Evaluation of Dunaliella salina growth and corresponding ß-carotene production in tubular photobioreactor / Avaliação do crescimento da Dunaliella salina e correspondente produção de ß-caroteno em fotobiorreator tubula

Microalgae, photosynthetic microorganisms, are rich in lipids, polyunsaturated fatty acids, carbohydrates, proteins, vitamins, as well as carotenoids, which are antioxidants that may protect human body from various diseases including obesity, cardiovascular disease, vision-related diseases such as macular degeneration and certain types of cancer. These natural pigments have applications in the pharmaceutical (nutraceutical), food (coloring, functional food, and supplements), and cosmetics industries (e.g. sunscreen), as well as in aquaculture (animal feed). The Dunaliella salina microalga can synthesize 10% of dry weight in ß-carotene (orange pigment, pro-vitamin A activity) under high light intensity and nitrogen and phosphorus limitation, among other stress conditions. The first chapter of this thesis presents a review focused on microalgae carotenoids: culture systems, mode of operation, and applications. In this bibliographic survey, the advantages of microalgae cultivation in relation to traditional sources (higher plants) were discussed, as well as a discussion of the main cultivation systems and their importance in cell growth. This review presented a critical analysis of the different operational regimes like batch, fed-batch, semi-continuous and continuous. Relevant information on the most important world producers of microalgae carotenoids were presented. Chapter II presents the development of a modified method of dispersive liquid-liquid microextraction (DLLME) for rapid extraction of ß-carotene from Dunaliella salina cultivated in tubular photobioreactor, with subsequent development of a rapid chromatographic screening method using a C4 column for separation of geometric isomer of ß-carotene. The use of benzene as extraction solvent and water with 50% acetone as dispersant provided the best condition for the extraction of this carotenoid. In HPLC (High Performance Liquid Chromatography), employing mobile phase composed of methanol and water (95:5, v/v), it was possible to detect/quantify ß-carotene at 14 min (retention time). Besides the short analysis time (<20 min), by the miniaturized extraction (< 10 mL organic waste) this method abide by green chemistry analytical principles. It is known that nitrogen, phosphorus, as well as carbon and vitamins are vital elements for the growth of microalgae, also determining the biochemical composition of biomass. In this sense, Chapter III presents the study of the influence of different amounts of sodium nitrate (1N = 75 mg L-1; 1.5N = 112.5 mg L-1, and 3N = 225 mg L-1) and phosphate monobasic dehydrate (1P = 5.65 mg L-1, 1.5P = 8.47 mg L-1, and 3P = 16.95 mg L-1) in seawater-based f/2 medium on the growth of Dunaliella salina and ß-carotene biosynthesis, by continuous process with different replenishment proportions (R = 20% and 80%). Best results of cell productivity were obtained by semicontinuous process (mean values of Px up to 6.7 x 104 cells mL-1 d-1 with medium 1N:1P; R =20%) in comparison with batch process cultivation. Maximum cell density (Xm) obtained in this work was not dependent of R, but the best results were obtained when using medium 1.5N:1.5P (mean values up to 5.6 x 105 cells mL-1 with R =80%) instead of 1N:1P. The content of ß-carotene in the cells, in general, was higher in cells grown in medium 1N:1P (mean yield values up to 57.5 mg g-1 with R =80%) in comparison with medium 1.5N:1.5P. The cultivation of D. salina with media 3N:3P led to a long lag phase, followed by decrease in cell density and cell lysis. The use of a tubular photobioreactor contributed to successfully cultivate this microalga without contamination by protozoa. The cultivation of Dunaliella salina in tubular photobioreactor with the use of 12:12 photoperiod was appropriate, as well as to induce carotenogenesis, in the second stage, by increasing the light intensity and absence of pH control

As microalgas, micro-organismos fotossintetizantes, são ricas em lipídios, ácidos graxos poli-insaturados, carboidratos, proteínas, vitaminas, além de carotenoides que são antioxidantes com potencial de proteger o organismo humano de várias doenças incluindo a obesidade, doenças cardiovasculares, doenças relacionadas à visão como a degeneração macular e certos tipos de câncer, entre outras. Esses pigmentos naturais têm aplicações em indústrias farmacêuticas (nutracêuticos), alimentícias (colorantes, alimentos funcionais e suplementos) e de cosméticos (exemplo: filtro solar) e na aquacultura (ração animal). A microalga Dunaliella salina é capaz de sintetizar, sob alta intensidade luminosa e limitação de nutrientes como fontes de fósforo e nitrogênio, dentre outras condições de estresse, 10 % do peso seco em ß-caroteno (pigmento laranja com atividade pró-vitamina A). Assim, neste trabalho, numa primeira etapa, foi feita uma revisão da literatura abordando a produção de carotenoides por microalgas, bem como sua aplicação. Nesse levantamento bibliográfico abordou-se, dentre outros assuntos, as vantagens do cultivo de microalgas em relação as fontes tradicionais (plantas superiores), assim como uma discussão dos diferentes sistemas de cultivos e sua importância no crescimento celular. Esse review apresentou uma análise crítica dos principais regimes operacionais como batch, fed-batch, semicontínuo e contínuo. Apresentou-se também informações relevantes sobre os mais importantes produtores mundiais de carotenoides de microalgas. Numa segunda etapa, foi desenvolvido um método modificado de microextração líquido-líquido dispersivo modificado (DLLME) para a rápida extração de ß-caroteno de Dunaliella salina cultivada em fotobiorreatores tubulares, com subsequente desenvolvimento de método cromatográfico em uma coluna C4 para a separação do isômero geométrico de ß-caroteno. A extração ótima de ß-caroteno foi obtida com benzeno como solvente extrator e água com 50% de acetona como dispersante. Empregando uma fase móvel composta por metanol e água (95:5, v/v) em HPLC, foi possível a detecção/quantificação de ß-caroteno com 14 minutos de tempo de retenção. Além dos tempos curtos de análises (<20 min), pela extração em volume reduzido (< 10 mL resíduos orgânicos) este método obedece aos princípios da química verde. Sabe-se que nitrogênio, fósforo, assim como carbono e vitaminas são elementos vitais para o crescimento das microalgas e também exercem influência na composição bioquímica da biomassa. Assim, na terceira etapa deste trabalho, estudou-se a influência das quantidades de nitrato de sódio (75 mg L-1, denominado 1N; 112,5 mg L-1, denominado 1,5N; 225 mg L-1, denominado 3N) e de fosfato monobásico dihidratado (5,65 mg L-1, denominado 1P; 8,47 mg L-1, denominado 1,5P; 16,95 mg L-1, denominado 3P) em meio f/2, que tem como base a água do mar, no crescimento e na síntese de ß-caroteno da Dunaliella salina por processo semicontínuo, com uso de frações de corte (R) de 20% e 80%. Foram obtidas produtividades celulares mais elevadas em processos semicontínuos do que em processo descontínuo, com produtividades médias de até 6,7 x 104 células mL-1 d-1 (meio 1N:1P; R =20%). A máxima concentração celular (Xm) obtida neste trabalho não foi dependente de R. Os melhores resultados de Xm foram obtidos quando se usou meio 1,5N:1,5P em vez de meio, com 1N:1P, com valores médios de até 5,6 x 105 células m L-1 (R =80%). O conteúdo de ß-caroteno nas células, de maneira geral, foi maior nas células cultivadas em meio 1N:1P do que no meio 1,5N:1,5P, com valores até 57,5 mg g-1 (R =80%). O cultivo de D. salina com o meio 3N:3P levou a uma longa fase lag, seguida por uma diminuição na concentração celular e sua lise. O cultivo de células em um fotobiorreator tubular contribuiu para um crescimento celular sem contaminação por protozoários. O cultivo de Dunaliella salina em fotobiorreator tubular com o uso de fotoperíodo 12:12 foi apropriado, assim como induzir a carotenogênese, no segundo estágio, por meio do aumento da intensidade luminosa e ausência de controle de pH

Protective and therapeutic potentials of Dunaliella salina on aging-associated cardiac dysfunction in rats

Objective: To investigate the possible protective and/or therapeutic potentials of Dunaliella salina (D. salina) biomass, its carotenoid and polar fractions on cardiac dysfunction associated with D-galactose (D-GAL) induced aging in rats. Methods: Aging associated cardiac dysfunction was induced in rats by injection of D-GAL (200 mg/kg; i.p) for 8 weeks. D-GAL injected rats were treated with two regimens; protective regimen where D. salina biomass (250 mg/kg), its carotenoid (250 μg/kg) and polar (250 μg/kg) fractions were given orally for two weeks concurrently with D-GAL injection as well as treatment regimen where the three treatments were given orally for 28 consecutive days after D-GAL injection. Results: D-GAL injection for 8 weeks was accompanied with dramatic electrocardiographic changes as well as profound elevation in serum levels of homocysteine, creatinine kinase isoenzyme and lactate dehydrogenase in addition to the reduction of the cardiac content of glucose trasporter 4. D-GAL also induced reduction in cardiac superoxide dismutase activity and elevation of inducible nitric oxide synthetase and interleukin-6. On the other hand, oral administration of D. salina carotenoid fraction as well as the total biomass significantly attenuated the D-GAL-induced disturbances in the above mentioned parameters where the protective regimen appeared more successful in controlling the manifestations of cardiac dysfunction. The histopathological examination further emphasized the promising results. Besides, the HPLC analysis of the carotenoid fraction of D. salina revealed the presence of 2.31％ β-carotene. Conclusions: D. salina carotenoid fraction as well as the total biomass ameliorate D-GAL-induced aging associated cardiac dysfunction which is attributed to the potent antioxidant activity of β-carotene.

Protective and therapeutic potentials of Dunaliella salina on aging-associated cardiac dysfunction in rats

Objective: To investigate the possible protective and/or therapeutic potentials of Dunaliella salina (D. salina) biomass, its carotenoid and polar fractions on cardiac dysfunction associated with D-galactose (D-GAL) induced aging in rats. Methods: Aging associated cardiac dysfunction was induced in rats by injection of D-GAL (200 mg/kg; i.p) for 8 weeks. D-GAL injected rats were treated with two regimens; protective regimen where D. salina biomass (250 mg/kg), its carotenoid (250 μg/kg) and polar (250 μg/kg) fractions were given orally for two weeks concurrently with D-GAL injection as well as treatment regimen where the three treatments were given orally for 28 consecutive days after D-GAL injection. Results: D-GAL injection for 8 weeks was accompanied with dramatic electrocardiographic changes as well as profound elevation in serum levels of homocysteine, creatinine kinase isoenzyme and lactate dehydrogenase in addition to the reduction of the cardiac content of glucose trasporter 4. D-GAL also induced reduction in cardiac superoxide dismutase activity and elevation of inducible nitric oxide synthetase and interleukin-6. On the other hand, oral administration of D. salina carotenoid fraction as well as the total biomass significantly attenuated the D-GAL-induced disturbances in the above mentioned parameters where the protective regimen appeared more successful in controlling the manifestations of cardiac dysfunction. The histopathological examination further emphasized the promising results. Besides, the HPLC analysis of the carotenoid fraction of D. salina revealed the presence of 2.31% β -carotene. Conclusions: D. salina carotenoid fraction as well as the total biomass ameliorate D-GAL-induced aging associated cardiac dysfunction which is attributed to the potent antioxidant activity of β -carotene.

Changes of the Total Lipid and Omega-3 Fatty Acid Contents in two Microalgae Dunaliella Salina and Chlorella Vulgaris Under Salt Stress

ABSTRACT Effect of salt stress on biomass, cell number, contents of total lipid, omega-3 fatty acids, including ALA (Alpha Linolenic Acid), EPA (Eicosapentaenoic Acid) and DHA (Docosahexaenoic Acid) and their biosynthetic pathway intermediates (palmitic acid, stearic acid, oleic acid and linoleic acid) of two microalgae Dunaliella salina and Chlorella vulgaris were investigated. Dilution stress from 1.5 to 0.5 M NaCl and salt stress from 1.5 to 3 M NaCl were incorporated into the D. salina medium. Salt stress of 200 mM NaCl was also applied to C. vulgaris culture. Results indicated that increasing salt concentration resulted in the reduced growth rate of C. vulgaris and substantial increase of the total lipid content in both species. Proper growth rate of D. salina observed at 1.5 M of NaCl, but higher and lower concentrations led to the decreased growth rate of D. salina. In addition, considerable increase in the degree of fatty acid unsaturation and thereby the total omega 3 fatty acid content of D. salina was observed under salt stress. Salt stress had little positive effect on the amount of total omega-3 fatty acid of C. vulgaris due to the slight increase of the EPA content. Results showed that salt stress is an effective way for enhancing the total lipid and omega-3 fatty acid production in D. salina.

Effects of menthone and piperitone on growth, chlorophyll a and β-carotene production in Dunaliella salina.

Recently, studying essential oils and secondary metabolites of plants and microalgae have received much attention. The biosynthesis of the secondary metabolites is strongly influenced by different environmental factors. Monoterpenes as a main fraction of essential oils of fruits and vegetables have many clinical applications. They could inhibit the carcinogenesis processes and therefore might be effective in treatment of cancers. Dunaliella salina, a photosynthetic green microalga is known as a rich source for β-carotene production. In this study, the effects of some monoterpenes including menthone and piperitone was investigated on yield of production of β-carotene were studied. Menthone and piperitone as parameters of stress can make tensions to the medium of D. salina increasing its β-carotene and chlorophyll a content in every single cell but on the other hand these two monoterpenes cause a decrease in the concentration of β-carotene and chlorophyll a.

Investigating the effects of phytohormones on growth and β-carotene production in a naturally isolates stain of Dunaliella salina.

The algae of the genus Dunaliella especially D. salina is among the microalgae most studied for mass culture. This alga is the richest algal source of glycerol and β-carotene, which is grown as a food source in aquaculture. In this study the effect of growth regulators (kinetin, gibberellic acid, indole-3-acetic acid, 6γ, γ-dimethylallyl aminopurine, salicylic acid and benzyl aminopurine) on the growth and β-carotene production in D. salina (MCCS 001) was investigated. Results pointed out that the β-carotene content and cell growth of D. salina could achieve the highest rates when kinetin and indole-3-acetic acid were used at 1 µM. Besides, it was shown that almost all of plant hormones has a positive effect on cell growth and β-carotene production in the microalga D. salina.

Effects of osmotic shock on production of β-carotene and glycerol in a naturally isolated strain of Dunaliella salina.

In the present study, the effects of hypo-osmotic and hyper-osmotic shock on β-carotene and glycerol production by a native strain of Dunaliella salina isolated from Maharlu Salt Lake, Fars province, Iran, were investigated. The amount of β-carotene and glycerol at 1 h, 2 h, 8 h and 24 h after initiating hypo-osmotic (1 M NaCl) and hyper-osmotic shocks (3 M NaCl); and at normal condition (2 M NaCl) were measured. At hyper-osmotic medium, β-carotene concentration reached to maximum amount after 2 h and remained constant up to 24 h. Even so, increasing of glycerol concentration was initiated after 2 h and reached the highest value at 24 h after salinity stress induction. At hypo-osmotic shock, β-carotene and glycerol concentrations were decreased. There are lots of lakes and salt marshes in Iran, which can be suitable environments for growing D. salina. So it seems that the isolated D. salina is potentially useful for planting in small locations to promote the commercial production of β-carotene and glycerol.

Effects of Sodium Nitrate and Mixotrophic Culture on Biomass and Lipid Production in Hypersaline Microalgae Dunaliella Viridis Teod

To access the potential application of Dunaliella viridis Teod. for biofuel production, the effects of culture media composition on biomass and lipid content of this microalgae were investigated. Measured at the 20 th day, sodium nitrate at 5.0 mM augmented biomass production by 26.5 percent compared to control (1 mM sodium nitrate). Total lipids expressed as µg mL-1 of culture also increased with increase in nitrate concentration up to 5.0 mM sodium nitrate, whereas when expressed on the per cell basis, total lipids stayed relatively constant at most of the tested nitrate concentrations except at 0.5 mM which was 31.4 percent higher compared to 1.0 mM nitrate. At 5.0 mM sodium nitrate, by using 20 g L-1 of glucose in mixotrophic culture of D. viridis, cell number augmented by 36.4 percent compared to the cultures with no added glucose. Llipid content per cell and per mL of culture was increased by 71.4 and 135.1 percent, respectively. Among plant hormones, 10-9 M indole-3- acetic acid (IAA) plus 10 -8 M trans-zeatin riboside led to 22.8 percent higher biomass relative to control (without hormone and at 1.0 mM sodium nitrate). It is concluded that altering the growth conditions of D. viridis can lead to higher cell densities and higher lipids content which can be exploited for biofuel production.

Biotechnological applications of microalgae

Microalgae are important biological resources that have a wide range of biotechnological applications. Due to their high nutritional value, microalgae such as Spirulina and Chlorella are being mass cultured for health food. A variety of high-value products including polyunsaturated fatty acids (PUFA), pigments such as carotenoids and phycobiliproteins, and bioactive compounds are useful as nutraceuticals and pharmaceuticals, as well as for industrial applications. In terms of environmental biotechnology, microalgae are useful for bioremediation of agro-industrial wastewater, and as a biological tool for assessment and monitoring of environmental toxicants such as heavy metals, pesticides and pharmaceuticals. In recent years, microalgae have attracted much interest due to their potential use as feedstock for biodiesel production. In Malaysia, there has been active research on microalgal biotechnology for the past 30 years, tapping into the potential of our rich microalgal resources for high-value products and applications in wastewater treatment and assessment of environmental toxicants. A culture collection of microalgae has been established, and this serves as an important resource for microalgal biotechnology research. Microalgal biotechnology should continue to be regarded as a priority area of research in this country.

Photoperiod influences endogenous indoleamines in cultured green alga Dunaliella bardawil.

Effect of light intensity and photoperiod on growth, indoleamines and carotenoid production was studied in unicellular green algae D. bardawil. Maximum biomass and carotenoid contents were found when cultures were grown in light (intensity of 2.0 Klux) at a photoperiod of 16/8h light and dark cycle. There was a profound influence of tested photoperiod conditions of light:dark viz. 8:16, 10:14, and 12:12 hr, continuous light on indoleamines (SER and MEL) production as estimated by HPLC and confirmed by mass spectral data obtained from LC-MS-ESI studies. Serotonin level increased from 908 to 1765 pg/g fresh wt with increase in light duration and melatonin level increased from 267 to 584 pg/g fresh wt during increase in dark phase. Carotenoids production was high in continuous light than other tested conditions.

Preliminary Study on Transformation of Human canstatin Gene to the Novel Bioreactor——Dunaliella salina / 中国生物工程杂志

The human canstatin cDNA was amplified by RT-PCR and then directionally cloned into pU? expression vector. The recombinant pU?-Can vector was connected with the screening marker (bar box), to construct a eukaryotic expression vector called pU?-Can-Bar. This expression vector was introduced into the D.salina by glass beads method. The screening culture of transformants of D.salina was performed in solid media containing 5 ?g/ml PPT, and the analyses of transformants were carried out through PCR and Southern blot. PCR results revealed that specific 700 bp products were detected in the different transformants of D.salina but not in negative control. Southern blot analysis further demonstrated that human canstatin gene was integrated into the D.salina genome. Moreover, the results of genetic stability analyses of transformants demonstrated that canstatin gene was stably inherited in the D.salina transformants. The successful preparation of the D.salina transformants will provide the experimentation evidence for producing canstatin protein cosmically by using the D.salina bioreactor and give a better prophase work basis for clinic application of canstatin protein early.

Prospect and Progress on Dunaliella salina in the Area of Molecular Biology / 中国生物工程杂志

Unicellular green alga,Dunaliella salina(D.salina),is a biflagellar alga without cell wall,which is a kind of very important eukaryotic microalga.In the previous study,the research of D.salina focus on the morphology,the mechanism of salt tolerance and ?-carotene,however,with the rapid development of microalgal biotechnology,a lot of work about D.salina was reported in recent years.In the area of molecular biology,the studies of D.salina mainly place emphasis on the cloning and analysis of important functional genes,regulatory sequences,and the expression of foreign genes using D.salina as host.The research advance in these aspects were reviewed.

Comparison of Stable Expressions of Foreign Genes Driven by Different Promoters in Transgenic Dunaliella salina / 中国生物工程杂志

The purpose was to compare the difference between transgene expressions driven by homologous duplicated carbonic anhydrase (DCA) promoter and foreign CaMV35S promoter in the unicellular green alga, Dunaliella salina(D.salina).The CaMV35S promoter-bar construct and DCA promoter-bar construct into D.salina by a Backon 2000 electroporation system were introduced. After the repeated selections with the phosphinothricin (PPT) of 3mg/L, 3 PPT-resistant phenotype transformants were isolated from the CaMV-bar and DCA-bar pools of transformants of D. salina, respectively. The results of PCR and sequencing showed that bar genes were stably integrated into the genome of D.salina, and Southern bolts showed the number of transgene copy had no significant difference between both promoters. Semi-quantitive RT-PCR indicated that the mRNA levels of bar gene were higher in DCA-bar transformants than the CaMV-bar transformants, and could be increased under the induction of high salt in DCA-bar transformants but not in the CaMV-bar transformants. Analysis of growth rate of transformants showed DCA-bar transformants achieved the log stage faster than the CaMV-bar transformants. It is concluded that the homologous promoters have more advantages than the foreign promoters in the transgenic D.salina.

Cloning and Characterization of 5′Flanking Region of Nitrate Reductase Gene Derived from Dunaliella salina / 中国生物工程杂志

Aim: Clone and characterize of the 5′- flanking region of the nitrate reductase (NR) gene derived from Dunaliella salina(D. salina). Methods : The genomic DNA from D. salina was respectively digested with BamHI, EcoRI, HindIII, Pst I, Sal I and Xba I. A genomic walking cassette was ligated to the ends of the digested DNA fragments, and then genomic walking libraries comprising BL, EL, HL, PL, SL and XL were constsucted. The 5′- flanking region of the NR gene from genomic walking libraries of D. salina was amplified by LA-PCR. The DNA sequences were analyzed with the software - Promoter Predictions. Isolated 5′-flanking regions fused to the GUS gene were tested for transient expression in the alga. Results: A single specific PCR product of about 1200bp in length from the HL library was generated. Also, several conserved motifs, such as CAAT-box, GAGA-box were found, which are related to regulation of transcription, and the putative binding sites of transcriptional factors such as EBP, EFII, NF-E1 and LV. BLAST showed that the DNA sequences shared high homology with 5′-upstream region of the NR gene from Dunaliella viridis. The isolated 5′-flanking regions were able to strongly drive GUS reporter gene expression, suggesting that it contains the promoter elements necessary for the transcription of the NR gene. The expression pattern of the GUS gene and the NR gene were similar, both ware induced by nitrate and repressed by ammonium. Conclusion: The cloned 5′- flanking sequences of NR gene derived from D. salina might be a specific promoter with the ability to“switch on or off” an expression of the heterologous gene in transgenic D. salina.

Study on Main Active Components in the Extract of Dunaliella Salina / 中国中医药信息杂志

Objective To provide a basis for further exploration of Dunaliella Salina by determining the main active components in the extract of Dunaliella salina. Methods The carotenoids and vitamins were determined by HPLC or colorimetric method, amino acids were analyzed by amino acid analyze. Unsaturated fatty acid was determined by GC. Atomic absorption spectrophotometry was used to detect K, Na ,Ca, Mg, Cu, Zn, P, Fe, Mn and SPF was used to detect Se. Results There were affluent carotenoids, vitamins, amino acids, unsaturated fatty acid and trace elements in the extract of Dunaliella salina. Conclusion The extract of Dunaliella salina could be used as natural raw material to develop the supplement food.

Extraction and purification of the polysaccharides from Dunaliella salina(PDS) residue / 中国海洋药物

Objective To study the extraction and purification of polysaccharides from D.salina residue after extraction of ?-carotene.Methods The crude polysaccharide was extracted by hot basic water,and then was isolated and purified by the DEAE-cellulose and Sepharose-4B.Results After having been purified by DEAE-cellulose chromatography,three components named PDS_(1),PDS_(2),PDS_(3)were obtained.Each component was divided into two components by Sepharose-4B chromatography,then six components were obtained.Conclusion The six components were identified to be homogeneous polysaccharide-protein complexes which were composed of sulfate radical and uronic acid.

Preparation of ?-carotene microemulsion from Dunaliella salina and its stability / 中国海洋药物

Objective To preparare the ?-carotene microemulsion (?-cm)from Dunaliella salina and study its stability.Methods The influences of some factors on the stability of ?-cm were studied.These factors included light,temperature,air(oxygen),storing time and so on.Results The appearance,color,Zeta potential,volume-Wt diameter and K_(e) were unchanged,but content of ?-cm was decreased with higher temperature(40℃)or stronger light(4500?500L_(x)).Conclusion The preparation should be stored at low temperature and keep away from light.Under this circumstance,the ?-cm was stable for more than 12 months.

Promoting effects of beta-carotene from Dunaliella Salina on learning and memory in rats and mice / 中国海洋药物

The effects of ?-carotene from Dunaliella salina(?-C) at three doses(12.5,25 and 50 mg?kg~(-1),ip) on learning and memory in rats and mice were studied by using step-down test and Y-maze test.In step-down tests,?-C at all three tested doses had significant effects on normal mice,and could remarkably antagonize the memory impairment induced by scopolamine and 20 % alcohol,but could not antagonize the impairment induced by sodium nitrite.As the same result,?-C at three tested doses administration had significant effects on rats in Y-maze tests.These results suggested that ?-C as an antioxidant could improve the ability of learning and memory in rats and mice.