Ectoin: an effective natural substance to prevent UVA-induced premature photoaging

Metabolic Engineering of Corynebacterium glutamicum for Highly Efficient Production of Ectoine

Ectoine is a compatible solute that functions as a cell protector from various stresses, protecting cells and stabilizing biomolecules, and is widely used in medicine, cosmetics, and biotechnology. Microbial fermentation has been widely used for the large-scale production of ectoine, and a number of fermentation strategies have been developed to increase the ectoine yield, reduce production costs, and simplify the production process. Here, Corynebacterium glutamicum was engineered for ectoine production by heterologous expression of the ectoine biosynthesis operon ectBAC gene from Halomonas elongata, and a series of genetic modifications were implemented. This included introducing the de3 gene from Escherichia coli BL21 (DE3) to express the T7 promoter, eliminating the lysine transporter protein lysE to limit lysine production, and performing a targeted mutation lysCS301Y on aspartate kinase to alleviate feedback inhibition of lysine. The new engineered strain Ect10 obtained an ectoine titer of 115.87 g/L in an optimized fed-batch fermentation, representing the highest ectoine production level in C. glutamicum and achieving the efficient production of ectoine in a low-salt environment.

Positive and ecobiological contribution in skin photoprotection of ectoine and mannitol combined in vivo with UV filters

BACKGROUND

Chronic exposure to ultraviolet (UV) irradiation causes immunosuppression, photoaging, and carcinogenesis by induction of a cascade of skin damages. Sunscreens currently on the market are not absorbing UV rays uniformly throughout the full UV range, high sun protection factor (SPF) sunscreens absorb most of UVB rays but are less effective in absorbing the UVA part of the spectrum. In the context, one approach could consist of preserving the skin natural resources and mechanisms, which is the foundation of the ecobiological approach, by combing UV filters and antioxidants to enhance their photoprotective effect.

METHODS

First, the photoprotection properties of ectoine and mannitol association were characterized by the quantification of glutathione, reactive oxygen species, and double-stranded DNA breaks and by the epidermal Langerhans cells functionality. Second, the protection of squalene oxidation, catalase activity, and trans-urocanic acid (UCA) by the ectoine and mannitol association combined or not with SPF30 UV filters was assessed in vivo via non-invasive skin samplings in 10 subjects on irradiated areas.

RESULTS

Using in vitro irradiated skin cell models, we demonstrated that this association significantly preserved intracellular glutathione levels, reduced DNA strand breaks induced by oxidative stress, and maintained Langerhans cell functionality. In vivo this association combined with UV filters presented significantly higher protection of three natural defense systems altered by UV compared to UV filters alone: squalene oxidation, catalase activity, and preservation of trans-UCA.

CONCLUSION

This study demonstrates the ecobiological potential of combining UV filters with biological protection to increase skin photoprotection provided by specific active ingredients with antioxidative and immunosuppressive properties.

Strategies for the biological production of ectoine by using different chassis strains

As an amino acid derivative and a typical compatible solute, ectoine can assist microorganisms in resisting high osmotic pressure. Own to its long-term moisturizing effects, ectoine shows extensive applications in cosmetics, medicine and other fields. With the rapid development of synthetic biology and fermentation engineering, many biological strategies have been developed to improve the ectoine production and simplify the production process. Currently, the microbial fermentation has been widely used for large scaling ectoine production. Accordingly, this review will introduce the metabolic pathway for ectoine synthesis and also comprehensively evaluate both wild-type and genetically modified strains for ectoine production. Furthermore, process parameters affecting the ectoine production efficiency and adoption of low cost substrates will be evaluated. Lastly, future prospects on the improvement of ectoine production will be proposed.

Pan-genome analysis of six Paracoccus type strain genomes reveal lifestyle traits

The genus Paracoccus capable of inhabiting a variety of different ecological niches both, marine and terrestrial, is globally distributed. In addition, Paracoccus is taxonomically, metabolically and regarding lifestyle highly diverse. Until now, little is known on how Paracoccus can adapt to such a range of different ecological niches and lifestyles. In the present study, the genus Paracoccus was phylogenomically analyzed (n = 160) and revisited, allowing species level classification of 16 so far unclassified Paracoccus sp. strains and detection of five misclassifications. Moreover, we performed pan-genome analysis of Paracoccus-type strains, isolated from a variety of ecological niches, including different soils, tidal flat sediment, host association such as the bluespotted cornetfish, Bugula plumosa, and the reef-building coral Stylophora pistillata to elucidate either i) the importance of lifestyle and adaptation potential, and ii) the role of the genomic equipment and niche adaptation potential. Six complete genomes were de novo hybrid assembled using a combination of short and long-read technologies. These Paracoccus genomes increase the number of completely closed high-quality genomes of type strains from 15 to 21. Pan-genome analysis revealed an open pan-genome composed of 13,819 genes with a minimal chromosomal core (8.84%) highlighting the genomic adaptation potential and the huge impact of extra-chromosomal elements. All genomes are shaped by the acquisition of various mobile genetic elements including genomic islands, prophages, transposases, and insertion sequences emphasizing their genomic plasticity. In terms of lifestyle, each mobile genetic elements should be evaluated separately with respect to the ecological context. Free-living genomes, in contrast to host-associated, tend to comprise (1) larger genomes, or the highest number of extra-chromosomal elements, (2) higher number of genomic islands and insertion sequence elements, and (3) a lower number of intact prophage regions. Regarding lifestyle adaptations, free-living genomes share genes linked to genetic exchange via T4SS, especially relevant for Paracoccus, known for their numerous extrachromosomal elements, enabling adaptation to dynamic environments. Conversely, host-associated genomes feature diverse genes involved in molecule transport, cell wall modification, attachment, stress protection, DNA repair, carbon, and nitrogen metabolism. Due to the vast number of adaptive genes, Paracoccus can quickly adapt to changing environmental conditions.

Ectoine Globally Hypomethylates DNA in Skin Cells and Suppresses Cancer Proliferation

Epigenetic modifications, mainly aberrant DNA methylation, have been shown to silence the expression of genes involved in epigenetic diseases, including cancer suppression genes. Almost all conventional cancer therapeutic agents, such as the DNA hypomethylation drug 5-aza-2-deoxycytidine, have insurmountable side effects. To investigate the role of the well-known DNA protectant (ectoine) in skin cell DNA methylation and cancer cell proliferation, comprehensive methylome sequence analysis, 5-methyl cytosine (5mC) analysis, proliferation and tumorigenicity assays, and DNA epigenetic modifications-related gene analysis were performed. The results showed that extended ectoine treatment globally hypomethylated DNA in skin cells, especially in the CpG island (CGIs) element, and 5mC percentage was significantly reduced. Moreover, ectoine mildly inhibited skin cell proliferation and did not induce tumorigenicity in HaCaT cells injected into athymic nude mice. HaCaT cells treated with ectoine for 24 weeks modulated the mRNA expression levels of Dnmt1, Dnmt3a, Dnmt3b, Dnmt3l, Hdac1, Hdac2, Kdm3a, Mettl3, Mettl14, Snrpn, and Mest. Overall, ectoine mildly demethylates DNA in skin cells, modulates the expression of epigenetic modification-related genes, and reduces cell proliferation. This evidence suggests that ectoine is a potential anti-aging agent that prevents DNA hypermethylation and subsequently activates cancer-suppressing genes.

Structural characterization of a novel cyclic 2,3-diphosphoglycerate synthetase involved in extremolyte production in the archaeon Methanothermus fervidus

The enzyme cyclic di-phosphoglycerate synthetase that is involved in the production of the osmolyte cyclic 2,3-diphosphoglycerate has been studied both biochemically and structurally. Cyclic 2,3-diphosphoglycerate is found exclusively in the hyperthermophilic archaeal methanogens, such as Methanothermus fervidus, Methanopyrus kandleri, and Methanothermobacter thermoautotrophicus. Its presence increases the thermostability of archaeal proteins and protects the DNA against oxidative damage caused by hydroxyl radicals. The cyclic 2,3-diphosphoglycerate synthetase enzyme has been crystallized and its structure solved to 1.7 Å resolution by experimental phasing. It has also been crystallized in complex with its substrate 2,3 diphosphoglycerate and the co-factor ADP and this structure has been solved to 2.2 Å resolution. The enzyme structure has two domains, the core domain shares some structural similarity with other NTP-dependent enzymes. A significant proportion of the structure, including a 127 amino acid N-terminal domain, has no structural similarity to other known enzyme structures. The structure of the complex shows a large conformational change that occurs in the enzyme during catalytic turnover. The reaction involves the transfer of the γ-phosphate group from ATP to the substrate 2,3 -diphosphoglycerate and the subsequent SN2 attack to form a phosphoanhydride. This results in the production of the unusual extremolyte cyclic 2,3 -diphosphoglycerate which has important industrial applications.

Topical Ectoin Versus Topical Dexpanthenol for Managing Acute Radiodermatitis Associated With Breast Cancer Radiotherapy: A Randomized Double-Blind Study

Background: Radiodermatitis is a common side effect of breast cancer radiotherapy; however, there is no current consensus regarding an effective standard therapy. Objective: To evaluate the efficacy of topical ectoin versus dexpanthenol in the management of acute radiodermatitis after breast cancer radiotherapy. Methods: Fifty patients randomly used dexpanthenol 5% cream (25 patients), or ectoin 7% cream (25 patients), applied twice daily to the irradiated area during and for 2 weeks after radiotherapy. The study was stratified by the radiotherapy schedule and was double-blind. Radiodermatitis grade, radiation-associated symptoms, and adverse events were assessed weekly during radiotherapy and 2 weeks thereafter. Skin-related quality of life (QOL) scores were measured using the Skindex-16 questionnaire. Results: Both agents were effective in preventing severe radiodermatitis (≥G3). Ectoin had a lower radiodermatitis grade level than dexpanthenol, with a significant difference at week 2 (P = 0.008). Radiation-associated pain (P = 0.003) and itching (P = 0.001) were lower with ectoin than dexpanthenol. Side effects were not significantly different between the 2 treatments (P = 0.107). Ectoin showed less QOL impairment than dexpanthenol. The radiation schedule was an independent predictor for radiodermatitis persistence. Conclusion: Ectoin showed some clinical benefit over dexpanthenol in improving radiation dermatitis and the radiation schedule is a predictor of radiodermatitis persistence.

NhaR, LeuO, and H-NS Are Part of an Expanded Regulatory Network for Ectoine Biosynthesis Expression

Bacteria accumulate compatible solutes to maintain cellular turgor pressure when exposed to high salinity. In the marine halophile Vibrio parahaemolyticus, the compatible solute ectoine is biosynthesized de novo, which is energetically more costly than uptake; therefore, tight regulation is required. To uncover novel regulators of the ectoine biosynthesis ectABC-asp_ect operon, a DNA affinity pulldown of proteins interacting with the ectABC-asp_ect regulatory region was performed. Mass spectrometry analysis identified, among others, 3 regulators: LeuO, NhaR, and the nucleoid associated protein H-NS. In-frame non-polar deletions were made for each gene and PectA-gfp promoter reporter assays were performed in exponential and stationary phase cells. PectA-gfp expression was significantly repressed in the ΔleuO mutant and significantly induced in the ΔnhaR mutant compared to wild type, suggesting positive and negative regulation, respectively. In the Δhns mutant, PectA-gfp showed increased expression in exponential phase cells, but no change compared to wild type in stationary phase cells. To examine whether H-NS interacts with LeuO or NhaR at the ectoine regulatory region, double deletion mutants were created. In a ΔleuO/Δhns mutant, PectA-gfp showed reduced expression, but significantly more than ΔleuO, suggesting H-NS and LeuO interact to regulate ectoine expression. However, ΔnhaR/Δhns had no additional effect compared to ΔnhaR, suggesting NhaR regulation is independent of H-NS. To examine leuO regulation further, a PleuO-gfp reporter analysis was examined that showed significantly increased expression in the ΔleuO, Δhns, and ΔleuO/Δhns mutants compared to wild type, indicating both are repressors. Growth pattern analysis of the mutants in M9G 6%NaCl showed growth defects compared to wild type, indicating that these regulators play an important physiological role in salinity stress tolerance outside of regulating ectoine biosynthesis gene expression. IMPORTANCE Ectoine is a commercially used compatible solute that acts as a biomolecule stabilizer because of its additional role as a chemical chaperone. A better understanding of how the ectoine biosynthetic pathway is regulated in natural bacterial producers can be used to increase efficient industrial production. The de novo biosynthesis of ectoine is essential for bacteria to survive osmotic stress when exogenous compatible solutes are absent. This study identified LeuO as a positive regulator and NhaR as a negative regulator of ectoine biosynthesis and showed that, similar to enteric species, LeuO is an anti-silencer of H-NS. In addition, defects in growth in high salinity among all the mutants suggest that these regulators play a broader role in the osmotic stress response beyond ectoine biosynthesis regulation.

Production and Recovery of Ectoine: A Review of Current State and Future Prospects

Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) is a revolutionizing substance with vast applications in the cosmetic and food industries. Ectoine is often sourced from halobacteria. The increasing market demand for ectoine has urged the development of cost-effective and sustainable large-scale production of ectoine from microbial sources. This review describes the existing and potential microbial sources of ectoine and its derivatives, as well as microbial production and fermentation approaches for ectoine recovery. In addition, conventional methods and emerging technologies for enhanced production and recovery of ectoine from microbial fermentation with a focus on the aqueous biphasic system (ABS) are discussed. The ABS is a practically feasible approach for the integration of fermentation, cell disruption, bioconversion, and clarification of various biomolecules in a single-step operation. Nonetheless, the implementation of the ABS on an industrial-scale basis for the enhanced production and recovery of ectoine is yet to be exploited. Therefore, the feasibility of the ABS to integrate the production and direct recovery of ectoine from microbial sources is also highlighted in this review.

Antioxidants in Sunscreens: Which and What For?

Ultraviolet (UV) radiation promotes the generation of reactive oxygen species (ROS) and nitrogen species (RNS), resulting in skin damage. Cosmetic industries have adopted a strategy to incorporate antioxidants in sunscreen formulations to prevent or minimize UV-induced oxidative damage, boost photoprotection effectiveness, and mitigate skin photoaging. Many antioxidants are naturally derived, mainly from terrestrial plants; however, marine organisms have been increasingly explored as a source of new potent antioxidant molecules. This work aims to characterize the frequency of the use of antioxidants in commercial sunscreens. Photoprotective formulations currently marketed in parapharmacies and pharmacies were analyzed with respect to the composition described on the label. As a result, pure compounds with antioxidant activity were found. The majority of sunscreen formulations contained antioxidants, with vitamin E and its derivatives the most frequent. A more thorough analysis of these antioxidants is also provided, unveiling the top antioxidant ingredients found in sunscreens. A critical appraisal of the scientific evidence regarding their effectiveness is also performed. In conclusion, this work provides an up-to-date overview of the use of antioxidants in commercial sunscreens for a better understanding of the advantages associated with their use in photoprotective formulations.

A randomized, observer-blind, vehicle-control, multi-center clinical investigation for assessing the efficacy and tolerability of a 1% ectoine and hyaluronic acid 0.1%-containing medical device in pediatric patients with mild-to-moderate atopic dermatitis

BACKGROUND

Ectoine is a widespread osmolyte enabling halophilic bacteria to withstand high osmotic stress that has many potential applications ranging from cosmetics to its use as a therapeutic agent.

OBJECTIVE

The aim of this study was to compare the efficacy and tolerability of ectoine 1% and hyaluronic acid 0.1% containing (EHA) cream with a vehicle cream in children with mild-to-moderate atopic dermatitis (AD).

METHODS

A randomized, controlled, observer-blind, multicenter clinical trial was conducted in children aged 2-18 years, diagnosed with mild-to-moderate AD (SCORAD ≤20). Patients were randomized to either receiving EHA cream or vehicle cream twice daily for 4 weeks. The primary outcome measure was the mean change in objective SCORAD from baseline to the final visit. The secondary outcome measures included the mean change in Investigator's Global Assessment score, patient's judgment of efficacy and patient's assessment of pruritus. Safety of EHA cream was also assessed.

RESULTS

A total of 70 patients (35 in each group) were randomized and 57 were included in the final analysis set. Based on SCORAD measurements, patients using EHA cream achieved superior clinical improvement compared to the control group at 28 days (p < .001). EHA cream was also superior to the vehicle cream regarding all secondary outcome measures. Eight (23.5%) patients receiving EHA cream and two (5.7%) patients receiving vehicle cream experienced mild cutaneous adverse events (AEs).

CONCLUSIONS

In children 2-18 years old with mild-to-moderate AD, EHA cream was superior to vehicle cream, with minor AEs.

Bioactivity profiling of the extremolyte ectoine as a promising protectant and its heterologous production

Ectoine is a compatible solutes that is diffusely dispersed in bacteria and archaea. It plays a significant role as protectant against various external pressures, such as high temperature, high osmolarity, dryness and radiation, in cells. Ectoine can be utilized in cosmetics due to its properties of moisturizing and antiultraviolet. It can also be used in the pharmaceutical industry for treating various diseases. Therefore, strong protection of ectoine creates a high commercial value. Its current market value is approximately US$1000 kg-1. However, traditional ectoine production in high-salinity media causes high costs of equipment loss and wastewater treatment. There is a growing attention to reduce the salinity of the fermentation broth without sacrificing the production of ectoine. Thus, heterologous production of ectoine in nonhalophilic microorganisms may represent the new generation of the industrial production of ectoine. In this review, we summarized and discussed the biological activities of ectoine on cell and human health protection and its heterologous production.

Prevention of Polymorphic Light Eruption Afforded by a Very High Broad-Spectrum Protection Sunscreen Containing Ectoin

Introduction

Polymorphic light eruption (PLE) is the most common idiopathic, acquired photodermatosis. The pathophysiology of PLE is not yet fully understood but seems to involve immunological mechanisms, UVA-induced oxidative stress, and the subsequent elicitation of a cellular stress response affecting keratinocyte gene expression and skin immune function. In the present study, a high broad-spectrum sunscreen medical device (MD), containing a very high protection complex of UVB and UVA filters and ectoin, was investigated for its ability to protect against UVA-induced PLE.

Methods

The study was carried out as a monocentric, double-blinded, randomized, untreated controlled design. The test MD was applied (2 mg/cm²) on one side of the chest according to a randomization list of 15 patients with a typical history of PLE, and the contralateral area remained untreated. After product application, the test areas were exposed daily to increasing doses of UVA radiation (from 40 to 60 J/cm²) until a PLE reaction was detected or for a maximum of five consecutive days. Evaluations of induced PLE included clinical scoring and chromametry for erythema and pigmentation.

Results

Overall, no positive PLE reaction was observed on the side of the chest treated by the test MD, whereas positive PLE reactions were triggered on the untreated side of 13 subjects. Subjective sensations were very rare on the MD-treated side but were numerous and more severe on the untreated side. Chromametry and clinical visual inspection indicated that the skin color was unchanged on the MD-protected side, whereas high increased values of erythema and pigmentation were observed on the untreated chest side.

Conclusion

This MD sunscreen based on a complex of UVA–UVB filters and 1% of ectoin may be effective in preventing UVA-induced PLE. New studies comparing this MD sunscreen versus the same product without ectoin should be conducted.

ClinicalTrials.gov identifier: NCT05320315 (retrospectively registered 09/17/2021).

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-022-00755-5.

Photoprotection for skin of all color: Consensus and clinical guidance from an expert panel

The negative effects of sun exposure have become better accepted among health care professionals and the lay public over recent decades. Most attention has been focused on the effects of UV light, particularly UVB wavelengths (290-320 nm). Accordingly, products to protect skin from sunlight-associated harm (sunscreens) have been developed to minimize UVB exposure. The effects of longer wavelengths, including UVA (320-400 nm) and visible light (VL, 400-700 nm), are increasingly appreciated. VL accounts for approximately half of the solar radiation that reaches the earth's surface and understanding of its effects on the skin is improving. Studies have shown that VL can induce hyperpigmentation in individuals with dark skin types (Fitzpatrick skin types IV-VI). In addition, VL can contribute to the exacerbation of pigmentary disorders, including melasma. Because these findings are relatively new, there are gaps in understanding the needs for photoprotection and guidance for clinicians. A panel of dermatologists and photobiologists was convened to develop consensus recommendations and clinical guidance about sunscreen use relevant to the current understanding of risks associated with sun exposure using a modified Delphi method.

Metabolic responses of plasma to extreme environments in overwintering Tibetan frogs Nanorana parkeri: a metabolome integrated analysis

Many animals lower their metabolic rate in response to low temperatures and scarcity of food in the winter in phenomena called hibernation or overwintering. Living at high altitude on the Tibetan Plateau where winters are very cold, the frog Nanorana parkeri, survives in one of the most hostile environments on Earth but, to date, relatively little is known about the biochemical and physiological adjustments for overwintering by this species. The present study profiled changes in plasma metabolites of N. parkeri between winter and summer using UHPLC-QE-MS non-target metabolomics in order to explore metabolic adaptations that support winter survival. The analysis showed that, in total, 11 metabolites accumulated and 95 were reduced in overwintering frogs compared with summer-active animals. Metabolites that increased included some that may have antioxidant functions (canthaxanthin, galactinol), act as a metabolic inhibitor (mono-ethylhexylphthalate), or accumulate as a product of anaerobic metabolism (lactate). Most other metabolites in plasma showed reduced levels in winter and were generally involved in energy metabolism including 11 amino acids (proline, isoleucine, leucine, valine, phenylalanine, tyrosine, arginine, tryptophan, methionine, threonine and histidine) and 4 carbohydrates (glucose, citrate, succinate, and malate). Pathway analysis indicated that aminoacyl-tRNA biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, and nitrogen metabolism were potentially the most prominently altered pathways in overwintering frogs. Changes to these pathways are likely due to fasting and global metabolic depression in overwintering frogs. Concentrations of glucose and urea, commonly used as cryoprotectants by amphibians that winter on land, were significantly reduced during underwater hibernation in N. parkeri. In conclusion, winter survival of the high-altitude frog, N. parkeri was accompanied by substantial changes in metabolomic profiles and this study provides valuable information towards understanding the special adaptive mechanisms of N. parkeri to winter stresses.

Shikimic acid protects skin cells from UV-induced senescence through activation of the NAD+-dependent deacetylase SIRT1

UV radiation is one of the main contributors to skin photoaging by promoting the accumulation of cellular senescence, which in turn induces a proinflammatory and tissue-degrading state that favors skin aging. The members of the sirtuin family of NAD⁺-dependent enzymes play an anti-senescence role and their activation suggests a promising approach for preventing UV-induced senescence in the treatment of skin aging. A two-step screening designed to identify compounds able to protect cells from UV-induced senescence through sirtuin activation identified shikimic acid (SA), a metabolic intermediate in many organisms, as a bona-fide candidate. The protective effects of SA against senescence were dependent on specific activation of SIRT1 as the effect was abrogated by the SIRT1 inhibitor EX-527. Upon UV irradiation SA induced S-phase accumulation and a decrease in p16^INK4A expression but did not protect against DNA damage or increased polyploidies. In contrast, SA reverted misfolded protein accumulation upon senescence, an effect that was abrogated by EX-527. Consistently, SA induced an increase in the levels of the chaperone BiP, resulting in a downregulation of unfolded protein response (UPR) signaling and UPR-dependent autophagy, avoiding their abnormal hyperactivation during senescence. SA did not directly activate SIRT1 in vitro, suggesting that SIRT1 is a downstream effector of SA signaling specifically in the response to cellular senescence. Our study not only uncovers a shikimic acid/SIRT1 signaling pathway that prevents cellular senescence, but also reinforces the role of sirtuins as key regulators of cell proteostasis.

Microbial production of ectoine and hydroxyectoine as high-value chemicals

Ectoine and hydroxyectoine as typical representatives of compatible solutes are not only essential for extremophiles to survive in extreme environments, but also widely used in cosmetic and medical industries. Ectoine was traditionally produced by Halomonas elongata through a "bacterial milking" process, of which the marked feature is using a high-salt medium to stimulate ectoine biosynthesis and then excreting ectoine into a low-salt medium by osmotic shock. The optimal hydroxyectoine production was achieved by optimizing the fermentation process of Halomonas salina. However, high-salinity broth exacerbates the corrosion to fermenters, and more importantly, brings a big challenge to the subsequent wastewater treatment. Therefore, increasing attention has been paid to reducing the salinity of the fermentation broth but without a sacrifice of ectoine/hydroxyectoine production. With the fast development of functional genomics and synthetic biology, quite a lot of progress on the bioproduction of ectoine/hydroxyectoine has been achieved in recent years. The importation and expression of an ectoine producing pathway in a non-halophilic chassis has so far achieved the highest titer of ectoine (~ 65 g/L), while rational flux-tuning of halophilic chassis represents a promising strategy for the next-generation of ectoine industrial production. However, efficient conversion of ectoine to hydroxyectoine, which could benefit from a clearer understanding of the ectoine hydroxylase, is still a challenge to date.

Ectoines as novel anti-inflammatory and tissue protective lead compounds with special focus on inflammatory bowel disease and lung inflammation

The compatible solute ectoine is one of the most abundant and powerful cytoprotectant in the microbial world. Due to its unique ability to stabilize biological membranes and macromolecules it has been successfully commercialized as ingredient of various over-the-counter drugs, achieving primarily epithelial protection. While trying to elucidate the mechanism of its cell protective properties in in-vitro studies, a significant anti-inflammatory effect was documented for the small molecule. The tissue protective potential of ectoine considerably improved organ quality during preservation. In addition, ectoine and derivatives have been demonstrated to significantly decrease inflammatory cytokine production, thereby alleviating the inflammatory response following organ transplantation, and launching new therapeutic options for pathologies such as Inflammatory Bowel Disease (IBD) and Chronic Obstructive Pulmonary Disease (COPD). In this review, we aim to summarize the knowledge of this fairly nascent field of the anti-inflammatory potential of diverse ectoines. We also point out that this promising field faces challenges in its biochemical and molecular substantiations, including defining the molecular mechanisms of the observed effects and their regulation. However, based on their potent cytoprotective, anti-inflammatory, and non-toxic properties we believe that ectoines represent promising candidates for risk free interventions in inflammatory pathologies with steeply increasing demands for new therapeutics.

Ionizing-radiation-resistant Kocuria rhizophila PT10 isolated from the Tunisian Sahara xerophyte Panicum turgidum: Polyphasic characterization and proteogenomic arsenal

A new strain belonging to the genus Kocuria, designed PT10, was isolated from irradiated roots of the xerophyte Panicum turgidum. Isolate PT10 is a Gram-positive, coccoid, aerobic and ionizing-radiation (IR)-resistant actinobacterium. PT10 has shown an ability to survive under extreme conditions, such as gamma irradiation, desiccation and high concentration of hydrogen peroxide. Phenotypic, chemotaxonomic and comparative genome analyses support the assignment of strain PT10 (LMG 31102 = DSM 108617) as Kocuria rhizophila. The complete genome sequence of PT10 consists of one chromosome (2,656,287 bps), with a 70.7% G + C content and comprises 2481 protein-coding sequences. A total of 1487 proteins were identified by LC-MS/MS profiling. In silico analyses revealed that the proteome of the oxidation-tolerant PT10 possesses several features explaining its IR-resistant phenotype and many adaptive pathways implicated in response to environmental pressures - desiccation, cold, reactive oxygen species and other stressors.

The saltern-derived Paludifilum halophilum DSM 102817T is a new high-yield ectoines producer in minimal medium and under salt stress conditions

In the present study, the growth conditions and accumulation of ectoines (ectoine and hydroxyectoine) by Paludifilum halophilum DSM 102817^T under salt stress conditions have been investigated. The productivity assay of this strain for ectoines revealed that the highest cellular content was reached in the minimal glucose sea water medium (SW-15) within 15% salinity. The addition of 0.1% (w/v) aspartic acid to the medium allowed an average of four times higher biomass production, and a dry mycelial biomass of 1.76 g L^-1 was obtained after 6 days of growth in shake flasks at 40 °C and 200 rpm. Among the inorganic cations supplemented to the glucose SW-15 medium, the addition of 1 mM Fe²⁺ yielded the highest amount of mycelial biomass (3.45 g L^-1) and total ectoines content (119 mg g^-1), resulting in about 410 mg L^-1 of products at the end of exponential growth phase. After 1 h of incubation in an osmotic downshock solution containing 2% NaCl, 70% of this content was released by the mycelium, and recovering cells maintained a high survival, with a maximal growth rate (µ _max) of about 93% of the control population exposed to 15% NaCl. During growth at optimal salinity and temperature (15% NaCl and 40 °C), P. halophilum developed a compact and circular pellets that were easy to separate by simple decantation from both fermentation media and after hypoosmotic shock. Overall, the ectoines excreting P. halophilum could be a promising resource for ectoines production in a commercially valuable culture medium and at a large-scale fermentation process.

What Does Ectoine Do to DNA? A Molecular-Scale Picture of Compatible Solute-Biopolymer Interactions

Compatible solutes accumulate in the cytoplasm of halophilic microorganisms, enabling their survival in a high-salinity environment. Ectoine is such a compatible solute. It is a zwitterionic molecule that strongly interacts with surrounding water molecules and changes the dynamics of the local hydration shell. Ectoine interacts with biomolecules such as lipids, proteins, and DNA. The molecular interaction between ectoine and biomolecules, in particular the interaction between ectoine and DNA, is far from being understood. In this paper, we describe molecular aspects of the interaction between ectoine and double-stranded DNA (dsDNA). Two 20 base pairs-long dsDNA fragments were immobilized on a gold surface via a thiol-tether. The interaction between the dsDNA monolayers with diluted and concentrated ectoine solutions was examined by means of X-ray photoelectron and polarization modulation infrared reflection absorption spectroscopies (PM IRRAS). Experimental results indicate that the ability of ectoine to bind water reduces the strength of hydrogen bonds formed to the ribose-phosphate backbone in the dsDNA. In diluted (0.1 M) ectoine solution, DNA interacts predominantly with water molecules. The sugar-phosphate backbone is involved in the formation of strong hydrogen bonds to water, which, over time, leads to a reorientation of the planes of nucleic acid bases. This reorientation destabilizes the strength of hydrogen bonds between the bases and leads to a partial dehybridization of the dsDNA. In concentrated ectoine solution (2.5 M), almost all water molecules interact with ectoine. Under this condition, ectoine is able to interact directly with DNA. Density functional theory (DFT) calculations demonstrate that the direct interaction involves the nitrogen atoms in ectoine and phosphate groups in the DNA molecule. The results of the quantum-chemical calculations show that rearrangements in the ribose-phosphate backbone, caused by a direct interaction with ectoine, facilitates contacts between the O atom in the phosphate group and H atoms in a nucleic acid base. In the PM IRRA spectra, an increase in the number of IR absorption modes in the base pair frequency region proves that the hydrogen bonds between bases become weaker. Thus, a sequence of reorientations caused by interaction with ectoine leads to a breakdown of hydrogen bonds between bases in the double helix.

Ectoine production in bioreactor by Halomonas elongata DSM2581: Using MWCNT and Fe-nanoparticle

Halomonas elongate produces ectoine to protect itselt from environmental stresses. In this research, important factors in the production of ectoine were optimized using statistical methods to achieve the best production efficiency in bioreactor. Screening important variables (ectoine, hydroxyectoine, l-aspartic acid, and glutamate) on H. elongate growth showed that ectoine and l-aspartic acid directly affect ectoine production. Two nanostructures, multiwalled carbon nanotube (MWCNT) and iron oxide nanoparticle (Fe₂ O₃ NPs), were used to increase the availability of substrate for the microorganism. The results showed that Fe₂ O₃ nanoparticles and MWCNT could have a negative or positive effect on bacterial growth and ectoine production depending on the concentration of nanoparticles. At optimized conditions, the amounts of bacterial growth and ectoine production in fermenter were 10.4 g/L and 14.25 g/L, respectively. Therefore, it could be concluded that nanoparticles improve bacterial growth and ectoine production at optimized concentrations.

Protective effect of the extremolytes ectoine and hydroxyectoine in a porcine organ culture

Purpose

Hypoxic damage to the retina is a relevant component of neurodegenerative pathologies such as glaucoma or retinal ischemia. In porcine retina organ cultures, hypoxic damage can be induced by applying cobalt chloride (CoCl₂). The aim of our study was to investigate possible neuroprotective effects of the extremolytes ectoine and hydroxyectoine in this hypoxia-damaged retina model.

Methods

To simulate hypoxia, porcine retina organ cultures were damaged with 300 μM CoCl₂ for 48 h starting on day 1 (n = 8–9/group). In order to investigate the possible neuroprotective effects of ectoine and hydroxyectoine, 0.5 mM of each extremolyte was added to the culture at the same time as the stressor and for the same duration. On day 8, the retina organ cultures were taken for (immuno)-histochemical examinations. Retinal ganglion cells (RGCs), macroglia, and apoptotic and hypoxic cells were detected with appropriate markers followed by cell counts and group comparisons.

Results

Treatment with ectoine resulted in RGC protection (p < 0.05) and reduced rate of apoptosis (p < 0.001) in hypoxia-treated retina organ cultures. However, the macroglia area and the amount of hypoxic, HIF-1α⁺ cells were unaffected by the ectoine treatment (p = 0.99). Treatment with hydroxyectoine also protected RGCs (p < 0.01) by inhibiting apoptosis (p < 0.001). In addition, the number of hypoxic, HIF-1α⁺ cells could be significantly reduced by treatment with hydroxyectoine (p < 0.05). The macroglia area on the other hand was unchanged after CoCl₂ and treatment with hydroxyectoine.

Conclusion

Both extremolytes had a protective effect on CoCl₂-induced hypoxia in the porcine retina organ culture. Regarding the reduction of hypoxic stress, hydroxyectoine appears to be more effective. Thus, both extremolytes represent an interesting potential new therapeutic approach for patients with ocular diseases in which hypoxic processes play a significant role.

Ectoine interaction with DNA: influence on ultraviolet radiation damage

Ectoine is a small zwitterionic osmolyte and compatible solute, which does not interfere with cell metabolism even at molar concentrations. Plasmid DNA (pUC19) was irradiated with ultraviolet radiation (UV-C at 266 nm) under quasi physiological conditions (PBS) and in pure water in the presence and absence of ectoine (THP(B)) and hydroxyectoine (THP(A)). Different types of UV induced DNA damage were analysed: DNA single-strand breaks (SSBs), abasic sites and cyclobutane pyrimidine dimers (CPDs). A complex interplay between these factors was observed with respect to the nature and occurrence of DNA damage with 266 nm photons. In PBS, the cosolutes showed efficient protection against base damage, whilst in pure water, a dramatic shift from SSB damage to base damage was observed when cosolutes were added. To test whether these effects are caused by ectoine binding to DNA, further experiments were conducted: small-angle X-ray scattering (SAXS), surface-plasmon resonance (SPR) measurements and Raman spectroscopy. The results show, for the first time, a close interaction between ectoine and DNA. This is in stark contrast to the assumption made by preferential exclusion models, which are often used to interpret the behaviour of compatible solutes within cells and with biomolecules. It is tentatively proposed that the alterations of UV damage to DNA are attributed to ectoine influence on nucleobases through the direct interaction between ectoine and DNA.

Complexes of Ectoine with the Anionic Surfactants as Active Ingredients of Cleansing Cosmetics with Reduced Irritating Potential

For many years, an increasing number of diagnosed atopy and skin problems have been observed. For people affected by the problem of atopy, the selection of skin care products, including cosmetics, is extremely important. Cleansing cosmetics, due to their ability to cause skin irritations and disturb the hydrolipidic barrier, can increase problems with atopic skin. New solutions to reduce the effects of these products on the skin are very important. In this work, the effect of ectoine on the properties of anionic surfactants was analyzed. Based on model systems, analysis of the effect of ectoine on the irritating effect of four anionic surfactants and their ability to solubilize model sebum was performed. Antioxidant activity was also evaluated, and cytotoxic studies were performed on cell cultures. It was shown that the addition of ectoine to the anionic surfactant solutions improves its safety of use. After introducing ectoine to the surfactant solution, a decrease of irritant potential (about 20%) and a decrease in the ability to solubilize of model sebum (about 10–20%) was noted. Addition of ectoine to surfactant solutions also reduced their cytotoxicity by up to 60%. The obtained results indicate that ectoine may be a modern ingredient that improves the safety of cleansing cosmetics.

The Skin-Whitening Effects of Ectoine via the Suppression of α-MSH-Stimulated Melanogenesis and the Activation of Antioxidant Nrf2 Pathways in UVA-Irradiated Keratinocytes

Ultraviolet A (UVA)-irradiation induced reactive oxygen species (ROS) production mediates excessive melanogenesis in skin cells leading to pigmentation. We demonstrated the depigmenting and anti-melanogenic effects of Ectoine, a natural bacterial osmolyte, in UVA-irradiated human (HaCaT) keratinocytes, and the underlying molecular mechanisms were elucidated. HaCaT cells were pre-treated with low concentrations of Ectoine (0.5-1.5 μM) and assayed for various depigmenting and anti-melanogenic parameters. This pre-treatment significantly downregulated ROS generation, α-melanocyte-stimulating hormone (α-MSH) production, and proopiomelanocortin (POMC) expression in UVA-irradiated HaCaT cells. Also, antioxidant heme oxygenase-1 (HO-1), NAD(P)H dehydrogenase [quinone 1] (NQO-1), and γ-glutamate-cysteine ligase catalytic subunit (γ-GCLC) protein expressions were mediated via the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) whose knockdown indeed impaired this effect signifying the importance of the Nrf2 pathway. Ectoine was mediating the activation of Nrf2 via the p38, protein kinase B (also known as AKT), protein kinase C (PKC), and casein kinase II protein kinase (CKII) pathways. The conditioned medium obtained from the Ectoine pre-treated and UVA-irradiated HaCaT cells downregulated the tyrosinase, tyrosinase-related protein-1 and -2 (TRP-1/-2), cyclic AMP (c-AMP) protein kinase, c-AMP response element-binding protein (CREB), and microphthalmia-associated transcription factor (MITF) expressions leading to melanoma B16F10 cells having inhibited melanin synthesis. Interestingly, this anti-melanogenic effect in α-MSH-stimulated B16F10 cells was observable only at 50-400 μM concentrations of Ectoine, signifying the key role played by Ectoine (0.5-1 μM)-treated keratinocytes in skin whitening effects. We concluded that Ectoine could be used as an effective topical natural cosmetic agent with depigmenting and anti-melanogenic efficacy.

Complex transitions between dihydrate and anhydrate forms of ectoine – unexpected behavior of a highly hygroscopic compatible solute in the solid state

Crystallizing the compatible solute ectoine from water yields a metastable dihydrate that readily degrades to a highly hygroscopic anhydrate at ambient conditions; this strange behavior is examined and a rationale is presented.

Ectoine production with indigenous Marinococcus sp. MAR2 isolated from the marine environment

Ectoine has fostered the development of products for skin care and cosmetics. In this study, we employed the marine bacterial strain Marinococcus sp. MAR2 to increase ectoine production by optimizing medium constituents using Response Surface Methodology (RSM) and a fed-batch strategy. The results from the steepest ascent and central composite design indicated that 54 g/L of yeast extract, 14.0 g/L of ammonium acetate, 74.4 g/L of sodium glutamate, and 6.2 g/L of sodium citrate constituted the optimal medium with maximum ectoine production (3.5 g/L). In addition, we performed fed-batch culture in the bioreactor, combining pH and dissolved oxygen to produce ectoine by Marinococcus sp. MAR2. The ectoine production, content, and productivity of 5.6 g/L, 10%, and 3.9 g/L/day were further reached by a fed-batch culture. Thus, the ectoine production by Marinococcus sp. MAR2 using RSM and fed-batch strategy shows its potential for industrial production.

Halophile, an essential platform for bioproduction

Industrial biotechnology aims to compete as a stronger alternative ensuring environmental friendly microbial-based production that seeks to curb the predicament of pollution. However, the high cost of bioprocessing is a severe drawback, and therefore, new approaches must be developed to overcome this challenge. Halophiles have shown potentials of overcoming this challenge and are of much preference for unsterile and continuous contamination-free bioprocess due to their unique ability to grow under harsh environmental conditions. Recent advances in genetic manipulations have been established to better the performance of halophiles for industrial applications. Many researchers produced various products such as polyhydroxyalkanoates (PHA), ectoines, biosurfactants, and antioxidants using halophiles, and further efforts have been established to develop halophiles as the foundation for low-cost bioprocess. This paper provides a useful reference for researchers on the merits, drawbacks, achievements, and application of halophiles for bioproduction.

Topical Ectoine: A Promising Molecule in the Upper Airways Inflammation-A Systematic Review

To date, topical therapies guarantee a better delivery of high concentrations of pharmacologic agents to the mucosa of the upper airways (UA). Recently, topical administration of ectoine has just been recognized as adjuvant treatment in the Allergic Rhinitis (AR) and Rhinosinusitis (ARS). The aim of this work is to review the published literature regarding all the potential therapeutic effects of ectoine in the acute and chronic inflammatory diseases of UA. Pertinent studies published without temporal limitation were selected searching on MEDLINE the following terms: “ectoine” and “nasal spray,” “oral spray,” “upper respiratory tract infections,” “rhinosinusitis,” “rhinitis,” “rhinoconjunctivitis,” “pharyngitis,” and “laryngitis.” At the end of our selection process, six relevant publications were included: two studies about the effect of ectoine on AR, one study about ARS, one study about rhinitis sicca anterior, and two studies about acute pharyngitis and/or laryngitis. Due to its moisturizing and anti-inflammatory properties, topical administration of ectoine could play a potential additional role in treatment of acute and chronic inflammatory diseases of UA, in particular in the management of sinonasal conditions improving symptoms and endoscopic findings. However, these results should be viewed cautiously as they are based on a limited number of studies; some of them were probably underpowered because of their small patient samples.

Terrestrial Microorganisms: Cell Factories of Bioactive Molecules with Skin Protecting Applications

It is well known that terrestrial environments host an immense microbial biodiversity. Exposed to different types of stress, such as UV radiation, temperature fluctuations, water availability and the inter- / intra-specific competition for resources, terrestrial microorganisms have been evolved to produce a large spectrum of bioactive molecules. Bacteria, archaea, protists, fungi and algae have shown a high potential of producing biomolecules for pharmaceutical or other industrial purposes as they combine a sustainable, relatively low-cost and fast-production process. Herein, we provide an overview of the different bioactive molecules produced by terrestrial microorganisms with skin protecting applications. The high content in polyphenolic and carotenoid compounds produced by several strains, as well as the presence of exopolysaccharides, melanins, indole and pyrrole derivatives, mycosporines, carboxylic acids and other molecules, are discussed in the context of their antioxidant, photo-protective and skin-whitening activity. Relevant biotechnological tools developed for the enhanced production of high added value natural products, as well as the protecting effect of some antioxidant, hydrolytic and degrading enzymes are also discussed. Furthermore, we describe classes of microbial compounds that are used or have the potential to be used as antimicrobials, moisturizers, biosurfactants, pigments, flavorings and fragrances.

Effect of ectoine, hydroxyectoine and β-hydroxybutyrate on the temperature and pressure stability of phospholipid bilayer membranes of different complexity

Previous research has shown that ectoines fluidize lipid monolayers by increasing the liquid expanded region in DPPC monolayers and also decreasing the line tension responsible for the phase morphology. Here, we explored possible effects of the compatible osmolytes ectoine, hydroxyectoine and β-hydroxybutyrate on lipid bilayer membranes, including effects of temperature and pressure. The effect of the protective osmolytes on the phase transition of DPPC bilayers was investigated by fluorescence spectroscopy, differential scanning calorimetry and pressure perturbation calorimetry. A slight change of the phase behavior was observed, which resulted in a stabilization of the gel phase, which may be caused by an alteration of the hydration properties at the lipid interface and H-bond and electrostatic interactions in the headgroup region. We then explored the cosolvents' effects on giant unilamellar vesicles (GUVs) formed by lipid mixtures exhibiting phase separation into liquid-ordered (l_o) and liquid-disordered (l_d) domains using BODIPY-PC and the DiI₁₈ dye as labels. The presence of both, ectoine and hydroxyectoine showed significant effects on the lateral organization increasing the fluid domains. Moreover, we observed a considerable increase in the adhesion behavior of small vesicles onto GUV surfaces. Diffusion studies by fluorescence recovery after photobleaching experiments on POPC giant vesicles quantitatively showed a hydroxyectoine-induced increase of the diffusion coefficient values, clearly demonstrating an increase in the lateral mobility of lipid within the bilayer membrane. This study provides clear evidence for the fluidizing effect of the compatible solutes on bilayer lipid membranes. A marked effect, however, was only detected if phase separated domains exist.

Topical effects of SCA® (Cryptomphalus aspersa secretion) associated with regenerative and antioxidant ingredients on aged skin: evaluation by confocal and clinical microscopy

Purpose

This was an open-label, single-center clinical study to evaluate a topical association of SCA^® (Cryptomphalus aspersa secretion) with regenerative and antioxidant ingredients, according to the type and area of the face, on the improvement of signs of skin aging.

Patients and methods

One hundred and twenty female participants aged between 40 and 65 years, with facial aging complaints (presence of static, dynamics wrinkles, loss of elasticity, and skin firmness) were randomized into two groups according to the type of skin: normal–oily and normal–dry, and 40 participants were randomized for evaluation of the periocular area (with the presence of wrinkles, expression lines, and dark circles) with both types of skin. The groups received serum for normal–oily skin, a cream for normal–dry skin, and a cream for periocular and eyelid skin (eye area). All the participants were evaluated by a dermatologist and submitted to hydration evaluation by corneometry, elasticity and firmness measures complementarily, and images were collected in confocal reflectance microscopy.

Results

Topical skin treatment with the association of SCA with antioxidant ingredients (green coffee oil, olive oil, ectoine, hyaluronic acid, and peptides) was able to promote significant clinical and subjective improvement of all signs of skin aging. This improvement was presented at the epidermal level, with improved hydration levels measured by corneometry and epidermal thickness, and at the dermal level, with improvement of the firmness and elasticity parameters, measured by cutometry, from 45 days of use.

Conclusion

All the evaluated topical formulations seemed to be an effective alternative for the progressive treatment of signs of skin aging, since they demonstrate a real improvement of dermal–epidermal structure and function with high safety margin for long-term use.

Homoectoine Protects Against Colitis by Preventing a Claudin Switch in Epithelial Tight Junctions

BACKGROUND

Inflammatory bowel diseases (IBD) are multifactorial disorders affecting millions of people worldwide with alarmingly increasing incidences every year. Dysfunction of the intestinal epithelial barrier is associated with IBD pathogenesis, and therapies include anti-inflammatory drugs that enhance intestinal barrier function. However, these drugs often have adverse side effects thus warranting the search for alternatives. Compatible solutes such as bacterial ectoines stabilize cell membranes and proteins.

AIM

To unravel whether ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) and homoectoine (4,5,6,7-tetrahydro-2-methyl-1H-(1,3)-diazepine-4-carboxylic acid), a synthetic derivative of ectoine, have beneficial effects during dextran sulfate sodium (DSS)-induced colitis in mice.

METHODS/RESULTS

We found that the disease activity index was significantly reduced by both ectoines. DSS-induced edema formation, epithelial permeability, leukocyte recruitment and tissue damage were reduced by ectoine and homoectoine, with the latter having stronger effects. Interestingly, the claudin switch usually observed during colitis (decreased expression of claudin-1 and increased expression of the leaky claudin-2) was completely prevented by homoectoine, whereas ectoine only reduced claudin-2 expression. Concomitantly, only homoectoine ameliorated the drop in transepithelial electrical resistance induced by IFN-γ and TNF-α in Caco-2 cells. Both ectoines inhibited loss of ZO-1 and occludin and prevented IFN-γ/TNF-α-induced increased paracellular flux of 4 kDa FITC-dextran in vitro. Moreover, both ectoines reduced expression of pro-inflammatory cytokines and oxidative stress during colitis.

CONCLUSION

While both ectoine and homoectoine have protective effects on the epithelial barrier during inflammation, only homoectoine completely prevented the inflammatory claudin switch in tight junctions. Thus, homoectoine may serve as diet supplement in IBD patients to reach or extend remission.

The promotion and suppression of DNA charge neutralization by the cosolute ectoine

Ectoine, a cosolute and osmolyte, is used by extremophilic microorganisms to maintain an osmotic equilibrium of cells with their surrounding medium under conditions of extreme salinity or thermal and pressure stresses. It is also considered a protectant of biomolecules such as protein and DNA in cells. In the present study, we investigate its influence on DNA charge neutralization and compaction through dynamic light scattering (DLS), atomic force microscopy (AFM) and single molecular magnetic tweezers (MT). We found that ectoine can promote DNA charge neutralization induced by multivalent cations at mild cosolute concentration in solution. When the concentration of ectoine is high enough, however, a mixed effect of promotion and suppression can be found under the same ionic conditions. In this case, the electrophoretic mobility (EM) of DNA is promoted in the region of low cation concentration, while suppressed in the region of high counterionic concentration. The charge neutralization of DNA by ectoine is also related to DNA compaction. The promotion and suppression of DNA compaction by ectoine was observed by AFM imaging. The condensed structure of DNA becomes more compact and then loose once more with the increasing concentration of ectoine. Meanwhile, the condensing forces of DNA measured by magnetic tweezers shows the same trend as does the DNA EM. We explained the experimental findings through the combined effect of two intrinsic features of ectoine, preferential exclusion and enhancement of the dielectric constant of the medium.

Ectoine can promote DNA charge neutralization at mild cosolute concentration in solution. When the concentration of ectoine is high enough, however, a mixing effect of promotion and suppression can be found in the same ionic condition.

Ectoine: a compatible solute in radio-halophilic Stenotrophomonas sp. WMA-LM19 strain to prevent ultraviolet-induced protein damage

AIM

Thiss study was conducted to investigate the possible role of a compatible solute from radio-halophilic bacterium against desiccation and ultra-violet radiation-induced oxidative stress.

METHODS AND RESULTS

Nine different radio-resistant bacteria were isolated from desert soil, where strain WMA-LM19 was chosen for detailed studies on the basis of its high tolerance to ultraviolet radiation among all these isolates. Here, 16S rRNA gene sequencing indicated the bacterium was closely related to Stenotrophomonas sp. (KT008383). A bacterial milking strategy was applied for extraction of intracellular compatible solutes in 70% (v/v) ethanol, which were purified by High Performance Liquid Chromatography (HPLC). The compound was characterized as ectoine by ¹ H and ¹³ C Nuclear Magnetic Resonance (NMR), and Mass Spectrometry (MS). Ectoine inhibited oxidative damage to proteins and lipids in comparison to the standard ascorbic acid. It also demonstrated more efficient prevention (54·80%) against lysis to erythrocytes membrane by surface active agents than lecithin. Furthermore, a high level of ectoine-mediated protection of bovine serum albumin against ionizing radiation (1 500-2 000Jm^-2 ) was observed, as indicated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis.

CONCLUSION

The results indicated that ectoine from Stenotrophomonas sp. WMA-LM19 can be used as a potential mitigator and radio-protective agent to overcome radiation- and salinity-mediated oxidative damages in extreme environment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Due to its anti-oxidant properties, ectoine from a radio-halophilic bacterium might be used in sunscreen formulation for protection against UV-induced oxidative stress.

Role of the Extremolytes Ectoine and Hydroxyectoine as Stress Protectants and Nutrients: Genetics, Phylogenomics, Biochemistry, and Structural Analysis

Fluctuations in environmental osmolarity are ubiquitous stress factors in many natural habitats of microorganisms, as they inevitably trigger osmotically instigated fluxes of water across the semi-permeable cytoplasmic membrane. Under hyperosmotic conditions, many microorganisms fend off the detrimental effects of water efflux and the ensuing dehydration of the cytoplasm and drop in turgor through the accumulation of a restricted class of organic osmolytes, the compatible solutes. Ectoine and its derivative 5-hydroxyectoine are prominent members of these compounds and are synthesized widely by members of the Bacteria and a few Archaea and Eukarya in response to high salinity/osmolarity and/or growth temperature extremes. Ectoines have excellent function-preserving properties, attributes that have led to their description as chemical chaperones and fostered the development of an industrial-scale biotechnological production process for their exploitation in biotechnology, skin care, and medicine. We review, here, the current knowledge on the biochemistry of the ectoine/hydroxyectoine biosynthetic enzymes and the available crystal structures of some of them, explore the genetics of the underlying biosynthetic genes and their transcriptional regulation, and present an extensive phylogenomic analysis of the ectoine/hydroxyectoine biosynthetic genes. In addition, we address the biochemistry, phylogenomics, and genetic regulation for the alternative use of ectoines as nutrients.

Post-irradiation protective effects of ectoine on brain and testicles in male mice

BACKGROUND

The present study aimed to investigate the possible post-irradiation protective effects of ectoine on CNS and testes of male mice.

METHODS

The study included thirty male Swiss albino mice (20-22 gm). Mice were divided into five groups (six each); controls (injected intraperitoneally with 0.2ml saline), irradiated group 1 (received six Gy whole body x-irradiation single dose, injected with saline, and sacrificed after one day), irradiated group 2 (x-irradiated, injected with saline, and sacrificed after one week), ectoine group 1 (x-irradiated, injected with 200mg/kg ectoine, and sacrificed after one day), and ectoine group 2 (x-irradiated, injected daily with 200mg/kg ectoine, and sacrificed after one week). IL-1β, IL-6, IL-10, PGE₂, MDA, GSH, GSSG, and GSH/GSSG ratio were evaluated in CNS and testes.

RESULTS

IL-1β, IL-6, IL-10, PGE₂, and MDA are significantly elevated in the CNS and testes of x-irradiated groups when compared with controls. IL-1β, IL-6, IL-10, and PGE₂ significantly elevated at one week than one day while MDA significantly decreased. A significant decrease in the concentration of GSH and in the GSH/GSSG ratios coupled with an opposite effect on GSSG was noted. Ectoine treatment significantly ameliorated the biochemical effects induced by whole body x-irradiation. All the tested parameters tended to go back to near control values. It was noted that the modulating action was dependent on the accumulation of ectoine as it was more effective after repeated administration.

CONCLUSION

Ectoine has post-irradiation protective effects on CNS and testes via its action on inflammatory and oxidative stress pathways.

DNA protection by ectoine from ionizing radiation: molecular mechanisms

Ectoine, a compatible solute and osmolyte, is known to be an effective protectant of biomolecules and whole cells against heating, freezing and extreme salinity. Protection of cells (human keratinocytes) by ectoine against ultraviolet radiation has also been reported by various authors, although the underlying mechanism is not yet understood. We present the first electron irradiation of DNA in a fully aqueous environment in the presence of ectoine and at high salt concentrations. The results demonstrate effective protection of DNA by ectoine against the induction of single-strand breaks by ionizing radiation. The effect is explained by an increase in low-energy electron scattering at the enhanced free-vibrational density of states of water due to ectoine, as well as the use of ectoine as an ˙OH-radical scavenger. This was demonstrated by Raman spectroscopy and electron paramagnetic resonance (EPR).

Influence of compatible solute ectoine on distinct DNA structures: thermodynamic insights into molecular binding mechanisms and destabilization effects

We study ectoine-induced destabilization effects on DNA hairpins by a combination of atomistic molecular dynamics simulations, experiments, and theoretical approaches.

Ectoine protects DNA from damage by ionizing radiation

Ectoine plays an important role in protecting biomolecules and entire cells against environmental stressors such as salinity, freezing, drying and high temperatures. Recent studies revealed that ectoine also provides effective protection for human skin cells from damage caused by UV-A radiation. These protective properties make ectoine a valuable compound and it is applied as an active ingredient in numerous pharmaceutical devices and cosmetics. Interestingly, the underlying mechanism resulting in protecting cells from radiation is not yet fully understood. Here we present a study on ectoine and its protective influence on DNA during electron irradiation. Applying gel electrophoresis and atomic force microscopy, we demonstrate for the first time that ectoine prevents DNA strand breaks caused by ionizing electron radiation. The results presented here point to future applications of ectoine for instance in cancer radiation therapy.

Poly(ectoine) Hydrogels Resist Nonspecific Protein Adsorption

The development of nonfouling zwitterionic materials has a wide range of biomedical and engineering applications. This work delineates the design and synthesis of a new zwitterionic material based on a naturally occurring compatible solute, ectoine, which is known to possess additional protective properties that stabilize even whole cells against ultraviolet radiation or cytotoxins. These properties and applications of ectoine inspire us to design a functional monomer containing the natural zwitterion moiety of ectoine imparting nonfouling properties and the methacrylate moiety for polymerization. The synthesis route designed for the ectoine methacrylate monomer is simple with a high yield, which is characterized by nuclear magnetic resonance spectroscopy and mass spectrometry. After monomer synthesis, we have prepared a poly(ectoine) hydrogel via thermal polymerization. The equilibrium water content, degree of cross-linking, mechanical strength, and nonfouling properties are determined for polyectoine hydrogels with different cross-linking conditions. Poly(ectoine) hydrogels are shown to have highly hydrated and excellent nonfouling properties and can be considered to be a promising biomaterial.

Ectoine as a promising protective agent in humans and animals

Ectoine is a compatible water molecule-binding solute (osmoprotectant) produced by several bacterial species in response to osmotic stress and unfavourable environmental conditions. This amino acid derivative can accumulate inside cells at high concentrations without interfering with natural processes and can protect the cell against radiation or osmotic stress. This brief review presents the current state of knowledge about the effects of ectoine on animals and focuses on its practical use for enzyme stabilisation, human skin protection, anti-inflammatory treatment, inhibitory effects in neurodegenerative diseases, and other therapeutic potential in human or veterinary medicine.