Padma Das

Synthesis, cytotoxicity, and structure―activity relationship (SAR) studies of andrographolide analogues as anti-cancer agent

A series of analogues of andrographolide, prepared through chemo-selective functionalization at C14 hydroxy, have been evaluated for in vitro cytotoxicities against human leukemic cell lines. Two of the analogues (6a, 9b) exhibited significant potency. Preliminary studies on structure-activity relationship (SAR) revealed that the α-alkylidene-γ-butyrolactone moiety of andrographolide played a major role in the activity profile. The structures of the analogues were established through spectroscopic and analytical data.

Monitoring of intracellular nitric oxide in leishmaniasis: Its applicability in patients with visceral leishmaniasis

Nitric oxide (NO) has been demonstrated to be a principal effector molecule responsible for mediating intracellular killing of Leishmania parasites, the causative organism of leishmaniasis. As measurement of intracellular NO remains a challenge to biologists, we have developed a flow cytometric approach to perform real time biological detection of NO within Leishmania parasites and parasitized macrophages using a membrane permeable derivative of diaminofluorescein [4,5‐diaminofluorescein diacetate (DAF‐2DA)]. Initially, assay optimization was performed in Leishmania donovani promastigotes, assay specificity being confirmed using both a NO donor [S‐nitroso‐N‐acetyl‐penicillamine (SNAP)] and a NO scavenger [2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide, C‐PTIO]. Using 40 μM DAF‐2DA, basal levels of intracellular NO were measured which varied in different Leishmania species; addition of conventional anti‐leishmanial drugs, antimony and miltefosine translated into a dramatic increase in DAF‐2T fluorescence. Furthermore, the assay also measured levels of NO in macrophages, but needed a 20 fold lower concentration of DAF‐2DA, being 2 μM. Following parasitization, levels of NO decreased which was normalized following treatment with anti‐leishmanial drugs. Similarly monocytes of patients with visceral leishmaniasis at disease presentation showed decreased levels of NO which too reverted on completion of treatment. Taken together, this study opens new perspectives of research regarding monocyte function and provides a real time approach for monitoring the effect of anti‐leishmanial compounds.

Menstrual Hygiene Practices, WASH Access and the Risk of Urogenital Infection in Women from Odisha, India

Menstrual hygiene management (MHM) practices vary worldwide and depend on the individual’s socioeconomic status, personal preferences, local traditions and beliefs, and access to water and sanitation resources. MHM practices can be particularly unhygienic and inconvenient for girls and women in poorer settings. Little is known about whether unhygienic MHM practices increase a woman’s exposure to urogenital infections, such as bacterial vaginosis (BV) and urinary tract infection (UTI). This study aimed to determine the association of MHM practices with urogenital infections, controlling for environmental drivers. A hospital-based case-control study was conducted on 486 women at Odisha, India. Cases and controls were recruited using a syndromic approach. Vaginal swabs were collected from all the participants and tested for BV status using Amsel’s criteria. Urine samples were cultured to assess UTI status. Socioeconomic status, clinical symptoms and reproductive history, and MHM and water and sanitation practices were obtained by standardised questionnaire. A total of 486 women were recruited to the study, 228 symptomatic cases and 258 asymptomatic controls. Women who used reusable absorbent pads were more likely to have symptoms of urogenital infection (AdjOR=2.3, 95%CI1.5-3.4) or to be diagnosed with at least one urogenital infection (BV or UTI) (AdjOR=2.8, 95%CI1.7-4.5), than women using disposable pads. Increased wealth and space for personal hygiene in the household were protective for BV (AdjOR=0.5, 95%CI0.3-0.9 and AdjOR=0.6, 95%CI0.3-0.9 respectively). Lower education of the participants was the only factor associated with UTI after adjusting for all the confounders (AdjOR=3.1, 95%CI1.2-7.9). Interventions that ensure women have access to private facilities with water for MHM and that educate women about safer, low-cost MHM materials could reduce urogenital disease among women. Further studies of the effects of specific practices for managing hygienically reusable pads and studies to explore other pathogenic reproductive tract infections are needed.

Berberine chloride causes a caspase-independent, apoptotic-like death in Leishmania donovani promastigotes.

Berberine chloride, a quarternary isoquinoline alkaloid, is a promising anti-leishmanial compound, IC50 being 7.1 µM in L. donovani promastigotes. This leishmanicidal activity was initiated by its pro-oxidant effect, evidenced by enhanced generation of reactive oxygen intermediates that was accompanied by depletion of thiols; pre-incubation in N-acetyl cysteine, attenuated its cell viability, corroborating that generation of free radicals triggered its parasiticidal activity. Externalization of phosphatidylserine and elevation of intracellular calcium preceded depolarization of the mitochondrial membrane potential, which translated into an increase in the sub G0/G1 population and was accompanied by DNA laddering, hallmarks of apoptosis. Berberine chloride failed to induce caspase activity and anti-leishmanial activity in the presence of a pan caspase inhibitor, Z-Val-Ala-DL-Asp (methoxy)-fluoromethylketone remained unchanged, which indicated that the apoptosis was caspase independent. Collectively, the data indicates that Berberine chloride triggers an apoptosis-like death following enhanced generation of reactive oxygen species, thus meriting further pharmacological investigations.

Andrographolide Analogue Induces Apoptosis and Autophagy Mediated Cell Death in U937 Cells by Inhibition of PI3K/Akt/mTOR Pathway.

Background Current chemotherapeutic agents based on apoptosis induction are lacking in desired efficacy. Therefore, there is continuous effort to bring about new dimension in control and gradual eradication of cancer by means of ever evolving therapeutic strategies. Various forms of PCD are being increasingly implicated in anti-cancer therapy and the complex interplay among them is vital for the ultimate fate of proliferating cells. We elaborated and illustrated the underlying mechanism of the most potent Andrographolide analogue (AG–4) mediated action that involved the induction of dual modes of cell death—apoptosis and autophagy in human leukemic U937 cells. Principal Findings AG–4 induced cytotoxicity was associated with redox imbalance and apoptosis which involved mitochondrial depolarisation, altered apoptotic protein expressions, activation of the caspase cascade leading to cell cycle arrest. Incubation with caspase inhibitor Z-VAD-fmk or Bax siRNA decreased cytotoxic efficacy of AG–4 emphasising critical roles of caspase and Bax. In addition, AG–4 induced autophagy as evident from LC3-II accumulation, increased Atg protein expressions and autophagosome formation. Pre-treatment with 3-MA or Atg 5 siRNA suppressed the cytotoxic effect of AG–4 implying the pro-death role of autophagy. Furthermore, incubation with Z-VAD-fmk or Bax siRNA subdued AG–4 induced autophagy and pre-treatment with 3-MA or Atg 5 siRNA curbed AG–4 induced apoptosis—implying that apoptosis and autophagy acted as partners in the context of AG–4 mediated action. AG–4 also inhibited PI3K/Akt/mTOR pathway. Inhibition of mTOR or Akt augmented AG–4 induced apoptosis and autophagy signifying its crucial role in its mechanism of action. Conclusions Thus, these findings prove the dual ability of AG–4 to induce apoptosis and autophagy which provide a new perspective to it as a potential molecule targeting PCD for future cancer therapeutics.

Malabaricone-A Induces A Redox Imbalance That Mediates Apoptosis in U937 Cell Line

Background The ‘two-faced’ character of reactive oxygen species (ROS) plays an important role in cancer biology by acting both as secondary messengers in intracellular signaling cascades and sustaining the oncogenic phenotype of cancer cells, while on the other hand, it triggers an oxidative assault that causes a redox imbalance translating into an apoptotic cell death. Principal Findings Using a tetrazolium [{3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl}-2H-tetrazolium] based cell viability assay, we evaluated the cytotoxicity of a plant derived diarylnonanoid, malabaricone-A on leukemic cell lines U937 and MOLT-3. This cytotoxicity hinged on its ability to cause a redox imbalance via its ability to increase ROS, measured by flow cytometry using 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate and by decreasing glutathione peroxidase activity. This redox imbalance mediated apoptosis was evident by an increase in cytosolic [Ca2+], externalization of phosphatidyl serine as also depolarization of the mitochondrial membrane potential as measured by flow cytometry. There was concomitant peroxidation of cardiolipin, release of free cytochrome c to cytosol along with activation of caspases 9, 8 and 3. This led to cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by labeling with 4′,6-diamidino-2-phenylindole (DAPI); furthermore, terminal deoxy ribonucleotide transferase catalysed incorporation of deoxy uridine triphosphate confirmed DNA nicking and was accompanied by arrest of cell cycle progression. Conclusions Taken together, compounds like MAL-A having pro-oxidant activity mediate their cytotoxicity in leukemic cells via induction of oxidative stress triggering a caspase dependent apoptosis.

Vitamin E-deficiency induced changes in ovary and uterus.

Female rats at weaning (30 days age) were maintained on vitamin E-deficient diet for 70 days. The vitamin E-deficient and control animals were sacrified on 100 days of age. To study recovery a group of animals were supplemented with normal diet for last 25 days after initial 45 days of deficient diet or vice versa. The most striking data found were (i) significant drop in uterine weight in deficient group (ii) significant decrease in estrogen, LH and estrogen-induced uterine enzymes alkaline phosphatase and peroxidase and (iii) ovarian dysfunction as noted by degenerating graffian follicles. The significance of these findings is discussed in this report.

Apoptotic and Autophagic Effects of Sesbania grandiflora Flowers in Human Leukemic Cells

Background Identification of cytotoxic compounds that induce apoptosis has been the mainstay of anti-cancer therapeutics for several decades. In recent years, focus has shifted to inducing multiple modes of cell death coupled with reduced systemic toxicity. The plant Sesbania grandiflora is widely used in Indian traditional medicine for the treatment of a broad spectrum of diseases. This encouraged us to investigate into the anti-proliferative effect of a fraction (F2) isolated from S. grandiflora flowers in cancer cells and delineate the underlying involvement of apoptotic and autophagic pathways. Principal Findings Using MTT based cell viability assay, we evaluated the cytotoxic potential of fraction F2. It was the most effective on U937 cells (IC50∶18.6 µg/ml). Inhibition of growth involved enhancement of Annexin V positivity. This was associated with elevated reactive oxygen species generation, measured by flow cytometry and reduced oxygen consumption – both effects being abrogated by anti-oxidant NAC. This caused stimulation of pro-apoptotic proteins and concomitant inhibition of anti-apoptotic protein expressions inducing mitochondrial depolarization, as measured by flow cytometry and release of cytochrome c. Interestingly, even with these molecular features of apoptosis, F2 was able to alter Atg protein levels and induce LC3 processing. This was accompanied by formation of autophagic vacuoles as revealed by fluorescence and transmission electron microscopy – confirming the occurrence of autophagy. Eventually, F2 triggered caspase cascade – executioners of programmed cell death and AIF translocation to nuclei. This culminated in cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by staining with Hoechst 33258 leading to cell death. Conclusions The findings suggest fraction F2 triggers pro-oxidant activity and mediates its cytotoxicity in leukemic cells via apoptosis and autophagy. Thus, it merits consideration and further investigation as a therapeutic option for the treatment of leukemia.

Abstract A19: Andrographolide analogue induces crosstalk between apoptosis and autophagy via inhibition of PI3K/Akt/mTOR pathway in human leukemic cells.

Current chemotherapeutic agents solely based on apoptosis induction have limited efficacy. Therefore, new therapeutic strategies and drugs still need to be explored. Various forms of programmed cell death are being increasingly implicated in anticancer therapy and the complex interplay among them is critical to the overall fate of cells. We elucidated the underlying mechanism of the most potent Andrographolide analogue (AG-4) mediated action that involved crosstalk between apoptosis and autophagy in human leukemic U937 cells. AG-4 induced cytotoxicity was associated with redox imbalance and apoptosis which involved mitochondrial depolarisation, altered apoptotic protein expressions, activation of the caspase cascade leading to cell cycle arrest. Incubation with caspase inhibitor Z-VAD-fmk or Bax siRNA decreased cytotoxic efficacy of AG-4 emphasising critical roles of caspase and Bax. In addition, AG-4 induced autophagy as evident from LC3-II accumulation, increased Atg protein expressions and autophagosome formation. Pre-treatment with 3-MA or Atg 5 siRNA suppressed the cytotoxic effect of AG-4 implying the pro-death role of autophagy. Furthermore, incubation with Z-VAD-fmk or Bax siRNA subdued AG-4 induced autophagy and pre-treatment with 3-MA or Atg 5 siRNA curbed AG-4 induced apoptosis - implying that apoptosis and autophagy act as partners in the context of AG-4 mediated action. AG-4 also inhibited PI3K/Akt/mTOR pathway. Inhibition of mTOR (by rapamycin or mTOR siRNA) or Akt (by LY294002 or Akt siRNA) augmented AG-4 induced apoptosis and autophagy signifying its role in apoptosis-autophagy crosstalk. Thus, these findings provide new perspective of AG-4 as potential molecule targeting programmed cell death for future cancer therapeutics. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A19. Citation Format: Deepak Kumar, Rajneeta Roy, Chinmay Chowdhury, Mitali Chatterjee, Padma Das. Andrographolide analogue induces crosstalk between apoptosis and autophagy via inhibition of PI3K/Akt/mTOR pathway in human leukemic cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A19.

Abstract B23: Apoptotic and autophagic effects of Sesbania grandiflora flowers in human leukemic cells.

Background: Identification of cytotoxic compounds that induce apoptosis has been the mainstay of anticancer therapeutics for several decades. In recent years, focus has shifted to inducing multiple modes of cell death coupled with reduced systemic toxicity. The plant Sesbania grandiflora is widely used in Indian traditional medicine for the treatment of a broad spectrum of diseases. This encouraged us to investigate into the anti-proliferative effect of a fraction (F2) isolated from S. grandiflora flowers in cancer cells and delineate the underlying involvement of apoptotic and autophagic pathways. Principal Findings: Using MTT based cell viability assay, we evaluated the cytotoxic potential of fraction F2. It was the most effective on U937 cells (IC50: 18.6 µg/ml). Inhibition of growth involved enhancement of Annexin V positivity. This was associated with elevated reactive oxygen species generation, measured by flow cytometry and reduced oxygen consumption– both effects being abrogated by antioxidant NAC. This caused stimulation of pro-apoptotic proteins and concomitant inhibition of anti-apoptotic protein expressions inducing mitochondrial depolarization, as measured by flow cytometry and release of cytochrome c. Interestingly, even with these molecular features of apoptosis, F2 was able to alter Atg protein levels and induce LC3 processing. This was accompanied by formation of autophagic vacuoles as revealed by fluorescence and transmission electron microscopy– confirming the occurrence of autophagy. Eventually, F2 triggered caspase cascade– executioners of programmed cell death and AIF translocation to nuclei. This culminated in cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by staining with Hoechst 33258 leading to cell death. Conclusions: The findings suggest fraction F2 triggers pro-oxidant activity and mediates its cytotoxicity in leukemic cells via apoptosis and autophagy. Thus, it merits consideration and further investigation as a therapeutic option for the treatment of leukemia. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B23. Citation Format: Rajneeta Roy, Deepak Kumar, Chinmay Chowdhury, Padma Das. Apoptotic and autophagic effects of Sesbania grandiflora flowers in human leukemic cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B23.