Search of new bioactive components and exploitation of their health promoting potentials as functional ingredients from brown seaweed Ecklonia cava and edible sea cucumber Holothuria edulis

Abstract

Functional foods, nutraceuticals, and dietary supplements are important for health promotion and disease risk reduction. Although a myriad of bioactive components are known to render the expected beneficial effects, the mechanisms involved are varied and may work individually or collectively in providing the effects. Hence, over the years, the biological activities of natural products could have gained a considerable research interest and studies about the extraction and isolation of active components from natural resources have attracted special attention in last recent years. It is well known that marine organisms are not only very important resources as food, feed, and energy rich source, but they are also rich sources of structurally novel and biologically active metabolites with valuable industrial potentials. Thus, efforts at discovery of novel active components from marine bioresources over the past years have yielded a considerable amount of new active metabolites which may not available in terrestrial environment. Therefore, marine derived active components, whose immense biochemically diversity looks like to become a rich source of novel chemical entities for the use as functional ingredients in many industrial applications such as functional foods, pharmaceuticals and nutraceuticals. This report deals with the antioxidant, anti-inflammatory and anticancer potentials of biologically active components from the brown seaweed Ecklonia cave and edible sea cucumber Holothuria edulis. The protective effect of bioactive components recovered from brown seaweed E. cava processing by-product on H2O2-mediated DNA damage in Vero cells was evaluated. E. cava processing by-product was fermented by edible yeast Candida utilis and its antioxidant activities were evaluated via radical scavenging using electron spin resonance (ESR) spectrometer. Effective fermentation duration was discovered as 24 h prior to being extracted with 80% EtOH. Major bioactive components in the extract were phlorotannins including triphlorethol-A, eckol, dieckol and eckstolonol. The phlorotannin rich fermented E. cava processing by-product extract (FEPBE) strongly enhanced the cell viability against H2O2-induced oxidative damage in Vero cells and exhibited good protective properties against H2O2-induced cell apoptosis as demonstrated by nuclear staining with Hoechst 33342 and flow cytometric analysis. The anti-inflammatory potential of the FEPBE was evaluated in vitro. The bioactive components recovered from E. cava processing by-product attenuate production of nitric oxide (NO) and prostaglandin-E2 (PGE2) by suppressing inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) protein expressions in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. The release of pro-inflammatory cytokines, interleukin-1β (IL-1β) and interleukin-6 (IL-6) was also significantly suppressed. Hence, it could be confirmed that the bioactive components responsible for the antioxidant and anti-inflammatory activity are still remaining in the E. cava processing by-product and can be recovered as a value-added bio-mass fraction after fermentation with C. utilis. In vitro anticancer and anti-inflammatory potentials of edible sea cucumber H. edulis were evaluated. The anticancer effect of aqueous fraction of edible sea cucumber H. edulis (ESC-AQ) on human leukemia HL-60 cells was assessed. ESC-AQ induced apoptosis in HL-60 cells as evidenced by the formation of apoptotic bodies and the accumulation of DNA in the sub-G1 phase of the cell cycle. The induced apoptosis was accompanied by down regulation of Bcl-xL, up regulation of Bax and activation of caspase-3. In this study, EtOAc solvent fraction of edible sea cucumber H. edulis (ESC-EA) modulated LPS- induced inflammatory responses in murine macrophages. ESC-EA significantly suppressed the NO production and PGE2 production by suppressing iNOS and COX-2 protein extrusions in LPS-induced RAW 264.7 macrophages. In addition, ESC-EA suppressed the release of pro-inflammatory cytokines TNF-α, IL-1β and IL-6. According to the results, it could be suggested that ESC-AQ and ESC-EA could be incorporated in food formulations as functional ingredients. Besides, they might be further developed as potential therapeutic agents in the particular applications.