Two pairs of chlorine-containing phenylpropanoid enantiomers from Acorus tatarinowii

Two pairs of chlorine-containing phenylpropanoid enantiomers (1a/1b and 2a/2b) were isolated from the rhizomes of Acorus tatarinowii. Interestingly, these optical isomers (1a/1b and 2a/2b) were co-existed in the same plant, which were characterized as the first halogen-containing natural products from the genus Acorus. Their structures and absolute configurations were elucidated by a combination of spectroscopic analysis and a single-crystal X-ray diffraction, assisted by a modified Mosher's method. The phenylpropanoid isomers (1a/1b and 2a/2b) were evaluated for their antioxidant activities using DPPH assay and cytotoxic activities against five human cancer cell lines.     

A new iridoid diglucoside from Harpagophytum procumbens

A new iridoid diglucoside has been isolated from an aqueous extract of Harpagophytum procumbens secondary roots, together with six known compounds. Its structure has been assigned as 6′-O-glucopyranosyl-8-O-trans-coumaroylharpagide by spectroscopic means.     

Developmental variation in floral volatiles composition of a fragrant orchid Zygopetalum maculatum (Kunth) Garay

Emitted scent volatile profile of an orchid species Zygopetalum maculatum was studied using dynamic headspace sampling technique with four different adsorbent matrices, namely Porapak Type Q polymer (mesh size: 80/100), Tenax (mesh size: 60/80), activated charcoal and graphite. In addition, developmental variations in scent emissions and endogenous volatile levels were also investigated. Gas chromatography-mass spectrometry analysis revealed the presence of 21 volatile compounds in the headspace, which was predominantly enriched with benzenoid compounds. Among these benzenoids, o-diethylbenzene and p-diethylbenzene were the major compounds followed by benzyl acetate and methyl salicylate. Among the phenylpropanoid compounds, 2-phenylethyl acetate was the major volatile. However, as compared to benzenoids, the quantity was much lesser, indicating the inclination of phenylalanine flux towards benzenoid pathway. The outcome of this study has the implications in enhancing fragrance and vase life of orchids of the Sikkim Himalaya region and thus may further help to meet the growing market demand.     

Chemical constituents from Glehnia littoralis and their chemotaxonomic significance

Abstract

Phytochemical investigation of the roots of Glehnia littoralis Fr. Schmidt. ex Miq. led to the isolation of 16 known compounds, including three β-carboline alkaloids (1–3), four phenylpropanoids (4–7), five phenolic acids (8–12), three polyacetylenes (13–15) and one fatty acid (16). The structures of these compounds were elucidated on the basis of spectral analysis and comparison with those reported in literatures. To the best of knowledge, the report of the first β-carboline alkaloid in the Umbelliferae family. Additionally, compounds 1–5, 9, 10 and 16 have not been reported from any species in Umbelliferae family, compounds 7, 8 and 12 were isolated from the genus Glehnia for the first time and could be of the chemotaxinomic significance and serve as valuable chemotaxonomic makers for G. littoralis. The chemotaxonomic significance of the isolated compounds was summarised.     

A new phenylpropanoid from the roots of Euphorbia nematocypha

A phytochemical investigation of the ethanolic extracts of the dried roots of Euphorbia nematocypha resulted in the isolation of a new phenylpropanoid, 16-O-caffeoyl-16-hydroxylhexadecanoic acid (1), together with 23 known compounds (2–24). Their structures were elucidated on the basis of spectroscopic data. Compound 1 was first to be isolated as a caffeic acyl long chain alkyl acid from the family Euphorbiaceae. The new isolated phenylpropanoid showed potent cytotoxic activities against the MCF-7 and HeLa cell lines.     

Determination of six bioactive components of Saussurea katochaete by capillary electrophoresis

The simultaneous determination of 3,4-dimethoxy-3'-hydroxy propiophenone, 5-hydroxy-7-methoxy coumarin, 7-hydroxy coumarin, 3',5'-dimethoxy apigenin, apigenin and 4-hydroxy cinnamic acid in the extract of S. katochaete has been investigated by capillary electrophoresis for the first time. The six active components were completely separated within 10 min in 20 mM Na(2)HPO(4) buffer at pH 11.00 with 10% (v/v) methanol and detected at 214 nm. The applied voltage was 15 kV and the temperature was kept at 25 degrees C. The effects of buffer pH, the concentration of Na(2)HPO(4) and the concentration of methanol on the separation efficiency were studied systematically. The regression equations revealed good linear relationships (correlation coefficients were 0.9987-0.9998) between the peak area of each analyte and its concentration. The relative standard deviations (RSD) of migration time and peak areas were <1.63 and <4.03%, respectively. The application of this method for the separation and determination of the six bioactive components in S. katochaete was reported. The contents of the six analytes ranged from 0.023 to 0.131 mg/g and recoveries ranged from 94.7 to 104.8%.     

Flow-injection potentiometric determination of triiodide by plasticized poly(vinyl chloride) membrane electrodes and its application to the determination of chlorine-containing disinfectants

Plasticized poly(vinyl chloride) (PVC) membranes of different compositions were tested for use in the construction of potentiometric flow detectors for triiodide. A membrane with a 2:1 (w/w) 2-nitrophenyl octyl ether to PVC ratio was selected. The influence of thiosulphate in the carrier solution composition and of the flow-injection variables on the determination of triiodide was studied. In the selected conditions, a linear relationship between peak height and log[I₃⁻] was obtained between 5 × 10⁻⁶ and 1 × 10⁻⁴ mol l⁻¹ triiodide. Peak height relative standard deviations for 2 × 10⁻⁵ and 1 × 10⁻⁴ mol l⁻¹ triiodide were ±0.4 and ±1.8%, respectively, and sampling frequency was 80 samples per hour. The method proposed was applied satisfactorily to the iodometric determination of different chlorine-containing disinfectants, among them trichloroisocyanuric acid and dichloroisocyanurate in several types of commercial sample.     

Six New Phenylpropanoid Derivatives from Chemically Converted Extract of Alpinia galanga (L.) and Their Antiparasitic Activities

Chemical conversion of the extract of natural resources is a very attractive way to expand the chemical space to discover bioactive compounds. In order to search for new medicines to treat parasitic diseases that cause high morbidity and mortality in affected countries in the world, the ethyl acetate extract from the rhizome of Alpinia galanga (L.) has been chemically converted by epoxidation using dioxirane generated in situ. The biological activity of chemically converted extract (CCE) of A. galanga (L.) significantly increased the activity against Leishmania major up to 82.6 ± 6.2 % at 25 μg/mL (whereas 2.7 ± 0.8% for the original extract). By bioassay-guided fractionation, new phenylpropanoids (1–6) and four known compounds, hydroquinone (7), 4-hydroxy(4-hydroxyphenyl)methoxy)benzaldehyde (8), isocoumarin cis 4-hydroxymelein (9), and (2S,3S,6R,7R,9S,10S)-humulene triepoxide (10) were isolated from CCE. The structures of isolated compounds were determined by spectroscopic analyses of 1D and 2D NMR, IR, and MS spectra. The most active compound was hydroquinone (7) with IC₅₀ = 0.37 ± 1.37 μg/mL as a substantial active principle of CCE. In addition, the new phenylpropanoid 2 (IC₅₀ = 27.8 ± 0.34 μg/mL) also showed significant activity against L. major compared to the positive control miltefosine (IC₅₀ = 7.47 ± 0.3 μg/mL). The activities of the isolated compounds were also evaluated against Plasmodium falciparum, Trypanosoma brucei gambisense and Trypanosoma brucei rhodeisense. Interestingly, compound 2 was selectively active against trypanosomes with potent activity. To the best of our knowledge, this is the first report on the bioactive “unnatural” natural products from the crude extract of A. galanga (L.) by chemical conversion and on its activities against causal pathogens of leishmaniasis, trypanosomiasis, and malaria.     

苷类研究ⅩⅩⅥ: 苯丙素苷Eutigoside A的合成研究

首次报道了苯丙素苷类化合物EutigosideA,即1-O-[2-(4-羟基苯基)乙基]-6-O-(E)-香豆酰基-β-D-吡喃葡萄糖的全合成。从四乙酰溴代葡萄糖出发,经过成苷、脱乙酰基两步反应,制备了2-对烯丙氧基苯基-β-D-吡喃葡萄糖苷(3),采用酰氯法在低温下将对乙酰氧基肉桂酰基引入化合物3的葡萄糖6位,再经过脱烯丙基、脱乙酰基两步,便顺利地合成了天然苯丙素苷EutigosideA。以化合物3为原料,经过对葡萄糖4,6位亚苄基化、2,3位乙酰化、4,6位脱亚苄基、选择性6位乙酰化及4位引入对乙酰氧基肉桂酰基等五步反应,得到了保护的苯丙素苷(OsmanthusideA(10);但在NH~3/MeOH条件下脱乙酰基时,化合物10中的香豆酰基从葡萄糖的4位迁移至6位,最终又得到了EutigosideA。     

Chrysosporazines Revisited: Regioisomeric Phenylpropanoid Piperazine P-Glycoprotein Inhibitors from Australian Marine Fish-Derived Fungi

A library of fungi previously recovered from the gastrointestinal tract (GIT) of several fresh, commercially sourced Australian mullet fish was re-profiled for production of a rare class of phenylpropanoid piperazine alkaloids (chrysosporazines) using an integrated platform of; (i) miniaturized 24-well plate cultivation profiling (MATRIX), (ii) UPLC-DAD and UPLC-QTOF-MS/MS (GNPS) chemical profiling, and; (iii) precursor directed biosynthesis to manipulate in situ biosynthetic performance and outputs; to detect two new fungal producers of chrysosporazines. Chemical analysis of an optimized PDA solid phase cultivation of Aspergillus sp. CMB-F661 yielded the new regioisomeric chrysosporazine T (1) and U (2), while precursor directed cultivation amplified production and yielded the very minor new natural products azachrysosporazine T1 (3) and U1 (4), and the new unnatural analogues neochrysosporazine R (5) and S (6). Likewise, chemical analysis of an optimized M1 solid phase cultivation of Spiromastix sp. CMB-F455 lead to the GNPS detection of multiple chrysosporazines and brasiliamides, and the isolation and structure elucidation of chrysosporazine D (7) and brasiliamide A (8). Access to new chrysosporazine regioisomers facilitated structure activity relationship investigations to better define the chrysosporazine P-glycoprotein (P-gp) inhibitory pharmacophore, which is exceptionally potent at reversing doxorubrin resistance in P-gp over expressing colon carcinoma cells (SW600 Ad300).