Non-reversibility of the isoleucine-acetate pathway in Datura

Five-month-old Datura meteloides plants were fed via the roots with 3-hydroxy-2-methylbutanoic acid-[1-¹⁴C] and isoleucine-[U-¹⁴C] as a positive control. After 5 days the plants were collected and in each case the root alkaloids 3α,6β-ditigloyloxytropane, 3α,6β-ditigloyloxytropan-7β-ol, meteloidine, hyoscine and hyoscyamine were isolated. Whereas isoleucine served as a precursor for the tiglic acid moieties 3-hydroxy-2-methylbutanoic acid did not.     

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.     

Three new oxygenated triterpenoids of the lupane series from Gymnosporia wallichiana

Two new epimeric triterpenoid acids, gymnosporic acid, 3β-hydroxy-(20R)-lupan-29-oic acid, wallichianic acid, 3β-hydroxy-(20S)-lupan-29-oic acid and a new diol wallichianol, (20S)-lupane-3β,29-diol have been isolated from Gymnosporia wallichiana, in addition to β-amyrin, friedelin, 3β-hydroxy-29-norlupan-20-one and dulcitol.     

Metabolic transformations of some ent-kaurenes in Gibberella fujikuroi

The conversion of ent-kaur-16-enes to gibberellic acid in Gibberella fujikuroi is blocked by A-ring modifications. Thus ent-3β-hydroxykaur-16-en-19-yl succinate gives good conversion (46%) to the 7β-hydroxy derivative.* Under the same conditions the 3β-epimer gives 7β- or 6α-hydroxylation and the former occurs for the 3-oxo analogue. The succinoyloxy function acts as a less efficient block and ent-kaur-16-en-19-yl succinate is converted to 7β-hydroxy and 6β,7β-dihydroxy derivatives along with gibberellic acid. Hydrolysis of the succinate block of the metabolities provides the 7β, 19-diol and 6β,7β, 19-triol. Of this pair only the former was effectively metabolized to gibberellic acid in G. fujikuroi.     

Chemical synthesis of 3β-sulfooxy-7β-hydroxy-24-nor-5-cholenoic acid: An internal standard for mass spectrometric analysis of the abnormal Δ-bile acids occurring in Niemann-Pick disease

In Niemann-Pick disease, type C1, increased amounts of 3β,7β-dihydroxy-5-cholenoic acid are reported to be present in urinary bile acids. The compound occurs as a tri-conjugate, sulfated at C-3, N-acetylglucosamidated at C-7, and N-acylamidated with taurine or glycine at C-24. For sensitive LC-MS/MS analysis of this bile acid, a suitable internal standard is needed. We report here the synthesis of a satisfactory internal standard, 3β-sulfooxy-7β-hydroxy-24-nor-5-cholenoic acid (as the disodium salt). The key reactions involved were (1) the so-called “second order” Beckmann rearrangement (one-carbon degradation at C-24) of hyodeoxycholic acid (HDCA) 3,6-diformate with sodium nitrite in a mixture of trifluoroacetic anhydride and trifluoroacetic acid, (2) simultaneous inversion at C-3 and elimination at C-6 of the ditosylate derivatives of the resulting 3α,6α-dihydroxy-24-nor-5β-cholanoic acid with potassium acetate in aqueous N,N-dimethylformamide, and (3) regioselective sulfation at C-3 of an intermediary 3β,7β-dihydroxy-24-nor-Δ⁵ derivative using sulfur trioxide-trimethylamine complex. Overall yield of the desired compound was 1.8% in 12 steps from HDCA.     

Triterpenoids from enkianthus campanulatus

From the leaves of Enkianthus campanulatus were isolated three new triterpenes, 3-oxo-19,23,24-trihydroxyurs-12-en-28-oic acid, 3β,6β, 19,23-tetrahydroxyurs-12-en-28-oic acid and 3β,6β,23-trihydroxyurs-12-en-28-oic acid.     

Biosynthesis of the tigloyl esters of Datura: Cis-trans isomerism

Datura innoxia plants were wick fed with angelic acid-[1-¹⁴C] and l-isoleucine-[U-¹⁴C] to act as a positive control. After 7 days the root alkaloids 3α-tigloyloxytropane, 3α,6β-ditigloyloxytropane, and 3α,6β-ditigloyloxytropan-7β-ol were isolated and it was determined that angelic acid is not a precursor for the tigloyl moiety of these alkaloids. Tiglic acid-[1-¹⁴C] which was fed via the roots to hydroponic cultures of Datura innoxia, was incorporated to a considerable degree after 8 days.     

Quinovic acid glycosides from Guettarda angelica

Two new triterpene glycosides isolated from the root bark Guettarda angelica were proven to be quinovic acid-3β-O-[β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside] and quinovic acid-3β-O-β-d-glucopyranosyl-(28 → 1)-β-d-glucopyranosyl ester. In addition quinovic acid and two known glycoside derivatives (quinovic acid-3β-O-β-d-glucopyranoside and quinovic acid-3β-O-α-l-rhamnopyranoside) were isolated. The structures were elucidated by spectroscopic analysis of the peracetyl methyl ester derivatives.     

Further triterpenoids and 13C NMR spectra of oleanane derivatives from Phytolacca acinosa

In addition to five known triterpenoids, namely acinosolic acid, phytolaccagenin, phytolaccagenic acid, esculentic acid and jaligonic acid, three new oleanane derivatives, designated as phytolaccagenin A, acinosolic acid A and acinosolic acid B, have been isolated and characterized from the defatted berries of Phytolacca acinosa. The new compounds have been identified as 3β-acetoxy-3β-methyloleanate-12-en-2β,23α-diol-28β-oic acid, 3β-acetoxy-28β-methyloleanate-12-en-2β-ol-30β-oic acid and 2β-acetoxy-28β-methyloleanate-12-en-3β-ol-30β-oic acid, respectively.     

Struktur der microphyllinsäure aus dem harz von Convolvulus microphyllus

The structure of microphyllic acid, the main glycosidic acid from the ether soluble resin of Convolvulus microphyllus has been elucidated as the O-α-l-rhamnopyranosyl-(1 → 6)-[O-α-l-rhamopyranosyl -(1 → 4)]-O-β-d-glucopyranosyl-(1 → 3)-O-α-l5-rhamnopyranosyl-(1 → 3)-O-β-d-fucopyranoside of 11-hydroxypalmitic acid, using mainly GLC and mass spectrometry of the derivatized sugars.     

Plectranthoic acid,acetylplectranthoic acid and plectranthadiol,three triterpenoids from Plectranthus rugosus

Sitosterol and three new pentacyclic triterpenoids, plectranthoic acid, acetylplectranthoic acid and plectranthadiol, have been isolated from leaves of P. rugosus. From spectroscopic evidence and chemical behaviour the structure of plectranthoic acid was established as (19S)-3α-hydroxy-18α-urs-12-en-29β-oic acid and acetylplectranthoic acid is the 3α-acetyl derivative of this compound. Plectranthadiol is (19S)- 3α-hydroxy-18α-urs-12-en-29β-ol.     

Synthesis, aggregation behavior and cholesterol solubilization studies of 16-epi-pythocholic acid (3α,12α,16β-trihydroxy-5β-cholan-24-oic acid)

Synthesis, aggregation behavior and in vitro cholesterol solubilization studies of 16-epi-pythocholic acid (3α,12α,16β-trihydroxy-5β-cholan-24-oic acid, EPCA) are reported. The synthesis of this unnatural epimer of pythocholic acid (3α,12α,16α-trihydroxy-5β-cholan-24-oic acid, PCA) involves a series of simple and selective chemical transformations with an overall yield of 21% starting from readily available cholic acid (CA). The critical micellar concentration (CMC) of 16-epi-pythocholate in aqueous media was determined using pyrene as a fluorescent probe. In vitro cholesterol solubilization ability was evaluated using anhydrous cholesterol and results were compared with those of other natural di- and trihydroxy bile acids. These studies showed that 16-epi-pythocholic acid (16β-hydroxy-deoxycholic acid) behaves similar to cholic acid (CA) and avicholic acid (3α,7α,16α-trihydroxy-5β-cholan-24-oic acid, ACA) in its aggregation behavior and cholesterol dissolution properties.     

Terpenoid and biflavonoid constituents of Calophyllum calaba and Garcinia spicata from Sri Lanka

A new bark acid, isochapelieric acid (cis-chapelieric acid), chapelieric acid, friedelin, friedelan-3β-ol, canophyllal, canophyllol, friedelan-3β,28-diol, canophyllic acid and amentoflavone have been isolated and characterized from leaf extractives of Calophyllum calaba. ¹³CNMR spectra of methyl chapelierate and methyl isochapelierate have been recorded and interpreted. Leaf extractives of Garcinia spicata afforded an unidentified long chain carboxylic acid, friedelin, friedelan-3β-ol, sitosterol and the biflavanones GB-1, GB-1a, GB-2a and morelloflavone. Chemotaxonomic significance of the occurrence of some of the above foliar constituents in Calophyllum and Garcinia species is discussed.     

Cytotoxic naphthoquinones,molluscicidal saponins and flavonols from Diospyros zombensis

7-Methyljuglone, isodiospyrin and three glucuronides of oleanolic acid were isolated from the lipophilic and the methanol extracts, respectively, of the root bark of Diospyros zombensis. Cytotoxic activities of the naphthoquinones and strong molluscicidal activity of 3-O-[O-α-L-rhamnopyranosyl-(1 → 3)-β-D-glucuronopyranosyl]-oleanolic acid were shown. In addition hyperoside, quercitrin and quercetin-3-O-β-D-glucuronopyranoside were isolated from a methanol extract of the leaves.     

The structure and stereochemistry of barrigenic acid,a new triterpene acid sapogenin from Barringtonia acutangula

A new triterpene acid, barrigenic acid, was isolated from the fruits of Barringtonia acutangula. Its structure was established as 2α,3β,19β-trihydroxyolean-12-en-23,28-dioic acid.     

Microbial transformation of glycyrrhetinic acid derivatives by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741

Glycyrrhetinic acid (GA), the major bioactive pentacyclic triterpene aglycone of licorice root, was known to play a vital role in anti-ulcer, anti-depressant, anti-inflammatory, and anti-allergic. In this study, we semi-synthesized five GA derivatives by a series of chemical reactions. They were selected as substrates for the biotransformation and yielded thirteen metabolites by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741. Their structures were identified on the basis of extensive spectroscopic methods and nine of them were found for the first time. Two main types of reactions, regio- and stereo-selective hydroxylation and glycosylation, especially in the unactivated C-H bonds including C-11, C-19 and C-27, were observed in the biotransformation process, which greatly expand the chemical diversities of GA derivatives. All compounds were tested for their inhibitory effects on nitric oxide (NO) generation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Among them, olean-12-ene-3β,7β,15α,19α,30-pentol (16) and olean-12-ene-3β,7β,15α,27,30-pentol (17) showed significant inhibitory effect with IC₅₀ values of 0.64 and 0.07 μM, respectively.     

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.     

A new triterpene lactone from Gymnocladus dioica

2β,23-Dihydroxyacacic acid lactone was isolated from Gymnocladus dioica as an artifact from 2β, 3β 16β, 21β, 23-pentahydroxyolean-12-ene-28-oic acid.     

The chemotaxonomic and medicinal significance of phenolic acids in Arctopus and Alepidea (Apiaceae subfamily Saniculoideae)

The occurrence of (R)-3′-O-β-d-glucopyranosylrosmarinic acid, rosmarinic acid and caffeic acid in two important South African medicinal plants is reported for the first time. (R)-3′-O-β-d-Glucopyranosylrosmarinic acid and rosmarinic acid were isolated and identified in several samples from three species of the genus Arctopus L. (sieketroos) and three species of the genus Alepidea F. Delaroche (ikhathazo), both recently shown to be members of the subfamily Saniculoideae of the family Apiaceae. The compounds occur in high concentrations (up to 15.3 mg of (R)-3′-O-β-d-glucopyranosylrosmarinic acid per g dry wt) in roots of Arctopus. Our results provide a rationale for the traditional uses of these plants, as the identified compounds are all known for their antioxidant activity, with rosmarinic acid further contributing to a wide range of biological activities. Furthermore, we confirm the idea that (R)-3′-O-β-d-glucopyranosylrosmarinic acid is a useful chemotaxonomic marker for the subfamily Saniculoideae.     

New triterpene saponins from Phryna ortegioides

Four new and three known oleanane-type saponins have been isolated from the methanolic extract of Phryna ortegioides, a monotypic and endemic taxon of Caryophyllaceae.The structures of the new compounds were determined as gypsogenic acid 28-O-β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→6)-O-β-d-glucopyranosyl ester (1), 3-O-α-l-arabinofuranosyl-gypsogenic acid 28-O-β-d-glucopyranosyl-(1→3)-O-[β-d-glucopyranosyl-(1→6)]-O-β-d-glucopyranosyl ester (2), 3-O-α-l-arabinofuranosyl-gypsogenic acid 28-O-β-d-glucopyranosyl-(1→3)-O-[β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→6)-O-]-β-d-glucopyranosyl ester (3), 3-O-α-l-arabinofuranosyl-16α-hydroxyolean-12-en-23,28-dioic acid-28-O-β-d-glucopyranosyl-(1→3)-O-[β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→6)]-O-β-d-glucopyranosyl ester (4). Their structures were established by a combination of one- and two-dimensional NMR techniques, and mass spectrometry. Noteworthy, none of isolated compounds possesses as aglycone moiety gypsogenin, considered a marker of Caryophyllaceae family.The cytotoxic activity of the isolated compounds was evaluated against three cancer cell lines including A549 (human lung adenocarcinoma), A375 (human melanoma) and DeFew (human B lymphoma) cells. Only compound 6 showed a weak activity against A375 and DeFew cell lines with IC₅₀ values of 77 and 52 μM, respectively. None of the other tested compounds, in a range of concentrations between 12.5 and 100 μM, caused a significant reduction of the cell number.