Structure of terminic acid,a dihydroxytriterpene carboxylic acid from Terminalia arjuna

The structure of terminic acid, a new dihydroxytriterpene carboxylic acid isolated from the roots of Terminalia arjuna, has been established as 3β, 13β-dihydroxylup-20(29)-en-28-oic acid by a study of its chemical reactions and spectroscopic data. Terminic acid and its derivatives were found to undergo skeletal rearrangement under protonic conditions to yield oleanene lactone.     

3β-hydroxy-21β-e-cinnamoyloxyolean-12-en-28-oic acid,a triterpenoid from enterolobium contorstisiliquum

The triterpenes 3β-hydroxy-21β-E-cinnamoyloxyolean-12-en-20-oic acid, 3β,21β-dihydroxyolean-12-en-28-oic acid (machaerinic acid) and its lactone (3β-hydroxyolean-12-en-21β→28-lactone) were isolated from the fruits of Enterolobium contorstisiliquum. Methyl and ethyl esters of 3β,21β-dihydroxyolean-12-en-oic acid were isolated and characterized as artifacts. The structures of these triterpenes have been established by a study of their chemical and spectroscopic (IR, MS and NMR) data.     

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.     

Sempervirenic acid,a diterpene acid from Solidago sempervirens

Sempervirenic acid, a new diterpene has been isolated from Solidago sempervirens and its structure determined by spectroscopic methods and chemical conversions to be 3β-acetoxy-labda-7,13-diene-15-oic acid.     

The neurolathyrogen, α-amino-β-oxalylaminopropionic acid in legume seeds

The neurotoxic lathyrogen, α-amino-β-oxalylaminopropionic acid (β-oxalyldiaminopropionic acid, ODAP) accumulates in the seeds of 13 species of Crotalaria and 17 species of Acacia as well as in seeds of Lathyrus. The compound was not detected in seeds representing 250 other legume genera—these are listed.     

Biosynthesis of the tigloyl esters in Datura: The role of 2-methylbutyric acid

Datura innoxia plants were wick fed with (±)-2-methylbutyric acid-[1-¹⁴C] and harvested after 7 days. The root alkaloids 3α,6β-ditigloyloxytropane and 3α,6β-ditigloyloxytropan-7β-ol were isolated and degraded. In each case the radioactivity was located in the ester carbonyl group indicating that this acid is an intermediate in the biosynthesis of tiglic acid from l-isoleucine. On the other hand, (±)-2-hydroxy-2-methylbutyric acid-[1-¹⁴C], which was fed to hydroponic cultures of Datura innoxia alongside isoleucine[U-¹⁴C] positive control plants, is not an intermediate.     

A novel abscisic acid metabolite from seeds of Robinia pseudacacia

Abscisic acid and its novel metabolise, which was a conjugated form of hydroxyabscisic acid (Metabolite C), were isolated from seeds of Robinia pseudacacia L. The structure of the conjugate was shown to be (+)-3-methyl-5 - [1(S),6(R) - 2,6 - dimethyl - 1 - hydroxy - 6 - (3 - hydroxy - 3 - methyl - 4 - carboxybutanoyloxymethyl) - 4 - oxo-cyclohex-2-enyl]-2-Z-4-E-pentadienoic acid and tentatively named β-hydroxy-β-methylglutarylhydroxyabscisic acid.     

Oxidative dimerization of ferulic acid by extracts from Sorghum

Extracts from leaves and first internodes of Sorghum bicolor catalyze the conversion of ferulic acid to a β-β-coupled dimer, the dilactone dimer of ferulic acid. The dilactone is then hydrolyzed, probably non-enzymatically, to a blue fluorescing compound, tentatively identified as a β-β-coupled dimer with at least one lactone ring opened to form a carboxylic acid. Both the initial enzymatic and the subsequent non-enzymatic steps are greater at pH 8 than pH 6. The most active preparation is a crude particulate fraction from leaves obtained by centrifugation at 37000 g; white light increases the amount of dimer formed.     

6β-Hydroxyursolic acid and other triterpenoids of Enkianthus cernuus

From the leaves of Enkianthus cernuus forma rubens, a new triterpene, 6β-hydroxyursolic acid, was isolated together with several known compounds     

6α-Hydroxylation of taurochenodeoxycholic acid and lithocholic acid by CYP3A4 in human liver microsomes

The aim of the present study was to identify the enzymes in human liver catalyzing hydroxylations of bile acids. Fourteen recombinant expressed cytochrome P450 (CYP) enzymes, human liver microsomes from different donors, and selective cytochrome P450 inhibitors were used to study the hydroxylation of taurochenodeoxycholic acid and lithocholic acid. Recombinant expressed CYP3A4 was the only enzyme that was active towards these bile acids and the enzyme catalyzed an efficient 6α-hydroxylation of both taurochenodeoxycholic acid and lithocholic acid. The V_max for 6α-hydroxylation of taurochenodeoxycholic acid by CYP3A4 was 18.2 nmol/nmol P450/min and the apparent K_m was 90 μM. Cytochrome b₅ was required for maximal activity. Human liver microsomes from 10 different donors, in which different P450 marker activities had been determined, were separately incubated with taurochenodeoxycholic acid and lithocholic acid. A strong correlation was found between 6α-hydroxylation of taurochenodeoxycholic acid, CYP3A levels (r²=0.97) and testosterone 6β-hydroxylation (r²=0.9). There was also a strong correlation between 6α-hydroxylation of lithocholic acid, CYP3A levels and testosterone 6β-hydroxylation (r²=0.7). Troleandomycin, a selective inhibitor of CYP3A enzymes, inhibited 6α-hydroxylation of taurochenodeoxycholic acid almost completely at a 10 μM concentration. Other inhibitors, such as α-naphthoflavone, sulfaphenazole and tranylcypromine had very little or no effect on the activity. The apparent K_m for 6α-hydroxylation of taurochenodeoxycholic by human liver microsomes was high (716 μM). This might give an explanation for the limited formation of 6α-hydroxylated bile acids in healthy humans. From the present results, it can be concluded that CYP3A4 is active in the 6α-hydroxylation of both taurochenodeoxycholic acid and lithocholic acid in human liver.     

Distribution of α-amino-β-methylaminopropionic acid in Cycas

α-Amino-β-methylaminopropionic acid, previously isolated from seeds of Cycas circinalis, has now been identified either free or bound in all th     

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.     

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.     

Engineering Escherichia coli for the synthesis of short- and medium-chain α,β-unsaturated carboxylic acids

Concerns over sustained availability of fossil resources along with environmental impact of their use have stimulated the development of alternative methods for fuel and chemical production from renewable resources. In this work, we present a new approach to produce α,β-unsaturated carboxylic acids (α,β-UCAs) using an engineered reversal of the β-oxidation (r-BOX) cycle. To increase the availability of both acyl-CoAs and enoyl-CoAs for α,β-UCA production, we use an engineered Escherichia coli strain devoid of mixed-acid fermentation pathways and known thioesterases. Core genes for r-BOX such as thiolase, hydroxyacyl-CoA dehydrogenase, enoyl-CoA hydratase, and enoyl-CoA reductase were chromosomally overexpressed under the control of a cumate inducible phage promoter. Native E. coli thioesterase YdiI was used as the cycle-terminating enzyme, as it was found to have not only the ability to convert trans-enoyl-CoAs to the corresponding α,β-UCAs, but also a very low catalytic efficiency on acetyl-CoA, the primer and extender unit for the r-BOX pathway. Coupling of r-BOX with YdiI led to crotonic acid production at titers reaching 1.5 g/L in flask cultures and 3.2 g/L in a controlled bioreactor. The engineered r-BOX pathway was also used to achieve for the first time the production of 2-hexenoic acid, 2-octenoic acid, and 2-decenoic acid at a final titer of 0.2 g/L. The superior nature of the engineered pathway was further validated through the use of in silico metabolic flux analysis, which showed the ability of r-BOX to support growth-coupled production of α,β-UCAs with a higher ATP efficiency than the widely used fatty acid biosynthesis pathway. Taken together, our findings suggest that r-BOX could be an ideal platform to implement the biological production of α,β-UCAs.     

Occurrence of betulinic acid in different callus cultures of Solanum aviculare

Betulinic acid (3β-hydroxy-lup-20(29)-en-28-oic acid) was obtained from in vitro cultures of Solanum aviculare in yields up to 3% of the dry weight. This is a further example of overproduction by cells cultured in vitro of a product not found in the original parent plant.     

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.     

7β-Acetoxytrachyloban-18-oic acid from the stem bark of Xylopia quintasii

A novel diterpene has been isolated from the stem bark of Xylopia quintasii and identified as 7β-acetoxytrachyloban-18-oic acid. The taxonomic si     

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.     

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.     

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.