Search results for: enzymes

Authors: Amandeep Thakur, Yi-Hsuan Chu, Chun-Hsu Pan, Kunal Nepali

Abstract:

The transfer of ADP-ribose residues onto target substrates from nicotinamide adenine dinucleotide (NAD) (PARylation) is catalyzed by Poly (ADP-ribose) polymerases (PARPs). Amongst the PARP family members, the DNA damage response in cancer is majorly regulated by PARP1 and PARP2. The blockade of DNA repair by PARP inhibitors leads to the progression of DNA single-strand breaks (induced by some triggering factors) to double-strand breaks. Notably, PARP inhibitors are remarkably effective in cancers with defective homologous recombination repair (HRR). In particular, cancer cells with BRCA mutations are responsive to therapy with PARP inhibitors. The aforementioned requirement for PARP inhibitors to be effective confers a narrow activity spectrum to PARP inhibitors, which hinders their clinical applicability. Thus, the quest to expand the application horizons of PARP inhibitors beyond BRCA mutations is the need of the hour. Literature precedents reveal that HDAC inhibition induces BRCAness in cancer cells and can broaden the therapeutic scope of PARP inhibitors. Driven by such disclosures, dual inhibitors targeting both PARP and HDAC enzymes were designed by our research group to extend the efficacy of PARP inhibitors beyond BRCA-mutated cancers to cancers with induced BRCAness. The design strategy involved the installation of Veliparib, an investigational PARP inhibitor, as a surface recognition part in the HDAC inhibitor pharmacophore model. The chemical architecture of veliparib was deemed appropriate as a starting point for the generation of dual inhibitors by virtue of its size and structural flexibility. A validatory docking study was conducted at the outset to predict the binding mode of the designed dual modulatory chemical architectures. Subsequently, the designed chemical architectures were synthesized via a multistep synthetic route and evaluated for antitumor efficacy. Delightfully, one compound manifested impressive anti-leukemic effects (HL-60 cell lines) mediated via dual inhibition of PARP and class I HDACs. The outcome of the western blot analysis revealed that the compound could downregulate the expression levels of PARP1 and PARP2 and the HDAC isoforms (HDAC1, 2, and 3). Also, the dual PARP-HDAC inhibitor upregulated the protein expression of the acetyl histone H3, confirming its abrogation potential for class I HDACs. In addition, the dual modulator could arrest the cell cycle at the G0/G1 phase and induce autophagy. Further, polymer-based nanoformulation of the dual inhibitor was furnished to afford targeted delivery of the dual inhibitor at the cancer site. Transmission electron microscopy (TEM) results indicate that the nanoparticles were monodispersed and spherical. Moreover, the polymeric nanoformulation exhibited an appropriate particle size. Delightfully, pH-sensitive behavior was manifested by the polymeric nanoformulation that led to selective antitumor effects towards the HL-60 cell lines. In light of the magnificent anti-leukemic profile of the identified dual PARP-HDAC inhibitor, in-vivo studies (pharmacokinetics and pharmacodynamics) are currently being conducted. Notably, the optimistic findings of the aforementioned study have spurred our research group to initiate several medicinal chemistry campaigns to create bifunctional small molecule inhibitors addressing PARP as the primary target.

Keywords: PARP inhibitors, HDAC inhibitors, BRCA mutations, leukemia

Procedia PDF Downloads 23

Authors: Sadaf Abbas, HimGauri Sabnis

Abstract:

Introduction: Peripartum cardiomyopathy is a rare but potentially life-threatening condition that presents as heart failure during the last month of pregnancy or within five months postpartum. The incidence of postpartum cardiomyopathy ranges from 1 in 1300 to 1 in 15,000 pregnancies. Risk factors include multiparty, advanced maternal age, multiple pregnancies, pre-eclampsia, and chronic hypertension. Study: A 30-year-old Para3+0 presented to the Emergency Department of St’Marry Hospital, Isle of Wight, on the seventh day postpartum, with acute shortness of breath (SOB), chest pain, cough, and a temperature of 38 degrees. The risk factors were smoking and class II obesity (BMI of 40.62). The patient had mild pre-eclampsia in the last pregnancy and was on labetalol and aspirin during an antenatal period, which was stopped postnatally. There was also a history of pre-eclampsia and haemolysis, elevated liver enzymes, low platelets (HELLP syndrome) in previous pregnancies, which led to preterm delivery at 35 weeks in the second pregnancy, and the first baby was stillborn at 24 weeks. On assessment, there was a national early warning score (NEWS score) of 3, persistent tachycardia, and mild crepitation in the lungs. Initial investigations revealed an enlarged heart on chest X-ray, and a CT pulmonary angiogram indicated bilateral basal pulmonary congestion without pulmonary embolism, suggesting fluid overload. Laboratory results showed elevated CRP and normal troponin levels initially, which later increased, indicating myocardial involvement. Echocardiography revealed a severely dilated left ventricle with an ejection fraction (EF) of 31%, consistent with severely impaired systolic function. The cardiology team reviewed the patient and admitted to the Coronary Care Unit. As sign and symptoms were suggestive of fluid overload and congestive cardiac failure, management was done with diuretics, beta-blockers, angiotensin-converting enzyme inhibitors (ACE inhibitors), proton pump inhibitors, and supportive care. During admission, there was complications such as acute kidney injury, but then recovered well. Chest pain had resolved following the treatment. After being admitted for eight days, there was an improvement in the symptoms, and the patient was discharged home with a further plan of cardiac MRI and genetic testing due to a family history of sudden cardiac death. Regular appointment has been made with the Cardiology team to follow-up on the symptoms. Since discharge, the patient made a good recovery. A cardiac MRI was done, which showed severely impaired left ventricular function, ejection fraction (EF) of 38% with mild left ventricular dilatation, and no evidence of previous infarction. Overall appearance is of non-ischemic dilated cardiomyopathy. The main challenge at the time of admission was the non-availability of a cardiac radiology team, so the definitive diagnosis was delayed. The long-term implications include risk of recurrence, chronic heart failure, and, consequently, an effect on quality of life. Therefore, regular follow-up is critical in patient’s management. Conclusions: Peripartum cardiomyopathy is one of the cardiovascular diseases whose causes are still unknown yet and, in some cases, are uncontrolled. By raising awareness about the symptoms and management of this complication it will reduce morbidity and mortality rates and also the length of stay in the hospital.

Keywords: cardiomyopathy, cardiomegaly, pregnancy, puerperium

Procedia PDF Downloads 29

Authors: Yogesh Dalvi, Ruby Varghese, Nibu Varghese, C. K. Krishnan Nair

Abstract:

Introduction: The Genus Phellinus, locally known as Phansomba is a well-known traditional folk medicine. Especially, in Western Ghats of India, many tribes use several species of Phellinus for various ailments related to teeth, throat, tongue, stomach and even wound healing. It is one of the few mushrooms which play a pivotal role in Ayurvedic Dravyaguna. Aim: The present study focuses on to investigate phytochemical analysis, antioxidant, and antitumor (in vitro and in vivo) potential of Phellinus robinae from South India, Kerala Material and Methods: The present study explores the following: 1. Phellinus samples were collected from Ranni, Pathanamthitta district of Kerala state, India from Artocarpus heterophyllus Lam. and species were identified using rDNA region. 2. The fruiting body was shadow dried, powdered and extracted with 50% alcohol using water bath at 60°C which was further condensed by rotary evaporator and lyophilized at minus 40°C temperature. 3. Secondary metabolites were analyzed by using various phytochemical screening assay (Hager’s Test, Wagner’s Test, Sodium hydroxide Test, Lead acetate Test, Ferric chloride Test, Folin-ciocalteu Test, Foaming Test, Benedict’s test, Fehling’s Test and Lowry’s Test). 4. Antioxidant and free radical scavenging activity were analyzed by DPPH, FRAP and Iron chelating assay. 5. The antitumor potential of Water alcohol extract of Phellinus (PAWE) is evaluated through In vitro condition by Trypan blue dye exclusion method in DLA cell line and In vivo by murine model. Result and Discussion: Preliminary phytochemical screening by various biochemical tests revealed presence of a variety of active secondary molecules like alkaloids, flavanoids, saponins, carbohydrate, protein and phenol. In DPPH and FRAP assay PAWE showed significantly higher antioxidant activity as compared to standard Ascorbic acid. While, in Iron chelating assay, PAWE exhibits similar antioxidant activity that of Butylated Hydroxytoluene (BHT) as standard. Further, in the in vitro study, PAWE showed significant inhibition on DLA cell proliferation in dose dependent manner and showed no toxicity on mice splenocytes, when compared to standard chemotherapy drug doxorubicin. In vivo study, oral administration of PAWE showed dose dependent tumor regression in mice and also raised the immunogenicity by restoring levels of antioxidant enzymes in liver and kidney tissue. In both in vitro and in vivo gene expression studies PAWE up-regulates pro-apoptotic genes (Bax, Caspases 3, 8 and 9) and down- regulates anti-apoptotic genes (Bcl2). PAWE also down regulates inflammatory gene (Cox-2) and angiogenic gene (VEGF). Conclusion: Preliminary phytochemical screening revealed that PAWE contains various secondary metabolites which contribute to its antioxidant and free radical scavenging property as evaluated by DPPH, FRAP and Iron chelating assay. PAWE exhibits anti-proliferative activity by the induction of apoptosis through a signaling cascade of death receptor-mediated extrinsic (Caspase8 and Tnf-α), as well as mitochondria-mediated intrinsic (caspase9) and caspase pathways (Caspase3, 8 and 9) and also by regressing angiogenic factor (VEGF) without any inflammation or adverse side effects. Hence, PAWE serve as a potential antioxidant and antitumor agent.

Keywords: antioxidant, antitumor, Dalton lymphoma ascites (DLA), fungi, Phellinus robinae

Procedia PDF Downloads 304