)-linked N-acetyl-β-d-glucosamine oligosaccharide residues were synthesized in a convergent manner. The structures of all compounds were confirmed by ¹H NMR and ¹³C NMR spectroscopy and by mass spectrometry, and their cytotoxic activities were assayed in three cancer cell lines. Only oleanolic acid-3-yl β-d-GluNAc showed significant cytotoxicity against HL-60 and BGC-823.     

Hydropiperoside,a novel coumaryl glycoside from the root of Polygonum hydropiper

From the methanol extract of the root of Polygonum hydropiper, a novel coumaryl glycoside hydropiperoside was isolated together with anthraquinone, ellagic acid 3,3′-di-O-methyl ether, gallic acid, two quercetin glycosides and an unidentified aromatic δ-lactone possessing antifertility activity. The structure of hydropiperoside was established as β-d-(1,3,6-tri-p-coumaryl)-fructofuranosyl-α-d-glucopyranoside by combination of extensive ¹H NMR and ¹³C NMR spectra, and the FD/MS spectrum.     

A diterpenoid of the atis-16-ene class from Elaeoselinum foetidum

A new diterpenoid has been isolated from the root of Elaeoselinum foetidum. Its structure was established as ent-15α-senecioxy-atis-16-en-19-oic acid mainly by ¹H NMR ¹³C NMR spectroscopic studies of its methyl ester derivative.     

Isolation,purification and nuclear magnetic resonance spectra of pulvilloric acid

A strain ofPenicillium pulvillorum which produces pulvilloric acid has been identified. Pulvilloric acid has been isolated and purified and modern techniques have been used to assign its¹³C and¹H nuclear magnetic resonance (NMR) spectra.     

Extraction, structural characterisation and evaluation of hydroxycinnamate esters of orchard grass (Dactylis glomerata) as substrates for polyphenol oxidase

Polyphenol oxidase (PPO) activity has been reported in orchard grass (Dactylis glomerata); however, to date, no endogenous substrates have been identified. In the present study, we report the isolation and structural elucidation of PPO substrates in this species. The free phenol fraction was extracted, separated by reverse-phase chromatography and six potential substrates, including two hydroxycinnamate esters, were identified by UV spectrometry, electrospray ionisation-tandem mass spectrometry (LC-ESI-MSⁿ) and 1D and 2D NMR analyses (¹H NMR, ¹³C NMR, DEPT, COSY, HMQC and HMBC). Furthermore, three caffeoylquinic acids (3-CQA, 4-CQA and 5-CQA) were identified by comparison of their spectral data (ESI-MS) with those of known compounds and literature data. Five of these compounds were demonstrated to be substrates for orchard grass PPO.     

New organotin complexes with trans(cis)-1,4-cyclohexanedicarboxylic acid: Synthesis, characterization and crystal structures of mononuclears, 2D network polymers and a tetratin macrocycle

A series of new organotin carboxylates have been synthesized by reactions of trans(cis)-1,4-cyclohexanedicarboxylic acid with triorganotin chloride and diorganotin dichloride. All the complexes were characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR spectroscopy; furthermore, complexes 1, 3, 5, 8 and 9 were characterized by X-ray diffraction analyses. The structural analyses show that complex 1 possesses a monomer structure; complex 5 possesses a 1D zigzag chain structure; both the complexes 3 and 8 have 2D network structures and complex 9 has a tetratin 36-membered macrocyclic structure.     

New depsidones from Lobaria oregana

From the lichen, Lobaria oregana, two new minor metabolises, methylstictic acid (4) and cryptostictic acid (5) were isolated. The structures of 4 and 5 were elucidated by ¹H NMR and MS analysis.     

2(S),4(R)-4-(β-d-Galactopyranosyloxy)-4-isobutyl-glutamic acid: A new amino acid in Reseda odorata

2(S),4(R)-4-(β-d-Galactopyranosyloxy)-4-isobutylglutamic acid (I) has been isolated from the flowers of Reseda odorata, wherein it occurs in substantial quantity. Hydrolysis of I gives d-galactose, 2(S),4(R)-4-hydroxy-4-isobutylglutamic acid (II) and 3(R),5(S)-3-hydroxy-3-isobutyl-2-pyrrolidone-5-carboxylic acid (III) and its treatment with nitrous acid yields a galactoside of a non-nitrogenous hydroxy acid lactone (IV). The structures of I and its degradation products are supported by PMR, ¹³C-NMR and other spectroscopic methods. ¹³C-NMR spectroscopy of the model compound 2-(β-d-galactopyranosyloxy)isobutyric acid confirmed the structure of the natural product. The S- (or l-) configuration at C(2) in the amino acid moiety of I has been established by the use of the Clough—Lutz—Jirgenson rule and the R-configuration at C(4) of the same unit has been assigned tentatively. I represents the first example of a glycoside of a higher plant amino acid in which the carbohydrate residue is linked to an aliphatic hydroxy group.     

Biosynthesis of the iridoids aucubin antirrinoside from 8-epi-deoxyloganic acid

²H NMR spectroscopy shows that 8-epi-deoxy[6,7,8,10-²H₄]loganic acid is efficiently incorporated into aucubin in Plantago major and Scrophularia racemosa, and into antirrinoside in Antirrhinum majus. Deoxyloganic acid produced no observable incorporation in these species.     

New indanone compounds from Onychium japonicum

A new indanone glucoside pteroside M has been isolated from fronds of Onychium japonicumPteridaceae. The structure of its aglycone pterosin M has been established by ¹³C NMR, PMR spectra and degradation with nitric acid.