Subhalakshmi Ghosh

Anti‐inflammatory and anticancer compounds isolated from Ventilago madraspatana Gaertn., Rubia cordifolia Linn. and Lantana camara Linn.

Objectives  The aim was to search for anti‐inflammatory and anticancer compounds from three medicinal plants, viz. Ventilago madraspatana Gaertn., Rubia cordifolia Linn. and Lantana camara Linn.

Diospyrin derivative, an anticancer quinonoid, regulates apoptosis at endoplasmic reticulum as well as mitochondria by modulating cytosolic calcium in human breast carcinoma cells

Diospyrin diethylether (D7), a bisnaphthoquinonoid derivative, exhibited an oxidative stress-dependent apoptosis in several human cancer cells and tumor models. The present study was aimed at evaluation of the increase in cytosolic calcium [Ca(2+)](c) leading to the apoptotic cell death triggered by D7 in MCF7 human breast carcinoma cells. A phosphotidylcholine-specific phospholipase C (PC-PLC) inhibitor, viz. U73122, and an antioxidant, viz. N-acetylcysteine, could significantly prevent the D7-induced rise in [Ca(2+)](c) and PC-PLC activity. Using an endoplasmic reticulum (ER)-Ca(2+) mobilizer (thapsigargin) and an ER-IP3R antagonist (heparin), results revealed ER as a major source of [Ca(2+)](c) which led to the activation of calpain and caspase12, and cleavage of fodrin. These effects including apoptosis were significantly inhibited by the pretreatment of Bapta-AM (a cell permeable Ca(2+)-specific chelator), or calpeptin (a calpain inhibitor). Furthermore, D7-induced [Ca(2+)](c) was found to alter mitochondrial membrane potential and induce cytochrome c release, which was inhibited by either Bapta-AM or ruthenium red (an inhibitor of mitochondrial Ca(2+) uniporter). Thus, these results provided a deeper insight into the D7-induced redox signaling which eventually integrated the calcium-dependent calpain/caspase12 activation and mitochondrial alterations to accentuate the induction of apoptotic cell death.

The prospective role of plant products in radiotherapy of cancer: a current overview.

Treatment of cancer often requires exposure to radiation, which has several limitations involving non-specific toxicity toward normal cells, reducing the efficacy of treatment. Efforts are going on to find chemical compounds which would effectively offer protection to the normal tissues after radiation exposure during radiotherapy of cancer. In this regard, plant-derived compounds might serve as “leads” to design ideal radioprotectors/radiosensitizers. This article reviews some of the recent findings on prospective medicinal plants, phytochemicals, and their analogs, based on both in vitro and in vivo tumor models especially focused with relevance to cancer radiotherapy. Also, pertinent discussion has been presented on the molecular mechanism of apoptotic death in relation to the oxidative stress in cancer cells induced by some of these plant samples and their active constituents.

Evaluation of a diospyrin derivative as antileishmanial agent and potential modulator of ornithine decarboxylase of Leishmania donovani

World health organization has called for academic research and development of new chemotherapeutic strategies to overcome the emerging resistance and side effects exhibited by the drugs currently used against leishmaniasis. Diospyrin, a bis-naphthoquinone isolated from Diospyros montana Roxb., and its semi-synthetic derivatives, were reported for inhibitory activity against protozoan parasites including Leishmania. Presently, we have investigated the antileishmanial effect of a di-epoxide derivative of diospyrin (D17), both in vitro and in vivo. Further, the safety profile of D17 was established by testing its toxicity against normal macrophage cells (IC₅₀∼20.7 μM), and also against normal BALB/c mice in vivo. The compound showed enhanced activity (IC₅₀∼7.2 μM) as compared to diospyrin (IC₅₀∼12.6 μM) against Leishmania donovani promastigotes. Again, D17 was tested on L. donovani BHU1216 isolated from a sodium stibogluconate-unresponsive patient, and exhibited selective inhibition of the intracellular amastigotes (IC₅₀∼0.18 μM). Also, treatment of infected BALB/c mice with D17 at 2mg/kg/day reduced the hepatic parasite load by about 38%. Subsequently, computational docking studies were undertaken on selected enzymes of trypanothione metabolism, viz. trypanothione reductase (TryR) and ornithine decarboxylase (ODC), followed by the enzyme kinetics, where D17 demonstrated non-competitive inhibition of the L. donovani ODC, but could not inhibit TryR.

Inhibitory effect of Nymphaea pubescens Willd. flower extract on carrageenan-induced inflammation and CCl4-induced hepatotoxicity in rats

Nymphaea pubescens Willd. is used as ingredient of ethnic diet and folk medicine in South-East Asia. The water (NPW), methanol (NPM) and chloroform (NPC) extracts of N. pubescens flowers were investigated for NO·, O₂·⁻ and DPPH radical scavenging and iron chelating activities in vitro. NPW was found to be the most potent free radical scavenger (EC₅₀<100 μg/mL) whereas NPC did not show EC₅₀ at 500 μg/mL. Therefore, NPW was selected for further studies on anti-inflammatory and hepatoprotective activities, using standard in vitro and in vivo models. NPW exhibited inhibition of nitrogen radical generation in LPS-activated macrophages (IC₅₀=75.5 μg/mL) through suppression of iNOS protein, with no associated toxicity in the cells. Further, 500 mg/kg of NPW reduced rat paw edema by ~50% after 6h of carrageenan administration. Hepatoprotective activity of NPW was also evaluated in vivo on CCl4-induced hepatotoxicity model in rats. NPW treatment (500 mg/kg/day for ten days) attenuated CCl4-induced increase in serum enzymes, viz. alanine and aspartate aminotransferases (ALT and AST) and bilirubin. Also, glutathione and superoxide dismutase (SOD)-levels were restored towards normalcy in the liver of CCl4-treated rats, indicating the hepatoprotective role of NPW, which was found to contain a fair amount of flavonoids, phenolics, and saponin constituents.

Polyphenolic Secondary Metabolites Synergize the Activity of Commercial Antibiotics against Clinical Isolates of β-Lactamase-producing Klebsiella pneumoniae.

Emergence of worldwide antimicrobial resistance prompted us to study the resistance modifying potential of plant‐derived dietary polyphenols, mainly caffeic acid, ellagic acid, epigallocatechin‐3‐gallate (EGCG) and quercetin. These compounds were studied in logical combination with clinically significant antibiotics (ciprofloxacin/gentamicin/tetracycline) against Klebsiella pneumoniae, after conducting phenotypic screening of a large number of clinical isolates and selecting the relevant strains possessing extended‐spectrum β‐lactamase (ESBL) and K. pneumoniae carbapenemase (KPC)‐type carbapenemase enzymes only. The study demonstrated that EGCG and caffeic acid could synergize the activity of tested antibiotics within a major population of β‐lactamase‐producing K. pneumoniae. In spectrofluorimetric assay, ~17‐fold greater ciprofloxacin accumulation was observed within K. pneumoniae cells pre‐treated with EGCG in comparison with the untreated control, indicating its ability to synergize ciprofloxacin to restrain active drug‐efflux. Further, electron micrograph of ESBL‐producing K. pneumoniae clearly demonstrated the prospective efficacy of EGCG towards biofilm degradation. Copyright

Nucleotide variability of protamine genes influencing bull sperm motility variables

Protamines (PRMs), important proteins of chromatin condensation in spermiogenesis, are promising candidate genes to explore markers of sperm motility. The coding and in-silico predicted promoter regions of these genes were investigated in 102 crossbred and 32 purebred cattle. Also, mRNA quantification was done to explore its possibility as diagnostic tool of infertility. The PCR-SSCP analysis indicated there were two band patterns only in fragment I of the PRM1 and fragment II of the PRM2 gene. The sequence analysis revealed A152G and G179A transitions in the PRM1 gene. Similarly, G35A, A49G and A64G transitions were identified in the PRM2 gene which resulted in altered amino acid sequences from arginine (R) to glutamine (Q), from arginine (R) to glycine (G) and from arginine (R) to glycine (G), respectively. This caused the reduction in molecular weight of PRM2 from 2157.66 to 1931.33 Da due to reduction in the number of basic amino acids. These altered properties of the PRM2 protein led to the reduction in Mass Motility (MM: P < 0.01), Initial Progressive Motility (IPM; P < 0.05) and Post Thaw Motility (PTM; P < 0.05) in crossbred bulls. The least squares analysis of variance indicated there was an effect of PRM2 haplotypes on MM (P = 0.0069), IPM (P = 0.0306) and PTM (P = 0.0500) in crossbred cattle and on PTM (P = 0.0408) in the overall cattle population. Based on the RT-qPCR analysis, however, there was not any significant variation of PRM1 and PRM2 gene expression among sperm of Vrindavani bulls with relatively lesser and greater sperm motility.

Phytochemicals With Antileishmanial Activity: Prospective Drug Targets

Abstract Protozoan parasites are among the most common causative agents of some of the major tropical diseases occurring in both humans and domestic animals, leading to enormous loss of life and productivity. Leishmaniases are classified as “neglected tropical diseases” with a huge global burden of vector-borne diseases caused by parasites belonging to the genus Leishmania . Typically manifested in visceral, cutaneous, and mucocutaneous forms, leishmaniasis is endemic in some regions of Asia, Africa, and South America. Visceral leishmaniasis (VL) is the most severe clinical appearance of this ailment, known as kala-azar in the Indian subcontinent. Characterized by its effect on the internal organs—particularly the liver, spleen, and bone marrow—VL is often associated with marked suppression of the hosts cell-mediated immune response, leading to severe morbidity, even mortality, if left untreated. The management of leishmaniasis depends solely on a limited range of drugs, since a vaccine to combat the disease is not available till date. Pentavalent antimonials are the oldest and foremost line of therapeutics, despite shortcomings like prolonged intravenous regimen, lack of efficacy, and side effects. The other alternatives like pentamidine and amphotericin B also suffer from the limitation of toxicity, while the liposomal formulation of the latter is too expensive. The situation is further aggravated due to the growing unresponsiveness of VL to the antimonials. Even miltefosine, the only oral formulation of an anticancer agent introduced for the treatment of kala-azar in India, has also indicated potential resistance, including concerns about the eventuality of teratogenicity. Thus, it is an ongoing challenge to discover new drugs for the treatment of leishmaniasis. Identification of a molecular target is an important step in drug development against any particular disease. It is expected that the plant kingdom would provide valuable “leads” that could be explored in order to design novel therapeutic agents specifically active against leishmania parasites. A glimpse of the recent findings on prospective compounds, their mechanism of action, and development of potent analogues based on the natural templates will be presented in this chapter.