Lipid-lowering and LDL-oxidation inhibitory effects of aqueous extract of freshwater clam (Corbicula fluminea)--using tilapia as an animal model

Freshwater Clam Extract Attenuates Indomethacin-Induced Gastric Damage In Vitro and In Vivo

Contemporary pharmacological studies have reported that freshwater clam (Corbicula fluminea) can provide a broad spectrum of bioactivities, including antioxidant, anticancer, antihypertensive, hepatoprotective, and hypocholesterolemic effects. The aim of this study was to evaluate the gastroprotective effects of water extract of freshwater clam (WEC) on indomethacin (IND)-induced gastric mucosal cell damage in vitro and gastric ulcer in vivo. The cell viability of rat gastric mucosa RGM-1 cells was markedly decreased by 0.8 mM of IND treatment, and pre-treated with various concentration of WEC significantly restored IND-induced cell damage in a dose-dependent manner. WEC also significantly attenuated the elevated reactive oxygen species (ROS) levels, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, and nuclear factor-κB (NF-κB) p65 nuclear translocation induced by IND. In the in vivo study, IND caused severe gastric ulcer in Wistar rats, while WEC pretreatment effectively reduced the ulcer area and edema in the submucosa. We found that WEC significantly restored glutathione (GSH) content in gastric mucosa in a dose-dependent manner (p < 0.05). The reduction of prostaglandin E2 (PGE2) caused by IND was also improved with higher doses of WEC administration. Moreover, the overexpression of COX-2, iNOS, and tumor necrosis factor-α (TNF-α) proteins in gastric mucosa was downregulated by administration of WEC. Consequently, WEC can be used as a potential nutritional supplement to improve NSAIDs-caused gastric mucosal lesions.

A global synthesis of ecosystem services provided and disrupted by freshwater bivalve molluscs

Identification of ecosystem services, i.e. the contributions that ecosystems make to human well-being, has proven instrumental in galvanising public and political support for safeguarding biodiversity and its benefits to people. Here we synthesise the global evidence on ecosystem services provided and disrupted by freshwater bivalves, a heterogenous group of >1200 species, including some of the most threatened (in Unionida) and invasive (e.g. Dreissena polymorpha) taxa globally. Our systematic literature review resulted in a data set of 904 records from 69 countries relating to 24 classes of provisioning (N = 189), cultural (N = 491) and regulating (N = 224) services following the Common International Classification of Ecosystem Services (CICES). Prominent ecosystem services included (i) the provisioning of food, materials and medicinal products, (ii) knowledge acquisition (e.g. on water quality, past environments and historical societies), ornamental and other cultural contributions, and (iii) the filtration, sequestration, storage and/or transformation of biological and physico-chemical water properties. About 9% of records provided evidence for the disruption rather than provision of ecosystem services. Synergies and trade-offs of ecosystem services were observed. For instance, water filtration by freshwater bivalves can be beneficial for the cultural service 'biomonitoring', while negatively or positively affecting food consumption or human recreation. Our evidence base spanned a total of 91 genera and 191 species, dominated by Unionida (55% of records, 76% of species), Veneroida (21 and 9%, respectively; mainly Corbicula spp.) and Myoida (20 and 4%, respectively; mainly Dreissena spp.). About one third of records, predominantly from Europe and the Americas, related to species that were non-native to the country of study. The majority of records originated from Asia (35%), with available evidence for 23 CICES classes, as well as Europe (29%) and North America (23%), where research was largely focused on 'biomonitoring'. Whilst the earliest record (from 1949) originated from North America, since 2000, annual output of records has increased rapidly in Asia and Europe. Future research should focus on filling gaps in knowledge in lesser-studied regions, including Africa and South America, and should look to provide a quantitative valuation of the socio-economic costs and benefits of ecosystem services shaped by freshwater bivalves.

The Effects of Freshwater Clam (Corbicula fluminea) Extract on Activated Hepatic Stellate Cells

Background

The extract of freshwater clams has been used to protect the body against liver diseases in traditional folk medicine. This study aims at investigating the effects of freshwater clam extract on activated hepatic stellate cells (aHSCs), which are critical contributors to liver fibrosis.

Methods

The aHSCs used in this study were derived from hepatic stellate cells that were isolated and purified from the livers of male Wistar rats and then transformed into the activated phenotype by culturing on uncoated plastic dishes. Freshwater clam extract (CE) was collected after the outflow from the live freshwater clams in a water bath at 100°C for 60 min. The effects of CE on aHSCs were analyzed by MTT assay, flow cytometry, Oil Red O (ORO) staining, western blot, and real-time RT-PCR.

Results

The results indicated that CE suppressed the proliferation of aHSCs through G0/G1 cell cycle arrest by downregulating cyclin D1 and upregulating p27. The expression levels of a-SMA, collagen I, TGF-β, and TNF-α were inhibited in the CE-treated aHSCs. In addition, the CE treatment increased the lipid contents in aHSCs by promoting PPARγ expression. Furthermore, CE modulated the expression of ECM-related genes, i.e., by upregulating MMP-9 and downregulating TIMP-II.

Conclusions

These data revealed that CE could induce the deactivation of aHSCs. We therefore suggest that CE has potential as an adjuvant therapeutic agent against hepatic fibrosis.

Isolation and Characterization of Bioactive Proteoglycan-Lipid Nanoparticles from Freshwater Clam (Corbicula fluminea Muller) Soup

Nanoparticles can be prepared by several sophisticated processes but until now, it cannot be prepared by simple home cooking. Here, we report that two incidental food nanoparticles (iFNPs) consisting of proteoglycans and phytosterols were isolated from soup made from freshwater clam (Corbicula fluminea Muller), a renowned folk remedy for liver problems in China and other parts of East Asia. These two bioactive iFNPs were obtained and characterized by anionic exchange chromatography coupled with multi-angle laser light scattering measurement. Their hydrodynamic diameters and ζ-potentials were 50 ± 0.2 nm and -28.0 mV and 67 ± 0.4 nm and -9.96 mV, respectively. FT-IR revealed that the proteoglycans in the particles contained α-type heteropolysaccharides. Both iFNPs were resistant to pH changes and separation by mechanical force but responsive to temperature changes. They effectively inhibited cholesterol uptake in vitro, which resonates with the traditional belief that freshwater clam soup provides hepatoprotective benefits. This study suggests that these two proteoglycan-lipid iFNPs are the active moieties and offers a supramolecular structure-based approach to study the function of such complex matrices derived from food.

Bacteriostatic Effect of a Calcined Waste Clamshell-Activated Plastic Film for Food Packaging

The addition of calcined waste clamshells (CCS) into polyethylene (PE) plastic bags imparts antibacterial properties due to the presence of CaO. In this study, different proportions of calcined waste clamshells were added to PE to explore its bacteriostatic effects. The PE plastic bags with 9% and 11% of CCS exhibited antibacterial efficacy. Further, total aerobic viable count (TVC) values for raw fish fillet packaging in 9% and 11% CCS-PE plastic bags for five days were similar to the 0% CCS-PE plastic bag group after three days of incubation. In addition, the CCS-PE plastic bag demonstrated stability against solvents when examined using the metal migration test under heptane, ethanol, and acetic acid treatments. The results revealed that the CCS-PE bag retains its CaO bacteriostatic efficacy and that the addition of CCS powder to PE prolongs the shelf life of raw fish fillets, as well as mitigating safety concerns from metal leakage.

Blood biochemical parameters and melanomacrophage centers in Nile tilapia fed essential oils of clove basil and ginger

Nile tilapia (Oreochromis niloticus) is the most farmed freshwater fish in the world, however, disease outbreaks are the main cause of losses in production. Due to this, there is an increasing interest in natural products for enhancing disease resistance, without causing physiological impairment. The aim of this study was to verify the effect of the essential oils of clove basil (Ocimum gratissimum) and ginger (Zingiber officinale) on physiological and immunological parameters of nile tilapia. After 35 and 55 days of supplementation (0.5%, 1.0% and 1.5%), blood collection was performed for determination of metabolites (glucose, cholesterol, triglycerides, serum total protein and immunoglobulins) and lysozyme activity. Spleen tissue was also collected at 55 days for analyzing melanomacrophages centers. At 35 days, cholesterol showed significant reduction in the treatments 0.5% and 1.5 ginger and 1.5% clove basil. The serum triglycerides showed significant reduction in these same treatments, in addition to 1.0% clove basil. At 55 days all the supplemented groups showed significant reduction for both parameters. The lysozyme activity at 35 days was significantly higher in fish supplemented with 1.0% ginger and showed no difference among the treatments at 55 days. Regarding the melanomacrophage centers, at 35 days increased number in fish supplemented with 0.5% clove basil was observed but with no significant difference in the total percent area of spleen occupied by centers. The levels of glucose, total serum protein and immunoglobulins did not show significant differences in both sampling times. The addition of essential oils showed to be useful for improving physiological status of the fish, without excessive activation of defense mechanisms.

Hepatoprotective mechanism of freshwater clam extract alleviates non-alcoholic fatty liver disease: elucidated in vitro and in vivo models

In vitro and in vivo hepatoprotective model-verified freshwater clam extract alleviated NAFLD.

Effects of replacing soybean meal with rubber seed meal on growth, antioxidant capacity, non-specific immune response, and resistance to Aeromonas hydrophila in tilapia (Oreochromis niloticus × O. aureus)

This study evaluated the effects of replacing soybean meal (SBM) with rubber seed meal (RSM) on growth, antioxidant capacity, non-specific immune response and resistance to Aeromonas hydrophila in tilapia (Oreochromis niloticus × Oreochromis aureus). Five experimental diets were formulated with 0 (control), 10, 20, 30, and 40% RSM replacing graded levels of SBM, respectively. Fish were fed one of the five experimental diets for eight weeks, and then challenged by A. hydrophila via intraperitoneal injection and kept for seven days. Dietary RSM inclusion level up to 30% did not affect the weight gain and daily growth coefficient, whereas these were depressed by a further inclusion. Fish fed diet with 40% RSM showed the lowest serum total antioxidant capacity, lysozyme, alternative complement pathway, respiratory burst and phagocytic activities. Dietary RSM inclusion gradually depressed the post-challenge survival rate, and that was significantly lower in fish fed diet with 40% RSM compared to fish fed the control diet. Conversely, the inclusion of RSM generally increased the serum total cholesterol level, the plasma alanine aminotransferase and aspartate aminotransferase activities, and these were significantly higher in fish fed diet with 40% RSM compared to fish fed the control diet. The results indicated that RSM can be included at level up to 30% in diet for tilapia without obvious adverse effects on the growth, antioxidant capacity, non-specific immune response and resistance to A. hydrophila infection, whereas these were depressed by a further inclusion.

Freshwater Clam Extract Inhibits Inflammatory Responses in LPS-Activated Macrophages by Reducing the Activation of Mitogen-Activated Protein Kinases and NF-κB

Recent studies demonstrated that freshwater clam (Corbicula fluminea) has lipid-lowering and hepatoprotective activities, but its effect on immune responses has not yet been addressed. Here we showed that ethanol extracts of C. fluminea (ECF) reduced nitrite oxide, interleukin-1β, interleukin-6, and tumor necrosis factor-α in lipopolysaccharide-activated macrophages. Further, ECF was fractionated into n-hexane, ethyl acetate, ethanol, and water soluble fractions. Of these, the ethyl acetate soluble fraction (EACF) had the highest capacity to inhibit pro-inflammatory mediators expression. The underlying mechanisms for the anti-inflammatory activity of EACF were demonstrated as down-regulation of ERK1/2, JNK1/2, and p38 phosphorylation and NF-κB activity. Using gas chromatography-mass spectrometric analysis EACF was found to be composed mainly of fatty acids and steroids. Our results provide evidence that freshwater clam has anti-inflammatory activity, and support the possibility for the development of freshwater clam as a health supplement or adjuvant therapeutic agent for either preventing or treating inflammation related diseases.

Increased LDL susceptibility to oxidation accelerates future carotid artery atherosclerosis

BACKGROUND

We analyzed the causal relationship between LDL susceptibility to oxidation and the development of new carotid artery atherosclerosis over a period of 5 years. We previously described the determinants related to a risk of cardiovascular changes determined in a Japanese population participating in the Niigata Study, which is an ongoing epidemiological investigation of the prevention of cardiovascular diseases.

METHODS

We selected 394 individuals (169 males and 225 females) who underwent a second carotid artery ultrasonographic examination in 2001 - 2002 for the present study. The susceptibility of LDL to oxidation was determined as the photometric absorbance and electrophoretic mobility of samples that had been collected in 1996 - 1997. The measurements were compared with ultrasonographic findings obtained in 2001 - 2002.

RESULTS

The multivariate-adjusted model showed that age (odds ratio (OR), 1.034; 95% confidence interval (95%CI), 1.010 - 1.059), HbA1c (OR, 1.477; 95%CI, 0.980 - 2.225), and photometric O/N (OR, 2.012; 95%CI, 1.000 - 4.051) were significant variables that could independently predict the risk of new carotid artery atherosclerosis.

CONCLUSION

The susceptibility of LDL to oxidation was a significant parameter that could predict new carotid artery atherosclerosis over a 5-year period, and higher susceptibility was associated with a higher incidence of new carotid artery atherosclerosis.

Freshwater Clam Extract Decreased Hemorrhagic Shock–Induced Liver Injury by Attenuating TNF-α Production

Freshwater clam ( Corbicula fluminea), a popular edible shellfish in Asia, is said to have beneficial effects on liver function. However, scientific evidence for such benefit is limited. In this study, the authors aimed to assess the treatment effects of freshwater clam extract (FCE) administration after hemorrhagic shock (HS) in rats. The authors randomly divided animals into three groups. After inducing HS in rats in the HS + FCE ( n = 12) and HS groups, the authors fed 20 mg/kg FCE orally to rats in the HS group only. The authors neither induced HS in nor fed FCE to rats ( n = 8) in the vehicle group. The authors measured the blood levels of white blood cells (WBC), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and tumor necrosis factor-alpha (TNF-α) at several time points during the experiment. After 48 hr, the authors sacrificed the rats and harvested the livers for hematoxylin and eosin (HE) staining. The HS significantly decreased mean arterial pressure (MAP), increased blood AST, ALT, and LDH levels and induced liver injury in rats. Treatment with FCE increased MAP level and decreased AST, ALT, LDH, and TNF-α levels after hemorrhage. The HE staining showed diminished organ injury in the FCE-treated group. In conclusion, the administration of posttreatment FCE suppressed the release of pro-inflammatory TNF-α production after HS and decreased the levels of markers of liver injury associated with HS in rats. These beneficial effects suggest that FCE is a potential immunomodulator.