Research

15 pages, 3609 KiB

Open AccessArticle

Purification and Characterization of a Novel Alginate Lyase from a Marine Streptomyces Species Isolated from Seaweed

by Thi Nhu Thuong Nguyen, Timothy Chataway, Ricardo Araujo, Munish Puri and Christopher Milton Mathew Franco

Mar. Drugs 2021, 19(11), 590; https://doi.org/10.3390/md19110590 - 20 Oct 2021

Cited by 10 | Viewed by 2621

Abstract

Alginate, a natural polysaccharide derived from brown seaweed, is finding multiple applications in biomedicine via its transformation through chemical, physical, and, increasingly, enzymatic processes. In this study a novel alginate lyase, AlyDS44, was purified and characterized from a marine actinobacterium, Streptomyces luridiscabiei, [...] Read more.

Alginate, a natural polysaccharide derived from brown seaweed, is finding multiple applications in biomedicine via its transformation through chemical, physical, and, increasingly, enzymatic processes. In this study a novel alginate lyase, AlyDS44, was purified and characterized from a marine actinobacterium, Streptomyces luridiscabiei, which was isolated from decomposing seaweed. The purified enzyme had a specific activity of 108.6 U/mg, with a molecular weight of 28.6 kDa, and was composed of 260 amino acid residues. AlyDS44 is a bifunctional alginate lyase, active on both polyguluronate and polymannuronate, though it preferentially degrades polyguluronate. The optimal pH of this enzyme is 8.5 and the optimal temperature is 45 °C. It is a salt-tolerant alginate lyase with an optimal activity at 0.6 M NaCl. Metal ions Mn²⁺, Co²⁺, and Fe²⁺ increased the alginate degrading activity, but it was inhibited in the presence of Zn²⁺ and Cu²⁺. The highly conserved regions of its amino acid sequences indicated that AlyDS44 belongs to the polysaccharide lyase family 7. The main breakdown products of the enzyme on alginate were disaccharides, trisaccharides, and tetrasaccharides, which demonstrated that this enzyme acted as an endo-type alginate lyase. AlyDS44 is a novel enzyme, with the potential for efficient production of alginate oligosaccharides with low degrees of polymerization. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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18 pages, 3497 KiB

Open AccessFeature PaperArticle

Enzyme-Assisted Fucoidan Extraction from Brown Macroalgae Fucus distichus subsp. evanescens and Saccharina latissima

by Thuan Thi Nguyen, Maria Dalgaard Mikkelsen, Vy Ha Nguyen Tran, Vo Thi Dieu Trang, Nanna Rhein-Knudsen, Jesper Holck, Anton B. Rasin, Hang Thi Thuy Cao, Tran Thi Thanh Van and Anne S. Meyer

Mar. Drugs 2020, 18(6), 296; https://doi.org/10.3390/md18060296 - 02 Jun 2020

Cited by 69 | Viewed by 5636

Abstract

Fucoidans from brown macroalgae (brown seaweeds) have different structures and many interesting bioactivities. Fucoidans are classically extracted from brown seaweeds by hot acidic extraction. Here, we report a new targeted enzyme-assisted methodology for fucoidan extraction from brown seaweeds. This enzyme-assisted extraction protocol involves [...] Read more.

Fucoidans from brown macroalgae (brown seaweeds) have different structures and many interesting bioactivities. Fucoidans are classically extracted from brown seaweeds by hot acidic extraction. Here, we report a new targeted enzyme-assisted methodology for fucoidan extraction from brown seaweeds. This enzyme-assisted extraction protocol involves a one-step combined use of a commercial cellulase preparation (Cellic^®CTec2) and an alginate lyase from Sphingomonas sp. (SALy), reaction at pH 6.0, 40 °C, removal of non-fucoidan polysaccharides by Ca²⁺ precipitation, and ethanol-precipitation of crude fucoidan. The workability of this method is demonstrated for fucoidan extraction from Fucus distichus subsp. evanescens (basionym Fucus evanescens) and Saccharina latissima as compared with mild acidic extraction. The crude fucoidans resulting directly from the enzyme-assisted method contained considerable amounts of low molecular weight alginate, but this residual alginate was effectively removed by an additional ion-exchange chromatographic step to yield pure fucoidans (as confirmed by ¹H NMR). The fucoidan yields that were obtained by the enzymatic method were comparable to the chemically extracted yields for both F. evanescens and S. latissima, but the molecular sizes of the fucoidans were significantly larger with enzyme-assisted extraction. The molecular weight distribution of the fucoidan fractions was 400 to 800 kDa for F. evanescens and 300 to 800 kDa for S. latissima, whereas the molecular weights of the corresponding chemically extracted fucoidans from these seaweeds were 10–100 kDa and 50–100 kDa, respectively. Enzyme-assisted extraction represents a new gentle strategy for fucoidan extraction and it provides new opportunities for obtaining high yields of native fucoidan structures from brown macroalgae. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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19 pages, 4852 KiB

Open AccessArticle

Purification and Characterization of a Novel Endolytic Alginate Lyase from Microbulbifer sp. SH-1 and Its Agricultural Application

by Jin Yang, Dandan Cui, Diwen Chen, Wenkang Chen, Shuo Ma and Hong Shen

Mar. Drugs 2020, 18(4), 184; https://doi.org/10.3390/md18040184 - 31 Mar 2020

Cited by 22 | Viewed by 2990

Abstract

Alginate, an important acidic polysaccharide in marine multicellular algae, has attracted attention as a promising biomass resource for the production of medical and agricultural chemicals. Alginate lyase is critical for saccharification and utilization of alginate. Discovering appropriate and efficient enzymes for depolymerizing alginate [...] Read more.

Alginate, an important acidic polysaccharide in marine multicellular algae, has attracted attention as a promising biomass resource for the production of medical and agricultural chemicals. Alginate lyase is critical for saccharification and utilization of alginate. Discovering appropriate and efficient enzymes for depolymerizing alginate into fermentable fractions plays a vital role in alginate commercial exploitation. Herein, a unique alginate lyase, AlgSH7, belonging to polysaccharide lyase 7 family is purified and characterized from an alginate-utilizing bacterium Microbulbifer sp. SH-1. The purified AlgSH7 shows a specific activity of 12,908.26 U/mg, and its molecular weight is approximately 66.4 kDa. The optimal temperature and pH of AlgSH7 are 40 °C and pH 9.0, respectively. The enzyme exhibits stability at temperatures below 30 °C and within an extensive pH range of 5.0–9.0. Metal ions including Na⁺, K⁺, Al³⁺, and Fe³⁺ considerably enhance the activity of the enzyme. AlgSH7 displays a preference for poly-mannuronic acid (polyM) and a very low activity towards poly-guluronic acid (polyG). TLC and ESI-MS analysis indicated that the enzymatic hydrolysates mainly include disaccharides, trisaccharides, and tetrasaccharides. Noteworthy, the alginate oligosaccharides (AOS) prepared by AlgSH7 have an eliciting activity against chilling stress in Chinese flowering cabbage (Brassica parachinensis L.). These results suggest that AlgSH7 has a great potential to design an effective process for the production of alginate oligomers for agricultural applications. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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10 pages, 2313 KiB

Open AccessArticle

Clavukoellians G–K, New Nardosinane and Aristolane Sesquiterpenoids with Angiogenesis Promoting Activity from the Marine Soft Coral Lemnalia sp.

by Qi Wang, Xuli Tang, Hui Liu, Xiangchao Luo, Ping Jyun Sung, Pinglin Li and Guoqiang Li

Mar. Drugs 2020, 18(3), 171; https://doi.org/10.3390/md18030171 - 20 Mar 2020

Cited by 11 | Viewed by 2855

Abstract

The chemical examination of the marine soft coral Lemnalia sp., collected at the Xisha islands in the South China Sea, resulted in the isolation of four new nardosinane-type sesquiterpenoids, namely clavukoellians G–J (1–4), and one new aristolane sesquiterpene, namely [...] Read more.

The chemical examination of the marine soft coral Lemnalia sp., collected at the Xisha islands in the South China Sea, resulted in the isolation of four new nardosinane-type sesquiterpenoids, namely clavukoellians G–J (1–4), and one new aristolane sesquiterpene, namely clavukoellian K (5), together with five known compounds, 6–10. The structure elucidation of the isolated natural products was based on various spectroscopic techniques including HRESIMS and NMR, while their absolute configurations were resolved on the basis of comparisons of the ECD spectra with the calculated ECD data. The isolated new compounds 1–5 were evaluated for their anti- and pro- angiogenesis activities in a transgenic fluorescent zebrafish (Tg(vegfr2:GFP)) model. Quantitative analysis revealed that compound 5 displayed pro-angiogenesis activity in a PTK787-induced vascular injury zebrafish model at 2.5 μM. Data showed that compound 5 significantly promoted the angiogenesis in a dose-dependent manner. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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11 pages, 2177 KiB

Open AccessArticle

Extraction, Identification, Modification, and Antibacterial Activity of Histone from Immature Testis of Atlantic salmon

by Boyu Fu, Hong Lin, Tushar Ramesh Pavase, Nasha Mi and Jianxin Sui

Mar. Drugs 2020, 18(3), 133; https://doi.org/10.3390/md18030133 - 26 Feb 2020

Cited by 8 | Viewed by 2460

Abstract

In the present study, histone from immature testis of Atlantic salmon was extracted and identified, and its antibacterial activity after enzymolysis was investigated. Histone extracted from Atlantic salmon (Salmo salar) testis using the acid extraction method was successfully identified by LC-MS/MS, and [...] Read more.

In the present study, histone from immature testis of Atlantic salmon was extracted and identified, and its antibacterial activity after enzymolysis was investigated. Histone extracted from Atlantic salmon (Salmo salar) testis using the acid extraction method was successfully identified by LC-MS/MS, and revealed significant inhibitory activity on both the Gram-negative and Gram-positive bacteria. With a low concentration of 10 mg/mL, the observed inhibitory zone diameter (IZD) could significantly reach up to 15.23 mm. After modification of enzymatic hydrolysis by pepsin, histone could be digested to three fragments, while the antibacterial activity increased up to 57.7%. All the results suggested the leftovers from commercial fishing could be utilized for the extraction of antimicrobial peptides. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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10 pages, 1356 KiB

Open AccessArticle

One-Step Preparative Separation of Phytosterols from Edible Brown Seaweed Sargassum horneri by High-Speed Countercurrent Chromatography

by Menglu Xia, Chunping Liu, Lei Gao and Yanbin Lu

Mar. Drugs 2019, 17(12), 691; https://doi.org/10.3390/md17120691 - 09 Dec 2019

Cited by 12 | Viewed by 3443

Abstract

Sargassum horneri, a sargassaceae brown alga, is one of the main species in the subtidal seaweeds flora extensively distributed in the Yellow and East China Sea. It has been proven that the phytosterols are an important class of bioactive substances in S. [...] Read more.

Sargassum horneri, a sargassaceae brown alga, is one of the main species in the subtidal seaweeds flora extensively distributed in the Yellow and East China Sea. It has been proven that the phytosterols are an important class of bioactive substances in S. horneri. In this work, a counter-current chromatography approach is proposed for preparative separation of phytol and two analogue sterols from a crude extract of S. horneri. A two-phase solvent system composed of n-hexane-acetonitrile-methanol (5:5:6, v/v) was selected and optimized. The effects of rotary speed and flow rate on the retention of the stationary phase were carefully studied. Under the optimum conditions, phytol and two analogue sterols, fucosterol and saringosterol, were baseline separated, producing 19.8 mg phytol, 23.7 mg fucosterol, and 3.1 mg saringosterol from 300 mg of crude S. horneri extract in one-step separation. The purities of three target compounds were all above 85%. The structures of phytol and two sterols were identified by nuclear magnetic resonance spectroscopy. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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15 pages, 2863 KiB

Open AccessArticle

α-Glucosidase Inhibition and Molecular Docking Studies of Natural Brominated Metabolites from Marine Macro Brown Alga Dictyopteris hoytii

by Najeeb Ur Rehman, Kashif Rafiq, Ajmal Khan, Sobia Ahsan Halim, Liaqat Ali, Nadiya Al-Saady, Abdullah Hilal Al-Balushi, Haitham Khamis Al-Busaidi and Ahmed Al-Harrasi

Mar. Drugs 2019, 17(12), 666; https://doi.org/10.3390/md17120666 - 26 Nov 2019

Cited by 46 | Viewed by 3685

Abstract

Bioassay guided isolation of the methanolic extract of marine macro brown alga Dictyopteris hoytii afforded one new metabolite (ethyl methyl 2-bromobenzene 1,4-dioate, 1), one new natural metabolite (diethyl-2-bromobenzene 1,4-dioate, 2) along with six known metabolites (3–8) reported [...] Read more.

Bioassay guided isolation of the methanolic extract of marine macro brown alga Dictyopteris hoytii afforded one new metabolite (ethyl methyl 2-bromobenzene 1,4-dioate, 1), one new natural metabolite (diethyl-2-bromobenzene 1,4-dioate, 2) along with six known metabolites (3–8) reported for the first time from this source. The structure elucidation of all these compounds was achieved by extensive spectroscopic techniques including 1D (¹H and ¹³C) and 2D (NOESY, COSY, HMBC and HSQC) NMR and mass spectrometry and comparison of the spectral data of known compounds with those reported in literature. The in vitro α-glucosidase inhibition studies confirmed compound 7 to be the most active against α-glucosidase enzyme with IC₅₀ value of 30.5 ± 0.41 μM. Compounds 2 and 3 demonstrated good inhibition with IC₅₀ values of 234.2 ± 4.18 and 289.4 ± 4.91 μM, respectively, while compounds 1, 5, and 6 showed moderate to low inhibition. Furthermore, the molecular docking studies of the active compounds were performed to examine their mode of inhibition in the binding site of the α-glucosidase enzyme. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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20 pages, 1950 KiB

Open AccessArticle

Zebrafish-Based Discovery of Antiseizure Compounds from the North Sea: Isoquinoline Alkaloids TMC-120A and TMC-120B

by Daniëlle Copmans, Sara Kildgaard, Silas A. Rasmussen, Monika Ślęzak, Nina Dirkx, Michèle Partoens, Camila V. Esguerra, Alexander D. Crawford, Thomas O. Larsen and Peter A. M. de Witte

Mar. Drugs 2019, 17(11), 607; https://doi.org/10.3390/md17110607 - 25 Oct 2019

Cited by 18 | Viewed by 3804

Abstract

There is a high need for the development of new and improved antiseizure drugs (ASDs) to treat epilepsy. Despite the potential of marine natural products (MNPs), the EU marine biodiscovery consortium PharmaSea has made the only effort to date to perform ASD discovery [...] Read more.

There is a high need for the development of new and improved antiseizure drugs (ASDs) to treat epilepsy. Despite the potential of marine natural products (MNPs), the EU marine biodiscovery consortium PharmaSea has made the only effort to date to perform ASD discovery based on large-scale screening of MNPs. To this end, the embryonic zebrafish photomotor response assay and the larval zebrafish pentylenetetrazole (PTZ) model were used to screen MNP extracts for neuroactivity and antiseizure activity, respectively. Here we report the identification of the two known isoquinoline alkaloids TMC-120A and TMC-120B as novel antiseizure compounds, which were isolated by bioactivity-guided purification from the marine-derived fungus Aspergillus insuetus. TMC-120A and TMC-120B were observed to significantly lower PTZ-induced seizures and epileptiform brain activity in the larval zebrafish PTZ seizure model. In addition, their structural analogues TMC-120C, penicisochroman G, and ustusorane B were isolated and also significantly lowered PTZ-induced seizures. Finally, TMC-120A and TMC-120B were investigated in a mouse model of drug-resistant focal seizures. Compound treatment significantly shortened the seizure duration, thereby confirming their antiseizure activity. These data underscore the possibility to translate findings in zebrafish to mice in the field of epilepsy and the potential of the marine environment for ASD discovery. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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22 pages, 4535 KiB

Open AccessArticle

Identification and Characterization of a Novel Protein ASP-3 Purified from Arca subcrenata and Its Antitumor Mechanism

by Zhongyi Guo, Hui Shi, Chunlei Li, Yuanyuan Luo, Sixue Bi, Rongmin Yu, Haoran Wang, Wanying Liu, Jianhua Zhu, Weijuan Huang and Liyan Song

Mar. Drugs 2019, 17(9), 528; https://doi.org/10.3390/md17090528 - 09 Sep 2019

Cited by 6 | Viewed by 3203

Abstract

Diverse bioactive substances derived from marine organisms have been attracting growing attention. Besides small molecules and polypeptides, numerous studies have shown that marine proteins also exhibit antitumor activities. Small anticancer proteins can be expressed in vivo by viral vectors to exert local and [...] Read more.

Diverse bioactive substances derived from marine organisms have been attracting growing attention. Besides small molecules and polypeptides, numerous studies have shown that marine proteins also exhibit antitumor activities. Small anticancer proteins can be expressed in vivo by viral vectors to exert local and long-term anticancer effects. Herein, we purified and characterized a novel protein (ASP-3) with unique antitumor activity from Arca subcrenata Lischke. The ASP-3 contains 179 amino acids with a molecular weight of 20.6 kDa. The spectral characterization of ASP-3 was elucidated using Fourier Transform infrared spectroscopy (FTIR) and Circular Dichroism (CD) spectroscopy. Being identified as a sarcoplasmic calcium-binding protein, ASP-3 exhibited strong inhibitory effects on the proliferation of Human hepatocellular carcinoma (HepG2) cells with an IC₅₀ value of 171.18 ± 18.59 μg/mL, measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The RNA-seq analysis showed that ASP-3 regulated the vascular endothelial growth factor receptor (VEGFR) signaling pathway in HepG2 cells. Immunofluorescence results indicated that ASP-3 effectively reduced VEGFR2 phosphorylation in HepG2 cells and affected the downstream components of VEGF signaling pathways. The surface plasmon resonance (SPR) analysis further demonstrated that ASP-3 direct interacted with VEGFR2. More importantly, the therapeutic potential of ASP-3 as an anti-angiogenesis agent was further confirmed by an in vitro model using VEGF-induced tube formation assay of human umbilical vein endothelial cells (HUVECs), as well as an in vivo model using transgenic zebrafish model. Taken together, the ASP-3 provides a good framework for the development of even more potent anticancer proteins and provides important weapon for cancer treatment using novel approaches such as gene therapy. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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8 pages, 580 KiB

Open AccessCommunication

Bromophenolics from the Red Alga Polysiphonia decipiens

by James Lever, Grace Curtis, Robert Brkljača and Sylvia Urban

Mar. Drugs 2019, 17(9), 497; https://doi.org/10.3390/md17090497 - 26 Aug 2019

Cited by 9 | Viewed by 2785

Abstract

The isolation and the structure determination of a new bromophenolic compound, polysiphonol (10), as well as five previously reported compounds, (4–8), from the red alga Polysiphonia decipiens is reported. In addition, the absolute configuration of the natural [...] Read more.

The isolation and the structure determination of a new bromophenolic compound, polysiphonol (10), as well as five previously reported compounds, (4–8), from the red alga Polysiphonia decipiens is reported. In addition, the absolute configuration of the natural product rhodomelol (8) could be unequivocally confirmed for the first time, and on biosynthetic grounds, the absolute configuration of polysiphonol (10) was tentatively suggested. Compounds 4–8 were evaluated for their antibacterial activity against both Gram-positive and Gram-negative bacteria, but none of the compounds showed any appreciable activity. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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13 pages, 1694 KiB

Open AccessArticle

Purification, Characterization and Evaluation of Inhibitory Mechanism of ACE Inhibitory Peptides from Pearl Oyster (Pinctada fucata martensii) Meat Protein Hydrolysate

by Pengru Liu, Xiongdiao Lan, Muhammad Yaseen, Shanguang Wu, Xuezhen Feng, Liqin Zhou, Jianhua Sun, Anping Liao, Dankui Liao and Lixia Sun

Mar. Drugs 2019, 17(8), 463; https://doi.org/10.3390/md17080463 - 08 Aug 2019

Cited by 45 | Viewed by 4628

Abstract

Angiotensin-I-converting enzyme (ACE) inhibitory peptides derived from natural products have shown a blood pressure lowering effect with no side effects. In this study, two novel ACE inhibitory peptides (His-Leu-His-Thr, HLHT and Gly-Trp-Ala, GWA) were purified from pearl oyster (Pinctada fucata martensii) [...] Read more.

Angiotensin-I-converting enzyme (ACE) inhibitory peptides derived from natural products have shown a blood pressure lowering effect with no side effects. In this study, two novel ACE inhibitory peptides (His-Leu-His-Thr, HLHT and Gly-Trp-Ala, GWA) were purified from pearl oyster (Pinctada fucata martensii) meat protein hydrolysate with alkaline protease by ultrafiltration, polyethylene glycol methyl ether modified immobilized metal ion affinity medium, and reverse-phase high performance liquid chromatography. Both peptides exhibited high ACE inhibitory activity with IC₅₀ values of 458.06 ± 3.24 μM and 109.25 ± 1.45 μM, respectively. Based on the results of a Lineweaver-Burk plot, HLHT and GWA were found to be non-competitive inhibitor and competitive inhibitor respectively, which were confirmed by molecular docking. Furthermore, the pearl oyster meat protein hydrolysate exhibited an effective antihypertensive effect on SD rats. These results conclude that pearl oyster meat protein is a potential resource of ACE inhibitory peptides and the purified peptides, HLHT and GWA, can be exploited as functional food ingredients against hypertension. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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19 pages, 4335 KiB

Open AccessFeature PaperArticle

Identification of Antimicrobial Peptides from the Microalgae Tetraselmis suecica (Kylin) Butcher and Bactericidal Activity Improvement

by Fanny Guzmán, Genezareth Wong, Tanya Román, Constanza Cárdenas, Claudio Alvárez, Paulina Schmitt, Fernando Albericio and Verónica Rojas

Mar. Drugs 2019, 17(8), 453; https://doi.org/10.3390/md17080453 - 01 Aug 2019

Cited by 78 | Viewed by 7101

Abstract

The outburst of microbial resistance to antibiotics creates the need for new sources of active compounds for the treatment of pathogenic microorganisms. Marine microalgae are of particular interest in this context because they have developed tolerance and defense strategies to resist the exposure [...] Read more.

The outburst of microbial resistance to antibiotics creates the need for new sources of active compounds for the treatment of pathogenic microorganisms. Marine microalgae are of particular interest in this context because they have developed tolerance and defense strategies to resist the exposure to pathogenic bacteria, viruses, and fungi in the aquatic environment. Although antimicrobial activities have been reported for some microalgae, natural algal bioactive peptides have not been described yet. In this work, acid extracts from the microalga Tetraselmis suecica with antibacterial activity were analyzed, and de novo sequences of peptides were determined. Synthetic peptides and their alanine and lysine analogs allowed identifying key residues and increasing their antibacterial activity. Additionally, it was determined that the localization of positive charges within the peptide sequence influences the secondary structure with tendency to form an alpha helical structure. Full article

(This article belongs to the Special Issue Advancements in Purification, Isolation and Chemical Profiling to Expedite the Discovery of Marine Natural Products)

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