New alkaloids from Banisteriopsis caapi

Three new alkaloids isolated from Banisteriopsis caapi, were identified as harmic amide (1-carbamoyl-7-methoxy β-carboline), acetyl norharmine (1-acetyl-7-methoxy β-carboline) and ketotetrahydronorharmine (7-methoxy-1,2,3,4-tetrahydro-1-oxo-β-carboline)     

Hydroxycinnamic acid esters from Polygala chamaebuxus

Three new glycosides have been isolated from the aerial parts of Polygala chamaebuxus by preparative liquid chromatography on an axially-compressed silica column. The compounds were identified as 1,3-diesters of β-D-fructofuranosyl-α-D-glucopyranoside with sinapoyl, feruloyl and acetyl ester moieties on the furanose ring. The structures were elucidated by a combination of chemical and spectroscopic methods (D/CI-MS, ¹H and ¹³C NMR).     

Resin acids from two amazonian species of Hymenaea

The major diterpene acid constituents of two Amazonian species of Hymenaea have been isolated and identified. A new resin acid, guamáic acid, is described.     

New alkaloids from Strychnos icaja

The alkaloids of Strychnos icaja (Loganiaceae) have been studied. An extract from Zaire leaf material yielded nine alkaloids, comprising novacine, the new base 21,22-α-epoxy-4,14-dihydroxy-3-methoxy-N-methyl-sec.-pseudostrychnine, and seven others of known structure previously obtained from the plant. Cameroun leaf material gave five alkaloids, of which one, 21,22-α-epoxy-3,4-dimethoxy-N-methyl-sec.-pseudostrychnine, is new. Fruits from Gabon afforded eight alkaloids; two of them are new and are formulated as 21,22-α-epoxy-4-methoxy-N-methyl-sec.-pseudostrychnine and the corresponding 14-hydroxy derivative.     

Two triterpenoid glycosides from leaves of Ilex cornuta

Two new triterpene glycosides, a diglycoside (as the corresponding methyl ester) and a bis-desmoside were isolated from leaves of Ilex cornuta. The     

Iridoid glucosides from Pedicularis

Pedicularis palustris contains the iridoid glucosides aucubin and gardoside methyl ester, and five hydroxy derivatives of 8-epi-deoxyloganin, together with boschnaloside and three hydroxy derivatives of boschnaloside. From P. silvatica, plantarenaloside, 8-epiloganin and euphroside have been isolated. Euphroside is also present in P. lapponica, in addition to aucubin and mussaenoside. Chemical evidence for the structure of euphroside is presented. Pedicularioside is shown to be identical with penstemoside, and the former name is thus redundant.     

Mechaism of Arthrobacter sialophilus neuraminidase: The binding of substrates and transition-state analogs

2-Deoxy-2,3-dehydro-N-acetylneuraminic acid and its methyl ester are competitive inhibitors of Arthrobacter sialophilus neuraminidase with K_i = 1.4 × 10^?6$\text{M}$ and 4.8 × 10^?5$\text{M}$, respectively. The K_m for the substrate, N-acetylneuraminlactose, is 1.0 × 10^?3$\text{M}$. These data, taken together with the conformation of these compounds, indicate that these compounds are transition-state analogs of the enzyme. These results also suggest that the substrate upon binding to neuraminidase is distorted to a conformation approaching that of a half-chair.     

Seven aristololactams from Aristolochia argentina

Seven aristololactam alkaloids were isolated from Aristolochia argentina. Five are reported for the first time.     

Biosynthetic relationship between tetrahydroanthracene and anthraquinone in Aloe saponaria

The incorporation of Me¹⁴COONa into aloesaponol I, laccaic acid D methyl ester and aloesaponarin I was demonstrated. The biosynthetic relation between aloesaponol I and aloesaponarin I was established, but incorporation of aloesaponol I into laccaic acid D methyl ester, or vice versa was not demonstrated and this result was confirmed by an investigation using labelled laccaic acid D methyl (¹⁴CH₃) ester. It was possible to show that aloesaponol I and laccaic acid D methyl ester were biosynthesized in parallel in Aloe saponaria.     

Tropane alkaloids from Anthocercis and Anthotroche

In addition to known tropane alkaloids, 3α-iso-butyryloxytropan-6β-ol and 3α-n-butyryloxytropane have been characterized as respective components of the aerial parts of two subspecies of Anthocercis albicans. Aponoratropine, not previously recorded as a natural product, has been detected in the leaves of Anthotroche myoporoides and A. walcottii; similarly aponorhyoscine is indicated as a component of the roots of a subspecies of Anthocercis genistoides.     

Three new alkaloids from Buxus papillosa

Three new steroidal alkaloids have been obtained from Buxus papillosa Schneider. These are (?)-cyclobuxupaline-C (IV)(+)-cyclopapilosine-D (VII) and (+)-buxamine-C (IX). A known alkaloid also present is desoxy-16-buxidienine (X).     

New peptide alkaloids from Hovenia dulcis and H. tomentella

From the root bark of Hovenia dulcis Thunb. and H. tommentella (Makino) Nakai (Rhamnaceae), three peptide alkaloids, frangulanine, hovenins-A and -B have been isolated. Hovenin-A has been shown to be des-N-methylfrangulanine (II).     

Aromatic compounds from Delphinium venulosum

From the non-alkaloidal fractions of Delphinium venulosum, four known aromatic compounds cis and trans p-coumaric acids, p-hydroxybenzoic acid, protocatechuic acid methyl ester and a new aromatic compound 2,5,6-trihydroxypiperonylic acid methyl ester were isolated together with kaempferol, sitosterol and sitosteryl 3-glucoside. The structures of the compounds were established by spectral data.     

Peptide alkaloids of Scutia buxifolia

Two new components, the peptide alkaloid scutianine D and scutianene C have been isolated from Scutia buxifolia and their structures elucidated. The configuration of some of the asymmetric centers of scutianine A has been determined by gas chromatography.     

Iridoid and other constituents of Canthium subcordatum

The main constituent of the stem bark of Canthium subcordatum was found to be shanzhiside methyl ester, an iridoid recently described for two Mussaenda species; it is accompanied by the new iridoid shanzhisin methyl ester gentiobioside. No alkaloids were detected.     

Flavonoids from Artemisia frigida

Twelve flavonoids including a new flavone were isolated from Artemisia frigida. The structure of the new highly oxygenated flavone was determined b     

Prenylated p-coumarates from Werneria stuebelii

The aerial parts of Werneria stuebelii afforded in addition to β-cedrene and bicyclogermacrene eight derivatives of methyl p-coumarate, all being formed by prenylation. The structures were elucidated by their molecular formulae and their ¹H NMR spectra. The chemotaxonomy of the Andean genus Werneria is discussed briefly.     

Organic bases from Brazilian Piptadenia species

Basic compounds have been detected in five Brazilian Piptadenia species by means of electrophoresis. Bufotenine was detected in P. contorta Benth., and P. moniliformis Benth. The seeds of P. leprostachya Benth. contained theobromine, a new constituent in Leguminosae.     

以DL-丝氨酸为原料制备D-丝氨酸的新方法

以DL-丝氨酸为原料经过酯化、拆分和水解制备D-丝氨酸。使L-2,3-二苯甲酰酒石酸(L-DBTA)与DL-丝氨酸甲酯在无水乙醇中于60℃反应形成非对映体盐,冷却到0℃,D-丝氨酸甲酯.L-DBTA二盐析出,过滤后再经水解,得到D-丝氨酸,总收率为74.8%,旋光纯度达到98%以上。     

Pyrrolizidine alkaloids from Senecio cacaliaster

Four pyrrolizidine alkaloids have been isolated from Senecio cacaliaster and their structures analysed by spectroscopic methods (IR, mass, ¹H, ¹³CNMR). One of them is new and the name sencalenine (3) is proposed. Alkaloids O⁷-senecioylretronecine (1) and 7-senecioyl-9-sarracinylretronecine (2) have recently been identified elsewhere. The fourth is bulgarsenine (4) which was isolated from a Senecio species before.