Eresha Mendis

Inhibition of inducible nitric oxide synthase and cyclooxygenase-2 in lipopolysaccharide-stimulated RAW264.7 cells by carboxybutyrylated glucosamine takes place via down-regulation of mitogen-activated protein kinase-mediated nuclear factor-κB signaling

Glucosamine (GlcN) has been reported to possess several biomedical properties, and currently a great deal of attention has been focused on improving the functional properties of GlcN for different applications. Therefore, this study was conducted to introduce a carboxybutyryl functional group to GlcN and to find out the inhibitory mechanism of a novel GlcN derivative, carboxybutyrylated GlcN (CGlcN), on the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase‐2 (COX‐2) in bacterial lipopolysaccharide (LPS)‐induced mouse macrophages (RAW264.7 cells). In the initial experiments, the production of NO and prostaglandin E2 (PGE2) was inhibited by CGlcN pretreatment and suggested the possibility of down‐regulating their respective genes, iNOS and COX‐2. Reverse transcription‐polymerase chain reaction and Western blot analysis revealed that CGlcN can affect both transcriptional and translational levels of iNOS and COX‐2 expression. The data from the nuclear factor‐κB (NF‐κB) promoter gene transfection experiment supported the idea that inhibition of iNOS and COX‐2 is caused by the down‐regulation of their transcription factor, NF‐κB. Following stimulation with LPS, p38 mitogen‐activated protein kinase (p38 MAPK) and c‐Jun N‐terminal kinase (JNK) present upstream of NF‐κB signaling were also inhibited by CGlcN treatment. However, the protein level of another MAPK, extracellular signal‐regulated kinase (ERK), remained unaffected. Moreover, following treatment with CGlcN, the protein expression of I‐κB kinase (IKK) clearly confirmed that its down‐regulation directly inhibited the degradation of IκB and release of NF‐κB. Therefore, it can be concluded that CGlcN is capable of inhibiting iNOS and COX‐2 expression in LPS‐induced RAW264.7 cells via attenuation of NF‐κB signaling by p38 MAPK and JNK, but not by ERK.

An in vitro cellular analysis of the radical scavenging efficacy of chitooligosaccharides.

Despite extensive study on biological activities of chitosan and chitooligosaccharides (COS), there is no experimental evidence available as to COS mediated inhibition of free radical damage in cellular oxidizing systems. In this study, radical scavenging efficacies of different molecular weight bearing COS were assessed and their intracellular radical scavenging effects were tested employing B16F1, murine melanoma cell line. The results exhibited appreciable suppression in occurrence of intracellular radical species in the presence of low molecular weight bearing COS (<1 kDa) confirming low molecular weight is important for observed activities in biological systems. However, DNA oxidation carried out in the presence of COS clearly exhibited that COS exert protective effect on oxidative damage of purified genomic DNA regardless of molecular weight. Low molecular weight bearing COS was observed to be successively participated in suppression of NF-kappaB gene promoter activity suggesting its capability to prevent oxidative stress related disease complications. Moreover, induction of intracellular glutathione (GSH) level in the presence of COS promoted the effectiveness of COS to act against cellular oxidative stress.

Present and Future Prospects of Seaweeds in Developing Functional Foods

There has been a combined effort among scientists to explore and utilize varying food sources to develop functional foods to cater the ever-increasing demand from the consumers, who seek health-promoting roles of dietary compounds. Considering the diversity of biochemicals in seaweeds that are capable of exerting bioactivities, a growing trend is developing across globe to employ seaweeds in functional food development. Proteins, peptides, amino acids, polysaccharides, phenolics, lipids, vitamins, and minerals in seaweeds and their functional properties provide insights into the success of potential functional food products that can be developed utilizing seaweeds. However, several factors need to be taken into consideration in designing seaweed-based functional foods to obtain the market success. This chapter elaborates on the prospects of seaweeds in developing seaweed-based functional food products.

The inhibitory mechanism of a novel cationic glucosamine derivative against MMP-2 and MMP-9 expressions.

A number of recent researches have demonstrated the therapeutic effects of glucosamine (Glc) in a range of human diseases including arthritis. For the first time, we identified that a novel Glc derivative having quaternized amino functionality (QAGlc) suppresses MMP-9 and MMP-2, gelatinases in HT1080, human fibrosarcoma cells at 40microg/ml, following stimulation with PMA. Reporter gene assay results revealed that, the mechanism of suppression involves decreased transcriptional activation of MMP-9 and MMP-2 via transcription factors NF-kappaB and AP-1. However based on western blot results, QAGlc did not attenuate the nuclear translocation of both NF-kappaB and AP-1. Apparently, phorbol myristate acetate (PMA) stimulated expressions of ERK, JNK and p38 were altered in the presence of potent tumour inducer, phorbol myristate acetate QAGlc, suggesting their suppression also contributes to QAGlc-mediated inhibition of MMP-9 and MMP-2. Moreover, the ability of QAGlc to inhibit gelatinases was confirmed by its ability to act against invasiveness of HT1080 cells through extracellular matrix components.

Suppression of cytokine production in lipopolysaccharide-stimulated mouse macrophages by novel cationic glucosamine derivative involves down-regulation of NF-κB and MAPK expressions

Exposure of macrophages to bacterial lipopolysaccharide (LPS) induces release of proinflammatory cytokines that play crucial roles in chronic inflammation. Glucosamine has reported to possess anti-inflammatory properties and currently is the oral supplement of choice for the management of inflammation related complications including osteoarthritis. In this study, quaternized amino glucosamine (QAGlc), a newly synthesized cationic glucosamine (Glc) derivative was found to inhibit LPS-stimulated production of IL-1beta, IL-6, TNF-alpha, and PGE(2) in RAW264.7, mouse macrophages more potently than its starting material Glc. Since production of cytokines is regulated mainly via activation of NF-kappaB and regulation of mitogen-activated protein kinases (MAPKs), we examined if QAGlc could be responsible for the suppression of NF-kappaB pathway and MAPKs. We used reporter gene assay and Western blotting to examine the effects of QAGlc on activation and translocation of NF-kappaB. Further, QAGlc-mediated inhibition of NF-kappaB was accompanied with a suppression of its translocation. Apparently, QAGlc was shown to attenuate LPS-induced activation of p38 MAPK and JNK in RAW264.7 cells suggesting that inhibition of MAPK-mediated LPS signaling also contribute to suppression of cytokine production following stimulation of macrophages with LPS.

Effect of spongin derived from Hymeniacidon sinapium on bone mineralization

Marine sponges have been known to provide a source of novel bone and cartilage replacements because of their secondary metabolites and specific skeleton structures. In particular, it has been reported that spongin as a component of fibrous skeleton, pseudokeratin, neurokeratin, horny protein, and collagen-like protein in sponges can be used in several biomedical applications including osteoarthritis (OA). However, the pharmacological mechanism of action of spongin remains obscure. In this study, it was investigated whether spongin derived from Hymeniacidon sinapium can promote bone mineralization of osteoblast-like MG-63 cells. Our present study provides the first evidence that spongin is effective in activating bone mineralization. Furthermore, spongin increased ALP activity, collagen synthesis, and osteocalcin secretion in addition to bone mineralization in osteoblastic cells in vitro. In addition, it was demonstrated that spongin exerted the inhibitory effect on production of inflammatory mediators such as TNF-alpha, IL-1beta, and PGE(2) in macrophage, RAW264.7 cells. These results suggest that the anti-inflammatory effect of spongin derived from Hymeniacidon sinapium can play a critical role in bone mineralization of osteoblast-like MG-63 cells.

Laurencia okamurai extract containing laurinterol induces apoptosis in melanoma cells.

Laurinterol is a marine sesquiterpene that has been known to have antimicrobial activity. The purpose of this study is to investigate the effect of Laurencia okamurai extract containing laurinterol (LOEL) on induction of apoptosis in melanoma cells (B16F1). Anticancer activity of LOEL against melanoma cells was shown in a dose-dependent manner by the 1-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. It was for the first time found that LOEL exhibited an excellent effect on the induction of apoptosis as determined by DNA fragmentation, terminal deoxynucleotidyl transferase-mediated dUTP in situ nick-end labeling assay, cell cycle analysis, and measurement of activities of several caspases in melanoma cells. It was also demonstrated that transcriptional activation of p53, a tumor suppressor gene, and activation of p21 promoter by LOEL were involved in the induction of apoptosis by reporter gene assay. In particular, western blot analysis confirmed that LOEL above 5 microg/mL significantly increased the expression level of phospho-p53, the active form. These results indicate that LOEL can induce apoptosis through a p53-dependent pathway in melanoma cells.

Biological, Physical, and Chemical Properties of Fish Oil and Industrial Applications

In the recent past, there has been an increasing demand for fish oil in the pharmaceutical industry, due to the findings of the health benefits provided by omega-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Fish oils are unique in the variety of fatty acids of which they are composed, and are an excellent source of the highly unsaturated C20 and C22 omega-3 fatty acids of medical interest. In the past, fish oil was mainly used as an important ingredient in aquaculture feeds and was also used in feeds for livestock, such as poultry and swine. Due to increasing awareness on the potential health beneficial roles of omega-3 fatty acids in humans, there has been an increasing interest in the use of fish oils for human consumption. The nutritional and physical properties of fish oil have made hardened fish oils an attractive constituent in the human diet. A wide range of food products containing fish oils have been launched over the past decade. The instability of EPA and DHA and the fishy odor have become major problems in incorporating long-chain omega-3 oils into food products. There is an established market for dietary supplements, as well as a developing market for food ingredients produced from fish oils and concentrates of fish oil. Increasing scientific evidence in the health beneficial roles of fish oil has led to a tremendous growth in its use in the pharmaceutical industry and it is expected to play a dominant role in the future.