Trispara-aspidin,ein neues Phloroglucid aus dem Farn Dryopteris remota (A. Br.) Hayek

Dryopteris remota (A. Br.) Hayek is regarded as a triploid apogamous species, perhaps a hybrid of ♀ D. assimilis Walker with ♂ diploid D. borreri Newm. The phloroglucides (phloroglucinol derivatives) of its rhizomes were investigated; their nature is compatible with the mentioned hypothesis. Besides several known compounds a new tricyclic phloroglucide C₃₆H₄₄O₁₂, designated trispara-aspidin was isolated. According to mass spectrum and products of reductive cleavage it has the structure given in formula 14 .     

Die Phloroglucide von Dryopteris caucasica (A. Br.) Fraser-Jenkins et Corley

Rhizomes of the recently rediscovered diploid fern Dryopteris caucasica were shown to contain the following phloroglucides: much filixic acid and para-aspidin, appreciable amounts of desaspidin and traces of flavaspidic acid, trisdesaspidin and aspidinol (artefact), i.e. exactly the same compounds as recently found in D. villarii ssp. villarii. These results are compatible with the hypothesis that either D. caucasica or a member of the D. villarii complex is the second, still unknown, ancestor of the allotetraploid D. filix-mas (L.) Schott. They also demonstrate the limitations of the chemical method which is quicker but less informative than the classical hybridisation procedures.     

The Phloroglucinols of Dryopteris aitoniana PICHI SERM. (Dryopteridaceae,Pteridophyta)

The phenolic compounds of the fern Dryopteris aitoniana were analyzed by improved methods avoiding alcaline reagents and contact with unbuffered SiO₂, which can cause deterioration. We confirmed the presence of five of the formerly (1971) reported six compounds, while the sixth, formerly incorrectly assumed to be aspidin (based on a spot in TLC), has now been isolated as cristals (TR-1579). It has the empirical formula C₂₇H₅₂O₂, but its structure is still unknown. Five other compounds were isolated in pure form, tetra-albaspidin BBBB ( 25 -BBBB) a known but rare phloroglucinol, and four new compounds: penta-albaspidin BBBBB ( 37 -BBBBB), hexa-albaspidin BBBBBB ( 38 -BBBBBB), tetraflavaspidic acid BBBB ( 26 -BBBB) and hexaflavaspidic acid BBBBBB ( 39 -BBBBBB). The structures were established by degradation NMR and partly by field-desorption and fast-atom-bombardment (FAB) mass spectra. The oligoflavaspidic acids are very unstable compounds, deteriorating during isolation procedures using the older ‘standard method’.     

Die phloroglucide von neun dryopteris-arten aus kenya sowie der d. oligodonta (desv.) pic.-serm. und d. “dilatata” von den canarischen inseln

Among the eight species of the fern genus Dryopteris which have been recorded from Kenya (East Africa), the group of D. inacqualis, D. pentheri and D. schimperana is regarded as critical. There is no agreement among experts as to whether D. inaequalis s. str. is restricted to South Africa and whether it should be separated specifically from D. pentheri Chemical and, as far as possible, cytological investigations of available material showed that the following taxa of Dryopteris occur in Kenya (ploidy in brackets) : 1. D. athamantica (2 × );2. D. callolepis (4 × ); 3. D. inaequalis (4 × ); 4. D. kilenzensis (2 × ); 5. D. manniana (4 × ); 6. D. pentheri (2 × ); 7. D. schimperana (2 × ); 8. D. sp. RBF-71/885 (TR-330.5) (4 × ); 9. D. squamiseta(ploidy not determined). The nomenclature of the four critical taxa, 3, 6, 7 and 8 is provisional. For comparison, two taxa from the Canary Islands, 10. D. ‘dilatata’ (4 × ) and 11. D. oligodonta (2 × ) were also investigated. Among the nine taxa from Kcnya, two (4 and 9) did not contain any phloroglucides. Dryopteris kilomensis must be regarded as one of the few representatives of the genus Dryopteris which lacks such compounds. On the other hand, the negative result for 9 is in agreement with the fact that this species has recently been transferred to a new genus Nothopevanema. The following three new compounds havc been isolated: Trisaspidinol ( 8 ), from D. inaequalis; Pentherin-I (not quitc pure) and Pentherin-I1 (hypothetical partial formula 25 ), from D. pentheri. Pentherin-I is also present in D. sp. RBF-71/885. Chemical and cytological results are compatiblc with the hypothesis that the latter is an allotetraploid derived from the diploids 6 and 7. The chemical patterns of 6, 7 and 8 show similarities to that of D. manniana, which in turn also shows similarities to the European D. filix-mas. Dryopteris ‘dilatata’ from the Canary Islands is chemically different from Europcan D. dilatata s. str. in lacking para-aspidin, while D. oligodonta gave results rather different from D. inaequalis or other East African species, and also from known European taxa.     

INTERMEDIATES IN THE PHOTOCONVERSION OF FUNCTIONAL PHYTOCHROME IN FERN SPORES OF Dryopteris-I DEMONSTRATION AND QUANTITATIVE CHARACTERIZATION OF THE PHOTOCHROMIC SYSTEM Pr⇔ Ii700USING NANOSECOND-LASER PULSES*,†

Abstract— Spores of Dryopteris paleacea and D. filix-mas are positively photoblastic with an optimum in the action spectrum around 665 nm. Light is perceived by phytochrome and the relationship between germination and mole fraction of the far-red-absorbing form of this pigment, P_fr, was investigated with saturating irradiations between 662 and 747 nm under low-fluence-rate conditions. These control irradiations establish a proportion of the total phytochrome, P,_tot, as P_fr with P_fr/P_tot–φ at equilibrium. These φ -values were calculated according to data for native oat phytochrome (Kelly and Lagarias, 1985, Biochemistry 24, 6003) and the spectral characteristics of the interference filters. With this method a linear relationship could be found between φ and germination from 2 to 70% for D. paleacea and from 2 to 90% for D. filix-mas, if probit germination was plotted vs probit φ This correlation formed the basis of investigating the phytochrome photoconversion by dye-laser pulses of 380 ± 30 ns under high-fluence-rate conditions, and thus to test quantitatively the impact of the photoreversibility of intermediate reactions of the photoconversion and the red-absorbing form of phytochrome, P_fr on the final P_fr-level. Spore germination was initiated by a single-laser pulse in the range from 592 to 700 nm. The most effective wavelengths were 649 and 660 nm in both species, and at saturation maximal germination (ca. 50%) was obtained from 592 to 665 nm for D. paleacea or ca. 60% germination from 592 to 670 nm for D. filix-mas. Both saturation levels correspond to a ø-value between 0.40 and 0.45. This significantly diminished photoconversion is a consequence of the high-fluence-rate conditions during the laser pulse which establishes the photochromic system between P_r and a set of very early intermediates, Iⁱ_700, (= P_r? Iⁱ₇₀₀). This system can be described by the extinction coefficients of P_r and the intermediates Iⁱ₇₀₀, and by the quantum yields, 4,φ for the forward and reverse reactions as φ If φ is calculated, assuming a quantum yield of 1:1 for both reactions and with the extinction coefficients of P_r and Iⁱ_7(l() (= lumi-R) given by Eilfeld and Riidiger (1985, Z. Naturforsch. 40c , 109), significantly higher values are calculated for / as compared to φ found in the control experiments. These results can be explained either: (i) with a quantum yield ratio φ_pr-φ1700: φ_1700φpr=1:1 and an assumed additional dark reaction leading from Iⁱ₇₀₀ or later intermediates back to P_r: or (ii) with a quantum yield ratio φ_{pr φ 1700}: φ_{1700 φpr}=1:2. In this case all Iⁱ₇₀₀ have to relax to P_fr. In this case all Iⁱ₇₀₀ have to relax to P_fr.     

A new carbamic acid from Dryopteris wallichiana

A new carbamic acid, (1,7a-dihydro-1H-inden-2(7aH)-ylidene)methylcarbamic acid (1), along with three known ones, 12-ursen-28-oic acid-3-O-β-D-glucopyranoside (2), 12-ursen-3-O-β-D-glucopyranoside (3), and 3,7,11,15-tetramethyl-2-hexadecen-1-ol (4), was isolated and identified from Dryopteris wallichiana.     

Two new cytotoxic furoquinoline alkaloids isolated from Aegle marmelos (Linn.) Correa

Two new cytotoxic furoquinoline alkaloids were isolated from the leaves of Aegle marmelos (Linn.) Correa; one from the total alkaloidal fraction (acid/base shake-out method) of the CHCl₃ extract and identified as 7,8-dihydroxy-4-hydrofuroquinoline and named trivially as Aegelbine-A. The other new alkaloid isolated from the pet. ether extract and identified as 4-hydro-7-hydroxy-8-prenyloxyfuroquinoline and named trivially as Aegelbine-B, together with a known alkaloid; aegeline and a known phenolic acid; ρ-hydroxybenzoic acid. The structures of all the isolated compounds were established based on 1D and 2D NMR spectroscopy and HR-ESI/MS. The cytotoxic activity of the isolated compounds was evaluated in vitro against HepG-2, PC3, A549 and MCF-7 cell lines. The obtained results revealed promising activity with structure-based relationship which is discussed briefly.     

New cyclopeptides from Trichoderma polysporum (Link ex Pers.) Rifai: cyclosporins B, D and E (author's transl)

New Cyclopeptides from Trichoderma polysporum (LINK EX PERS .) RIFAI : Cyclosporins B, D and E Cyclosporins represent a new group of biologically active metabolites produced by Trichoderma polysporum (LINK EX PERS .) RIFAI and other fungi imperfecti. The structures of the main components, cyclosporins A ( 1 ) and C( 3 ) have been determined as neutral cyclic oligopeptides composed of 11 amino acids, among them a new C₉-amino acid [2–4]. In addition, three minor metabolites, cyclosporins B, D and E, have now been isolated and characterized. Chemical investigation, spectroscopic evidence and X-ray analysis led to the structural formulae of cyclosporins B (2) and D (4) . Both compounds have the same sequence of amino acids as cyclosporin A (1) , with the exception of L -α-aminobutyric acid, replaced in cyclosporin B (2) by L -alanine and in cyclosporin D (4) by L -valine, respectively. Cyclosporins undergo a characteristic intramolecular N,O-acyl migration to furnish the corresponding basic isocompounds. The antifungal activities of cyclosporins are reported.     

A new acylated flavonol from the aerial parts of Asteriscus maritimus (L.) Less (Asteraceae)

Phytochemical investigation of the flowering aerial parts of Asteriscus maritimus (L.) Less (Asteraceae) led to the isolation of a new compound: patuletin 7-O-β-D-[(2″′S) 6″(3″′-hydroxy-2″′-methyl-propanoyl)] glucopyranoside, together with five known metabolites; β-sitosterol 2, chlorogenic acid 3, P-hydroxy -methylbenzoate 4, luteolin 5 and protocatechuic acid 6. The structures of the isolated compounds were determined by comprehensive analyses of its 1D and 2D NMR, HRMS and compared with previously known analogues. The ethanolic extract of the flowering aerial parts of A. maritimus was found to be safe (LD₅₀ = 4.6 mg/kg) and possess significant antioxidant and anti-inflammatory activities and this was in accordance with its high phenolic content (107.36 ± 0.051 mg GAE/g extract).     

Der Einfluss von D-Aminosäureresten auf das konformative Verhalten von Kollagenmodellpeptiden

The influence of D -amino acid residues upon the conformative behaviour of collagen model peptides. (L -Pro-L -Pro-Gly)₁₀ and (L -Pro-D (L )-Pro-Gly)₁₀ with 10 percent D -Prolin residues have been synthesized by the Merrifield technique. Further Poly-(Gly-Pro-Pro) and Poly-(Ala-Gly-Pro) with various amounts of D -amino acid residues have been synthesized by polycondensation of the proper tripeptides. The conformational behaviour of all these polypeptides has been studied by measurements at varying temperatures of optical rotation, circular dichroism and molecular weight. The results show that limited amounts of D -amino acid residues do not impedecollagen-like triple helical conformations. The denaturation temperatures, however, are considerably lowered by D -amino acid residues. The implications of these findings for the understanding of the properties of partially racemized degraded gelatins with relatively low gel melting points are discussed.     

Phloroglucinol Derivatives from Dryopteris crassirhizoma as Potent Xanthine Oxidase Inhibitors

Dryopteris crassirhizoma rhizomes are used as a traditional medicine in Asia. The EtOAc extract of these roots has shown potent xanthine oxidase (XO) inhibitory activity. However, the main phloroglucinols in D. crassirhizoma rhizomes have not been analyzed. Thus, we investigated the major constituents responsible for this effect. Bioassay-guided purification isolated four compounds: flavaspidic acid AP (1), flavaspidic acid AB (2), flavaspidic acid PB (3), and flavaspidic acid BB (4). Among these, 1 showed the most potent inhibitory activity with a half-maximal inhibitory concentration (IC₅₀) value of 6.3 µM, similar to that of allopurinol (IC₅₀ = 5.7 µM) and better than that of oxypurinol (IC₅₀ = 43.1 µM), which are XO inhibitors. A comparative activity screen indicated that the acetyl group at C3 and C3′ is crucial for XO inhibition. For example, 1 showed nearly 4-fold higher efficacy than 4 (IC₅₀ = 20.9 µM). Representative inhibitors (1–4) in the rhizomes of D. crassirhizoma showed reversible and noncompetitive inhibition toward XO. Furthermore, the potent inhibitors were shown to be present in high quantities in the rhizomes by a UPLC-QTOF-MS analysis. Therefore, the rhizomes of D. crassirhizoma could be used to develop nutraceuticals and medicines for the treatment of gout.     

Die Glykoside der Samen von Dregea volubilis (L.) BENTH. ex HOOK. 2. Mitt. Isolierung weiterer Drevogenine Glykoside und Aglykone, 277. Mitteilung

A total of fifteen substances were identified through thin-layer chromatography, after mild acid hydrolysis of the chloroform extract from the seeds of Dregea volubilis (L.) BENTH . ex HOOK . Of these fifteen substances, eight (B, D, P, O; U, V, H and T) were isolated in crystalline form. Two of these were identical with the known genins drevogenin B (B) and drevogenin D (D). Drevogenin P (P) and the unknown substance O (probably a genin) were isolated for the first time. U proved to be identical with D -cymarose, V with the biose U1 obtained from Asclepias lilacina, and H with (+)-methyl-pachybioside. T was not investigated (probably a sugar derivative).     

Cytotoxicity of new secondary metabolites,fatty acids and tocols composition of seeds of Ducrosia anethifolia (DC.) Boiss

Two new monoterpene Ducrosin A (1) and sesquiterpene Ducrosin B (2) were isolated along with three known compounds, stigmasterol (3) and two furanocoumarins (4 and 5), from the dichloromethane extract of the seeds of Ducrosia anethifolia (DC.) Boiss. Their structures were determined using extensive 1D and 2D NMR, (ES)-HRMS and IR spectroscopic analyses and by comparison with literature data. Gas chromatography analysis of the fatty acids (FAs) of D. anethifolia seed oils (DAOs) showed high percentages of elaidic acid (C18:1 Δ9t) 65% and oleic acid (C18:1 Δ9c) 15%. The total tocopherol (tocols) content in DAOs was found to be 164 mg/100 g. The cytotoxic effect of the isolates was also evaluated using the MTT assay against the HCT-116 and SKOV-3 cell lines. The results showed that compound 2 was the most cytotoxic agent followed by compounds 1 and 4, which has an epoxide moiety that most likely contributes to its activity.     

Synthese von ‘D-Isothreonin’ und ‘L-Alloisothreonin’ aus L-Alanin

Synthesis of ‘D -Isothreonine’ and ‘L -Alloisothreonine’ Starting from L -Alanine Starting from L -alanine, ‘D -isothreonine’ ( = (2R, 3S)-3-amino-2-hydroxybutanoic acid) and ‘L -alloisothreonine’ ( = (2S, 3S)-3-amino-2-hydroxybutanoic acid) were synthesized.     

Preparation of Ultrathin Two‐Dimensional TixTa1−xSyOz Nanosheets as Highly Efficient Photothermal Agents

Although two‐dimensional (2D) metal oxide/sulfide hybrid nanostructures have been synthesized, the facile preparation of ultrathin 2D nanosheets in high yield still remains a challenge. Herein, we report the first high‐yield preparation of solution‐processed ultrathin 2D metal oxide/sulfide hybrid nanosheets, that is, Ti_x Ta_1−x S_y O_z (x =0.71, 0.49, and 0.30), from Ti_x Ta_1−x S₂ precursors. The nanosheet exhibits strong absorbance in the near‐infrared region, giving a large extinction coefficient of 54.1 L g⁻¹ cm⁻¹ at 808 nm, and a high photothermal conversion efficiency of 39.2 %. After modification with lipoic acid‐conjugated polyethylene glycol, the nanosheet is a suitable photothermal agent for treatment of cancer cells under 808 nm laser irradiation. This work provides a facile and general method for the preparation of 2D metal oxide/sulfide hybrid nanosheets.     

Elektronendonator-Akzeptor-Komplexe von Diazonium-Ionen und die Struktur von stabilisierten Diazonium-Salzen. 20. Mitteilung zur Kenntnis der Azokupplungsreaktion

1. In 0.1N HCl/H₂O, o- and p-nitrobenzenediazonium ions rapidly form a complex with 2-naphthol-6, 8-disulphonic acid anions. Visible and NMR, spectra show that it has the structure of a charge-transfer complex (π-complex). The latter is probably an intermediate in the electrophilic aromatic substitution (diazo coupling reaction). 2. Diazonium ions form charge-transfer complexes with naphthalene, 1-methylnaphthalene, naphthalene-1-sulphonic acid, 1-naphthyl-methanesulphonic acid and also 2-naphthol-1-sulphonic acid. The equilibrium constants of all these complexes have been determined. 3. The stabilisation of diazonium salts by arylsulphonic acids with regard to decomposition is due to charge-transfer complex formation and not to formation of diazosulphonates as assumed by former investigators. The sulphonic group is not essential for the stabilisation. 4. Charge-transfer complex formation decreases the electrophilicity of the diazonium ion (rate of diazo coupling reaction) only slightly.     

Zur Photochemie von 2, 1-Benzisoxazolen (Anthranilen) und thermischen und photochemischen Umsetzungen von 2-Azido-acylbenzolen in stark saurer Lösung

On the Photochemistry of 2, 1-Benzisoxazoles (Anthraniles) and on the Thermal and Photochemical Decomposition of 2-Azido-acylbenzenes in Strongly Acidic Solution Anthranils 6 (Scheme 3), when irradiated with a mercury high-pressure lamp, in 96% sulfuric acid yielded, after work-up, 2-amino-5-hydroxy-acylbenzenes 8 and as side products 2-amino-3-hydroxy-acylbenzenes 9 (cf. Schemes 5–7 and Table 1). When C(5) of the anthranils 6 carries a methyl group a more complex reaction mixture is found after irradiation in 96% sulfuric acid (cf. Schemes 8 and 9): 3, 5-dimethyl-anthranil ( 6d ) yielded (after irradiation and acetylation) 2-acetyl- amino-5-methyl-acetophenone ( 15 ), 2-acetylamino-5-acetoxymethyl-acetophenone ( 18d ) and 2-acetylamino-5-acetoxy-6-methyl-acetophenone ( 12c ). The latter product was also formed after irradiation of 3, 4-dimethylanthranil ( 6c ) in 96% sulfuric acid. 3, 5, 7-Trimethyl-anthranil ( 6f ) formed under the same conditions 2-acetylamino-3, 5-dimethyl-acetophenone ( 15f ) and 2-acetylamino-5-acetoxymethyl-3-methyl-acetophenone ( 18f ). Since qualitatively the same product patterns were observed when the corresponding 2-azido-acetophenones 7 were decomposed in 96% sulfuric acid it is concluded that anthranilium ions (cf. 6b -H⊕, Scheme 11) on irradiation are transformed by cleavage of the N, O-bond into 2-acyl-phenylnitrenium ions (cf. 25b -H⊕) in the singlet ground state. The nitrenium ions are trapped directly by nucleophiles ( HSO ?₄ in 96% sulfuric acid), thus, yielding the hydroxy-acetophenones 8 and 9 (Scheme 11). If C(5) is blocked by a methyl group a [1, 2]-rearrangement of the methyl group may occur (cf. Scheme 13) or loss of sulfuric acid can lead to quinomethane iminium ions (cf. 32-H⊕ , Scheme 13) which will react with HSO ?₄ ions to yield, after hydrolysis and acetylation, the 5-acetoxymethyl substituted acetophenones 18d and 18f . It is assumed that the reduction products (2-acetylamino-acetophenones 15 ) are formed from the corresponding nitrenium ions in the triplet ground state.     

Herstellung von Hilfsstoffen für die asymmetrische Synthese aus Weinsäure. Addition von Butyllithium an Aldehyde in chiralem Medium

Preparation of Auxiliaries for Asymmetric Syntheses from Tartaric Acid. Additions of Butyllithium to Aldehydes in Chiral Media. Chiral derivatives of the complexing 1,2-diheterosubstituted ethanes A–D are prepared from tartaric acid. The key starting materials are the succinic acid derivative 1 , the dioxolane 2a , and the diamide 3a . These are converted to the ethers, alkoxyamines, and alkylthio-amines listed in the first column of Table 2 which also contains the derivatives 21c, 22d , and 23d made from lactic acid, malic acid, and proline, respectively. It is shown that the highest optical yields (up to 40%) in reactions of butyllithium with aldehydes are obtained when mixtures of (?)-1,2,3,4-tetramethoxy-butane ( 4b ), (+)-2,3-dimethoxy-N,N,N′,N′-tetramethyl-1,4-butanediamine ( 17a ), and (?)-1,4-dimethoxy-N,N,N′,N′-tetramethyl-2,3-butanediamine ( 14c ) with pentane are used at temperatures down to ?150° and ratios of auxiliary/butyllithium of up to 10:1 (see equation (1), Tables 2–4).     

Chemical Constituents of Cassia abbreviata and Their Anti-HIV-1 Activity

Three new (1–3) and 25 known compounds were isolated from the crude extract of Cassia abbreviata. The chemical structures of new compounds were established by extensive spectroscopic analyses including 1D and 2D NMR and HRESIMS. Cassiabrevone (1) is the first heterodimer of guibourtinidol and planchol A. Compound 2 was a new chalcane, while 3 was a new naphthalene. Cassiabrevone (1), guibourtinidol-(4α→8)-epiafzelechin (4), taxifolin (8), oleanolic acid (17), piceatannol (22), and palmitic acid (28), exhibited potent anti-HIV-1 activity with IC₅₀ values of 11.89 µM, 15.39 µM, 49.04 µM, 7.95 µM, 3.58 µM, and 15.97 µM, respectively.     

(C6H13NH3)2(NH2CHNH2)Pb2I7: A Two‐dimensional Bilayer Inorganic–Organic Hybrid Perovskite Showing Photodetecting Behavior

Inorganic–organic hybrid perovskites, especially two‐dimensional (2D) layered halide perovskites, have attracted significant attention due to their unique structures and attractive optoelectronic properties, which open up a great opportunity for next‐generation photosensitive devices. Herein, we report a new 2D bilayered inorganic–organic hybrid perovskite, (C₆H₁₃NH₃)₂(NH₂CHNH₂)Pb₂I₇ ( HFA , where C₆H₁₃NH₃⁺ is hexylaminium and NH₂CHNH₂⁺ is formamidinium), which exhibits a remarkable photoresponse under broadband light illumination. Structural characterizations demonstrate that the 2D perovskite structure of HFA is constructed by alternant stacking of inorganic lead iodide bilayered sheets and organic hexylaminium layers. Optical absorbance measurements combined with density functional theory (DFT) calculations suggest that HFA is a direct band gap semiconductor with a narrow band gap (E_g) of ≈2.02 eV. Based on these findings, photodetectors based on HFA crystal wafer are fabricated, which exhibit fascinating optoelectronic properties including large on/off current ratios (over 10³), fast response speeds (τ_rise=310 μs and τ_decay=520 μs) and high responsivity (≈0.95 mA W^?1). This work will contribute to the design and development of new two‐dimensional bilayer inorganic–organic hybrid perovskites for high‐performance photosensitive devices.