Design, synthesis, antibacterial and antitumor activities of novel pyrazolo3,4-bpyridine-4-one-5-carboxylic acid derivatives / 药学学报

To discover new structural hits, based on the important role of pyrazole ring and fragment of pyridinone carboxylic acid in drug design, novel title pyrazolo[3,4-b]pyridine-4-one-5-carboxylic acid derivatives (10a-10p) were designed and synthesized, the structures were confirmed by spectral data and elemental analyses. The antibacterial and antitumor activities were evaluated by the measured minimum inhibitory concentration (MIC) values against the tested four strains and half inhibitory concentration (IC50) values against the tested four cancer cells, respectively. The results displayed markedly poor antibacterial activity and observably potent antitumor activity. In particularly, the title difluorophenyl (10d, 10e, 10f), pyridyl (10j), ethyl (10k) and cycloproyl (10l) compounds exhibited comparable activity against Capan-1 and A549 cells to that of the comparison doxorubicin. Thus, pyrazolo[3,4-b]pyridine-4-one-5-carboxylic acid derivatives as promising antitumor hits need to be developed.

Synthesis and antitumor activity of fluoroquinolone C-3 arylidene thiazolone derivatives from ciprofloxacin / 药学学报

To expand an efficient strategy for the conversion of antibacterial activity of fluoroquinolones into an antitumor activity, sixteen new compounds, 1-cyclopropyl-6- fluoro-7-(4-methyl-piperazin-1-yl)-3-(5-arylidene-thiazol-4(5H)-one-2-yl)-quinolon-4(1H)-ones (7a-7p), were designed and synthesized with a thiazolone ring and an arylidene moiety as an isostere and modified group, respectively, from ciprofloxacin. Their structures were characterized by elemental analysis and spectral data. The in vitro antitumor activity of the synthesized compounds were measured using Hep-3B, Capan-1 and HL60 cell lines and were found to be more potent than ciprofloxacin. Meanwhile, the SAR revealed that the halogenated phenyl compounds such as fluorophenyl (7h, 7i), chlorophenyl (7j, 7k) or bromophenyl compounds (7l, 7m), and aromatic heterocyclic substitution such as furyl (6n) or pyridyl compounds (6o, 6p) displayed better activity than the control compounds, especially the IC50 values of pyridyl compounds 6o and 6p against Capan-1 cell growth was comparable to doxorubicin. Thus, an arylidene-modified thiazolone scaffold as the replacement of the C-3 carboxylic acid group appears to be an alternative route for an improved antitumor activity of fluoroquinolones.

Clinical observation on the inflammatory indexes in septic gastrointestinal dysfunction treated with acupuncture at Jiaji (EX-B 2) / 中国针灸

OBJECTIVE@#To evaluate the effect on the inflammatory indexes of septic gastrointestinal dysfunction treated with acupuncture at Jiaji (EX-B 2).@*METHODS@#A total of 118 patients of septic gastrointestinal dysfunction were randomized into an observation group and a control group, 59 cases in each one. In the control group, mosapride citrate was prescribed for oral administration, 5 mg each time, 3 times a day, bifidobacterium triple viable capsules, 420 mg each time, twice a day, intravenous drip with omeprazole, 40 mg, twice a day. Additionally, the antibiotics and the symptomatic treatment were selected rationally for maintaining the functions of the important organs, e.g. heart, lung, brain and kidney, and water-electrolyte balance. In the observation group, on the routine management as the control group, acupuncture at Jiaji (EX-B 2, T-T) was added, the needles were retained for 30 min in each treatment, once a day, 10 days as one course and 1 course was required. Separately, on the 1st, 3rd, 6th and 10th days of treatment, the white blood cell (WBC) count, the levels of hypersensitive C-reactive protein (hs-CRP) and procalcitonin (PCT) were observed, the enteral nutrition feeding dose and gastrointestinal dysfunction score before and after treatment as well as the clinical effect were assessed in the two groups.@*RESULTS@#The differences were not significant in the indexes mentioned above on 1st and 3rd days of treatment between the two groups (>0.05). On the 6th and 10th days of treatment, regarding the gastrointestinal dysfunction score and inflammatory indexes count, the results in the observation group were lower than the control group (all <0.05), and feeding dose in the observation group was higher than the control group (<0.05). After treatment, the gastrointestinal dysfunction scores and inflammatory indexes count were all reduced and feeding dose was increased as compared with those before treatment in the patients of the two groups (all <0.05). After treatment, the total effective rate was 91.5% (54/59) in the observation group, higher than 76.3% (45/59) in the control group (<0.05).@*CONCLUSION@#Acupuncture at Jiaji (EX-B 2) points achieves the satisfactory effect on septic gastrointestinal dysfunction and reduces the inflammatory indexes count.

Synthesis and antitumor activity of fluoroquinolon-3-yl-s-triazole sulfide ketones and their derivatives from ciprofloxacin / 药学学报

To discover an efficient strategy for the conversion of the antibacterial activity of fluoroquinolones into the antitumor activity, the three series of C-3 s-triazole-based derivatives including sulfide ketones (6a-6g), thiosemicarbazones (7a-7g) and fused heterocyclic thiazolotriazoles (8a-8g) were synthesized from ciprofloxacin (1), respectively. The structures were characterized by elemental analysis and spectral data. The antitumor activity was tested against three tumor cell lines (Hep-3B, Capan-1 and HL60) using the MTT assay. The three types of compounds all exhibited stronger anti-proliferative activities than ciprofloxacin in the test. The order of their activities was in compounds 7>8>6, and the order of selectivity against cancer cell lines was Capan-1, Hep-3B and HL60. Meanwhile, the SAR revealed that some compounds with electron-drawing group substituted such as fluoro- and nitro-phenyl compounds (6f, 7f, 8f) and (6g, 7g, 8g) displayed more significant activity than the control compounds, especially the IC50 values of thiosemicarbazone compounds 7f and 7g against Capan-1 was comparable to doxorubicin. Thus, a five-membered triazole as the C-3 bioisostere modified with the functionalized side-chain of sulfide-ketone thiosemicarbazone warrants special attention and further investigation.

Synthesis and anti-proliferative activity of fluoroquinolone C-3 fused heterocyclic α,β-unsaturated ketones derived from ciprofloxacin / 药学学报

To discover novel antitumor fluoroquinolone lead compounds from a rational modification for antibacterial fluoroquinolones, a fused heterocyclic ketone corresponding to thiazolo[2,3- b][1,2,4]triazolone used as a bioisosteric replacement of the C-3 carboxylic acid group of ciprofloxacin 1, and further modification by a Claisen condensation reaction with substituted benzaldehydes formed novel fluoroquinolone C-3 fuse heterocyclic α, β-unsaturated ketones as the title compounds (6a-6r), separately. The structures of eighteen title compounds were characterized by elemental analysis, 1H NMR and MS, and the in vitro anti-proliferative activity against human hepatoma Hep-3B cells, pancreatic Capan-1 cells and leukemia HL60 cells was evaluated by a MTT assay. The preliminary results showed that the title compounds not only had more significant anti-proliferative activity against three tested cancer cell lines than that of the parent ciprofloxacin 1, but also exhibited the highest activity against Capan-1 cells. In particular, compounds carrying an electron-withdrawing carboxyl (6k, 6m) or sulfonamide substituent (6q, 6r) attached to benzene ring were comparable to or better than constractive drug doxorubicin against Capan-1 cells. As such, it suggests that it is favorable for a fused heterocyclic α, β-unsaturated ketone scaffold instead of the C-3 carboxylic acid group to improve the antitumor activity of fluoroquinolones.

Synthesis and anti-proliferative activity of fluoroquinolone (rhodanine unsaturated ketone) amide derivatives / 药学学报

To discover novel antitumor rhodanine unsaturated ketones, a series of fluoroquinolone (rhodanine α, β-unsaturated ketone) amine derivatives (5a-5r) were designed and synthesized with fluoroquinolone amide scaffold as a carrier. The structures of eighteen title compounds were characterized by elemental analysis, 1H NMR and MS. The in vitro anti-proliferative activity against Hep-3B, Capan-1 and HL60 cells was evaluated by MTT assay. The results showed that the title compounds not only had more significant anti-proliferative activity against three tested cancer cell lines than that of the parent ciprofloxacin 1, but also exhibited the highest activity against Capan-1 cells. The SAR revealed that some compounds carrying aromatic heterocyclic rings or phenyl attached to an electron-withdrawing carboxyl or sulfonamide substituent were comparable to or better than comparison doxorubicin against Capan-1 cells. As such, it suggests that fluoroquinolone (rhodanine α, β-unsaturated ketone) amines are promising leads for the development of novel antitumor fluoroquinolones or rhodanine analogues.

Design, synthesis, antibacterial and anti-cell proliferation activities of 1,2,4triazino3,4-h 1,8naphthyridine-8-one-7-carboxylic acid derivatives / 药学学报

To discover novel fluoroquinolone lead compounds as possible anti-infective or/and antitumor chemotherapies, combination principle of pharmacophore-based drug design, a series of novel tricyclic fluoroquinolone title compounds, [1,2,4]triazino[3,4-h][1,8]naphthyridine-8-one-7-carboxylic acid derivatives ( 5a-5p), were designed and synthesized with a fused [1,2,4]-triazine ring unit. Their structures were characterized by spectral data and elemental analysis and the in vitro antibacterial and anti-cell proliferation activities were also evaluated. The results showed that the titled compounds exhibited more significant inhibitory activities against drug-resistant bacteria (Methicillin-resistant Staphylococcus aureus and multi drug-resistant Escherichia coli strains) and three tested cancer cell lines (human hepatoma SMMC-7721, murine leukemia L1210 and human murine leukemia HL60 cells). Interestingly, SAR showed that compounds with electron-donating groups attached to benzene ring had stronger antibacterial activity than antitumor activity, but electron-withdrawing compounds displayed more potential antitumor activity than antibacterial activity, especially antitumor activity of nitro compounds was comparable to comparison doxorubicin. Thus, novel triazine-fused tricyclic fluoroquinolones as potent anti-infective or/and antitumor lead compounds are valuable to pay attention and for further development.

Synthesis, antitumor activity and SAR of C-3 oxadiazole sulfanylacetylhydrazone-substituted fluoroquinolone analogues / 药学学报

To explore an efficient strategy for the conversion of antibacterial fluoroquinolones into antitumor fluoroquinolones, an azole heterocyclic ring of oxadiazole instead of the C-3 carboxylic acid group with a functionalized hydrazone group as a modified side-chain, fifteen novel 2-(fluoroquinolon-3-yl)-oxadiazole-5- sulfanylacetylhydrazone derivatives 7a-7o were designed and synthesized on the basis of the pharmacophore hybridization principle from pefloxacin, separately. The structures for fifteen title compounds were characterized by elemental analysis, 1H NMR and MS, and their in vitro antitumor activity against Hep-3B cell line was evaluated by a MTT assay. The results showed that the title compounds exhibited more significantly inhibitory activity than that of the parent pefloxacin, in which compounds with electron-withdrawing group attached on aryl ring had more potency than that of compounds with electron donating group, especially compounds with a carboxylic substituent were comparable to comparison doxorubicin. It suggests that it is favorable for an improvement of antitumor activity to remain a carboxylic acid unit at the aromatic ring.

Molecular mechanism of ophiopogonin B induced cellular autophagy of human cervical cancer HeLa cells / 药学学报

This study is to investigate the antitumor activity of ophiopogonin B (OP-B). MTT assay, flow cytometric analysis, acridine orange staining, Lyso-Tracker Red staining and HeLa-GFP-LC3 transfect cells assay were used to detect the proliferation activity, apoptosis and autophagy of HeLa cells. The results showed that OP-B exerted potent antiproliferative activity on HeLa cells, the cell growth inhibition effect of OP-B was not due to apoptosis and OP-B could induce autophagy of HeLa cells. OP-B also induced the protein expression up-regulation of Beclin-1 and promoted LC3 I transformation LC3 II, which were representative proteins of autophagy. Furthermore, 3-MA, an inhibitor of autophagy, not only inhibited OP-B-mediated autophagy but also almost completely reversed the antiproliferative effect of OP-B, suggesting that the growth inhibition effect of OP-B was autophagy dependent. Western blotting demonstrated that OP-B inhibited the phosphorylation of Akt and its' downstream vital protein, such as mTOR and p70S6K. In addition, OP-B also induced the protein expression up-regulation of PTEN, which is a negative regulation protein for Akt/mTOR signaling pathway. However, OP-B did not affect the protein expression of total Akt. Collectively, the antitumor effects of OP-B were autophagy-dependent via repression Akt/mTOR signaling pathway. Therefore, OP-B is a prospective inhibitor of Akt/mTOR and may be used as an alternative compound to treat cervical carcinoma.

Synergistic antitumor effects of tanshinone II A in combination with cisplatin via apoptosis in the prostate cancer cells / 药学学报

Treatment with the combination of Chinese herbs and cytotoxic chemotherapies showed a higher survival rate in clinical trials. In this report, the results demonstrated that the tanshinone II A, a key component of Salvia miltiorrhiza bunge, when it is combined with the cytotoxic drug cisplatin showed synergistic antitumor effects on human prostate cancer PC3 cells and LNCaP cells in vitro. Antiproliferative effects were detected with MTT assay. Cell cycle distribution and apoptosis were detected by flow cytometer. Protein expression was detected by Western blotting. The intracellular concentration of cisplatin was detected by high performance liquid chromatography. The results demonstrated that tanshinone II A significantly enhanced the antiproliferative effects of cisplatin on human prostate cancer PC3 cells and LNCaP cells with the increase of the intracellular concentration of cisplatin. These effects were correlated with cell cycle arrested at S phase and cell apoptosis. The apoptosis might be achieved through death receptor pathway and mitochondrial pathway. Furthermore, the Bcl-2 family members were also involved in this apoptotic process. Collectively, these results indicated that the combination of tanshinone II A and cisplatin had a better treatment effect in vitro not only on androgen-dependent LNCaP cells but also on androgen-independent PC3 cells.

Effect of different developmental stage on plant growth and active compounds in Scutellaria baicalensis / 中国中药杂志

<p><b>OBJECTIVE</b>To study the developmental phase on the growth and active compounds in Scutellaria baicalensis.</p><p><b>METHOD</b>Seeds of wild plants were collected from Laiwu and sowed in Fangshan (Beijing) and Laiwu (Shandong). Samples of aerial and underground parts were collected in five growth periods of sprouts, seedlings, flowering, seed drop and withered periods respectively. The length of taproot, fresh weight of root, diameter of taproot and the length of stem were determined. The content of active compounds and total flavonoids were determined by HPLC and ultraviolet spectrophotometry respectively. The transcripted level of PAL1, PAL2, PAL3, C4H, 4CL, CHS, GUS and UBGAT were analyzed with RT-PCR.</p><p><b>RESULT</b>The results showed that the aerial part of S. baicalensis grew quickly before flowering stage, and the underground part grew mostly between the periods of flowering and withered. In the whole growing developmental periods, the content of total flavonoids was not changed significantly, the content of baicalin was increased gradually and the content of baicalein was decreased gradually. Expression level of PAL and 4CL was the highest in withered period, CHS was increased between flowering and seed drop and decreased in withered period.</p><p><b>CONCLUSION</b>Seedlings and withered periods may be the key phase affecting the growth and active compounds in S. baicalensis.</p>

Part IV. Synthesis and antitumor evaluation of s-triazolothiadiazines and pyrazolo s-triazoles derived from ciproxacin / 药学学报

An efficient modified route based on the targeting mechanism of antibacterial fluoroquinolones for the shift from the antibacterial activity to the antitumor one was further developed. Using a fused heterocyclic ring, s-triazolothiadiazine as a carboxyl bioisostere of ciprofloxacin, the title compounds, 1-cyclopropyl-6-fluoro-7-piperazin-1-yl-3-(6-substituted-phenyl-7H-[1, 2, 4]triazolo[3, 4-b][1, 3, 4]thiadiazin-3-yl)-quinolin-4(1H)-ones (5a-5e) and their corresponding N-acetyl products (6a-6e), were designed and synthesized, separately. Meaningfully, a ring-contraction of fused six-membered thiadiazine occurred by a sulfur extrusion reaction gave new tri-acetylated fused heterocycles related to pyrazolo[5, 1-c][1, 2, 4] triazoles (7a-7e). The in vitro antitumor activity against L1210, CHO and HL60 cell lines was also evaluated for the synthesized fifteen heterocycles compared to parent ciprofloxacin by methylthiazole trazolium (MTT) assay. Interestingly, the results displayed that fifteen fused heterocyclic compounds showed more significant growth inhibitory activity (IC50 < 25.0 micromo x L(-1)) than that of parent ciprofloxacin (IC50 > 150.0 micromol x L(-1)), and the active order decreased from 7a-7e to 5a-5e to 6a-6e, respective.

Effects of plant growth regulator mepiquat chloride on content of active compounds in Scutellaria baicalensis / 中国中药杂志

<p><b>OBJECTIVE</b>To study the effect of plant growth regulator mepiquat chloride (DPC) on the growing development of plant and the content of active compounds in Scutellaria baicalensis.</p><p><b>METHOD</b>After spraying DPC during the seedling period, the length of taproot, fresh weight of root, diameter of taproot and the length of stem were measured. The contents of baicalin, baicalein and wogonin were determined by HPLC, respectively. Total flavonoids and scavenging DPPH were determined with ultraviolet spectrophotometry.</p><p><b>RESULT</b>After spraying DPC, fresh weight of S. baicalensis root was significant increased, and root diameter was also increased. The contents of baicalin and total flavonoids were significantly increased and baicalein and wogonin were decreased remarkably. Compared with controls, scavenging activity of ethanol extracts on DPPH free radical was no significant changed after spraying DPC.</p><p><b>CONCLUSION</b>Plant growth regulator DPC could regulate the growth on the ground and underground effectively, and could enhance the content of flavonoids compounds of S. baicalensis.</p>

Synthesis of fluoroquinolone C-3 heterocycles, bis-oxadiazole methylsulfides and methiodides, and their antitumor activity / 中国药学杂志

OBJECTIVE: To explore an efficient structure modification route to transform antibacterial fluoroquinolones to antitumor ones. METHODS: Compound A[1,3,4] oxadiazol-5-thiol 3 derived from ofloxacin 1 was subjected to nucleophilic substitution with each of chloromethyl-1,3,4-oxadiazoles 4a-4g gave di-oxadiazolyl methylsulfides 5a-5g, followed by a quaternization to form the corresponding methiodides 6a-6g, respectively. The in vitro antitumor activity of the title compounds 5a-5g and 6a-6g against three cancer cell lines was evaluated by MTT method. RESULTS: Fourteen title compunds were synthesized and the structures were characterized by corresponding spectral data. The bioactive assay showed that compounds 5a-5g and 6a-6g exhibited a potential anticancer activity (IC50 < 25 μmol · L-1). The activity of the quaternary ammoniums 6a-6g was higher than that of the corresponding free bases 5a-5g. CONCLUSION: The design and synthesis of antitumor fluoroquinolone based on antibacterial fluoroquinolone C-3 heterocycle are worthy of further study.

Part IV: Design, synthesis and antitumor activity of fluoroquinolone C-3 heterocycles: bis-oxadiazole methylsulfide derivatives derived from ciprofloxacin / 药学学报

To explore an efficient strategy for further development of anticancer fluoroquinolone candidates derived from ciprofloxacin, a heterocyclic ring as the bioisosteric replacement of C3 carboxyl group led to a key intermediate, oxadiazole thiol (5), which was further modified to the bis-oxadiazole methylsulfides (7a-7h) and the corresponding dimethylpiperazinium iodides (8a-8h), respectively. Structures were characterized by elemental analysis and spectra data, and their anticancer activities in vitro against CHO, HL60 and L1210 cancer cells were also evaluated by MTT assay. The preliminary results show that piperazinium compounds (8) possess more potent activity than that of corresponding free bases (7).

Cinnamaldehyde ofloxacin-3-ylhydrazone induces apoptosis of human hepatocarcinoma SMMC-7721 cells / 药学学报

This study is to observe the effect of N-(3-phenylallylidene)-6-fluoro-1, 8-(2, 1-propoxy)-7-(4-methylpiperazin-1-yl)-quinolin-4(1H)-one-3-carbonyl hyarazine (FQ16) on apoptosis of hepatocarcinoma SMMC-7721 cells in vitro. With different concentrations of FQ16 at different times used to treat SMMC-7721 cells in vitro, the proliferation of the cells and the inhibition effect of FQ16 on the cell proliferation were examined by MTT assay. Cell apoptosis was determined by Hoechst 33258/PI fluorescence staining, TUNEL and agarose gel electrophoresis method. The effect of FQ16 on topoisomerase II activity was measured by agarose gel electrophoresis using Plasmid pBR322 DNA as the substrate. Mitochondrial membrane potential (MMP, delta psi m) was measured by high content screening image system. The reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the expression changes of Bcl-2 mRNA and Bax mRNA. The caspase-9, caspase-8, caspase-3, p53, Bcl-2 and Bax protein expressions were detected by Western blotting analysis. The results showed that the cell proliferation was inhibited by FQ16 at 0.625 - 10 micromol L(-1) in a time-dose dependent manner. Treatment of SMMC-7721 cells with different concentrations of FQ16 for 24 h increased the percentage of the apoptosis cells obviously (P<0.05), the typical ladder DNA in apoptotic cells and a concomitant dissipation of the mitochondrial membrane potential. Compared with control group, FQ16 influenced obviously DNA topoisomerase II activity, stimulated DNA cleavage and inhibited DNA reunion mediated by topoisomerase II. In addition, FQ16 (3 - 7.39 micromol L(-1)) increased mRNA expression of Bax and protein expression of p53, Bax, caspase-9, caspase-3, separately, and induced cytosolic accumulation of activities caspase-9 and caspase-3, whereas the mRNA and protein expression of Bcl-2 decreased with no change of caspase-8. Therefore it can be concluded that the effects of inhibited topoisomerase II and mitochondrial-dependent pathways were involved in FQ16 induction of apoptosis of SMMC-7721 cells.

Part II: Design, synthesis and antitumor action of C3/C3 bisfluoroquinolones linked-cross 2, 5-1, 3, 4oxadiazole / 药学学报

To develop a new small molecular probe for discovering an antitumor lead compound from the replacement of carboxylic group of two molecular antibacterial fluoroquinolones with a heterocyclic ring, a series of the C3/C3 bis-fluoroquinolones tethered with an 1, 3, 4-oxadiazole ring were synthesized as their respective HCl salts, and their structures were characterized by elemental analysis and spectral data. The in vitro antitumor activity against L1210, CHO and HL60 cell lines was also evaluated via the respective IC50 values by methylthiazole trazolium (MTT) assay.

Synthesis and antitumor activity of anthracene-9-carbaldehyde amino-s-triazole Schiff-bases with side-chain of S-acetic acid / 药学学报

To find out a novel lead compound from heterocyclic amine Schiff bases for developing new antitumor agents, each of (4-amino-5-substituted-s-triazol-3-ylthio) -acetic acids 2a-j was condensed with anthracene-9-carbaldehyde to obtain Schiff-bases of [4-(anthracen-9-yl methylene) amino] -5-substituted-s-triazol-3-ylsulfanyl] -acetic acids 3a-j. The structures of new compounds synthesized were characterized by elemental analysis and spectral data, and in vitro antitumor activity was also evaluated against CHO, HL60 and L1210 cell lines by MTT assay.

Effects on lymphangiogenesis and angiogenesis of lung cancer with antisense oligonucleotides of vascular endothelial growth factor C / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the effects on lymphangiogenesis and angiogenesis of orthotopic implantation of lung cancer in nude mice with antisense oligonucleotides of VEGF-C.</p><p><b>METHODS</b>The model in nude mice was established with orthotopic implantation for the human lung cancer cell line A549. Thirty nude mice were randomized into three groups: PBS control group, sense oligonucleotides control group and antisense oligonucleotides group (AODN group). After treatments were completed, the expression of VEGF-C and lymphatic microvessel density (LMVD) and microvessel density (MVD) of lung cancer were detected by RT-PCR,Western Blot and immunohistochemistry.</p><p><b>RESULTS</b>The expression of VEGF-C in AODN group was inhibit significantly (P < 0.05). The LMVD in AODN group was decreased significantly (P < 0.1). Though the MVD in AODN group was also decreased, but there were no significant differences compared with control groups (P > 0.05).</p><p><b>CONCLUSIONS</b>The antisense oligonucleotides of VEGF-C can inhibit the expression of VEGF-C in nude mice of orthotopic implantation of lung cancer. It could inhibit the lymphangiogenesis.</p>

Synthesis and antibacterial activity of imidazothiadiazoles and heterocyclic-amine Mannich-base hydrochloride / 药学学报

To optimize the synthetic method and antibacterial activity of fused heterocyclic thiadiazole compounds, cyclocondensation of 2-(4-methoxyphenyl)-5-amino-1,3,4-thiadiazole (2) with alpha-chloro-4-chloro acetophenone (3) resulted in a key intermediate (4), 6 -(4-chlorophenyl)-2-(4-methoxyphenyl)-imidazo-[2,1-b][1,3,4]thiadiazole, which was carried out an nucleophilic substitution with substituted piperazine to give the corresponding free bases of piperazine (5a-5c), then followed by Mannich reaction with heterocyclicamines and formaldehyde to yield the corresponding Mannich bases, (1a-11) as respective hydrochloride salts. The structures were confirmed by IR, 1H NMR, MS and elemental analysis and the antibacterial activities in vitro of fifteen newly synthesized compounds were also tested against Gram positive bacteria and Gram negative bacteria with the standard 2-fold agar dilution method. The antibacterial results showed that the introduction of a polar group resulted in the enhancement of antibacterial activity in vitro. Thus, the structures of these fused compounds could further be investigated.