Medicinal and health benefit effects of functional sea cucumbers
Journal of Traditional and Complementary Medicine
Volume 8, Issue 3, July 2018, Pages 341-351
Abstract Sea cucumbers have long been used as food and traditional medicine in Asian countries with Stichopus hermanni, Thelenota ananas, Thelenota anax, Holothuria fuccogilva, and Actinopyga mauritiana as most highly-valued species. These organisms are potential source of high value-added compounds with therapeutic properties such as triterpene glycosides, carotenoids, bioactive peptides, vitamins, minerals, fatty acids, collagens, gelatins, chondroitin sulfates, amino acids. In the recent years, health benefit effects of sea cucumbers have been validated through scientific research and have shown medicinal value such as wound healing, neuroprotective, antitumor, anticoagulant, antimicrobial, and antioxidant. These functional materials lead to potential development in various foods and biomedicine industries. In this review, we have presented a general view of major medicinal and health benefit effects of functional sea cucumbers from Asia region. The structural significance and the potential application of sea cucumber-derived functional materials as well as their nutritional value are also discussed.
The increasing number of scientific papers published in the last few decades correlating functional materials derived from natural resources and some chronic diseases has shown the extraordinary possibilities of functional foods and nutraceuticals as well as biomedicine products to support, or even to improve, our health beyond the provision of basic nutritional requirements.1, 2 As a consequence, consumer's interest in the relationship between health, diseases prevention, and well-being has grown substantially worldwide. The sources of functional foods, nutraceuticals and biomedicine products are exist in many reservoirs and may be found in terrestrial and marine environments. Terrestrial resources such as fruits, vegetables, cereals, probiotics, and mushrooms; however, is by far more explored than the marine resources.2 Even though the majority of those products in the marketplace are of terrestrial origin, marine organisms-based products are gaining attention due to their unique features, which are not found in terrestrial-based resources.3
Among marine organisms, sea cucumber is an interesting natural source of novel functional materials with biological activities that could be used in food as well as biomecicine industries. Sea cucumbers are soft bodied marine invertebrate from the class Holothuroidea. Sea cucumbers have a leathery skin and an elongated body containing a single branched gonad. These organisms constitute 1716 species, with the greatest biodiversity being in the Asia Pacific region. Sea cucumber is also known as “teripang or trepang” in Indonesian; “beche-de-mer”, a French term that means marine food product, and “balate” in Chamorro. Sea cucumbers are organisms that live in complex environments submitted to extreme conditions, therefore, they must adapt to the new environmental conditions to survive, and produce secondary biologically active metabolites which cannot be found in other organisms. According to the Ming dynasty report (1368–1644 BC), the sea cucumber harbored the same medicinal properties as the herb ginseng, therefore, it also called as “haishen” which means “ocean ginseng”.4Indonesia is well known as mega biodiversity country located in the center of Coral Triangle (the earth's storehouse of biological diversity), and also one of the largest sovereign nation in the worlds. It has been reported that Indonesia is the oldest and major sea cucumber exporter in the world.5Approximately, 350 sea cucumber species from Indonesian waters have been recorded with more than half were collected from the depth of more than 3000 m. Of the 350 sea cucumber species, at least 26 with economic value have been reported, these economic value sea cucumbers which bring benefits to fishers for centuries were called as trepan or teripang in Indonesia.6 Not only, Indonesia, Malaysia and Philippines are also an important exporter of the sea cucumber and their products.7 Globally, The Southeast Asia represents the global market hotspots for sea cucumbers trade due to their known mega biodiversity. Many of sea cucumber is gathered for human consumption and some are cultivated in aquaculture systems.
Hence, the objectives of this article are first to present the results obtained of a detailed bibliographical search about the composition of sea cucumbers from tropical regions especially Asia and secondly, to discuss their biological activities and possibilities as new sources of functional ingredients. The information provided on the various species of sea cucumbers does not refer in many cases to the same constituents since it has been taken from different research papers with different objectives. However, we believe the information provided can be useful to many research groups considering a huge interest in the search for nutritional and medicinal value of sea cucumbers.
2. Chemical composition of various sea cucumbers
Functional ingredients from sea cucumbers have become an increasingly interesting way to develop new foods as well as biomedicine products. Sea cucumbers are a source of high value-added compounds with health benefit effects to be used as functional ingredients. Bioactive peptides, vitamins, minerals, fatty acids, saponins, carotenoids, collagens, gelatins, chondroitin sulfates, amino acids, fatty acids and other bioactive compounds are example of such sea cucumber derived functional ingredients that can be added at different stages of the food and biomedisine production process.8 The sea cucumber species (Stichopus hermanni, Thelenota ananas, Thelenota anax, Holothuria fuscogilva, Holothuria leucospilota, Holothuria atra, Holothuria scabraand Actinopyga mauritiana) described in this article has been selected considering edible species, medicinal effects, and low toxicity. The aforementioned selected varieties are some of high-value sea cucumbers in Asia. Assuming that any new functional ingredient obtained from sea cucumbers could be used for further development of new products in food and pharmaceuticals industries. Another important factor is their nutritional value and potential as new sources of functional ingredients.
2.1. S. hermanni (local name in Indonesia: gamat emas, gamat kacang, taikongkong)
Sea cucumber S. hermanni (curryfish, golden sea cucumbers) belongs to the genus Stichopus; these species were formerly known as Stichopus variegatus. In Indonesia and Malaysia, sea cucumber S. hermanni (Fig. 1) has long been used for the preparation of traditional medicinal products like gamat water and gamat oil.9 These species are gaining much recognition among consumers, medical and biomedical researchers due to their potential health benefits. In Asian region communities, S. hermanni have been exploited for medicinal purposes; however such applications needs to be proven on a scientific basis using some clinical models.
As shown in Table 1, S. hermanni contains high amount of protein (47.00% ± 0.36%) and low percentage of lipid (0.80% ± 0.02%).
This sea cucumber contain significant amount of sulfated glycosaminoglycan. Glycosaminoglycan are long, unbranched polysaccharides composed of repeating disaccharide units consisting of alternating uronic acids (D-glucuronic acid or L-iduronic acid) and amino sugars (d-galactosamine or D-glucosamine) Glycosaminoglycan are divided into non-sulfated and sulfated glycosaminoglycan. Sulfated glycosaminoglycan extracted from S. hermannipossess various chemico-biological functions.10 Compared to other parts such as internal organs and coelomic fluid; integument body wall of S. hermanni contain highest glycosaminoglycan, both sulfated and non-sulfated. Further, sulfated glycosamioglican from integument has been demonstrated to accelerate wound healing process in rats.11 More than 60% of wound heal area in rats was observed after daily treatment with sulfated glycosaminoglycan (20 μL of 1 μg/mL) for 12 days. The healing activity of sulfated glycosaminoglycan was mediated through acceleration of wound contraction in wound healing phase I. In addition, 40% of Stichopus hermaniiextract were able increase the number of lymphocytes during the healing process of traumatic ulcer on Wistar rat's oral mucous.12 Most recently, Arundina et al. (2016) extracted S. hermanni from Kalimantan, Indonesia and demonstrated their growth stimulating effects in mesenchymal stem cells.13Mesenchymal stem cells are self-renewing cells that have the capacity to differentiate into adipocytes, chondrocytes, myocytes, and osteoblast. Following treatment with S. hermanni extract and osteogenic induction medium for 4 weeks, mesenchymal stem cells were differentiated into osteoblast. Collectively, it can be assumed that sea cucumber S. hermanni is able to accelerate wound healing process. Further, these sea cucumber species can be used to prepare lotion or a topical ointment for wound healing management.
Neuroprotection may defined as mechanisms and strategies used in order to protect neuronal cells against injury, apoptosis, dysfunction and or degeneration in the central nervous system (CNS).3 In the CNS, there are two classes of cells, including neuron, and glia (microglia, astrocytes and the related Schwann cells and oligodendrocytes). Astrocytes plays an important structures that provide housekeeping functions necessary to maintain neuronal function, actively shape synaptic function, and act as neural precursors in adult neurogenic regions. In addition, astrocytes also preserve the host integrity following injury. Recently, Patar et al. (2012) prepared water extract of S. hermanni from Malaysia and showed their growth promoting effect to promote proliferation of spinal astrocytes.14 In pathological cases like spinal cord injury, proliferating reactive astrocytes are proven essential for early regeneration process, provide neuroprotective effects and preserve motor function after acute injury. Further, it was demonstrated by GC-MS results that 37% of the total S. hermanni water extracts were comprised of amino acids (37%) followed by hydrocarbon (21%), ester compounds (16%), the orther remaining compounds consisted of phenols, alcohol groups and unidentified compounds. The 2-carbamoyl-3-methylquinoaxaline was found to be the most abundant compounds in S. hermanni extracts.15 Interestingly, quinoxaline derivatives has been reported to involved in reducing neurological deficits and glia loss after spinal cord injury. These, quinoxaline may contribute to the neuroprotective effects of S. hermanni.
Based on several findings it may conclude that S. hermanni are valuable source of functional materials and could be introduced for the preparation of novel functional ingredients in food and biomedicine as a good approach for the treatment and or prevention of many diseases. Furthermore, it can be suggested that S. hermanni is an alternative source to synthetic ingredients that can contribute in wound healing and neuroprotection. Until now, wound healing as well as neuroprotective activities of S. hermanni have been observed in vitro. Therefore, further research studies are needed in order to investigate S. hermanni biological activities in vivo as well as human subject.
2.2. T. ananas (local Indonesian name: teripang nanas) and T. anax(local Indonesian name: teripang babi, teripang donga, teripang duyung)
T. ananas and T. anax are two sea cucumber species belong to the Stichopodidae family which found in tropical waters. T. ananas (Fig. 2) are known as pineapple sea cucumber or prickly redfish. These species is considered as commercial sea cucumber species and one of the most popular edible sea cucumber species consumed in China and Southeast Asian countries.16 Due to intense commercially exploitation population, these sea cucumber species declined by 80–90% in at least 50% of its range and listed as endangered species by the International Union for Conservation of Nature. Medicinal value of T. ananas including antioxidant, antiinflammatory, antitumor, antiproliferative, anticoagulant and antiviral effects have been established.
Wu et al. (2010) have isolated novel fucosylated chondroitin sulfate (Fig. 3) from the body wall of the sea cucumber T. ananas, which consisted of N-acetylgalactosamine (GalNAc), glucuronic acid (GlcUA), fucose and ester sulfate with about 1:1:1:3.7, respectively.17, 18 Fucosylated chondroitin sulfate is a water-soluble depolymerized glycosaminoglycan isolated from echinoderm sea cucumber.19 Physicochemical of the fucose branch are differ according to the sea cucumber species. Anticoagulant activity of the fucosylated chondroitin sulfate from T. ananas as measured by the activated partial thromboplastin time assay varies in proportion to the molecular weight follows a logarithmic-like function.20 The molar ratio for types of fucose branch found in T. ananas is 25:22:53 for 3-monosulfate, 4-monosulfate and 2,4-disulfate, respectively. Fucose content and composition correlate with anticoagulant activities of fucosylated chondroitin sulfate; in addition to the composition. More recently, it was demonstrated that anticoagulant activity of fucosylated chondroitin sulfate from T. ananas was mediated by inhibition of intrinsic tenase.21 However, fucosylated chondroitin sulfate from sea cucumber T. ananas also activated factor XIIwhich further lead to hypotension when injected intravenously in rats. Interestingly, the activation of factor XII could be diminished by the low molecular weight fucosylated chondroitin sulfate; suggesting that molecular weight also plays an important role in anticoagulant effect of fucosylated chondroitin sulfate. Not only anticoagulant activity, low molecular weight fragment of fucosylated chondroitin sulfate from sea cucumber T. ananaswhich prepared by free radical depolymerization has been demonstrated to inhibit virus HIV replication.19 Fucosylated chondroitin sulfate was effective in blocking laboratory strain HIV-1IIIB entry and replication, and inhibiting infection by clinic isolate HIV-1KM018 and HIV-1TC-2. Fucosylated chondroitin sulfate might possess potential to be further developed as a novel HIV-1 entry inhibitor for treatment of HIV/AIDS patients, particularly for those infected by T-20-resistant variants. However, further study to elucidate fucosylated chondroitin sulfate structure and activity relationship will be required in the near future.
Fucoidan (Fig. 3) is sulfated polysaccharide found in brown algae and sea cucumbers. In sea cucumbers, it was first isolated from Ludwigothurea grisea. Recently, low molecular weight fucoidan which composed of a novel tetrafucose repeating units has been isolated from sea cucumber T. ananas by enzymatic degradation. Fucoidan from T. ananas was proven to possess a significant superoxide radical scavenging activity with an IC50 value of 17.46 ± 0.14 μg/mL.16 The radical scavenging effect of fucoidan on superoxide radicals improved along with the increasing sulfate content. However, additional 2-O-sulphation in a specific residue increase the radical scavenging effect; suggesting that antioxidant activity of fucoidan derived from T. ananas depends on the sulfation pattern not simply on sulfate content.
Triterpene glycosides or also referred as saponins are substances consisting of a sugar moiety attached to a triterpene or steroid aglycone. These substances are widely distributed in plants, marine invertebrates and are characteristic secondary metabolites of echinoderms, octocorals, and sponges Two triterpene glycosides (stichoposide C and stichoposide D) have been isolated from the T. ananas and T. anax.22 The structural differences between stichoposide C and stichoposide D are sugar residue; where stichoposide C has quinovose, and stichoposide D has glucose as the second monosaccharide unit. Stichoposide C showed potent anticancer activity in leukemia cells (HL-60) and mouse subcutaneous tumor cells (CT-26) by inducing apoptosis through the activation of both intrinsic and extrinxic pathway.23 Further, these compounds also showed antitumor activity in vivo which appears to be related to its membranotropic effects.24 Antifungal activity of stichoposide C from sea cucumber T. anax has also been reported.25 Guo et al (2016) has investigated antiobesity effect of triterpene glycosides-enriched extracts from 10 sea cucumbers (including T. ananas). Among them, T. ananas showed potent antiobesity effect through inhibition of pancreatic lipase activity.26
Nutritional value of T. ananas and T. anax (Fig. 4) were characterized by high protein with low lipid content (Table 1). Eicosapentaenoic acid (EPA, C20: 5n-3) was the primary n-3 polyunsaturated fatty acids (PUFA) in T. ananas(3.92%) and T. anax (3.10%); however, docosahexaenoic acid (DHA, C22: 6n-3) was not detected in both species.25 EPA is the major n3-PUFA in sea cucumber. Consumption of EPA are associated with decreased risk of coronary heart disease, cancer and wound healing activity.27
2.3. H. fuscogilva (local Indonesian name: teripang susu)
The popular name for H. fuscogilva (Fig. 5) is white teatfish.5 H. fuscogilva is one of the most prized of the commercially sea cucumber species in the world.28 These species distributed throughout the Indo-Pacific and has a patchy distribution on reef slopes, seagrass, and lagoons at depth of 3–40 m. Due to their ease of capture, strong demand, improved fishing technologies; H. fuscogilva wild populations have been depleted by overfishing. In the recent years, stock enhancement and restocking of these species have been practiced successfully in Japan and Republic of Kiribati. For commercial purposes, once H. fuscogilva are caught, they usually are gutted, boiled and then dried. In China, H. fuscogilva are highly valued for their reputed effects as an aphrodisiac.
2.4. Holothuria atra (local Indonesian name: teripang susu)
H. atra (Fig. 6) is commonly referred as black sea cucumber or lollyfish. Recently, their importance as a source of novel bioactive substances is growing rapidly and researchers have revealed that H. atra originated compounds exhibit various biological activities. As an example, phosphate-buffered saline extract of H. atra from Malaysia, exhibited significant antimicrobial activity and inhibited the growth of gram-negative and gram-positive bacteria. Interestingly, extracts obtained from the inner part of H. atra, showed stronger antimicrobial action compared to outer part extracts.30 The higher antimicrobial activity of inner part may correlate to the presences of microorganisms which are taken in together with the food substances. Antifungal activity of H. atra from Indonesia has also been reported. The antifungal activity of the above sea cucumber has been determined in Candida albicans by agar well diffusion assays. H. atra extract were not cytotoxic togingiva-derived mesenchymal stem cell in the concentration of ≤ 0.5%; suggesting the extract safety and can be develop for further phase of clinical trial.31 The use of human cells could increase the correlation between safety studies and clinical trials, an important benefit since conventional animal models of toxicity are not always predictive of human responses. Extract of H. atra were also effective against the Malasseziafurfur fungus that causes tinea versicolor.32 More recently, antifungal activity of H. atra extracts against various fungal strains such as Trichoderma viride, Aspergillus niger, Aspergillus flavis, C. albicans and Penicillium chrysogenum has also been reported.33 Antifungal activity of H. atra has opened the potency of sea cucumber as antifungal agent and could become the novel alternative solution as oral therapy of candidiasis and others.
Fig. 6. Holothuria atra from Lembeh strait, Indonesia.
Dhinakaran and his colleagues studied pharmacological effect of H. atrafrom the Indian ocean.34 They demonstrated antiinflammatory,