Sea Hare Dolabella Auricularia Research Articles

Antibacterial activity of sea hare (Dolabella auricularia) egg string extracts against potentially pathogenic bacteria

Abstract. Liguez CGO, Tabugo SR. 2023. Antibacterial activity of sea hare (Dolabella auricularia) egg string extracts against potentially pathogenic bacteria. Biodiversitas 24: 6675-6683. Pharmaceutical industries now recognize the vast variety of ocean organisms, each possessing distinct biological characteristics. Sea hares, for example, are marine organisms that use bioactive chemicals to defend against predators, including their eggs. To explore the potential antibacterial properties of sea hare species (Dolabella auricularia) found in Pujada Bay, Philippines, egg strings were collected and extracted using hexane and methanol solvents. The antibacterial activity of each fraction was then determined through Minimum Inhibitory Concentration (MIC) testing against four potentially pathogenic bacteria, two gram-positive strains (Staphylococcus aureus, Bacillus subtilis) and two gram-negative strains (Escherichia coli, Pseudomonas aeruginosa). The broth microdilution method was employed to assess the antibacterial activity of Dolabella auricularia egg strings. The results revealed the MIC values for the four bacterial strains. The hexane extracts of both extract 1 and extract 2 exhibited a MIC of 0. 23 and 0.33 mg/mL and a MIC of 0.52 and 0.125 mg/mL against P. aeruginosa, respectively. The methanolic extracts (1 and 2) displayed a MIC of 1.46 and 2.83 mg/mL against E. coli and an even more potent MIC of 1.33 and 0.79 mg/mL against P. aeruginosa. In the case of B. subtilis, the hexane extracts (1 and 2) had a MIC of 1.5 and 0.54 mg/mL, while the methanolic extracts (1 and 2) exhibited a MIC of 1.17 mg/mL and 0.83 mg/mL. Lastly, against S. aureus, hexane extracts (1 and 2) suppressed the growth with a MIC of 0.77 mg/mL and 0.25 mg/mL, respectively, while both methanolic extracts (1 and 2) demonstrated a MIC of 3.33 mg/mL. These findings showcase the promising antibacterial activity of Dolabella auricularia egg string extracts and highlight their potential for further investigation and development in the pharmaceutical field.

Potential extracts of wedge sea hare (Dolabella auricularia) as immunostimulators in comet fish (Carassius auratus auratus) infected by Aeromonas hydrophila

Abstract. Nurhalisa N, Nur I, Suryani S. 2022. Potential extracts of wedge sea hare (Dolabella auricularia) as immunostimulators in comet fish (Carassius auratus auratus) infected by Aeromonas hydrophila. Biodiversitas 23: 1884-1893. Microencapsulation is an innovative method to protect the active compound of pharmaceutical material from environmental impacts or unwanted conditions. This study aims to determine the active compound content and appropriate concentration of wedge sea hare extract (Dolabella auricularia) using the microencapsulation method to treat Aeromonas hydrophila bacterial which infected in comet fish (Carassius auratus auratus). The treatment consisted of three concentrations of D. auricularia extract (6.3, 7 and 7.7 g/kg feed) and commercial feed as a positive control in triplicates. C. a. auratus fed with experimental diets twice a day (8.00 a.m and 4.00 p.m) for 30 days of culture period before being challenged with an injection of A. hydrophila. Blood profile, weight gain, survival and relative survival of C. a. auratus were observed before and after the challenge test. The characteristics and types of active compounds in the extract were observed qualitatively, as well as the morphology and particle size distribution of the microcapsules. The results showed that D. auricularia extract contained phenol, tannins, steroids, terpenoids, alkaloids, and saponins. The microcapsules in all treatments were a spherical shape. The average diameter was similar to all extract treatments. The addition of D. auricularia extract microcapsules in the feed produced significantly different results on the blood profile, weight gain and survival. The highest of total leukocytes, total erythrocytes, hematocrit and blood hemoglobin were obtained in addition to 7.7 g D. auricularia extract/kg of feed with respective values ??of 7.35±0.94×104 cell.mm-3, 2.83±0.03×106 cell.mm-3, 22.43±0.03% and 6.72±0.02 g.dL-1, respectively. The highest weight gain was found in fish-fed diets contained of 7.7 g of D. auricularia extract (3.37 g). The highest relative survival and survival were found in the treatment of 7 and 7.7 g extract/kg of feed, which was 100%. This study concluded that microencapsulated with D. auricularia extract at dose 7 g extract/kg of feed was the optimum dose for C. a. auratus infected with A. hydrophila.

Egg Strings of Dolabella auricularia: Its in vitro Antioxidants and Antibacterial Activities

This study aimed to evaluate the antioxidants concentration and antimicrobial activities of the different crude extracts of egg strings from sea hare (Dolabella auricularia) taken from Guangguang, Pujada Bay, Davao Oriental. The determination of phenolics using the Aluminum chloride colorimetric method yielded 0.01 – 0.17 mg gallic acid equivalent / gram. On the other hand, Folin-ciocalteau assay for the total flavonoids gave a range of 6.27 – 8.83 mg quercetin/ gram. Furthermore, the antibacterial activity assay using the agar disk diffusion method gave a promising zone of inhibition for ethyl acetate extract against Staphylococcus aureus and Escherichia coli (20 mm and 26.56 mm, respectively). The findings of this work may add to the overall value of the nutritional and medicinal potential of the egg strings from sea hare.

Short communication: Environment and morphometric of sea hare Dolabella auricularia from shrimp pond, Sorong, West Papua, Indonesia

Abstract. Sofian A, Suhermanto A, Saidin, Sayuti M, Novianto D, Widyasari F. 2021. Short communication: Environment and morphometric of sea hare Dolabella auricularia from shrimp pond, Sorong West Papua, Indonesia. Biodiversitas 22: xxxx. Dolabella auricularia is a herbivorous marine biota living on the shallow seabed, which is found mostly in Indo-Pacific waters. The purpose of this study was to analyze the environmental and morphometric characteristics of Dolabella auricularia which live in vaname shrimp pond, Sorong, West Papua, Indonesia. Samples were collected from April to June 2020. From the measurement of pond waters environmental conditions, the following data were obtained: temperatures ranging from 31.47 ± 1.08oC, salinity ranging from 31.91 ± 2.29 ppt, pH ranging from 8.02 ± 0.20, brightness 108.00 ± 45.63 cm, and Dissolved Oxygen (DO) ranging from 4.10 ± 0.22 mg/L. The morphometrics of D. auricularia consisted of R-Anterior resp distances with sizes ranging from 38.9 ± 17 mm, wet weight ranging from 170 ± 34 g total lengths ranging from 112 ± 57.83 mm, posterior diameters ranging from 71 ± 41 mm. D. auricularia was found in pond waters as a pest for shrimp culture. However, D. auricularia also has biomedical and economic potentials as raw materials for the pharmaceutical industry. So, further studies are needed for their development.

Investigation of Chemical Composition and Antibacterial Activity of Ink from Sea Hare Dolabella auricularia

This study was conducted to determine the chemical composition of ink from sea hare (Dolabella auricularia) of Pujada Bay, City of Mati, Davao Oriental. The proximate and mineral composition were determined by using the standard official methods of the Association of Official Analytical Chemists (AOAC). The presence of secondary metabolites was investigated by using different qualitative tests, namely Froth test (saponins), Libermann-Buchard (sterols), Bate-Smith and Metacalf (flavonoids), Dragendorff and Maeyer (alkaloids), Keller-kiliani (glycoside), ferric chloride (tannins) and Bortnträger (anthraquinones). Its antibacterial activity against Escherichia coli and Staphylococcus aureus was determined by using agar well diffusion method. The results for proximate analyses showed that ink contained 90.4 % moisture, 2.044 % ash, 5.324 % crude fat and 0.75 % protein. The mineral analyses were 0.25 % phosphorous, 578 µg/g potassium, 0.662 % sodium, 310.8 µg/g calcium, 664 µg/g magnesium, 2.146 µg/g iron and 1.898 µg/g zinc. Secondary metabolites screening revealed that ink contained saponins, steroids and flavonoids. Further, the ink extract showed weak antibacterial factor. This is the first study conducted on the ink of sea hare in Davao region and its preliminary results showed that it is a good source of primary and secondary metabolites. These findings can be added to the potential medicinal value of sea hare and a basis for further chemical studies that will hopefully lead to the discovery of compounds with pharmacological importance.

Microplastic abundance in the water, seagrass, and sea hare Dolabella auricularia in Pramuka Island, Seribu Islands, Jakarta Bay, Indonesia

This research focused on the amount of abundance of microplastics in the sea hare Dolabella auricularia as well as the seagrass fields along the southern coast of Pramuka Island. Sampling of 8 individuals of Dolabella auricularia along with seagrass Cymodocea rotundata leafblades was done at the southern coast of Pramuka Island, after which the samples were preserved and brought to a laboratorium in Depok for microplastic analysis. The sea hares’ digestive tracts were extracted and dissolved in strong nitric acid. A 1 cm2 portion of a seagrass leaf blade was cut for observation. Prepared samples were observed under a monocular microscope and further analysis was done. Microplastic fibers and film particles were found in highest abundance within the digestive tracts of each sample of Dolabella auricularia as well as on the seagrass surface where the sea hare obtains its algae from, with fragment particles found in much lower amounts. Overall, number of microplastics was found between 40.1 to 73.7 particles/g weight of sea hare digestive tract and the estimated amount of microplastic found at seagrass leafblade was 185 particles/cm2. Results provide evidence that microplastics in the ocean brought by water currents could adsorb on to algae through which it enters the food chain as it is consumed by marine biota.

Enrichment of bacteria and alginate lyase genes potentially involved in brown alga degradation in the gut of marine gastropods

Gut bacteria of phytophagous and omnivorous marine invertebrates often possess alginate lyases (ALGs), which are key enzymes for utilizing macroalgae as carbon neutral biomass. We hypothesized that the exclusive feeding of a target alga to marine invertebrates would shift the gut bacterial diversity suitable for degrading the algal components. To test this hypothesis, we reared sea hare (Dolabella auricularia) and sea snail (Batillus cornutus) for two to four weeks with exclusive feeding of a brown alga (Ecklonia cava). Pyrosequencing analysis of the gut bacterial 16S rRNA genes revealed shifts in the gut microbiota after rearing, mainly due to a decrease in the variety of bacterial members. Significant increases in six and four 16S rRNA gene phylotypes were observed in the reared sea hares and sea snails, respectively, and some of them were phylogenetically close to known alginate-degrading bacteria. Clone library analysis of PL7 family ALG genes using newly designed degenerate primer sets detected a total of 50 ALG gene phylotypes based on 90% amino acid identity. The number of ALG gene phylotypes increased in the reared sea hare but decreased in reared sea snail samples, and no phylotype was shared between them. Out of the 50 phylotypes, 15 were detected only after the feeding procedure. Thus, controlled feeding strategy may be valid and useful for the efficient screening of genes suitable for target alga fermentation.

Extracts from egg strings of sea hare (Dolabella auricularia): Yield, antioxidant activity, zoochemical profile, and toxicity

Extracts from egg strings of sea hare (Dolabella auricularia): Yield, antioxidant activity, zoochemical profile, and toxicity

Gathering Internal Organs of the Wedge Sea Hare (Dolabella auricularia): A Case on Mactan Island, Cebu, the Philippines

Gathering Internal Organs of the Wedge Sea Hare (Dolabella auricularia): A Case on Mactan Island, Cebu, the Philippines

<b>An account of the occurrence of Wedge Sea Hare <I>Dolabella auricularia</I> (Lightfoot, 1786) (Gastropoda: Aplysiidae) from Andaman Islands, India</b>

In the present article we provide a detailed account on the occurrence of Wedge Sea Hare Dolabella auricularia, from two different locations (Hut Bay and Burmanallah) of Andaman Islands. This species has been reported by Rao (2003) from Andamans but there is no specific location mentioned. First occurrence of this species was observed in Hut Bay coast of Little Andaman and after a three month interval a group of Wedge Sea Hares were again spotted from Burmanallah, South Andaman. In the present article we have given a detailed account on the occurrence and morphological features with field and laboratory pictures of D. auricularia and its biomedical importance based on literature.

40 海洋動物タツナミガイから得られた新規細胞毒性物質、ドラスタチンG、H、イソドラスタチンHの構造と合成研究(口頭発表の部)

40 海洋動物タツナミガイから得られた新規細胞毒性物質、ドラスタチンG、H、イソドラスタチンHの構造と合成研究(口頭発表の部)

Antineoplastic Agents. 603. Quinstatins: Exceptional Cancer Cell Growth Inhibitors.

Discovery of the exceptionally powerful anticancer drug dolastatin 10 (1), contained in the sea hare Dolabella auricularia, opened a new frontier needed for improving human cancer treatment. Subsequently, major advances have been achieved based on results of structurally modifying this unusual natural peptide while maintaining the remarkable anticancer activity necessary for preparation of successful monoclonal antibody drug conjugates (ADC). Among the first several hundred SAR products based on dolastatin 10 our group synthesized and termed auristatins was auristatin E (2a). An anticancer activity-equivalent, desmethylaurisatin E (2b), linked to a CD30 monoclonal antibody is the very successful anticancer drug Adcetris, now approved for use in 65 countries. In the present investigation, we discovered a new subset of auristatins designated quinstatins derived from dolastatin 10 by replacing the C-terminal Doe unit with a carefully designed quinoline, which led to low or subnanomolar levels of cancer cell growth inhibition required for construction of chemically unique ADC drugs. The synthesis of quinstatins 2-8 is presented along with their cancer cell line biological data.

Nutritional Quality of the Egg Mass Locally Known as “Lukot’ of the Wedge Seahare Dolabella auricularia (Lightfoot, 1786)

Abstract The egg mass of the wedge seahare Dolabella auricularia has been gathered as human food for quite a long time without knowing its nutritional composition. Thus, this study was conducted in order to determine some nutritional aspects of the egg mass as basis of its utilization as human food. Important composition of the egg mass that were determined were its proximate composition, mineral contents and amino acid profile. In terms of proximate composition, the egg mass has a moisture content of 91.10 percent, fat of 0.85 percent, protein of 2.85 percent, ash of 3.43 percent and 1.77 percent for carbohydrates. The mineral content such as: calcium, iron, potassium, sodium and zinc contain 1040 mg/kg, 25.3 mg/kg, 599 mg/kg, 9803 mg/kg and 41.6 mg/kg, respectively. The amino acid profile has six (6) essential amino acids such as: threonine, valine, isoleucine, leucine, phenylalanine and hstidine while it has nine (9) non-essential amino acid like: taurine, aspartic acid, serine, glutamic acid, glumatimine, glycine, alanine, tyrosine, proline. It has also eight (8) other amino acids components such as: Phospo-serine, urea, aromatic amino acid, citrulline, beta-alanine, gamma-aminobutyric acid, ammonia, ornithine. Results show that the egg mass of the wedge seahare contains some nutritional components that are very essential in maintaining a healthy and balanced life, thus making it as another food commodity from the marine environment.

“Partial Biochemical Characterization of Egg Masses of the Wedge Seahare Dolabella Auricularia (Lightfoot, 1786)”

Abstract Egg masses of the wedge sea hare Dolabella auricularia are gathered as human food in the Visayas region and other areas in the Philippines, but there have been no studies examining their appropriateness for human consumption. This study was conducted to characterize the biochemical components of the egg masses. Biochemical characterization was assessed through proximate composition analysis and an amino acid profile. The egg masses comprised 91.10 percent moisture, 3.43 percent ash, 2.85 percent crude protein, 1.77 percent carbohydrates, and 0.85 percent fats. The 23 amino acid included six (6) essential components, nine (9) non-essential components, and eight (8) others. The essential amino acids included leucine, valine, isoleucine, phenylalanine, threonine and histidine, while the non-essential amino acids included taurine, tyrosine, serine, glycine, aspartic acid, glutamic acid, alanine, glutamine and proline. The other components included phospho-serine, urea, aromatic amino acid, citrulline, beta-alanine, gamma-aminobutyric acid, ammonia and ornithine. The results show that egg masses contain amino acids that are important for human health, thus making it another food commodity from the ocean.

Synthetic study on dolastatin 16: concise and scalable synthesis of two unusual amino acid units

A convenient and scalable synthesis of two unusual amino acid units found in dolastatin 16, dolaphenvaline, and dolamethylleuine, is described. Dolastatin 16, which was first isolated from the sea hare Dolabella auricularia by Pettit, exhibits not only strong inhibition of growth for a variety of human cancer cell lines but also potent antifouling activity against the larvae of the barnacle Balanus amphitrite. The key element of the synthesis is an organocatalytic Mannich reaction to construct two contiguous stereocenters in the amino acid units with almost complete enantio- and diastereoselectivity.

位置選択的5-<i>exo</i>および6-<i>endo</i>環化を利用した海洋産含ハロゲントリテルペンポリエーテルの全合成と立体化学

Aurilol (1), intricatetraol (3), and enshuol (5), marine halogen-containing members of a family of squalene-derived triterpene polyethers named oxasqualenoids, were isolated from the sea hare Dolabella auricularia, the red alga Laurencia inricata, and omaezakiana Masuda, respectively. Although their planar structures and partial configurations were elucidated by spectroscopic and chemical analyses, until now their entire configurations had not been determined. Many other types of oxasqualenoids have also been isolated from both marine and terrestrial organisms; however, it is often difficult to determine their stereostructures even by modern highly advanced spectroscopic methods, especially in the case of acyclic systems that include stereogenic quaternary carbon centers. Such systems expose the technical limitations of the current highly advanced NMR spectroscopic methods used for the structural elucidation of diverse and complex natural products. Herein, we report the total assignments of the previously incomplete stereostructures of 1, 3, and 5 to 2, 4, and 6, respectively, through the first asymmetric total syntheses featuring regioselective 5-exo and 6-endo cyclizations of bishomoepoxy alcohols.

Antineoplastic agents. 592. Highly effective cancer cell growth inhibitory structural modifications of dolastatin 10.

The dolastatin series of unique peptides, originally discovered as constituents of the sea hare Dolabella auricularia, is of increasing importance in providing biological leads, especially to new and useful anticancer drugs. Dolastatin 10 and three analogues, minor structural modifications designated auristatins, are currently in human cancer clinical trials. The present study was undertaken to explore delivery to the cancer sites by way of phosphate or quinoline modifications. The initial objectives, auristatin TP as sodium phosphate 3b (GI50 10(-2)-10(-4) μg/mL), auristatin 2-AQ (4, GI50 10(-2)-10(-3) μg/mL), and auristatin 6-AQ (5, GI50 10(-4) μg/mL), exhibited superior cancer cell growth inhibitory properties.

ChemInform Abstract: Synthesis of Dolastatin I, a Cytotoxic Cyclic Hexapeptide from the Sea Hare Dolabella auricularia.

Abstract Dolastatin I, a cytotoxic cyclic hexapeptide isolated from the Japanese sea hare Dolabella auricularia , was enantioselectively synthesized, which confirmed its stereostructure.

In Hot Water: Global Warming Takes a Toll on Coral Reefs

In the summer of 2005, while Atlantic hurricanes battered coastlines from Cuba to Mexico, the Eastern Caribbean baked under a relentless sun with barely a breeze to cool the air. Tourists and locals alike wilted in the heat, and below the sea, marine life and corals in particular suffered as well. The windless calm settled in just as a buildup of unusually warm water began accumulating in the region. Ordinarily, easterly trade winds would have churned the sea, helping it to cool. But thanks to an unprecedented heat wave beginning in May—the result of a confluence of factors related to climate change, scientists say—water temperatures in the Eastern Caribbean climbed and stayed high for months, reaching levels that by September would be warmer than any recorded in 150 years. The heat disturbed a symbiotic partnership that coral animals normally maintain with a type of algae called zooxanthellae. Zooxanthellae supply corals with essential nutrients produced by photosynthesis, particularly carbon, in return for the shelter and access to sunlight provided by the reefs. The algae also impart color to the corals, which themselves are colorless. But as sea temperatures rose, the zooxanthellae disappeared, leaving their carbon-deprived hosts behind to starve. The reefs turned snow white, the color of the underlying stonelike structures they had built up over centuries, in a phenomenon known as coral bleaching. As the heat wave progressed, it left a trail of bleached reefs the likes of which had never been seen in the Caribbean. By year’s end, coral cover ranging from 90% in the Virgin Islands to 52% in the French West Indies was affected. Coral bleaching isn’t always fatal—if water temperatures cool in time, the zooxanthellae might return, allowing corals to recover. But in parts of the Eastern Caribbean, the reefs never got a chance. Almost as soon as their recovery started, they were attacked by diseases affecting a range of coral species down to 60 feet. By 2007, roughly 60% of the coral cover in the Virgin Islands and 53% in Puerto Rico’s La Parguera Natural Reserve was dead—an unprecedented tragedy. The Eastern Caribbean disease outbreak came on the heels of what’s been a rough several decades for coral reefs worldwide. Long suffering from land-based pollution, habitat destruction, and overfishing, coral reefs now must also contend with climate change, which has accelerated their global decline. This puts a wealth of biodiversity at risk. Reefs support up to 800 types of coral, 4,000 fish species, and countless invertebrates. Reef-dwelling species numbering in the hundreds of thousands may not even be catalogued yet, some scientists speculate. The implications of these declines could be as disastrous for human health as they are for marine life. Globally, reefs provide a quarter of the annual fish catch and food for about 1 billion people, according to the United Nations Environment Programme. Reefs protect shorelines from storm surges, which could become more powerful as sea levels rise with climate change. Tourism—a mainstay of coastal economies in the tropics, worth billions in annual revenue—could suffer if reefs lose their appeal. Reefs are also a long-standing source of medicines to treat human disease. Being attached to reefs, corals and other immobilized marine animals can’t escape predators, so they deploy a range of chemical compounds to deter hunters, fight disease, and thwart competing organisms. Two antiviral drugs (vidarabine and azidothymidine) and the anticancer agent cytarabine were developed using compounds extracted from Caribbean reef sponges. Another product called dolastatin 10, isolated from the sea hare (Dolabella auricularia) of the Indian Ocean, has been investigated as a treatment for breast and liver cancers and leukemia. Many more lifesaving medicines and useful chemical products could one day be derived from reef dwellers, experts say. Saving these ecosystems is imperative on a range of levels, says Caroline Rogers, a marine ecologist with the U.S. Geological Survey in St. John, U.S. Virgin Islands. “We have to save them for economic, ecological, aesthetic, and even spiritual reasons,” she says. “People need to feel connected with nature and with systems that are bigger than they are. Coral reefs are awe-inspiring—we’re losing something that we barely understand.”

Isolation and Structure Determination of Malevamide E, a Dolastatin 14 Analogue, from the Marine Cyanobacterium Symploca laete-viridis

A new depsipeptide, malevamide E (1), was isolated from field-collected colonies of the filamentous cyanobacterium Symploca laete-viridis. The gross structure of 1 was determined by spectroscopic analyses, including one- and two-dimensional NMR and accurately measured MS/MS. Chiral HPLC analyses of an acid hydrolysate of 1 allowed the stereochemical assignments of its amino acid residues, which include N-methyl-L-alanine, alpha-N,gamma-N-dimethyl-L-asparagine, N-methyl-L-phenylalanine, L-proline, D-valine, and N-methyl-L-valine. LC-MS/MS analysis of S. laete-viridis fractions established the co-occurrence of malevamide E (1) and its homologue dolastatin 14 (2), which was previously reported in low yield from the sea hare Dolabella auricularia. Malevamide E (1) demonstrated a dose-dependent (2-45 microM) inhibition of store-operated Ca(2+) entry in thapsigargin-treated human embryonic kidney (HEK) cells, indicating an inhibitory effect on Ca(2+) release-activated Ca(2+) (CRAC) channels.