Nagendra Sastry Yarla

Targeting arachidonic acid pathway by natural products for cancer prevention and therapy

Arachidonic acid (AA) pathway, a metabolic process, plays a key role in carcinogenesis. Hence, AA pathway metabolic enzymes phospholipase A2s (PLA2s), cyclooxygenases (COXs) and lipoxygenases (LOXs) and their metabolic products, such as prostaglandins and leukotrienes, have been considered novel preventive and therapeutic targets in cancer. Bioactive natural products are a good source for development of novel cancer preventive and therapeutic drugs, which have been widely used in clinical practice due to their safety profiles. AA pathway inhibitory natural products have been developed as chemopreventive and therapeutic agents against several cancers. Curcumin, resveratrol, apigenin, anthocyans, berberine, ellagic acid, eugenol, fisetin, ursolic acid, [6]-gingerol, guggulsteone, lycopene and genistein are well known cancer chemopreventive agents which act by targeting multiple pathways, including COX-2. Nordihydroguaiaretic acid and baicalein can be chemopreventive molecules against various cancers by inhibiting LOXs. Several PLA2s inhibitory natural products have been identified with chemopreventive and therapeutic potentials against various cancers. In this review, we critically discuss the possible utility of natural products as preventive and therapeutic agents against various oncologic diseases, including prostate, pancreatic, lung, skin, gastric, oral, blood, head and neck, colorectal, liver, cervical and breast cancers, by targeting AA pathway. Further, the current status of clinical studies evaluating AA pathway inhibitory natural products in cancer is reviewed. In addition, various emerging issues, including bioavailability, toxicity and explorability of combination therapy, for the development of AA pathway inhibitory natural products as chemopreventive and therapeutic agents against human malignancy are also discussed.

Neuroinflammation in Alzheimer's Disease: The Preventive and Therapeutic Potential of Polyphenolic Nutraceuticals

Brain inflammation, characterized by increased microglia and astrocyte activation, increases during aging and is a key feature of neurodegenerative diseases, such as Alzheimers disease (AD). In AD, neuronal death and synaptic impairment, induced by amyloid-β (Aβ) peptide, are at least in part mediated by microglia and astrocyte activation. Glial activation results in the sustained production of proinflammatory cytokines and reactive oxygen species, giving rise to a chronic inflammatory process. Astrocytes are the most abundant glial cells in the central nervous system and are involved in the neuroinflammation. Astrocytes can be activated by numerous factors, including free saturated fatty acids, pathogens, lipopolysaccharide, and oxidative stress. Activation of astrocytes produces inflammatory cytokines and the enzyme cyclooxygenase-2, enhancing the production of Aβ. Furthermore, the role of the receptor for advanced glycation end products/nuclear factor-κB (NF-κB) axis in neuroinflammation is in line with the nonenzymatic glycosylation theory of aging, suggesting a central role of the advanced glycation end products in the age-related cognitive and a possible role of nutraceuticals in the prevention of neuroinflammation and AD. However, modulation of P-glycoprotein, rather than antioxidant and anti-inflammatory effects, could be the major mechanism of polyphenolic compounds, including flavonoids. Curcumin, resvertrol, piperine, and other polyphenols have been explored as novel therapeutic and preventive agents for AD. The aim of this review is to critically analyze and discuss the mechanisms involved in neuroinflammation and the possible role of nutraceuticals in the prevention and therapy of AD by targeting neuroinflammation.

Synthesis of new secretory phospholipase A2-inhibitory indole containing isoxazole derivatives as anti-inflammatory and anticancer agents

Secretory phospholipase A2 (sPLA2) is an important enzyme that plays a key role in various inflammatory diseases including cancer and its inhibitors have been developed as preventive or therapeutic agents. In the present study, a series of new indole containing isoxazole derivatives (10a-10o) is synthesized and evaluated for their sPLA2 inhibitory activities. All compounds (10a-10o) showed significant sPLA2 inhibition activities both in vitro and in vivo studies which is substantiated in in silico studies. Among all the tested compounds, 10o showed potent sPLA2 inhibition activity, that is comparable or more to ursolic acid (positive control). Further studies demonstrated that 10o showed in vitro antiproliferative activity when tested against MCF-7 breast and DU145 prostate cancer cells. Furthermore, compounds 10a-10o obeyed lipinskys rule of 5 and suggesting druggable properties. The in vitro, in vivo and in silico results are encouraging and warrant pre-clinical studies to develop sPLA2-inhibitory compound 10o as novel therapeutic agent for various inflammatory disorders and several malignancies.

Phospholipase A2 Isoforms as Novel Targets for Prevention and Treatment of Inflammatory and Oncologic Diseases

Phospholipase A2s (PLA2s) are group of enzymes, which cleave phospholipids specifically at sn-2 position to liberate free fatty acid, mostly arachidonic acid (AA) and lysophospholipids (LPLs). Inhibition of PLA2 prevents the liberation of AA and LPLs. Hence, researchers have been considering PLA2s could be a better therapeutic target than the downstream enzymes cyclooxygense and lipoxygenase. Several isoforms of PLA2s exist; they are mainly divided into secretory PLA2s (sPLA2), cytosolic PLA2s (cPLA2), and calcium independent PLA2s (iPLA2), platelet activating factor- acyl hydrolase (PAF-AH), lysosomal PLA2 (LPLA2), adipose-specific PLA2 (Ad- PLA). Each isoform of PLA2s is different in its chemical structure and physiological functions. sPLA2s (Groups IIA, V and X) are well characterized as proinflammatory mediating enzymes but their role in cancer is controversial. Groups IVA, IVB and IVC cPLA2s are present in humans but only Group IVA cPLA2 plays key role in pathophysiology of various cancers and inflammation. The role of iPLA2 in inflammation and cancer is limited. Lipoprotein associated PLA2 (Group VIIA PLA2), a PAF-AH isoform, has key role in atherosclerosis. Several isoform specific PLA2 inhibitors have been developed and some of the PLA2s inhibitors are currently under clinical trials for various inflammatory and oncologic diseases. This review focuses on the recent experimental evidences to support the notion that PLA2s are causally implicated in the pathobiology of cancer and inflammatory related disorders and discuss the potential utility of isoform specific PLA2 inhibitors as preventive and/or therapeutic agents.

Phospholipase A2: A Potential Therapeutic Target in Inflammation and Cancer (In silico, In vitro, In vivo and Clinical Approach)

Phospholipase A2 (PLA2) (EC 3.1.1.4) is the initial enzyme of arachidonic acid cascade, has key role in inflammation and cancer. Hence, PLA2 inhibitors have wide medicinal importance. This short review focused on PLA2 structure, function and role in inflammation and cancer. Further we tried to collect PLA2 inhibitors from the previous literature and explained the possibility of their utility as anti-inflammatory and anticancer agents.

Evaluation of Anti-Inflammatory Properties of Isoorientin Isolated from Tubers of Pueraria tuberosa

Inflammation is the major causative factor of different diseases such as cardiovascular disease, diabetes, obesity, osteoporosis, rheumatoid arthritis, inflammatory bowel disease, and cancer. Anti-inflammatory drugs are often the first step of treatment in many of these diseases. The present study is aimed at evaluating the anti-inflammatory properties of isoorientin, a selective cyclooxygenase-2 (COX-2) inhibitor isolated from the tubers of Pueraria tuberosa, in vitro on mouse macrophage cell line (RAW 264.7) and in vivo on mouse paw edema and air pouch models of inflammation. Isoorientin reduced inflammation in RAW 264.7 cell line in vitro and carrageenan induced inflammatory animal model systems in vivo. Cellular infiltration into pouch tissue was reduced in isoorientin treated mice compared to carrageenan treated mice. Isoorientin treated RAW 264.7 cells and animals showed reduced expression of inflammatory proteins like COX-2, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), 5-lipoxygenase (5-LOX), and interleukin 1-β (IL-1-β) both in vitro and in vivo. The antioxidant enzyme levels of catalase and GST were markedly increased in isoorientin treated mice compared to carrageenan treated mice. These results suggest that isoorientin, a selective inhibitor of COX-2, not only exerts anti-inflammatory effects in LPS induced RAW cells and carrageenan induced inflammatory model systems but also exhibits potent antioxidant properties.

Evaluating the anticancer potential of ethanolic gall extract of Terminalia chebula (Gaertn.) Retz. (combretaceae)

Plants have been an important source for discovery of anticancer compounds. With the current decline in the number of new molecular entities from the pharmaceutical industry, novel anticancer agents are being sought from traditional medicines; therefore the anticancer efficacy of many plants that are used in traditional medicine is yet to be verified. The objective of the study was to evaluate the cytotoxic potential of ethanolic leaf gall extract of Terminalia chebula are evaluated against buffalo rat liver 3A, MCF-7 (Human mammary gland adenocarcinoma) and A-549 (Human lung cancer) cell lines. The cytotoxic effect of the ethanolic extract was evaluated by MTT assay. The extract was potent and effective in inducing cytotoxic effects in all the cell lines with an IC50value of 305.18 ± 1.7 μg/mL, 643.13 ± 4.2 μg/mL, and 208.16 ± 3.7 μg/mL, respectively. The extract was more effective against A549 cell lines when compared to others. The presences of phenolics, triterpenoids, and flavonoids were identified in the extract. The extract showed total phenolic and flavonoid content of 478 ± 2.2 mg of gallic acid equivalent/g d.w and 538 ± 1.4 mg of quercetin equivalent/g d.w, respectively. This higher content of total phenolics and flavonoids found in the ethanolic extract was directly associated to higher cytotoxicity activity. Conclusion: The ethanolic leaf gall extract of T. chebula showed effective cytotoxic activities; which might be attributed to the phenolics/flavonoids present in higher concentration. Future work will be interesting to know the chemical composition of the extract and also better understand the mechanism of action of the constituents present in the extract to develop it as drug for therapeutic application. SUMMARY The present investigation establishes the anticancer activities of T. chebula leaf gall extracts on BRL3A, MCF-.7, and A-.549 cells. Presumably, these activities could be attributed in part to the phenolics/flavanoids features of the extract that has been demonstrated to act as cytotoxic agents. The experimental evidence obtained in the laboratory model could provide a rationale for the traditional use of plant as a source of easily available effective anticancer agents to the people, particularly in developing countries.

Can Probiotics Cure Inflammatory Bowel Diseases

Gastrointestinal (GI) disorders, especially microbial dysbiosis play role in several GI ailments such as irritable bowel syndrome, colorectal cancer, inflammatory bowel diseases, and antibiotic-associated diarrhoea. Role of inflammatory bowel disease (IBD) is multifactorial as it involves loss of maintaining intestinal epithelial barrier integrity, increased release of pro-inflammatory molecules, and microbial dysbiosis in gut microflora. Some specific pathogens also play a key role in the IBD development. The origin and causation are still in unfathomable condition and the exact root cause is unknown. Recently probiotic studies have been gaining importance because of their positive responses in their IBD experimental results. According to joint Food and Agricultural Organisation/World Health Organisation working group, probiotics are defined as live microorganisms which when administered in adequate amount confer health benefit on the host. These live beneficial microorganisms are considered helpful in improving gut colonization and perseverance thereby improves prophylactic effect. In the direction of IBD research, a number of studies are needed to standardize its methodology and its applicability on human usage. The particular review presents an overview of gut microflora and its impact on host health, types of IBD and existing therapies to treat this disorder, mechanism of several probiotic actions, role of probiotics in IBD prevention with their supporting evidences.

Medicinal Plants as Protective Strategies Against Parkinson’s Disease

Parkinsons disease is a neurodegenerative disease caused by the loss of dopaminergic neurons in the substantia nigra pars compacta region. An important mechanism contributing to its development is oxidative stress, induced by the imbalance between the endogenous antioxidant defenses and free radicals production. Naturally occurring bioactive compounds exhibit high antioxidant capacity that may help reducing oxidative stress and even reverse the damage induced by ROS. Fruits are particularly rich in phytochemicals with antioxidant effect, and their properties against the development of neurodegenerative diseases are of great interest. This review discusses how the fruits bioactive compounds and synthetic analogs have been assessed for their ability to regulate molecular pathways involved in neuronal survival such as MAPK, Nrf2, and NF-κB, thus elucidating the possible therapeutic and neuroprotective actions of these compounds.

Design and synthesis of novel HDAC8 inhibitory 2,5-disubstituted-1,3,4-oxadiazoles containing glycine and alanine hybrids with anti cancer activity.

Oxadiazole is a heterocyclic compound containing an oxygen atom and two nitrogen atoms in a five-membered ring. Of the four oxadiazoles known, 1,3,4-oxadiazole has become an important structural motif for the development of new drugs and the compounds containing 1,3,4-oxadiazole cores have a broad spectrum of biological activity. Herein, we describe the design, synthesis and biological evaluation of a series of novel 2,5-disubstituted 1,3,4-oxadiazoles (10a-10j) as class I histone deacetylase (HDAC) inhibitors. The compounds were designed and evaluated for HDAC8 selectivity using in silico docking software (Glide) and the top 10 compounds with high dock score and obeying Lipinskis rule were synthesized organically. Further the biological HDAC inhibitory and selectivity assays and anti-proliferative assays were carried out. In in silico and in vitro studies, all compounds (10a-10j) showed significant HDAC inhibition and exhibited HDAC8 selectivity. Among all tested compounds, 10b showed substantial HDAC8 inhibitory activity and better anticancer activity which is comparable to the positive control, a FDA approved drug, vorinostat (SAHA). Structural activity relation is discussed with various substitutions in the benzene ring connected on 1,3,4-oxadizole and glycine/alanine. The study warranted further investigations to develop HDAC8-selective inhibitory molecule as a drug for neoplastic diseases. Novel 1,3,4-oxadizole substituted with glycine/alanine showed HDAC8 inhibition.