(+)-Isorangiformic acid,a lichen substance from Lecanora stenotropa

(+)-Isorangiformic acid from the lichen Lecanora stenotropa has been shown to be (+)-2S-methoxycarbonyl-3S-heptadecanedicarboxylic acid.     

Biosynthesis of (+)-catechin glycosides using recombinant amylosucrase from Deinococcus geothermalis DSM 11300

Amylosucrase (ASase, EC 2.4.1.4) is a glucosyltransferase that hydrolyzes sucrose into glucose and fructose and produces amylose-like glucan polymers from the released glucose. (+)-Catechin is a plant polyphenolic metabolite having skin-whitening and antioxidant activities. In this study, the ASase gene from Deinococcus geothermalis (dgas) was expressed in Escherichia coli, while the recombinant DGAS enzyme was purified using a glutathione S-transferase fusion system. The (+)-catechin glycoside derivatives were synthesized from (+)-catechin using DGAS transglycosylation activity. We confirmed the presence of two major transglycosylation products using TLC. The (+)-catechin transglycosylation products were isolated using silica gel open column chromatography and recycling-HPLC. Two (+)-catechin major transfer products were determined through ¹H and ¹³C NMR to be (+)-catechin-3′-O-α-d-glucopyranoside with a glucose molecule linked to (+)-catechin and (+)-catechin-3′-O-α-D-maltoside with a maltose linked to (+)-catechin. The presence of (+)-catechin maltooligosaccharides in the DGAS reaction was also confirmed via recycling-HPLC and enzymatic analysis. The effects of various reaction conditions (temperature, enzyme concentration, and molar ratio of acceptor and donor) on the yield and type of (+)-catechin glycosides were investigated.     

New lignans from leaves of Macropiper excelsum

Four new lignans, (+)-diayangambin; (+)-excelsin; (+)-epiexcelsin and (+)-demethoxyexcelsin, were isolated from leaves of Macropiper excelsum and their structures and configurations have been determined by spectroscopic studies. Diayangambin is only the second naturally occurring diaxially substituted 3,7-dioxabicyclo-[3,3,0]-octane to have been isolated.     

Nupharopumiline,a new quinolizine alkaloid from Nuphar pumila

A new quinolizine alkaloid, (+)-nupharopumiline, has been isolated from the rhizomes of Nuphar pumila. It has been shown by spectroscopic and chemi     

An alkaloid from Haplophyllum tuberculatum

A new alkaloid (+)-tuberine was isolated from Haplophyllum tuberculatum. Physicochemical and spectral evidence established its structure and stereochemistry as N- benzoyl-4′-[(2″S,3″S,6″S)-(+)-7″-acetoxy-2″-hydroxy-3″,7″-dimethyl-3″,6″-epoxyoctyloxy]phenethylamine.     

Enhanced production of (+)-terrein by Aspergillus terreus strain PF26 with epigenetic modifier suberoylanilide hydroxamic acid

New strategies for improving the fermentation yield of (+)-terrein which is a fungal metabolite with multiple bioactivities are very urgent. In this study, the effect of suberoylanilide hydroxamic acid, one kind of epigenetic modifier, on the biosynthesis of (+)-terrein by Aspergillus terreus strain PF26 isolated from the marine sponge Phakellia fusca was investigated. It was found that suberoylanilide hydroxamic acid exhibited a positive impact on (+)-terrein production, resulting from promoting the biosynthesis of 6-hydroxymellein, the precursor of (+)-terrein. Through optimization of feeding concentration and time of suberoylanilide hydroxamic acid, 5.58 g/L (+)-terrein could be obtained in shake flask cultivation, 29.5% higher than the control. Correspondingly, the fermentation of A. terreus strain PF26 in 7.5-L stirred bioreactor with feeding suberoylanilide hydroxamic acid (900 μM, day 4) yielded 9.07 g/L (+)-terrein, 77.1% higher than the control. These results showed that the epigenetic modifier-suberoylanilide hydroxamic acid could be utilized to enhance the production of (+)-terrein, which laid the foundation of massive production of (+)-terrein by fermentation.     

(+)-5,17-dehydromatrine N-oxide,a new alkaloid in Euchresta japonica

A new lupin alkaloid, (+)-5,17-dehydromatrine N-oxide, was isolated from the fresh aerial parts of Euchresta japonica. Its structure was confirmed by spectrometric data and by direct comparison with a synthetic sample, prepared from (+)-sophoranol ((+)-5-hydroxymatrine). It was also concluded that (+)-5,17-dehydromatrine N-oxide and (+)-matrine N-oxide possess the same configuration with respect to the asymmetric nitrogen by NMR spectra.     

Coupling cell growth and biochemical pathway induction in Saccharomyces cerevisiae for production of (+)-valencene and its chemical conversion to (+)-nootkatone

(+)-Nootkatone is a valuable, functional sesquiterpene that is widely used in food, cosmetics, pharmaceutical, agriculture, and other fields. However, only traces of it accumulate in plants, which is insufficient to meet the market demand. Therefore, commercial (+)-nootkatone is currently synthesized from (+)-valencene. Here, we engineered Saccharomyces cerevisiae to achieve high production of (+)-valencene. Employing gene screening, protein engineering and biosynthetic pathway optimization, we achieved 12.4 g/L (+)-valencene production with the mutant strain. This titer was further increased to 16.6 g/L, the highest titer reported to date, by coupling critical factors for cell growth and biochemical pathway induction. Subsequently, (+)-nootkatone was chemically synthesized from bio-fermented (+)-valencene with a yield of 80%. This study achieved efficient microbial synthesis of (+)-valencene, which may be utilized in industrial production and stabilize the supply of (+)-nootkatone.     

Chiral analogues of (+)-cyclazosin as potent α1B-adrenoceptor selective antagonist

(+)-Cyclazosin [(+)-1] is one of most selective antagonists of the α_1B-adrenoceptor subtype (selectivity ratios, α_1B/α_1A?=?13, α_1B/α_1D?=?38–39). To improve the selectivity, we synthesized and pharmacologically studied the blocking activity against α₁-adrenoceptors of several homochiral analogues of (+)-cyclazosin featuring different substituents on the carbonyl or amine groups, namely (?)-2, (+)-3, (?)-4–(?)-8, (+)-9. Moreover, we studied the activity of some their opposite enantiomers, namely (?)-1, (?)-3, (+)-6, and (?)-9, to evaluate the influence of stereochemistry on selectivity. The benzyloxycarbonyl and methyl (4aS,8aR) analogues (+)-3 and (?)-6 improved in a significant way the α_1B selectivity of the progenitor compound: 4 and 14 time vs. the α_1D subtype and 35 and 77 times vs. the α_1A subtype, respectively. The study confirmed the importance of the hydrophobic cis-octahydroquinoxaline moiety of these molecules for the establishment of interactions with the α₁-adrenoceptors as well that of their (4aS,8aR) stereochemistry to grant selectivity for the α_1B subtype. Hypotheses on the mode of interaction of these compounds were advanced on the basis of molecular modeling studies performed on compound (+)-3.     

Jinkohol,a prezizane sesquiterpene alcohol from agarwood

A new tricyclic sesquiterpene, jinkohol, has been isolated from an agarwood (Aquillaria sp.) which is different from that obtained from Aquillaria agallocha. Its structure was shown to be 2β-hydroxy-(+)-prezizane by spectroscopic methods and by chemical transformation. The two kinds of agarwood are readily identified from their sesquiterpene components.     

Biochimica et biophysica acta,vol. 586 (1979)

3-Hydroxyisobutyric acid has been isolated from the urine of rats loaded with sodium isobutyrate. An optical rotation measurement of the methyl ester derivative shows this compound to be the S(+) stereoisomer. This is the same stereoisomer that has been previously identified in cultures of bacteria incubated with ammonium isobutyrate     

The volatile herb oil of Kippistia suaedifolia

Steam-distillation of the whole flowering plant of Kippistia suaedifolia yielded a volatile oil rich in (+)-perillyl acetate and (+)-limonene. Ten minor oil components were also identified by co-chromatography and capillary GC/MS.     

Aporphine alkaloids and lignans in heartwood of Liriodendron tulipifera

The following compounds were isolated from heartwood of Liriodendron tulipifera: glaucine, dehydroglaucine, asimilobine, N-acetylnornuciferine, norushinsunine, liriodenine, O-methylatheroline, (+)-syringaresinol, (+)-syringaresinol dimethyl ether and syringaldehyde. The occurrence of 1-benzyltetrahydroisoquinoline alkaloids also has been indicated by mass spectroscopy. Some characteristic spectral properties of these aporphine alkaloids and their probable biosynthetic pathways are discussed.     

Un nouvel acide amine dans les graines de Vigna vexillata

A new natural amino acid, l-(+)-p-aminophenylalanine, has been isolated from a legume, Vigna vexillata (L.) A. Rich. Its structure was determined and confirmed by synthesis.     

NMR for direct determination of Km and Vmax of enzyme reactions based on the Lambert W function-analysis of progress curves

¹H NMR spectroscopy was used to follow the cleavage of sucrose by invertase. The parameters of the enzyme's kinetics, K_m and V_max, were directly determined from progress curves at only one concentration of the substrate. For comparison with the classical Michaelis-Menten analysis, the reaction progress was also monitored at various initial concentrations of 3.5 to 41.8 mM. Using the Lambert W function the parameters K_m and V_max were fitted to obtain the experimental progress curve and resulted in K_m = 28 mM and V_max = 13 μM/s. The result is almost identical to an initial rate analysis that, however, costs much more time and experimental effort. The effect of product inhibition was also investigated. Furthermore, we analyzed a much more complex reaction, the conversion of farnesyl diphosphate into (+)-germacrene D by the enzyme germacrene D synthase, yielding K_m = 379 μM and k_cat = 0.04 s^− 1. The reaction involves an amphiphilic substrate forming micelles and a water insoluble product; using proper controls, the conversion can well be analyzed by the progress curve approach using the Lambert W function.     

Mono- and sesquiterpenoids of Conocephalum supradecompositum

The liverwort Conocephalum supradecompositum belonging to the Marchantiales is a rich source of the germacranolides (+)-costunolide and (+)-dihydro     

Neoflavanoids of Dalbergia parviflora

Besides two arylbenzofurans, parvifuran and isoparvifuran, the heartwood extract of Dalbergia parviflora yielded four neoflavanoids: R(?)-latifolin, R(?)-5-O-methyllatifolin, R(+)-4-methoxydalbergione, 2,5-dihydroxy-4-methoxybenzophenone (cearoin) and the new R(+)-dalbergiphenol. The structures of these compounds have been elucidated by physical methods.     

13a-hydroxytylophorine from tylophora hirsuta

13a-hydroxytylophorine isolated from Tylophora hirsuta on heating with concentrated hydrochloric acid gave a quaternized salt which was reduced with sodium borohydride to (+)-tylophorine. An amine and a ketoamine having a seco[10–13a] bond were formed after lithium aluminium hydride reduction and chromium trioxide oxidation, respectively.     

(+)-α(S)-butyramido-γ-butyrolactone from Lyngbya majuscula

(+)-α(S)-Butyramido-γ-butyrolactone is a minor constituent of the toxic marine blue-green alga Lyngbya majuscula.