Dhanaraju Mandalapu

Dithiocarbamate-thiourea hybrids useful as vaginal microbicides also show reverse transcriptase inhibition: design, synthesis, docking and pharmacokinetic studies.

Prophylactic prevention is considered as the most promising strategy to tackle STI/HIV. Twenty-five dithiocarbamate-thiourea hybrids (14-38) were synthesized as woman controlled topical vaginal microbicides to counter Trichomonas vaginalis and sperm along with RT inhibition potential. The four promising compounds (18, 26, 28 and 33) were tested for safety through cytotoxic assay against human cervical cell line (HeLa) and compatibility with vaginal flora, Lactobacillus. Docking study of most promising vaginal microbicide (33) revealed that it docked in a position and orientation similar to known reverse transcriptase inhibitor Nevirapine. The preliminary in vivo pharmacokinetics of compound 33 was performed in NZ-rabbits to evaluate systemic toxicity in comparison to Nonoxynol-9.

Disulfiram and its novel derivative sensitize prostate cancer cells to the growth regulatory mechanisms of the cell by re‐expressing the epigenetically repressed tumor suppressor—estrogen receptor β

Estrogen Receptor‐β (ER‐β), a tumor‐suppressor in prostate cancer, is epigenetically repressed by hypermethylation of its promoter. DNA‐methyltransferases (DNMTs), which catalyze the transfer of methyl‐groups to CpG islands of gene promoters, are overactive in cancers and can be inhibited by DNMT‐inhibitors to re‐express the tumor suppressors. The FDA‐approved nucleoside DNMT‐inhibitors like 5‐Azacytidine and 5‐Aza‐deoxycytidine carry notable concerns due to their off‐target toxicity, therefore non‐nucleoside DNMT inhibitors are desirable for prolonged epigenetic therapy. Disulfiram (DSF), an antabuse drug, inhibits DNMT and prevents proliferation of cells in prostate and other cancers, plausibly through the re‐expression of tumor suppressors like ER‐β. To increase the DNMT‐inhibitory activity of DSF, its chemical scaffold was optimized and compound‐339 was discovered as a doubly potent DSF‐derivative with similar off‐target toxicity. It potently and selectively inhibited cell proliferation of prostate cancer (PC3/DU145) cells in comparison to normal (non‐cancer) cells by promoting cell‐cycle arrest and apoptosis, accompanied with inhibition of total DNMT activity, and re‐expression of ER‐β (mRNA/protein). Bisulfite‐sequencing of ER‐β promoter revealed that compound‐339 demethylated CpG sites more efficaciously than DSF, restoring near‐normal methylation status of ER‐β promoter. Compound‐339 docked on to the MTase domain of DNMT1 with half the energy of DSF. In xenograft mice‐model, the tumor volume regressed by 24% and 50% after treatment with DSF and compound‐339, respectively, with increase in ER‐β expression. Apparently both compounds inhibit prostate cancer cell proliferation by re‐expressing the epigenetically repressed tumor‐suppressor ER‐β through inhibition of DNMT activity. Compound‐339 presents a new lead for further study as an anti‐prostate cancer agent.

Ammonium salts of carbamodithioic acid as potent vaginal trichomonacides and fungicides

Chemical attenuation of the reactive oxygen species (ROS)-sensitive anaerobes Trichomonas vaginalis, which is the most prevalent non-viral sexually transmitted infection, and two often coexisting vaginal infections, namely Candida albicans and Staphylococcus aureus, which are opportunistic reproductive tract infections, was attempted with novel ammonium salts of carbamodithioic acid through inhibition of free thiols. In vitro and in vivo efficacies of the designed compounds were evaluated as topical vaginal microbicides. Five compounds showed exceptional activity against drug-resistant and -susceptible strains with negligible toxicity to host (HeLa) cells in vitro in comparison with the standard vaginal microbicide nonoxynol-9 (N-9), without disturbing the normal vaginal flora (i.e. Lactobacillus). The compounds significantly inhibited the cytopathic effects of Trichomonas on HeLa cells in vitro with efficacies comparable with metronidazole (MTZ); however, their efficacy to rescue host cells from co-infection (protozoal and fungal) was greater than that of MTZ. The compounds inhibited β-haemolysis of red blood cells caused by Trichomonas and were found to be active in vivo in the mouse subcutaneous abscess assay. Some compounds rapidly immobilized human sperm. A mechanism involving inhibition of free thiols and consequently the cysteine proteases of T. vaginalis by the new compounds has been proposed. Thus, a unique scaffold of antimicrobial agents has been discovered that warrants further investigation for development as contraceptive vaginal microbicides.

Synthesis and biological evaluation of some novel triazole hybrids of curcumin mimics and their selective anticancer activity against breast and prostate cancer cell lines

The anti-cancer property of curcumin, an active component of turmeric, is limited due to its poor solubility, stability and bioavailability. To enhance its efficacy, we designed a novel series of twenty-four monocarbonyl curcumin analogue-1,2,3-triazole conjugates and evaluated their anti-cancer activity towards endocrine related cancers. The new compounds (17-40) were synthesized through CuAAC click reaction and SAR analysis carried out. Out of these all, compound 17 showed most significant anti-cancer activity against prostate cancer cells with IC50 values of 8.8μM and 9.5μM in PC-3 and DU-145 cells, respectively. Another compound 26 showed significant anti-cancer activity against breast cancer cells with IC50 of 6μM, 10μM and 6.4μM in MCF-7, MDA-MB-231 and 4T1 cells, respectively while maintaining low toxicity towards non-cancer originated cell line, HEK-293. Compounds 17 and 26 arrested cell cycle and induced mitochondria-mediated apoptosis in cancer cells. Further, both of these compounds significantly down-regulated cell proliferation marker (PCNA), inhibited activation of cell survival protein (Akt phosphorylation), upregulated pro-apoptotic protein (Bax) and down-regulated anti-apoptotic protein (Bcl-2) in their respective cell lines. In addition, in vitro stability, solubility and plasma binding studies of the compounds 17 and 26 showed them to be metabolically stable. Thus, this study identified two new curcumin monocarbonyl-1,2,3-triazole conjugate compounds with more potent activity than curcumin against breast and prostate cancers.

Design and synthesis of substituted morpholin/piperidin-1-yl-carbamodithioates as promising vaginal microbicides with spermicidal potential.

A series of seventeen morpholin/piperidin-1-yl-carbamodithioate (3-19) were synthesized as topical vaginal microbicidal spermicides. The synthesized compounds were evaluated for their anti-Trichomonas activity against MTZ susceptible and resistant strains along with their spermicidal and antifungal potential. All the synthesized compounds were assessed for their safety through cytotoxic assay against human cervical cell line (HeLa) and compatibility with vaginal flora, Lactobacillus. The study identified eleven dually active compounds with apparent safety. The plausible mode of action of these compounds was through sulfhydryl binding, confirmed via reduction in available free thiols on human sperm. The most promising compound 9 significantly inhibited (P<0.001) thiol-sensitive sperm hexokinase. The stability of compound 9 in simulated vaginal fluid (SVF) was performed via HPLC-PDA method, which supported its utility for vaginal administration.

Innovative Disulfide Esters of Dithiocarbamic Acid as Women-Controlled Contraceptive Microbicides: A Bioisosterism Approach.

In an ongoing effort to discover an effective, topical, dual‐function, non‐surfactant contraceptive vaginal microbicide, a novel series of 2,2′‐disulfanediylbis(3‐(substituted‐1‐yl)propane‐2,1‐diyl) disubstituted‐1‐carbodithioates were designed by using a bioisosterism approach. Thirty‐three compounds were synthesized, and interestingly, most demonstrated multiple activities: they were found to be spermicidal at a minimal effective concentration of 1–0.001 %, trichomonacidal against drug‐susceptible and resistant Trichomonas strains at minimal inhibitory concentration (MIC) ranges of 10.81–377.64 and 10.81–754.14 μM, respectively, and fungicidal at MIC 7.93–86.50 μM. These compounds were also found to be non‐cytotoxic to human cervical (HeLa) epithelial cells and vaginal microflora (Lactobacilli) in vitro. The most promising compound, 2,2′‐disulfanediylbis(3‐(pyrrolidin‐1‐yl)propane‐2,1‐diyl)dipyrrolidine‐1‐carbodithioate (5), exhibited spermicidal activity 15‐fold higher than that of the marketed spermicide Nonoxynol‐9 (N‐9) and also demonstrated microbicidal potency. To identify common structural features required for spermicidal activity, a 3D‐QSAR analysis was carried out, as well as in vivo efficacy studies and fluorescent labeling studies to determine the biological targets of compound 5.

Discovery of monocarbonyl curcumin hybrids as a novel class of human DNA ligase I inhibitors: in silico design, synthesis and biology

A pharmacophore model was generated and validated by using known human DNA ligase inhibitors for the identification of a novel series of monocarbonyl curcumin–thiourea/thiazole hybrids as human DNA ligase I (hLigI) inhibitors. These compounds (14–49) were synthesized and their antiligase and cytotoxic activities were evaluated in vitro. Several compounds from this series have shown significant inhibition of purified hLigI activity and exhibited a low micro molar range of cytotoxic activity against one or more cancer cell lines, with IC50 values ranging from 1.3–48.8 μM. Among these, compound 23 showed antiligase activity at an IC50 value 24.9 ± 1.8 μM, and selective cytotoxicity against DLD1 cancer cell line (IC50 value 8.7 ± 1.9 μM) compared to the reference curcumin (IC50 values were 51.9 ± 8.7 μM and 33.2 ± 1.8 μM for antiligase and cytotoxic activities against DLD1 cell line, respectively), and docking studies showed considerable interactions of compound 23 with hLigI. This new class of potent hLigI inhibitors will serve as a potential lead for further optimization and drug development.

New orally active DNA minor groove binding small molecule CT-1 acts against breast cancer by targeting tumor DNA damage leading to p53-dependent apoptosis.

Targeting tumor DNA damage and p53 pathway is a clinically established strategy in the development of cancer chemotherapeutics. Majority of anti‐cancer drugs are delivered through parenteral route for reasons like severe toxicity, lack of stability, and poor enteral absorption. Current DNA targeting drugs in clinical like anthracycline suffers from major drawbacks like cardiotoxicity. Here, we report identification of a new orally active small molecule curcumin‐triazole conjugate (CT‐1) with significant anti‐breast cancer activity in vitro and in vivo. CT‐1 selectively and significantly inhibits viability of breast cancer cell lines; retards cells cycle progression at S phase and induce mitochondrial‐mediated cell apoptosis. CT‐1 selectively binds to minor groove of DNA and induces DNA damage leading to increase in p53 along with decrease in its ubiquitination. Inhibition of p53 with pharmacological inhibitor as well as siRNA revealed the necessity of p53 in CT‐1‐mediated anti‐cancer effects in breast cancer cells. Studies using several other intact p53 and deficient p53 cancer cell lines further confirmed necessity of p53 in CT‐1‐mediated anti‐cancer response. Pharmacological inhibition of pan‐caspase showed CT‐1 induces caspase‐dependent cell death in breast cancer cells. Most interestingly, oral administration of CT‐1 induces significant inhibition of tumor growth in LA‐7 syngeneic orthotropic rat mammary tumor model. CT‐1 treated mammary tumor shows enhancement in DNA damage, p53 upregulation, and apoptosis. Collectively, CT‐1 exhibits potent anti‐cancer effect both in vitro and in vivo and could serve as a safe orally active lead for anti‐cancer drug development.

Design, synthesis and biological profiling of aryl piperazine based scaffolds for the management of androgen sensitive prostatic disorders

In the quest for novel scaffolds for the management of androgen sensitive prostatic disorders like prostate cancer and benign prostatic hyperplasia, a series of twenty-six aryl/heteroaryl piperazine derivatives have been described. Three compounds, 8a, 8c and 9a, exhibited good activity profiles against an androgen sensitive prostate cancer cell line (LNCaP) with EC50 values of 9.8, 7.6 and 11.2 μM, respectively. These compounds caused a decrease in luciferase activity and a decline in PSA and Ca2+ levels, which are indicative of their anti-androgenic and α1A-adrenergic receptor blocking activities, respectively. Compound 9a reduced the prostate weight of rats (47%) and in pharmacokinetic analysis at 10 mg kg−1 it demonstrated an MRT of ∼14 h post dose, exhibiting high levels in prostate. Compound 9a docked in a similar orientation to hydroxyflutamide on an androgen receptor and showed strong π–π interactions. These findings reveal that compound 9a is a promising candidate for management of prostatic disorders with anti-androgenic and α1A-blocking activities.