Shiqi Peng

Novel N-(3-carboxyl-9-benzyl-β-carboline-1-yl)ethylamino acids: Synthesis, anti-tumor evaluation, intercalating determination, 3D QSAR analysis and docking investigation

Sixteen novel N-(3-carboxyl-9-benzyl-beta-carboline-1-yl)ethylamino acids (6a-p) were synthesized as intercalating lead compounds. In the in vitro cytotoxic assay their IC(50) values against five human carcinoma cell lines ranged from 10.95 microM to about 400 microM. On S180 mouse model eight of them exhibited anti-tumor action, four of them showed the same anti-tumor potency as that of cytarabine. The preliminary toxicity evaluation revealed that the LD(50) values of 6a-p should be more than 500 mg/kg. With CT DNA as model system an intercalating mechanism was explored. Using 3D QSAR analysis the relationship of the in vivo anti-tumor activity and the structure was quantitatively described. By docking 6a-p onto d(CGATCG)(2) oligonucleotides the intercalation was demonstrated.

Application of high-performance liquid chromatography–mass spectrometry to detection of diuretics in human urine

A rapid, sensitive and reliable high-performance liquid chromatographic-mass spectrometric method for the detection of 25 diuretics in human urine has been developed. Atmosphere pressure chemical ionization (APCI) and electrospray ionization (ESI) modes were evaluated. A 2-ml volume of urine was extracted under basic conditions and separated on an Agilent Zorbax SB-C(18) column (150 x 2.1 mm, 5 microm). The mobile phase consisted of formic ammonium-formic acid buffer (pH 3.5) and acetonitrile. The effects of capillary temperature, sheath gas pressure and compositions of mobile phase on the sensitivity were studied. The recoveries of most of the diuretics were 75-95%. In the full scan mode, the limits of detection of the 25 diuretics were 0.25-25 ng/ml for APCI and 0.6-250 ng/ml for ESI. Under the optimal conditions, 14 diuretics from authentic urine samples were detected successfully by LC-APCI-MS. To obtain more fragmentation information on the chemical structure for positive confirmation, tandem mass analysis was also investigated.

A class of novel N-(3S-1,2,3,4-tetrahydroisoquinoline-3-carbonyl)-L-amino acid derivatives: their synthesis, anti-thrombotic activity evaluation, and 3D QSAR analysis

To find new anti-thrombotic agents, a natural amino acid was introduced into the 3-position of anti-platelet aggregation active 3S-tetrahydroisoquinoline-3-carboxylic acid (THIQA), and 20 novel dipeptide derivatives, 3S-tetrahydroisoquinoline-3-carboxyamino acids (6a-t), targeting the intestinal peptide transport system were provided. In vitro anti-platelet aggregation assay of 6a-t indicated that their potencies of inhibiting adenosine diphosphate (ADP), arachidonic acid (AA), platelet-activating factor (PAF), and thrombin (TH) induced platelet aggregations were higher than that of THIQA, and the in vivo anti-thrombotic assay of 6a-t indicated that their potencies of inhibiting thrombogenesis in rats were also higher than that of THIQA. According to MFA based Cerius2 QSAR module, using training/test set of 6a,b,d,g-p/6c,e,f,q and training/test set of 6a-p/6q-t, two equations (r, 0.984 and 0.996) correlating the structures with in vitro or in vivo activity of 6a-t were established.

Synthesis and antithrombotic activity of carbolinecarboxyl RGD sequence

3S-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid, RGDS, RGDV, RGDF and their linkers were synthesized. The anti-aggregation and adhesion of platelet indicated that the in vitro activities of the linkers remained at the same level as RGDS, RGDV, and RGDF (p>0.05). The antithrombotic activities in vivo suggested, however, that the potencies of RGDS, RGDV and RGDF were enhanced by the introduction of 3S-1,2,3,4-tetrahydro-beta-carboline-3-carboxyl group into their alpha amino group (p<0.05, 0.01 or 0.001).

(3S)-N-(L-Aminoacyl)-1,2,3,4-tetrahydroisoquinolines, a class of novel antithrombotic agents: synthesis, bioassay, 3D QSAR, and ADME analysis.

To increase antithrombotic activity, 3S-tetrahydroisoquinoline-3-carboxylic acid (1) was modified with natural amino acids to form 19 novel dipeptide analogs, 3S-tetrahydroisoquinoline-3-carboxyamino acids (5a-s), targeting the intestinal peptide transport system. In vitro assay of 5a-s indicated that their potencies for inhibiting adenosine diphosphate (ADP), arachidonic acid (AA), platelet-activating factor (PAF), and thrombin (TH)-induced platelet aggregations were higher than that of 1. Additionally, in vivo assay of 5a-s indicated that their potencies for inhibiting thrombogenesis in rats were also higher than that of 1. Among the candidates, 5h with Ser attachment showed the most impressive features for further development. According to molecular field analysis based Cerius(2) QSAR module, two equations (r, 0.961 and 0.988) correlating the structures with both in vitro and in vivo activities of 5a-s were established. ADMET calculations predict higher intestinal absorption for compounds 5a-s. Further investigation with 5h as a lead compound is underway.

2,3-Diamino acid modifying 3S-tetrahydroisoquinoline-3-carboxylic acids: Leading to a class of novel agents with highly unfolded conformation, selective in vitro anti-platelet aggregation and potent in vivo anti-thrombotic activity

In the preparation of anti-thrombotic agents the 2- and 3-positions of 3S-tetra-hydroisoquinoline-3-carboxylic acid (THIQA) were simultaneously modified with amino acids to form 20 novel N-(3S-N-aminoacyl-1,2,3,4-tetrahydroisoquinoline-3-carbonyl)amino acids (8a-t). On an in vitro platelet aggregation model 8a-t selectively inhibit ADP-induced platelet aggregation and their IC(50) values are leas than 3.5 nM. On an extracorporeal circulation of arterioveinos cannula model of rats both orally and intraveously effective doses of 8a-t are less than 30 nmol/kg. Cerius(2) based stereoview of explores 8a-t having highly unfolded conformation. 3D QSAR analysis gives the importance of the unfolded conformation to high in vitro anti-platelet aggregation and in vivo anti-thrombotic potency rational understanding.

A class of novel carboline intercalators: Their synthesis, in vitro anti-proliferation, in vivo anti-tumor action, and 3D QSAR analysis.

Based on DOCK scores 18 N-(3-benzyloxycarbonylcarboline-1-yl)ethylamino acid benzylesters (6a-r) were synthesized as anti-tumor agents. Their IC(50) values against five human carcinoma cell lines ranged from 11.1muM to more than 100muM. The in vivo assay identified five derivatives of them had no anti-tumor action, the anti-tumor activity of nine derivatives of them equaled that of cytarabine, and the anti-tumor activity of three derivatives of them was higher than that of cytarabine. The UV and fluorescence spectra, as well as the relative viscosity and melting temperature measurements of calf thymus DNA (CT DNA) with and without the representative compound suggested that DNA intercalation could be their action mechanism. The 3D QSAR analysis of N-(3-benzyloxycarbonylcarboline-1-yl)ethylamino acid benzylesters (6a-r) revealed that their in vivo anti-tumor activity significantly depends on the molecular electrostatic and steric fields of the side chain of the amino acid residue.

Synthesis and evaluation of anti-tumor activities of N4 fatty acyl amino acid derivatives of 1-β-arabinofuranosylcytosine

1-Beta-D-arabinofuranosylcytosine (Ara-C, Cytarabine) is one of the drugs used for acute nonlymphocytic leukemia (ANLL). However, the bioavailability of Ara-C is relatively low due to its low lipophilicity. In order to improve the lipophilicity and bioavailability of Ara-C, a series of N(4) derivatives of Ara-C, i.e., (fatty acid)-(amino acid)-Ara-C analogues, were prepared. The 15 derivatives synthesized were characterized by their melting points, optical rotations and partition coefficients. It was found that the Ara-C derivatives synthesized in this study were more lipophilic than Ara-C as determined by their partition coefficients. Their in vitro cytotoxicity and in vivo anti-tumor activity were determined and compared with that of Ara-C. It was found that the derivatives were more active than Ara-C in Hela cells, but not in HL-60 cells. The in vivo results showed that some of the derivatives were more effective than Ara-C in mice bearing S(180) tumor while others showed a decreased activity in comparison with Ara-C.

Synthesis and analgesic effects of kyotorphin-steroid linkers.

Kyotorphin (KTP, H-Tyr-Arg-OH) was covalently bonded with hydrocortisone or estrone to form the corresponding hydrocortisone-21-O-yl-succinyl-Tyr-ArgOH or estrone-3-O-yl-acyl-Tyr-Arg-OH. Their analgesic activities were investigated using the tail flick test. The potency of the two linkers were significantly higher than that of KTP and the mixture of KTP and hydrocortisone or estrone in the CNS and/or the periphery administration.

2-Substituted (S)-2-(3,3-dimethyl-1-oxo-10,10a-dihydroimidazo[1,5-b]isoquinolin-2(1H,3H,5H)-yl)acetic acids: Conformational prediction, synthesis, anti-thrombotic and vasodilative evaluation.

(S)-1,2,3,4-Tetrahydroisoquinoline-3-carboxylic acid (TIC) can inhibit thrombosis by inhibiting platelet aggregation. The investigation of amino acids modified TIC reveals that a stretching conformation is critical for high anti-thrombotic activity. The conformational modeling shows that introducing a ring into amino acid modified TIC results in a desirable stretching conformation. According to this hypothesis, we synthesized seventeen novel 2-substituted (S)-2-(3,3-dimethyl-1-oxo-10,10a-dihydroimidazo[1,5-b]isoquinolin-2(1H,3H,5H)-yl)acetic acids (5a-q). In the in vitro anti-platelet aggregation assay, for ADP-induced platelet aggregation the IC(50) values of 5a-q are 1.8-3.4-folds lower than that of TIC. In the in vivo anti-thrombotic assay, the effective dose of 5a-q was 167-folds lower than that of TIC. The vessel strip assay showed that 5a-q had mild vasorelaxation activity.