Ami Ben-Amotz

NBT Ltd Eilat Israel

Vitamin A and provitamin A carotenoids are involved in the regulation of adipose tissue metabolism and inflammation. We examined the effect of dietary supplementation using all-trans and 9-cis β-carotene-rich Dunaliella bardawil alga as the sole source of vitamin A on obesity-associated comorbidities and adipose tissue dysfunction in a diet-induced...

Valorisation of the efficacy of 9-cis beta-carotene in treating atherosclerosis, psoriasis, and inhibiting atherogenesis and retinitis pigmentosa is becoming increasingly urgent, but supplies of 9-cis beta-carotene are scarce and this compound is difficult to synthesise chemically, unlike the much more common all-trans form. Innovative products, pr...

The single-celled green alga Dunaliella salina is a model system for studies on stress biology, in particular regarding secondary carotenoid accumulation. Under non-stress conditions the cells are green, but under abiotic stress the cells turn orange, because they switch their metabolism and accumulate β-Carotene in globules in the chloroplast. For...

The green alga Dunaliella has long been a model organism for studying abiotic stress responses, and its commercial use for β-carotene production is still being expanded. In the context of the special issue on “The Alga Dunaliella”, we present an overview of the research status of Dunaliella. We highlight some of the existing challenges and provide...

Vitamin A deficiency (VAD) is a major health problem, especially in developing countries. In this study, we investigated the effect of VAD from weaning to adulthood in apoE-/- mice. Three-week-old male mice were allocated into four diet groups: I. VAD II. VAD+vitamin A (VA), 1500 IU retinyl-palmitate; III. VAD+β-carotene (BC), 6 g/kg feed, containi...

High plasma levels of LDL-cholesterol play a causative role in atherogenesis. The first step in atherogenesis is characterized by oxidation of retained LDL particles in the arterial wall, and scavenger receptors-mediated entry of oxidized-LDL into macrophages, resulting in the accumulation of cholesterol within macrophages. Therefore, cholesterol e...

The halotolerant microalga Dunaliella salina has been widely studied for natural β-carotene production. This work shows biochemical characterization of three newly isolated Dunaliella salina strains, DF15, DF17, and DF40, compared with D. salina CCAP 19/30 and D. salina UTEX 2538 (also known as D. bardawil). Although all three new strains have been...

The halotolerant microalga Dunaliella salina has been widely studied for natural β-carotene production. This work shows biochemical characterization of three newly isolated Dunaliella salina strains DF15, DF17 and DF40 compared with D. salina CCAP 19/30 (confirmed to be D. tertiolecta) and D. salina UTEX 2538 (also known as D. bardawil). Although a...

Cholesterol efflux from macrophages is a key process in reverse cholesterol transport and, therefore, might inhibit atherogenesis. 9-cis-β-carotene (9-cis-βc) is a precursor for 9-cis-retinoic-acid (9-cis-RA), which regulates macrophage cholesterol efflux. Our objective was to assess whether 9-cis-βc increases macrophage cholesterol efflux and indu...

Vitamin A is involved in regulation of glucose concentrations, lipid metabolism, and inflammation, which are major risk factors for atherogenesis. However, the effect of vitamin A deficiency on atherogenesis has not been investigated. Therefore, the objective of the current study was to examine whether vitamin A deficiency accelerates atherogenesis...

Background:Several epidemiological studies have shownthat diets rich in carotenoids are associated with a reduced risk of cardiovascular disease.However, administration of synthetic all-trans-carotene was reported to have no effect on cardiovascular disease. We previously showed that the 9-cis-carotene-rich powder of the alga Dunaliella bardawili...

Atherosclerosis is a major cause of morbidity and mortality in developed societies, and begins when activated endothelial cells recruit monocytes and T-cells from the bloodstream into the arterial wall. Macrophages that accumulate cholesterol and other fatty materials are transformed into foam cells. Several epidemiological studies have demonstrate...

The study discusses the development of an integrated process that addresses the coproduction of glycerol, β-carotene and proteins from microalgae biomass using a multitude of solvents and scoping to reduce energy consumption. An evolutionary approach is adopted in order to establish feasible and sustainable flowsheeting. Process integration is appl...

Fuel-only algal systems are not economically feasible because yields are too low and costs too high for producing microal- gal biomass compared to using agricultural residues e.g. straw. Biorefineries which integrate biomass conversion processes and equipment to produce fuels, power and chemicals from biomass, offer a solution. The CO2 microalgae b...

Introduction: β-Carotene-rich diet has been shown to be inversely associated with the risk of coronary heart disease. However, clinical trials using synthetic all-trans-β-carotene failed to demonstrate a beneficial effect. We therefore sought to study the effect of natural source of β-carotene, the alga Dunaliella, containing both all-trans and 9-...

Several species of the alga Dunaliella contain high levels of β-carotene. Low dietary β-carotene intake is associated with type 2 diabetes. Dunaliella contains high levels of all-trans and 9-cis isomers of β-carotene and is the best known naturally occurring nutritional source of 9-cis β-carotene. Since vitamin A has been suggested to play a role i...

Our aim is to increase the range of commercially viable biofuels by developing a low-cost system for producing industrial quantities of glycerol from the halophytic microalga, Dunaliella, cultivated on saline water. Glycerol can be combusted at very high efficiencies and with very low emissions without chemical alteration or the addition of combust...

This work offers an optimized method for the direct conversion of harvested Nannochloropsis algae into bio-diesel using two novel techniques. The first is a unique bio-technology-based environmental system utilizing flue gas from coal burning power stations for microalgae cultivation. This method reduces considerably the cost of algae production. T...

Fat tissue mediates the production of inflammatory cytokines and oxidative products, which are key steps in the development of type 2 diabetes and atherosclerosis. Antioxidant-rich diets protect against chronic diseases. Antioxidants may interfere with pro-inflammatory signals. To investigate the effect of the potent tomato-derived antioxidant caro...

Present data suggest that obesity is an independent risk factor for cardiovascular diseases. Enhanced lipid peroxidation leading to oxidative modification of lipoproteins may link obesity to cardiovascular morbidity. We investigated the oxidizability and plasma antioxidant vitamins in 22 subjects divided into very obese and lean groups (body mass i...

Our aim was to study the effect of 9-cis beta-carotene-rich powder of the alga Dunaliella bardawil on lipid profile, atherogenesis, and liver steatosis in high-fat diet-fed LDL receptor knockout mice. In 4 sets of experiments, mice were distributed into the following groups: control, fed an unfortified diet; Dunaliella 50, fed a diet composed of 50...

The antioxidative effect of the carotenoids phytoene and phytofluene in biological systems has not yet been studied. We therefore sought to investigate the effect of these carotenoids, isolated from the alga Dunaliella bardawil, in a biological system and used the in vitro low density lipoprotein (LDL) oxidation method to assay their antioxidative...

A number of chemical compounds are known to affect the biosynthetic pathways of β-carotene. Both site-specific inhibitors as well as general stimulators of carotenogenesis have been described. It has been reported that veratrole enhances β-carotene synthesis when applied to agar cultures of Phycomyces blakesleeanus but we found no significant stimu...

The holophilic alga Dunaliella parva produces glycerol as a major product of photosynthetic ¹⁴ CO 2 incorporation and accumulates very large amounts of intracellular glycerol. A method was adopted for the determination of the cell water space based on the distribution of ¹⁴ C sorbitol and ³ H 2 O between the cells and the medium. Using these measur...

Dunaliella bardawil Ben-Amotz & Avron, a β-carotene-accumulating halotolerant alga, was analyzed for the effect of growth temperatures on its pigment content and on the stereoisomeric composition of β-carotene by the use of advanced liquid chromatography and photodiode array detection. Decreasing culture temperature from 30° to 10°C increased the β...

Controversy exists regarding the possible protective role of carotenoids against cancer. Evidence is mainly against all-E-beta-carotene, while there is no evidence against other carotenoids or against mixtures of beta-carotene stereoisomers. Carotenoid isomers could account for the variability in study results but are rarely estimated, and referenc...

Biology and halotoleranceβ-Carotene biologyBiotechnology of β-carotene production by DunaliellaBiotechnology of phytoene productionDunaliella market productsCommercial producers

Exhaustive exercise is associated with increased metabolic rate and accelerated generation of reactive oxygen species. Cigarette smoke also contains oxidants that may participate in the development of atherosclerosis. However, data on the association between exercise and smoking are sparse. A homogenous group of 30 young men (15 smokers and 15 nons...

Gonad colour, determined by accumulated carotenoids, is an important marketability factor in sea urchin products. In this study, dietary carotenoids were fed to Paracentrotus lividus in prepared diets to test their effects on the sea urchin's gonad colour. All diets had the same basic content of protein, lipid, carbohydrate, ash and energy. Four di...

The effect of fibrates on high density lipoprotein (HDL)-cholesterol levels is suggested to be mediated by its binding to peroxisome proliferator-activated receptor-alpha (PPARalpha). Upon ligand binding, PPARalpha heterodimerizes with the 9-cis retinoic acid receptor (RXR) and it is this heterodimer which regulates gene expression. We assessed the...

Gonad colour, determined by accumulated carotenoids, is an important marketability factor in sea urchin products. In this study, dietary carotenoids were fed to Paracentrotus lividus in prepared diets to test their effects on the sea urchin's gonad colour. All diets had the same basic content of protein, lipid, carbohydrate, ash and energy. Four di...

Atherosclerosis involves oxidative and inflammatory mediators regulated by fat and antioxidants. Therefore, we studied the postprandial evolution of plasma lipids, carotenoids, C-reactive protein (CRP), and human serum paraoxanase activity (PON1) following two different fatty meals. Eight healthy males consumed a 45% fat 1,000 Kcal Mediterranean-li...

Dunaliella, a β-carotene–accumulating alga containing equal amounts of 9-cis and all-trans β-carotene stereoisomers, was compared with synthetic β-carotene composed of all-trans β-carotene with small residues of 15-cis β-carotene in rats. This study determined the bioavailability of the β-carotene stereoisomers in rats that were vitamin A depleted...

It has been suggested that exercise-induced bronchoconstriction may involve oxidative stress. Strenuous exercise promotes free radical production, which can lead to many of the pathophysiologic changes associated with asthma, including bronchoconstriction, mucus secretion, and microvascular leakage. Lycopene has been shown to have high antioxidativ...

One of the major factors influencing marketability of sea urchins is their gonad colour. The effects of a prepared diet, algal diets, and rotational feeding of these diet treatments on the European sea urchin Paracentrotus lividus were studied to determine a diet that would provide optimal gonad colour and gonadal somatic index (GSI). P. lividus un...

One of the major factors influencing marketability of sea urchins is their gonad colour. The effects of a prepared diet, algal diets, and rotational feeding of these diet treatments on the European sea urchin Paracentrotus lividus were studied to determine a diet that would provide optimal gonad colour and gonadal somatic index (GSI). P. lividus un...

Dunaliella bardawil Ben-Amotz & Avron, but not most other Dunaliella species, has a unique property of being able to accumulate, in addition to glycerol, large amounts of β-carotene when cultivated under appropriate conditions. These include high light intensity, a high sodium chloride concentration, nitrate deficiency and extreme temperatures. Und...

The lipid profile of seven species of unicellular eukaryotic microalgae grown under controlled conditions was studied with emphasis on the hydrocarbons and the fatty acids as part of a search for oil-producing algae. Green, slow-growing colonies of Botryococcus braunii Kutz contained the highest lipid content of 45% based on the organic weight, wit...

The effects of nanomolar to micromolar concentrations of the herbicide norflurazon were studied in Dunaliella bardawil Ben-Amotz et Avron, a β-carotene-accumulating halotolerant alga. The large amount of β-carotene which Dunaliella bardawil can contain, around 8% of the algal dry weight, is reduced to 0.2% by treatment with 100 nm norflurazon. Simu...

We describe a procedure for the selection of β-carotenerich mutants of the halotolerant alga Dunaliella bardawil Ben-Amotz & Avron. Under normal growth conditions the isolated mutants had a several-fold higher content of β-carotene than the wild type. Under carotene-induction conditions, the mutants also possessed a higher β-carotene content than t...

Endoscopic retrograde cholangiopancreatography (ERCP) is a commonly used procedure. Pancreatitis is its most common complication. As the injury may be mediated by oxidative stress, it could be ameliorated by antioxidants. We conducted a double-blind trial, giving the patients a single dose of natural beta-carotene or placebo, 12 hours prior to proc...

Dunaliella bardawil, a beta-carotene-accumulating alga was treated by the bleaching herbicide norflurazon to select sub-species rich with a mixture of 9-cis and all-trans stereoisomers of phytoene and phytofluene. The present study determines the bioavailability of phytoene and phytofluene with their stereoisomers in rats fed on a diet supplemented...

Obesity is among the well-established risk factors for cardiovascular morbidity and mortality. However, the exact mechanisms are not well understood. Low concentrations of vitamins (fat soluble antioxidants and B vitamins) are linked to accelerated atherosclerosis through increased oxidative stress and homocysteine. To compare plasma antioxidant vi...

We present a clinical study aimed to compare plasma antioxidant vitamins, vitamin E, beta-carotene and vitamin A. The study consisted of a group (15 patients) with rheumatoid arthritis (RA) compared to a healthy control group. There was a significant decrease in plasma vitamin E, beta-carotene and vitamin A (vitamin E 30.4 +/- 4.9 VS 43.6 +/- 8.2 m...

Lycopene has previously been shown to have high antioxidative activity. In view of the controversy regarding the beneficial effect of antioxidants on asthma, the acute effects of lycopene (LYC-O-MATO) on airway hyperreactivity were assessed in patients with exercise-induced asthma (EIA). Twenty patients with EIA participated in our study to verify...

Accelerated atherosclerosis is common in patients with diabetes mellitus which may be linked to increased lipid peroxidation. Therefore, we compared the oxidation of LDL derived from patients with diabetes to normoglycemic controls and followed-up the effect of dietary beta-carotene supplementation on LDL oxidation. Twenty patients with long-standi...

Oxidative injury by reactive oxygen species (ROS) has been suggested to explain excess prevalence of vascular complications in diabetes mellitus. ROS are normally trapped by antioxidants such as β-carotene, vitamins C and E and glutathione. The consumption of reducing equivalents in the form of NADPH may interfere with the regeneration of glutathio...

The present study demonstrated the high bioavailability and antiperoxidative capacity of the natural beta-carotene isomer mixture of Dunaliella bardawil compared with synthetic beta-carotene under alcohol-induced oxidative stress. Weanling rats were adapted to ethanol by increasing ethanol levels in their drinking water to 30% at 5% intervals per w...

The unicellular alga Dunaliella bardawil was previously shown to contain very high concentrations of beta-carotene composed of equal amounts of the all-trans and 9-cis stereoisomers which differ in their physicochemical features and antioxidative activity. Due to the controversy regarding the beneficial effect of antioxidants on asthma, the acute e...

The biflagellate unicellular alga Dunaliella thrives in media with extreme concentrations of salt in desert lands exposed to high solar radiation. Dunaliella produces and accumulates large amounts of intracellular glycerol to counter high extracellular osmotic concentration in the surrounding medium, and a high content of a mixture of β-carotene st...

Attempts were made to evaluate 709 children (324 boys and 385 girls) who had been exposed long-term to different doses of radiation during and after the Chernobyl accident and had moved to Israel between 1990 and 1994. Upon arrival, all of them underwent a check-up for most common clinical disorders and were then divided into three groups according...

The aim of this study was to investigate the balance between prooxidative and protective mechanisms in patients with acute myocardial infarction (AMI) throughout streptokinase (STK) therapy. Patients who presented to coronary care unit within 3 hours of infarction were followed. Blood was collected before, 2 and 24 hours post STK. Plasma lipid pero...

Recent epidemiological studies have directed the attention from the synthetic all-trans β-carotene to natural carotenoids predominant in fruits and vegetables as possible active ingredients for prevention of cancer and cardiovascular diseases. Seventeen fruits and 17 vegetables commonly consumed in Israel and the β-car-otene-rich alga, Dunaliella b...

16 patients with hypercholesterolemia were treated with an extract of alpha-alpha leaves (esterol) while on a low-fat, low-cholesterol diet. Esterol is believed to inhibit the absorption of cholesterol and bile acids and may interfere with the absorption of essential nutrients. As oxidative modification of lipoproteins is required for the process o...

16 patients with hypercholesterolemia were treated with an extract of alpha-alpha leaves (esterol) while on a low-fat, low-cholesterol diet. Esterol is believed to inhibit the absorption of cholesterol and bile acids and may interfere with the absorption of essential nutrients. As oxidative modification of lipoproteins is required for the process o...

β-Carotene and other carotenoids are reported to be potent free radical quenchers, singlet oxygen scavengers, and lipid antioxidants. Whole-body irradiation is known to cause an immunosuppression effect in mammals through the possible initiation and production of reactive oxygen species. We decided to test the possible antioxidative effect against...

Oxidative modification of low density lipoprotein (LDL), a key step in early atherosclerosis, is protected by the lipoprotein-associated antioxidants. The present study analyzes the effect of beta-carotene in plasma, in LDL and in monocyte-macrophages, on macrophage-mediated oxidation of LDL. We investigated the effect of dietary supplementation of...

The unicellular alga Dunaliella bardawil was shown previously to contain very high concentrations of beta-carotene composed of about equal amounts of the all-trans and 9-cis isomers, which differ in their physicochemical features and antioxidative activity. The uptake of alpha- and beta-carotenes, oxycarotenoids, and other lipophilic substances fro...

A high performance liquid chromatography (HPLC) system was developed for the simultaneous separation and identification of carotenoids, retinol, its derivatives, and tocopherols. These lipophilic and semilipophilic products were chromatographed on a C18 Vydac column and were monitored and identified using an on-line, three-dimensional photodiode ar...

Attempts to adapt the laboratory experience of bi-phasic growth and carotenogenesis in Dunaliella to large-scale conditions were highly successful. Algae were initially cultivated in stage one for optimizing biomass production of cells containing a low β-carotene to chlorophyll ratio. The culture was then transferred to stage two, diluted to about...

Atherogenesis involves oxidative modification of low-density lipoprotein (LDL), which is associated with the depletion of the LDL endogenous anti-oxidants. Thus, enrichment of LDL with the anti-oxidant β-carotene has the potential of reducing the susceptibility of LDL to lipid peroxidation. We compared a pure synthetic all-trans β-carotene isomer w...

Plasma concentrations of the antioxidants, vitamin E, beta-carotene and vitamin A were studied. 29 patients in whom at least 70% obstruction of 1 coronary artery was found, and 73 who were normal according to noninvasive tests were compared using multivariable, logistic, regression analysis. The group with coronary disease had significantly lower p...

Beta-carotenes are reported to be potent free radical quenchers, singlet oxygen scavengers, and lipid antioxidants. Oxygen free radicals that are produced in excess during exposure to oxygen at high pressures and overwhelm the body's normal antioxidant defense systems seem to mediate the hyperoxic insult. We decided to test the possible protective...

Twenty healthy males were divided into two groups: 10 subjects were supplemented for 2 weeks with 400 ml of red wine (11% alcohol) per day and the other 10 subjects were given 400 ml of white wine (11% alcohol) per day for a similar period. Blood samples were drawn prior to wine supplementation, after 1 week and at the end of the study. No signific...

Rats and chicks were fed oil soluble mixtures of all-trans and 9-cis β-carotene. Based on the level of total liver carotene and its isomeric composition, a preferential accumulation of all-trans β-carotene was observed in rats, while in chicks the 9-cis isomer was more effectively stored. This species related difference is probably due to the intes...

The functional activity of a natural isomer mixture as compared with synthetic all-trans beta-carotene in rats was investigated in a rat model produced by water-immersion restraint stress. Five-week-old male rats were fed diets supplemented with synthetic all-trans beta-carotene, dry Dunaliella bardawil, and purified natural beta-carotene from D. b...

As a possible step to estimate the mechanism of the inhibitory role of Dunaliella bardawil (Db) in the initial progression of spontaneous mammary tumours of SHN virgin mice, the DNA synthesizing enzyme activities and the in vivo 31P-NMR spectroscopy of normal and neoplastic mammary cells were examined in mice fed Db. The blood levels of glucose and...

The synthetic all-trans isomer of beta-carotene was recently shown to possess antioxidant properties towards the formation of oxidized low density lipoprotein. In the present study, the binding of the all-trans and the 9-cis isomers of beta-carotene to plasma lipoproteins was investigated, and the effect of these isomers on the susceptibility of pl...

Gastrointestinal injury involves oxidative damage as the result of oxygen-derived free radicals which are formed during the inflammatory reactions. Chylomicrons which are synthesized by the intestine can thus be exposed to lipid peroxidation in celiac disease. Similarly, low-density lipoprotein (LDL) propensity to oxidation may be enhanced as a res...

A strain of Chlorella emersonii grown under high light intensity and low nitrogen degrades its chlorophyll and synthesizes canthaxanthin as the major carotenoid. Nitrogen starvation or high light alone does not induce canthaxanthin production. Norflurazon, a carotene inhibitor at the level of phytoene desaturase, inhibits production of canthaxanthi...

The synthetic all-trans isomer of beta-carotene was recently shown to possess antioxidant properties towards the formation of oxidized low density lipoprotein. In the present study, the binding of the all-trans and the 9-cis isomers of beta-carotene to plasma lipoproteins was investigated, and the effect of these isomers on the susceptibility of pl...

The purpose of this work was to test whether induction of massive -carotene synthesis in the alga Dunaliella bardawil is triggered by oxygen radicals. The following results were obtained: (i) The induction of -carotene synthesis is preceded by a lag period of about 4 h during which the cells swell and photosynthesis is partially inhibited, (ii) Add...

The chlorophyte Dunaliella is classified under the order Volvocales, which includes a variety of ill-defined unicellular species. Members of the genus Dunaliella are all motile, ovoid biflagellates with a cell volume ranging from 50 to 1000 µm3 (Butcher, 1959). The alga contains one large chloroplast with a single pyrenoid and many starch granules...

Phycomyces blakesleeanus, a β-carotene—producing fungi, has been tested as a source of vitamin A and β-carotene in the rat diet. The β-carotene in the fungi is composed of 80–90% of the all-trans stereoisomer, and the rest is the 9-cis stereoisomer. Female weanling rats were fed a vitamin A-deficient diet for 60 days. Thereafter, the rats were divi...

Publisher Summary Unicellular algae of the genus Dunaliella are classified in the order Volvocales, of the class Chlorophyta. Dunaliella are ovoid in shape, contain one large cup-shaped chloroplast, and are motile with two equal long flagellae. They lack a rigid polysaccharide cell wall and the cell is enclosed by an elastic plasma membrane Dunalie...

Dunaliella accumulates massive amounts of β-carotene when cultivated under high light intensity and growth-limiting conditions. The pathway for biosynthesis of β-carotene was elucidated by analysis of the effect of selected inhibitors. The presence of the inhibitors elicited the accumulation of the following intermediates: β-zeacarotene, lycopene,...

The relationship between growth rate, dry weight and epiphyte biomass of Gracilaria conferta (Schousboe) J. & G. Feldman was determined as a function of diverse environmental conditions in an outdoor pulse nutrient addition cultivation system. The independent variables were seawater treatments (pH control, interrupted aeration and water recycling),...

In vitro oxidation of plasma lipoproteins, derived from either normolipidemic or hypercholesterolemic subjects, was performed in the presence of copper ions. Following this procedure, hypercholesterolemic low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) demonstrated greater propensity for oxidat...

We previously found that beta-carotene-rich algae Dunaliella bardawil markedly inhibited spontaneous mammary tumourigenesis of mice. This study was carried out to clarify whether D. bardawil inhibits the development or the progression or both of mammary tumours. A high mammary tumour strain of SHN virgin mice were given vitamin A deficient AIN-76TM...

High plasma and tissue levels of beta-carotene have been implicated to be inversely related to the incidence of some types of cancer. Previous studies indicated that the availability of the natural beta-carotene isomer mixture of Dunaliella bardawil was severalfold higher than that of synthetic all-trans beta-carotene. This study illustrated that t...

-Carotene steroisomers, mainly all-trans and to a small extent 9-cis, may be produced by the fungus Phycomyces blakesleeanus under normal fermentation conditions. The amount of the 9-cis--carotene may comprise up to 15% of the total -carotene. Similarly, cis-lycopene or-phytoene stereoisomers may be obtained when the fungus is fermented in the pres...