Synthesis and α‐Mannosidase Inhibitory Evaluation of (2R,3R,4S)‐ and (2S,3R,4S)‐2‐(Aminomethyl)pyrrolidine‐3,4‐diol Derivatives

The synthesis of 46 derivatives of (2R,3R,4S)‐2‐(aminomethyl)pyrrolidine‐3,4‐diol is reported (Scheme 1 and Fig. 3), and their inhibitory activities toward α‐mannosidases from jack bean (B) and almonds (A) are evaluated (Table). The most‐potent inhibitors are (2R,3R,4S)‐2‐{[([1,1′‐biphenyl]‐4‐ylmethyl)amino]methyl}pyrrolidine‐3,4‐diol ( 3fs ; IC₅₀(B)=5 μM , K_i=2.5 μM ) and (2R,3R,4S)‐2‐{[(1R)‐2,3‐dihydro‐1H‐inden‐1‐ylamino]methyl}pyrrolidine‐3,4‐diol ( 3fu ; IC₅₀(B)=17 μM , K_i=2.3 μM ). (2S,3R,4S)‐2‐(Aminomethyl)pyrrolidine‐3,4‐diol ( 6 , R?H) and the three 2‐(N‐alkylamino)methyl derivatives 6fh, 6fs , and 6f are prepared (Scheme 2) and found to inhibit also α‐mannosidases from jack bean and almonds (Table). The best inhibitor of these series is (2S,3R,4S)‐2‐{[(2‐thienylmethyl)amino]methyl}pyrrolidine‐3,4‐diol ( 6o ; IC₅₀(B)=105 μM , K_i=40 μM ). As expected (see Fig. 4), diamines 3 with the configuration of α‐D ‐mannosides are better inhibitors of α‐mannosidases than their stereoisomers 6 with the configuration of β‐D ‐mannosides. The results show that an aromatic ring (benzyl, [1,1′‐biphenyl]‐4‐yl, 2‐thienyl) is essential for good inhibitory activity. If the C‐chain that separates the aromatic system from the 2‐(aminomethyl) substituent is longer than a methano group, the inhibitory activity decreases significantly (see Fig. 7). This study shows also that α‐mannosidases from jack bean and from almonds do not recognize substrate mimics that are bulky around the O‐glycosidic bond of the corresponding α‐D ‐mannopyranosides. These observations should be very useful in the design of better α‐mannosidase inhibitors.     

Synthesis,Cytotoxic Activity Evaluation of Novel 1,2,3‐Triazole Linked Quinazoline Derivatives

A series of novel 1,2,3‐triazole‐quinazoline derivatives were synthesized in five steps starting from anthranilamide by conventional methods. All the title compounds 10a — 10r were evaluated for cytotoxic activity against four human cancer cell lines (MGC ‐803, EC ‐109, MCF ‐7 and HGC ‐27) using MTT assay in vitro . Some of the synthesized compounds exhibited moderate to potent activity against tested cancer cell lines. Among them, compounds 10 h and 10q exhibited excellent growth inhibition against HGC ‐27 and compound 10 m also possessed excellent activity against MCF ‐7, with IC₅₀ values less than 1 µmol/L. Especially, compound 10 h was more cytotoxic than 5‐fluorouracil against all tested four human cancer cell lines.     

Total Synthesis of the Bicyclic Depsipeptide HDAC Inhibitors Spiruchostatins A and B, 5′′‐epi‐Spiruchostatin B,FK228 (FR901228) and Preliminary Evaluation of Their Biological Activity

The bicyclic depsipeptide histone deacetylase (HDAC) inhibitors spiruchostatins A and B, 5′′‐epi‐spiruchostatin B and FK228 were efficiently synthesized in a convergent and unified manner. The synthetic method involved the following crucial steps: i) a Julia–Kocienski olefination of a 1,3‐propanediol‐derived sulfone and a L ‐ or D ‐malic acid‐derived aldehyde to access the most synthetically challenging unit, (3S or 3R,4E)‐3‐hydroxy‐7‐mercaptohept‐4‐enoic acid, present in a D ‐alanine‐ or D ‐valine‐containing segment; ii) a condensation of a D ‐valine‐D ‐cysteine‐ or D ‐allo‐isoleucine‐D ‐cysteine‐containing segment with a D ‐alanine‐ or D ‐valine‐containing segment to directly assemble the corresponding seco‐acids; and iii) a macrocyclization of a seco‐acid using the Shiina method or the Mitsunobu method to construct the requisite 15‐ or 16‐membered macrolactone. The present synthesis has established the C5′′ stereochemistry of spiruchostatin B. In addition, HDAC inhibitory assay and the cell‐growth inhibition analysis of the synthesized depsipeptides determined the order of their potency and revealed some novel aspects of structure–activity relationships. It was also found that unnatural 5′′‐epi‐spiruchostatin B shows extremely high selectivity (ca. 1600‐fold) for class I HDAC1 (IC₅₀=2.4 nM ) over class II HDAC6 (IC₅₀=3900 nM ) with potent cell‐growth‐inhibitory activity at nanomolar levels of IC₅₀ values.     

Synthesis,Antiproliferative, and Antiplatelet Activities of Oxime‐Containing 3,4‐Dihydroquinolin‐2(1H)‐One Derivatives

Some oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were synthesized and evaluated for their antiplatelet and antiproliferative activities. These compounds were synthesized via alkylation of hydroxyl precursors followed by the reaction with NH₂OH. The preliminary assays indicated that (Z)‐7‐[2‐(4‐fluorophenyl)‐2‐(hydroxyimino)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13c) is the most active against U46619 induced platelet aggregation with an IC₅₀ value of 3.51 μM. For the inhibition of AA‐induced aggregation, (E)‐6‐[2‐(hydroxyimino)propoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (15 ) is the most potent with an IC₅₀ value of 1.85 μM. These oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive against thrombin induced platelet aggregation with an IC₅₀ value of greater than 26.78 μM. For the antiproliferative activity, most of these oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive while (Z)‐7‐[2‐(hydroxyimino)‐2‐(naphthalen‐2‐yl)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13a) exhibited only marginal activities with GI₅₀ value of 7.63, 7.34 and 6.36 μM against the growth of NPC‐TW01, NCI‐H661, and Jurkat respectively.     

Synthesis,in vitro Antimicrobial,and Cytotoxic Activities of New 1,3,4‐Oxadiazin‐5(6H)‐one Derivatives from Dehydroabietic Acid

A series of new 1,3,4‐oxadiazin‐5(6H)‐one derivatives ( 6a–n ) of dehydroabietic acid were designed and synthesized as potential antimicrobial and antitumor agents. Their structures were characterized by IR, ¹H NMR, ¹³C NMR, MS, and elemental analyses. All the title compounds were evaluated for their antimicrobial activity against four bacterial and three fungal strains using the serial dilution method. Among them, compound 6e showed the highest antibacterial activity against Bacillus subtilis with a minimum inhibitory concentration (MIC) value of 1.9 μg/mL. In addition, the in vitro cytotoxic activities of the title compounds were also assayed against three human carcinoma cell lines (MCF‐7, SMMC‐7721, and HeLa) through the MTT colorimetric method. As a result, compounds 6b , 6g , 6k, and 6m exhibited significant inhibition against at least one cell line with IC₅₀ values below 10 μM. Compound 6m was especially found to be the most potent derivative with IC₅₀ values of 2.26 ± 0.23, 0.97 ± 0.11, and 1.89 ± 0.31 μM against MCF‐7, SMMC‐7721, and HeLa cells, respectively, comparable to positive control etoposide.     

Synthesis and Cytotoxicity in Vitro of N‐Aryl‐4‐(tert‐butyl)‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazol‐2‐amine

A series of novel N‐aryl‐4‐(tert‐butyl)‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazol‐2‐amines synthesized in a green way. H₂O₂‐NaBr Brominating circulatory system was used in the synthesis of the key intermediate in a mild condition. All of the target compounds were confirmed by ¹H NMR and elemental analysis and tested for their cytotoxicity against two different human cancer cell lines. The cytotoxicity assay revealed that some of the title compounds showed moderate to strong cytotoxic activities. Compound 2i was the most potent compound with the IC₅₀ values of 9 μM against Hela cells and 15 μM against Bel–7402 cells, respectively.     

New Substituted 1‐Aryl‐4,4,6‐Trimethyl‐3,4‐Dihydropyrimidine‐2‐(1H)Thiones; A Metal‐Free and Solvent‐Free Synthesis,Characterization, and Lymphoid Tyrosine Phosphatase Inhibition Studies

A series of fourteen 3,4‐dihydropyrimidine‐2‐thiones ( 3a–n ) were synthesized by a green protocol, and their structures were characterized by spectroanalytical data. The compounds were obtained in high yields by efficient annulation of mesityl oxide (4‐methylpent‐3‐en‐2‐one) with anilines in the presence of potassium thiocyanate. The reaction is essentially metal‐catalyst‐ and solvent‐free, as mesityl oxide itself is the solvent as well as the reactant. The compounds were tested for their ability to inhibit the lymphoid tyrosine phosphatase PTPN22, and 5 of the 14 compounds exhibited IC₅₀ values in the mid‐micromolar range, with the most potent hit being the compound 3d , having a methoxy substituent at the 2‐position of the phenyl ring with an IC₅₀ = 18 ± 1 μM, and second most potent compound ( 3c ) with an IC₅₀ value of 45 ± 3 μM, having methyl substituents at both 2‐ and 4‐position of the phenyl ring.     

Synthesis of 2‐amino‐4‐oxo‐5‐substitutedbenzylthiopyrrolo[2,3‐d]‐pyrimidines as potential inhibitors of thymidylate synthase

A series of ten novel 2‐amino‐4‐oxo‐5‐[(substitutedbenzyl)thio]pyrrolo[2,3‐d]pyrimidines 2‐11 were synthesized as potential inhibitors of thymidylate synthase and as antitumor agents. The analogues contain various electron withdrawing and electron donating substituents on the benzylsulfanyl ring of the side chains and were synthesized from the key intermediate 2‐amino‐4‐oxo‐6‐methylpyrrolo[2,3‐d]pyrimidine, 14 . Appropriately substituted benzyl mercaptans were appended to the 5‐position of 14 via an oxidative addition reaction using iodine, ethanol and water. The compounds were evaluated against human, Escherichia coli and Toxoplasma gondii thymidylate synthase and against human, Escherichia coli and Toxoplasma gondii dihydrofolate reductase. The most potent inhibitor, ( 6 ) which has a 4′‐methoxy substituent on the side chain, has an IC₅₀=25 μM against human thymidylate synthase. Contrary to analogues of general structure 1 , electron donating or electron withdrawing substituents on the side chain of 2‐11 had little or no influence on the human thymidylate synthase inhibitory activity.     

Synthesis of 4‐alkyl‐1,2‐diphenyl‐3,5‐dioxopyrazolidines possessing aryl methylsulfonyl and sulfonamide pharmacophores for evaluation as selective cyclooxygenase‐2 (COX‐2) inhibitors

A group of 1,2‐diphenyl‐3,5‐dioxopyrazolidines possessing a methylsulfonyl ( 11 ) or sulfonamide ( 15 ) substituent at the para position of the N¹‐phenyl ring, in conjunction with a hydrogen, methyl or fluoro sub‐stituent at the para position of the N²‐phenyl ring, and a C‐4 n‐butyl, methyl or spiro‐cyclopropyl substituent were synthesized for evaluation as potential cyclooxygenase‐2 (COX‐2) selective inhibitor antiinflammatory agents. The title compounds 11 and 15 were synthesized using a four‐step and a three‐step reaction sequence, respectively. Thus, the acetic acid promoted condensation of a nitrosobenzene 5 with an aniline derivative ( 6, 12 ) gave the corresponding azobenzene product ( 8, 13 ) which was reduced with zinc dust in the presence of ammonium chloride to yield the corresponding hydrazobenzene ( 9, 14 ). Base‐catalyzed condensation of 9 and 14 with a malonyl dichloride ( 10 ) afforded the target 3,5‐dioxopyrazolidine product ( 11,15 ). 4‐n‐Butyl‐1‐(4‐methylsulfonylphenyl)‐2‐phenyl‐3,5‐dioxopyrazolidine ( 11a ) was a selective COX‐1 inhibitor (COX‐1 IC₅₀ = 8.48 μM). In contrast, 4‐n‐butyl‐1‐(4‐methylsulfonylphenyl)‐2‐(4‐tolyl)‐3,5‐dioxopyrazolidine ( 11b , COX‐2 IC₅₀ = 11.45 μM) and 4‐n‐butyl‐1‐(4‐methylsulfonylphenyl)‐2‐(4‐fluorophenyl)‐3,5‐dioxopyrazoli‐dine ( 11c , COX‐2 IC₅₀ = 9.86 μM) were about 46‐fold and 20‐fold less selective COX‐2 inhibitors respectively, relative to the reference drug celecoxib.     

Synthesis of 4‐Heteroaryl–Quinazoline Derivatives as Potential Anti‐breast Cancer Agents

4‐Heteroaryl or heteroalkyl–quinazoline derivatives were prepared as dual epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor‐2 (VEGFR‐2) inhibitors. The new compounds were tested for their dual enzyme inhibition as well as their cytotoxic activity on MCF7 cell line. The results indicated that almost all the compounds showed moderate dual inhibition of both enzymes. Compound 3 (methyl piperidine‐4‐carboxylate derivative) showed the highest inhibitory activity against both enzymes with IC₅₀ 97.6 and 64.0 µM against EGFR and VEGFR‐2 kinases, respectively. Most of the test compounds showed potent to moderate antitumor activity on MCF7 cell line. Five compounds ( 3 , 9c , 11 , 13 , and 15b ) showed potent cytotoxic activity with IC₅₀ values between 10 and 17 µM .     

Furo[2,3‐d]pyrimidines and Oxazolo[5,4‐d]pyrimidines as Inhibitors of Receptor Tyrosine Kinases (RTK)

Receptor tyrosine kinases such as VEGFR2 (vascular endothelial growth factor receptor 2, KDR) or EGFR (epidermal growth factor receptor) play crucial roles in a variety of diseases, such as cancer. Recently, some pyrrolopyrimidines were shown to be potent EGFR inhibitors. Therefore, new types of oxazolo[5,4‐d]pyrimidines and furo[2,3‐d]pyrimidines were synthesized (Schemes 1 and 2). Appropriately substituted derivatives of these classes of compounds inhibited VEGFR2 and EGFR with IC₅₀ values in the low nanomolar range (see Table). Generally, the furopyrimidines were somewhat more active than the oxazolopyrimidines. The best inhibitors, 20m, 20p , and 20r , had an IC₅₀ of 3 nM towards EGFR and showed a good selectivity, being distinctly less active towards VEGFR2.     

A PDE6δ‐KRas Inhibitor Chemotype with up to Seven H‐Bonds and Picomolar Affinity that Prevents Efficient Inhibitor Release by Arl2

Small‐molecule inhibition of the interaction between the KRas oncoprotein and the chaperone PDE6δ impairs KRas spatial organization and signaling in cells. However, despite potent binding in vitro (K _D<10 nm ), interference with Ras signaling and growth inhibition require 5–20 μm compound concentrations. We demonstrate that these findings can be explained by fast release of high‐affinity inhibitors from PDE6δ by the release factor Arl2. This limitation is overcome by novel highly selective inhibitors that bind to PDE6δ with up to 7 hydrogen bonds, resulting in picomolar affinity. Their release by Arl2 is greatly decreased, and representative compounds selectively inhibit growth of KRas mutated and ‐dependent cells with the highest activity recorded yet. Our findings indicate that very potent inhibitors of the KRas‐PDE6δ interaction may impair the growth of tumors driven by oncogenic KRas.     

Novel Symmetrical trans‐Bis‐Schiff Bases of N‐Substituted‐4‐ piperidones: Synthesis,Characterization, and Preliminary Antileukemia Activity Mensurations

A series of novel symmetrical trans‐bis‐Schiff bases ( 11a , 11b , 11c , 11d , 11e , 11f , 11g , 11h , 11i , 11j , 11k , 11l , 11m ) were designed and prepared as novel anticancer analogues, with the trans‐configuration confirmed by X‐ray diffraction. Preliminary inhibitory effects of these compounds on CML K562 cell growth were investigated, and the potential analogue 11e showed an excellent anti‐leukemia activity (IC₅₀=6.35 μg/mL), which is higher than that of the clinical drug 5‐fluorouracil (IC₅₀=8.48 μg/mL). Complete assignments had been achieved for the title compounds by spectroscopic techniques, and their structure–activity relationships have been studied.     

Synthesis,Antiproliferative, and c‐Src Kinase Inhibitory Activities of 4‐Oxo‐4H‐1‐benzopyran Derivatives

A new class of 4‐oxo‐4H‐1‐benzopyran derivatives were synthesized and their antiproliferative activity examined against a panel of three human cancer cell lines, that is, breast carcinoma (MDA‐MB‐468), ovarian adenocarcinoma (SK‐OV‐3), and colorectal adenocarcinoma (HT‐29). Two compounds, that is, 3‐hexyl‐7,8‐dihydroxy‐4‐oxo‐4H‐1‐benzopyran and (E)‐ethyl 3‐(7‐methoxy‐4‐oxo‐4H‐1‐benzopyran‐3‐yl)acrylate were found to be potent against all three cancer cell lines studied at 50 μM concentration. Also, the inhibitory potency of the compounds was evaluated against active Src kinase. A few of these compounds exhibited modest Src kinase inhibitory activity (IC₅₀ = 52–57 μM). Structure‐activity relationship studies with respect to the nature and position of substituents on the lead compounds could be further exploited for the design and development of more potent antiproliferative agents and/or Src kinase inhibitors.     

Synthesis of classical and nonclassical 2‐amino‐4‐oxo‐6‐benzylthieno‐[2,3‐d]pyrimidines as potential thymidylate synthase inhibitors

A series of seven nonclassical 2‐amino‐4‐oxo‐6‐substituted thieno[2,3‐d]pyrimidines 2‐8 and one classical N‐[4‐(2‐amino‐4‐oxo‐3,4‐dihydrothieno[2,3‐d]pyrimidin‐6‐ylmethyl)benzoyl]‐L‐glutamic acid 9 (Table I) were designed as the first in a series of 6‐substituted 6‐5 fused ring analogs as potential thymidylate synthase (TS) inhibitors and as antitumor agents. The target compounds were synthesized via a Heck coupling of appropriately substituted iodobenzenes and allyl alcohol followed by cyclization using cyanoacetate and sulfur powder to afford substituted thiophenes. The resulting thiophenes were then cyclocondensed with chloroformamidine hydrochloride to afford 2‐amino‐4‐oxo‐6‐substituted thieno[2,3‐d]pyrimidines 2‐8 and 26 . Hydrolysis of 26 followed by coupling with diethyl L‐glutamate afforded 28 . The classical analog 9 was obtained by hydrolysis of 28 . None of the target compounds inhibited human recombinant thymidylate synthase at 23 μm except 9 for which the IC₅₀ value was 100 μm.     

Flavonol Glycosides with α‐Glucosidase Inhibitory Activities and New Flavone C‐Diosides from the Leaves of Machilus konishii

Seventeen flavonoids, five of which are flavone C‐diosides, 1 – 5 , were isolated from the BuOH‐ and AcOEt‐soluble fractions of the leaf extract of Machilus konishii. Among 1 – 5 , apigenin 6‐C‐β‐D ‐xylopyranosyl‐2″‐O‐β‐D ‐glucopyranoside ( 2 ), apigenin 8‐C‐α‐L ‐arabinopyranosyl‐2″‐O‐β‐D ‐glucopyranoside ( 4 ), and apigenin 8‐C‐β‐D ‐xylopyranosyl‐2″‐O‐β‐D ‐glucopyranoside ( 5 ) are new. Both 4 and 5 are present as rotamer pairs. The structures of the new compounds were elucidated on the basis of NMR‐spectroscopic analyses and MS data. In addition, the ¹H‐ and ¹³C‐NMR data of apigenin 6‐C‐α‐L ‐arabinopyranosyl‐2″‐O‐β‐D ‐glucopyranoside ( 3 ) were assigned for the first time. The isolated compounds were assayed against α‐glucosidase (type IV from Bacillus stearothermophilus). Kaempferol 3‐O‐(2‐β‐D ‐apiofuranosyl)‐α‐L ‐rhamnopyranoside ( 12 ) was found to possess the best inhibitory activity with an IC₅₀ value of 29.3 μM .     

Design and Synthesis of Novel Thioureas Derived from 4‐(4‐Fluorophenoxy)aniline as Anticancer Agents

A new series of thiourea derivatives were obtained by the reaction of 4‐(4‐fluorophenoxy) aniline with different isothiocyanates. Their chemical structures were confirmed by ultraviolet (UV ), infrared (IR ), nuclear magnetic resonance (NMR ), and mass spectral data and elemental analysis. All the synthesized thiourea derivatives were evaluated for their in vitro cancer activity against the human breast cancer cell lines MCF ‐7 (human breast adenocarcinoma) and SKBr ‐3 (human epithelial breast adenocarcinoma). Most of the derivatives exhibited significant anticancer activity. Especially, compound 3 showed the most potent activity (IC₅₀ 20.1 μM ) against SKBr ‐3 when compared with the drugs 5‐fluorouracil and cisplatin, and, most importantly, it did not affect normal breast epithelial cells (4010).     

Design and Synthesis of Novel Pyrazole‐based Lp‐PLA2 Inhibitors

A series of novel pyrazole‐based lipoprotein‐associated phospholipase A₂ (Lp‐PLA₂) inhibitors have been designed and synthetized by a variety of acetophenones via a 10‐step convergent approach. The synthetic approach is carefully optimized, and an unsuccessful alternative route is also discussed. The in vitro biological activity reveals that all the synthesized compounds are potent Lp‐PLA₂ inhibitors with compound 13b being the most potent one (Lp‐PLA₂, IC₅₀=1.5 nmol/L).     

A New Class of Inhibitors for the Malarial Aspartic Protease Plasmepsin II Based on a Central 11‐Azatricyclo[6.2.1.02,7]undeca‐2,4,6‐triene Scaffold

A new class of nonpeptidic inhibitors of the malarial aspartic protease plasmepsin II (PMII) with up to single‐digit micromolar activities (IC₅₀ values) was developed by structure‐based de novo design. The active‐site matrix used in the design was based on an X‐ray crystal structure of PMII, onto which the major conformational changes seen in the structure of renin upon complexation of 4‐arylpiperidines – including the unlocking of a new hydrophobic (flap) pocket – were modeled. The sequence identity of 35% between mature renin and PMII had prompted us to hypothesize that an induced‐fit adaptation around the active site as observed in renin might also be effective in PMII. The new inhibitors contain a central 11‐azatricyclo[6.2.1.0^2,7]undeca‐2(7),3,5‐triene core, which, in protonated form, undergoes ionic H‐bonding with the two catalytic Asp residues at the active site of PMII (Figs. 1 and 2). This tricyclic scaffold is readily prepared by a Diels? Alder reaction between an activated pyrrole and a benzyne species generated in situ (Scheme 1). Two substituents with naphthyl or 1,3‐benzothiazole moieties are attached to the central core (Schemes 1–4) for accommodation in the hydrophobic flap and S1/S3 (or S2′, depending on the optical antipode of the inhibitor) pockets at the active site of the enzyme. The most‐potent inhibitors (±)‐ 19a – 19c (IC₅₀ 3–5 μM ) and (±)‐ 23b (2 μM ) (Table) bear an additional Cl‐atom on the 1,3‐benzothiazole moiety to fully fill the rear of the flap pocket. Optimization of the linker between the tricyclic scaffold and the 1,3‐benzothiazole moiety, based on detailed conformational analysis (Figs. 3 and 4), led to a further small increase in inhibitory strength. The new compounds were also tested against other aspartic proteases. They were found to be quite selective against renin, while the selectivity against cathepsin D and E, two other human aspartic proteases, is rather poor (Table). The detailed SARs established in this investigation provide a valuable basis for the design of the next generations of more‐potent and ‐selective PMII inhibitors with potential application in a new antimalarial therapy.     

A rapid and sensitive LC–MS/MS method for quantification of quercetin‐3‐O‐β‐d‐glucopyranosyl‐7‐O‐β‐d‐gentiobioside in plasma and its application to a pharmacokinetic study

A rapid and sensitive LC–MS/MS method with good accuracy and precision was developed and validated for the pharmacokinetic study of quercetin‐3‐O‐β‐d ‐glucopyranosyl‐7‐O‐β‐d ‐gentiobioside (QGG) in Sprague–Dawley rats. Plasma samples were simply precipitated by methanol and then analyzed by LC–MS/MS. A Venusil® ASB C₁₈ column (2.1 × 50 mm, i.d. 5 μm) was used for separation, with methanol–water (50:50, v/v) as the mobile phase at a flow rate of 300 μL/min. The optimized mass transition ion‐pairs (m/z) for quantitation were 787.3/301.3 for QGG, and 725.3/293.3 for internal standard. The linear range was 7.32–1830 ng/mL with an average correlation coefficient of 0.9992, and the limit of quantification was 7.32 ng/mL. The intra‐ and inter‐day precision and accuracy were less than ±15%. At low, medium and high quality control concentrations, the recovery and matrix effect of the analyte and IS were in the range of 89.06–92.43 and 88.58–97.62%, respectively. The method was applied for the pharmacokinetic study of QGG in Sprague–Dawley rats. Copyright © 2016 John Wiley & Sons, Ltd.