Screening and determination for potential α‐glucosidase inhibitory constituents from Dalbergia odorifera T. Chen using ultrafiltration‐LC/ESI‐MSn

In the present study, it was demonstrated that ethyl acetate soluble fraction partitioned from heartwood of Dalbergia odorifera T. Chen (HEF) had a remarkable inhibitory effect on α‐glucosidase. Therefore HEF was selected as a starting material for screening the potential α‐glucosidase inhibitors using ultrafiltration liquid chromatography/mass spectrometry (UF‐LC/MS). Twenty‐six compounds were identified with analysis of LC/MS. UF assay indicated that 18 compositions might be α‐glucosidase inhibitors in HEF; eight of them were estimated for their α‐glucosidase inhibitory activity, and the results showed that (2S)‐liquiritigenin, (2S)‐4′,6‐dihydroxy‐ 7‐methoxyflavanone and isoliquiritigenin displayed obvious inhibition of yeast α‐glucosidase. In addition, in order to control the quality of HEF, the content of five compounds in HEF was simultaneously determined for the first time. These results provide an important theoretical base for the further application of HEF to treat type 2 diabetes in the clinic and development of natural α‐glucosidase inhibitors with low toxicity. Copyright © 2013 John Wiley & Sons, Ltd.     

New Triterpenoid Saponins from the Roots of Gypsophila paniculata L.

The seven new triterpenoid saponins 1 – 7 were isolated from the roots of Gypsophila paniculata L. Their structures were established by 1D ‐ and 2D‐NMR techniques, HR‐MS, and acid hydrolysis. The isolated compounds include 3,28‐O‐bidesmosides with or without a 4‐methoxycinnamoyl group (see 1 vs. 2 and 3 ), and 3‐O‐monoglucosides 4 – 7 . All isolated saponins 1 – 7 and their aglycones were evaluated for their α‐glucosidase inhibition activity. Compound 1 showed inhibitory activity against yeast α‐glucosidase with an IC₅₀ value of 100.9±3.3 μM , whereas compounds 2 – 7 were inactive.     

Concise Synthesis and Antidiabetic Effect of Three Natural Triterpenoid Saponins Isolated from Fadogia ancylantha (Makoni tea)

The first concise synthesis of the bidesmosidic oleanolic acid saponins 1 – 3 isolated from Fadogia ancylantha (Makoni tea) have been accomplished through a ‘one‐pot sequential glycosylation’ strategy with two glycosyl 1‐(trichloroacetimidate)s as glycosyl donors. The synthesized natural products 1 – 3 were then evaluated for their inhibitory activities against α‐glucosidase, α‐amylase, and lipase. Among the assayed compounds 1 – 3 , compound 1 showed strong α‐glucosidase and α‐amylase inhibition, with IC₅₀ values of 160 and 180 μM , respectively. Moreover, compounds 2 and 3 showed strong inhibition against α‐glucosidase and lipase, with the respective IC₅₀ values of 170 and 190 μM , and 190 and 200 μM .     

Xanthones with α‐Glucosidase Inhibitory Activities from Aspergillus versicolor,a Fungal Endophyte of Huperzia serrata

Three new xanthones, namely huperxanthones A–C ( 1 – 3 , resp.), were obtained from the cultures of Aspergillus versicolor, a fungal endophyte of Huperzia serrata, together with 1,7‐dihydroxy‐8‐(methoxycarbonyl)xanthone‐3‐carboxylic acid ( 4 ), β‐diversonolic acid methyl ester ( 5 ), 4‐hydroxyvertixanthone ( 6 ), and sydowinin B ( 7 ). The structures of the new compounds were established by detailed NMR and MS analysis, especially by 2D‐NMR experiments. All xanthones were evaluated for their effects on α‐glucosidase. Compound 4 exhibited a potent inhibitory activity against α‐glucosidase with an IC₅₀ value of 0.24 mM (vs. 0.38 mM for acarbose). The rest of the compounds showed weak or no activity against α‐glucosidase.     

On‐line high‐performance liquid chromatography coupled with biochemical detection method for screening of α‐glucosidase inhibitors in green tea

An on‐line high‐performance liquid chromatography–biochemical detection (HPLC‐BCD) method, in which compounds separated by HPLC were on‐line reacted with enzyme and substrate solutions delivered by flow injection and the enzyme inhibition signal was collected by UV detection, was developed to rapidly screen α‐glucosidase inhibitors from green tea extracts in this study. The chromatographic fingerprints and enzyme inhibition profiles of the different brands of green tea could be simultaneously detected by the on‐line HPLC‐BCD method. Enzyme inhibition profiles were detected by the UV detector at 415 nm based on the reaction of α‐glucosidase and p‐nitrophenyl α‐d ‐glucopyranoside (PNPG). PNPG (1.25 mm ), α‐glucosidase (0.4 U/mL) and the flow rate 0.07 mL/min were applied as optimized parameters to detect α‐glucosidase inhibitors in green tea. Four components in green tea showed α‐glucosidase inhibition action and three of them were identified as HHDP‐galloyl glucose, (−)‐epigallocatechin‐3‐gallate and (−)‐epicatechin‐3‐gallate by HPLC–fourier‐transform mass spectrometry (HPLC‐FTMS). Two brands of green tea derived from Mengding and Enshi mountainous areas might be superior to the other samples in the prevention and treatment of diabetes owing to their stronger activities of enzyme inhibitors. The proposed on‐line HPLC‐BCD method could be used to rapidly identify the potential enzyme inhibitors in complex matrixes.     

Lycopodium Alkaloids from Huperzia serrata

Three new lycopodium alkaloids, huperserramines A–C ( 1 – 3 , resp.), along with 15 known ones, lycopodine‐6α,11α‐diol ( 4 ), lycoposerramine H ( 5 ), lycoposerramine I ( 6 ), lycopodine‐6α‐ol ( 7 ), lycoposerramine M ( 8 ), diphaladine A ( 9 ), lycoposerramine K ( 10 ), lycoposerramine W ( 11 ), huperzine M ( 12 ), luciduline ( 13 ), phlegmariuine N ( 14 ), huperzine A ( 15 ), huperzine B ( 16 ), lycodine ( 17 ), and lycoposerramine R ( 18 ), were isolated from the whole plant of Huperzia serrata. Their structures were established by spectroscopic methods, including 2D‐NMR and MS analyses. All the isolates were evaluated for their inhibitory effects on acetylcholinesterase (AChE) and α‐glucosidase. As a result, lycopodine‐6α,11α‐diol ( 4 ) exhibited more potent α‐glucosidase inhibitory activity (IC₅₀ 148±5.5 μM ) than the positive control acarbose (IC₅₀ 376.3±2.7 μM ).     

Lyciumaside and Lyciumate: A New Diacylglycoside and Sesquiterpene Lactone from Lycium shawii

One new diacylglycoside named lyciumaside ( 1 ) and a new sesquiterpene lactone named lyciumate ( 2 ) were isolated from Lycium shawii Roem . & Schult . The structures of the two new compounds were elucidated based on 1D‐ (¹H‐ and ¹³C‐NMR and NOE) and 2D‐NMR (COSY, HSQC, and HMBC) spectroscopic techniques, and mass spectrometry (ESI‐MS). Preliminary evaluations demonstrated lyciumaside ( 1 ) possesses strong antioxidant activity with an IC₅₀ = 30 μg/ml (80% inhibition) while it was inactive in α‐glucosidase and urease enzymes assays.     

Sulfated Triterpenes from Lemon Balm

The hydroalcoholic (EtOH/H₂O) extract of matured leaf margins of lemon balm (Melissa officinalis L.) afforded a new 3,23‐disulfate of 2α,3β‐23,29‐tetrahydroxyolean‐12‐en‐28‐oic acid 28‐O‐β‐D ‐glucopyranoside ( 1 ) and a new 23‐monosulfate of 2α,23‐dihydroxyurs‐12‐en‐28‐oic acid 3‐O‐β‐D ‐glucopyranoside ( 2 ), along with six known compounds, i.e., 23‐monosulfate of 2α,3β,19α,23‐tetrahydroxyurs‐12‐ene‐28‐oic acid 28‐O‐β‐D ‐glucopyranoside ( 3 ), 3,5,6‐trihydroxydehydro‐α‐ionol 9‐O‐β‐D ‐glucopyranoside ( 4 ), quadranoside III ( 5 ), rosmarinic acid ( 6 ), caffeic acid ( 7 ), and luteolin ( 8 ). All the isolated compounds were evaluated for their antioxidant, antimicrobial, antimalarial, and cytotoxic activities. Only rosmarinic acid exhibited substantial antioxidant and antimicrobial activities, whereas sulfated terpenes showed considerably lower or no antimicrobial activity.     

Synthesis,characterization and α‐amylase and α‐glucosidase inhibition studies of novel vanadyl chalcone complexes

A series of chalcone ligands and their corresponding vanadyl complexes of composition [VO (L^I–IV)₂(H₂O)₂]SO₄ (where L^I = 1,3‐Diphenylprop‐2‐en‐1‐one, L^II = 3‐(2‐Hydroxy‐phenyl)‐1‐phenyl‐propenone, L^III = 3‐(3‐Nitro‐phenyl)‐1‐phenyl‐propenone, L^IV = 3‐(4‐Methoxy‐phenyl)‐1‐phenyl‐propenone) have been synthesized and characterized using various spectroscopic (Fourier‐transform infrared, electrospray ionization mass, nuclear magnetic resonance, electron paramagnetic resonance, thermogravimetric analysis, vibrating sample magnetometer) and physico‐analytic techniques. Antidiabetic activities of synthesized complexes along with chalcones were evaluated by performing in vitro and in silico α‐amylase and α‐glucosidase inhibition studies. The obtained results displayed moderate to significant inhibition activity against both the enzymes by vanadyl chalcone complexes. The most potent complexes were further investigated for the enzyme kinetic studies and displayed the mixed inhibition for both the enzymes. Further, antioxidant activity of vanadyl chalcone complexes was evaluated for their efficiency to release oxidative stress using 2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate assay, and two complexes (Complexes 2 and 4 ) have demonstrated remarkable antioxidant activity. All the complexes were found to possess promising antidiabetic and antioxidant potential.     

Indolyl Linked Meta‐Substituted Benzylidenes as Novel Ligands: Synthesis,Biological Evaluation,and Molecular Docking Studies

Synthesis of indolyl linked benzylidene based meta‐substituted phenyl containing thiazolidinediones ( 4a – b ), rhodanine ( 5a – b ), and 1,3‐dicarbonyl based acyclic analogs of isoxazolidinediones ( 6a – 7b ) in an effort to develop novel α‐glucosidase inhibitors in the management of hyperglycemia for the treatment of type 2 diabetes is reported. The structure of all the novel synthesized compounds was confirmed through the spectral studies (LC–MS, ¹H‐NMR, ¹³C‐NMR, and FTIR). Comparative evaluation of these compounds revealed that the compound 5b showed maximum inhibitory potential against α‐amylase and α‐glucosidase giving an IC₅₀ value of 0.28 ± 0.01 μM. Furthermore, binding affinities in terms of G score values and hydrogen bond interactions between all the synthesized compounds and the AA residues in the active site of the protein (PDB code: 3TOP) to that of Acarbose (standard drug) were explored with the help of molecular docking studies. Compound 5b was considered as promising candidate of this series.     

Synthesis of New C(2)‐Substituted gluco‐Configured Tetrahydroimidazopyridines and Their Evaluation as Glucosidase Inhibitors

The gluco‐configured C(2)‐substituted tetrahydroimidazopyridines 8 – 14 were prepared and tested as inhibitors of the β‐glucosidases from Caldocellum saccharolyticum and from sweet almonds, and of the α‐glucosidase from brewer's yeast. All new imidazopyridines are nanomolar inhibitors of the β‐glucosidases and micromolar inhibitors of the α‐glucosidase. The 3‐phenylpropyl derivative 14 proved the strongest inhibitor of the Caldocellum β‐glucosidase (K_i = 0.9 nM ), only slightly weaker than the known 2‐phenylethyl analogue 7 , and the propyl derivative 13 is the strongest inhibitor of the sweet almond β‐glucosidases (K_i = 3.2 nM ), again slightly weaker than 7 . There is no strong dependence of the inhibition on the nature of the C(2)‐substituent and no clear correlation between the inhibitory strength of the known manno‐configured imidazopyridines 2 – 6 and the gluco‐analogues 8 – 12 . While most manno‐imidazopyridines are competitive inhibitors, the gluco‐analogues proved non‐competitive inhibitors of the Caldocellum β‐glucosidase and mixed‐type or partial mixed‐type inhibitors of the sweet almond β‐glucosidases.     

Determination of phenolic compounds by MALDI–TOF and essential oil composition by GC–MS during three development stages of Origanum majorana L.

This study aimed to investigate the effect of the maturation process of sweet marjoram (Origanum majorana L.) on essential oil composition, the phenolic profile of ethanolic extract and their antioxidant capacities. The essential oil composition was studied at three stages of maturity by GC–MS. Thirty compounds were detected representing 100% of the total essential oil. p‐Menth‐1‐en‐4‐ol was the major compound (37.15–76.94%) followed by cyclohexanol‐3,3,5 trimethyl (5.41–15.99%) and α‐terpineol (0.94–11.34%). During the maturation process, an accumulation of oxygenated monoterpenes was observed. The phenolic composition was studied using matrix‐assisted laser desorption/ionization time of flight. The analysis showed the presence of short flavonoid monomers at all stages of maturation. The antioxidant capacity of ethanolic extracts and essential oils was evaluated using the DPPH assay, iron chelating power and reducing power assay. The highest phenolic content and antioxidant capacity were found at flowering stage. These findings on essential oil composition, phenolic profile and antioxidant capacity of O. majorana at three different stages of development provide more information on how these secondary metabolites are accumulated.     

Pakistolides A and B,Novel Enzyme Inhibitory and Antioxidant Dimeric 4‐(Glucosyloxy)Benzoates from Berchemia pakistanica

Pakistolides A and B, novel dimeric β‐(glucosyloxy)benzoates were isolated from Berchemia pakistanica and assigned structures 1 and 2 on the basis of extensive NMR studies. In addition, the known compounds 7,5′‐dimethoxy‐3,5,2′‐trihydroxyflavone (=3,5‐dihydroxy‐2‐(2‐hydroxy‐5‐methoxyphenyl)‐7‐methoxy‐4H‐1‐benzopyran‐4‐one), 4′,5‐dihydroxy‐3,6,7‐trimethoxyflavone (=5‐hydroxy‐2‐(4‐hydroxyphenyl)‐3,6,7‐trimethoxy‐4H‐1‐benzopyran‐4‐one), 5,6‐dihydroxy‐4,7‐dimethoxy‐2‐methylanthracene‐9,10‐dione, and 1,3,4‐trihydroxy‐6,7,8‐trimethoxy‐2‐methylanthracene‐9,10‐dione were reported for the first time from the genus Berchemia. Both 1 and 2 showed significant α‐glucosidase and lipoxygenase inhibitory activities, while 2 also showed antioxidant potential.     

Two New Prenylated Xanthones from the Pericarp of Garcinia mangostana (Mangosteen)

Two new prenylated xanthones (=9H‐xanthen‐9‐ones), garcimangosxanthones D ( 1 ) and E ( 2 ), together with the six known xanthones 3 – 8 , were isolated from the pericarp of Garcinia mangostana. Their structures were determined by analysis of their spectroscopic data. All of the isolated compounds were biologically evaluated for their in vitro cytotoxic activity against A549, Hep‐G2, and MCF‐7 human‐cancer cell lines and antioxidant activity. Compound 1 exhibited moderate cytotoxicity against Hep‐G2 (IC₅₀=19.2 μM ) and weak cytotoxicity against MCF‐7 (IC₅₀=62.8 μM ) cell lines, and compound 2 showed moderate cytotoxicity against A549, Hep‐G2, and MCF‐7 cell lines with IC₅₀ values of 12.5–20.0 μM (Table 2). Both compounds 1 and 2 demonstrated a weak antioxidant activity with ferric reducing antioxidant power (FRAP) values of 41±7 and 130±4 μmol/g, respectively (Table 3).     

Screening of analgesic and anti‐inflammatory active component in Fructus Alpiniae zerumbet based on spectrum–effect relationship and GC–MS

Fructus Alpiniae zerumbet is widely used in Guizhou province as a miao folk herb with anti‐inflammatory, analgesic, protection against cardiovascular diseases, antihypertension and antioxidant activities. To further investigate the chemical material basis, the spectrum–effect relationship was established using gray relational analysis between the chromatographic fingerprint and its bioactivities. Herein, the fingerprints of essential oils from Fructus Alpiniae zerumbet (EOFAZ) from various sources were determined by gas chromatography mass spectrometry, and the analgesic and anti‐inflammatory bioactivities were investigated using the mouse model of acetic acid‐induced writhing test and dimethylbenzene‐induced mouse ear edema test. Finally, 17 common peaks were identified from nine batches of A. zerumbet, by comparison with the standard mass spectra in Nist2005, Wiley275 library. Meanwhile, the results showed significant analgesic and anti‐inflammatory effects in all of the different sources of EOFAZ. In particularly, peak 1 (α‐pipene), peak 3 (β‐pinene), peak 9 (camphor) and peak 16 (α‐cadinol) might be the main bioactive ingredients for analgesic and anti‐inflammatory activities. The model of the spectrum–effect relationships of EOFAZ was successfully discovered, which provided a novel platform for finding the bioactive components, a theoretical foundation for its further study and helping to establish quality control of Fructus A. zerumbet.     

Four New Pregnane Steroids from Aglaia abbreviata and Their Cytotoxic Activities

Four new pregnane steroids, aglaiasterols A–D ( 1 – 4 ), have been isolated from the EtOH extract of stems of Aglaia abbreviata. They were identified as (3α,5α,17Z)‐3‐hydroxypregn‐17‐en‐16‐one ( 1 ), (3β,5α,17E)‐3‐hydroxypregn‐17‐en‐16‐one ( 2 ), (3β,5α,17Z)‐3‐hydroxypregn‐17‐en‐16‐one ( 3 ), and (3α,5α,20S*)‐3‐hydroxy‐16‐oxopregnan‐20‐yl acetate ( 4 ) on the basis of spectroscopic methods, including 1D‐ and 2D‐NMR techniques. Compounds 1 – 4 were evaluated for their cytotoxic activities against K562 (human leukemia), MCF‐7 (human breast cancer), and KB (human oral epithelium cancer) cells, and drug‐resistant cells of K562/A02, MCF‐7/ADM, and KB/VCR. These isolates showed weak to moderate inhibitory effects on the growth of the tested cell lines.     

Accurate discrimination of Gastrodia elata from different geographical origins using high‐performance liquid chromatography fingerprint combined with boosting partial least‐squares discriminant analysis

Gastrodia elata from different geographical origins varies in quality and pharmacological activity. This study focused on the classification and identification of Gastrodia elata from six producing areas using high‐performance liquid chromatography fingerprint combined with boosting partial least‐squares discriminant analysis. Before recognition analysis, a principal component analysis was applied to ascertain the discrimination possibility with high‐performance liquid chromatography fingerprints. And then, boosting partial least‐squares discriminant analysis and conventional partial least‐squares discriminant analysis were applied in this study. Experimental results indicated that the adaptive iteratively reweighted penalized least‐squares algorithm could eliminate the baseline drift of high‐performance liquid chromatography chromatograms effectively. And compared with partial least‐squares discriminant analysis, the total recognition rates using high‐performance liquid chromatography fingerprint combined with boosting partial least‐squares discriminant analysis for the calibration sets and prediction sets were improved from 94 to 100% and 86 to 97%, respectively. In conclusion, high‐performance liquid chromatography combined with boosting partial least‐squares discriminant analysis, which has such advantages as effective, specific, accurate, non‐polluting, has an edge for discrimination of traditional Chinese medicine from different geographical origins. And the proposed methodology is a useful tool to classify and identify Gastrodia elata from different geographical origins.     

Synthesis and Evaluation of Four Hederagenin Glycosides as α‐Glucosidase Inhibitor

The four hederagenin glycosides 1 – 4 were efficiently synthesized through one‐pot sequential glycosylations with glycose 1‐(trichloroacetimidate)s as donors, resulting in a significantly simplified synthetic procedure without isolation of glycosylation intermediates. The activity of the synthetic hederagenin glycosides 1 – 4 against α‐glucosidase type IV was evaluated; hederagenin glycoside 4 containing an α‐L ‐rhamnopyranosyl unit showed the best activity with an IC₅₀ value of 47.9 μM .     

Synthesis and Evaluation as Glycosidase Inhibitors of Carbasugar‐Derived Spirodiaziridines,Spirodiazirines, and Spiroaziridines

The spirodiaziridines 6 and 9 , potential inhibitors of α‐ and β‐glucosidases, were prepared from the validoxylamine A‐derived cyclohexanone 5 . The trimethylsilyl protecting groups of 5 are crucial for the formation of 6 in good yields. Oxidation of 6 gave 7 . The diaziridine 6 (pK_HA=2.6) and the diazirine 7 did not inhibit the β‐glucosidases from almonds, the β‐glucosidase from Caldocellum saccharolyticum, and the α‐glucosidase from yeast. The N‐benzyl diaziridine 9 is a very weak inhibitor of the α‐glucosidase, but did not inhibit the β‐glucosidases. To see whether the weak inhibition is due to the low basicity of the diaziridines or to geometric factors, we prepared the spiro‐aziridines 21 and 25 and 1‐epivalidamine ( 32 ). The known cyclohexanone 10 was methylenated and epoxidised to 16 and 17 . Azide opening of 16 and 17 , mesylation, LiAlH₄ reduction, and deprotection gave the aziridines 21 and 25 respectively. 1‐Epivalidamine ( 32 ) was prepared from the known carba‐glucose 29 . The aziridine 25 (pK_HA=6.8) is a weak irreversible inhibitor of the β‐glucosidase from Caldocellum saccharolyticum and a weak reversible inhibitor of the α‐glucosidase from yeast, but did not inhibit the β‐glucosidases from almonds. The poorly stable aziridine 21 weakly inhibited the three enzymes. Similarly, 1‐epivalidamine (pK_HA=8.4) proved only a weak inhibitor. The known cyclopentylamine 34 (pK_HA=7.9), however, is a micromolar inhibitor of these enzymes. The much stronger inhibition by 34 is related to the pseudoaxial orientation of its amino group.     

Comparison of the nutritional and phytochemical composition and antioxidant activities of Aralia elata (Miq.) Seem fruits in Northeast China

Aralia elata (Miq.) Seem is a wild medicinal and culinary plant. The newly grown shoots are edible, and the stem and root bark are traditional materials used for medicinal extraction. However, few studies have examined the quality and biological activity of the fruit. In this study, we compared the nutritional and phytochemical composition and antioxidant activity of A. elata fruit (AF) picked from five regions (Harbin, Benxi, Raohe, Jiaohe, and Mudanjiang) in Northeast China. AF picked from Harbin had the highest saponin, anthocyanin, and flavonoid contents. UHPLC-MS/MS analyses showed that araloside A was one of the main saponin monomers in AF. The highest arloside A concentration was detected in fruits picked from Harbin and the lowest concentration was detected in fruits picked from Benxi. The relative reactive oxygen species production in cells after pretreatment with AFs from Harbin (50 μg/mL) was 0.78 ± 0.01, second only to those from Raohe. AFs (50 μg/mL) from Harbin had the highest catalase activity (43.61 ± 0.44 U/mg protein), followed by that of the AF collected from Jiaohe, Benxi, Mudanjiang and Raohe. The malondialdehyde levels of the AFs (50 μg/mL) obtained from Benxi, Raohe, Jiaohe, and Mudanjiang were significantly higher than those of the AF obtained from Harbin (2.67 ± 0.15 nmol/mg protein). Compared with AFs from Benxi, Raohe, Jiaohe, and Mudanjiang, the strongest H₂O₂ scavenging ability (144.95 ± 2.89 mmol TE/100 g dm) was observed for AF from Harbin. The ferric reducing antioxidant power of AFs ranged from 7.70 to 4.52 mmol TE/100 g dm in the order of Harbin > Mudanjiang > Raohe > Jiaohe > Benxi. The results provided support for the selection of the best quality AF and the expanded cultivation of A. elata.