Antioxidant activities of natural 9-cis and synthetic all-trans β-carotene assessed by human neutrophil chemiluminescence

Assessment of carotenoid production by Dunaliella salina in different culture systems and operation regimes

The effect of operation regime and culture system on carotenoid productivity by the halotolerant alga Dunaliella salina has been analyzed. Operation strategies tested included batch and semi continuous regime, as well as a two-stage approach run simultaneously in both, open tanks and closed reactor. The best results were obtained with the closed tubular photobioreactor. The highest carotenoid production (328.8 mg carotenoid l⁻¹ culture per month) was achieved with this culture system operated following the two-stage strategy. Also, closed tubular photobioreactor provided the highest carotenoid contents (10% of dry weight) in Dunaliella biomass and β-carotene abundance (90% of total carotenoids) as well as the highest 9-cis to all-trans β-carotene isomer ratio (1.5 at sunrise).

Comparative evaluation of hepatoprotective activity of carotenoids of microalgae

The present study deals with evaluation of the hepatotoprotective activity of carotenoids from two well-known microalgae, Spirulina platensis and Dunaliella salina. Carotenoids were extracted in hexane:isopropyl alcohol (1:1 vol/vol) and fed orally in olive oil to Wistar albino rats at a dose of 100 microg/kg of body weight/day (in terms of carotenoids). The degree of hepatoprotection was measured by estimation of biochemical parameters like serum transaminases [serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT)], serum alkaline phosphatase, total albumin, and total protein. The results were compared with those for a control group, a CCl4-induced hepatic damage group, and a group treated with synthetic beta-carotene (all-trans) at the same dose. The protein content of the CCl4-treated group, which received normal diet and a dose of toxin, showed a significant decrease, i.e., 3.92 mg/mL, whereas the protein levels were higher, i.e., 6.96 and 6.32 mg/mL, in the case of the Dunaliella and Spirulina, respectively, carotenoid-treated groups. The CCl4-treated group shown higher activity of transaminases (128.68 units/mL SGPT and 171.52 units/mL SGOT). However, the activity of SGPT was 62.83 units/mL for Dunaliella and 76.83 units/mL for Spirulina, i.e., carotenoids of Dunaliella showed a higher degree of protection. For serum alkaline phosphatase, the standard beta-carotene value was 81.52 units/mL, compared with 84.46 units/mL for the CCl4-treated group; however, natural algal carotenoids yielded 38.45 units/mL (D. salina) and 44.73 units/mL (Spirulina). The total albumin value diminished with CCl4 treatment (2.46 mg/mL); the effect was highest for Dunaliella, followed by the Spirulina carotenoid-treated group. The results clearly indicate that carotenoids from Dunaliella possess better hepatoprotection compared with those from Spirulina. High-performance liquid chromatography of the carotenoids indicated that Spirulina contains only beta-carotene and Dunaliella contains other carotenoids and xanthophyll. The increase in protection with Dunaliella indicates that mixed carotenoids exhibit better biological activity than beta-carotene alone. The results of this study indicate that carotenoids obtained from an algal source have a higher antihepatotoxic effect, compared with synthetic beta-carotene and with beta-carotene alone from a natural source.

Carotenoid actions and their relation to health and disease

Based on extensive epidemiological observation, fruits and vegetables that are a rich source of carotenoids are thought to provide health benefits by decreasing the risk of various diseases, particularly certain cancers and eye diseases. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein and zeaxanthin. In part, the beneficial effects of carotenoids are thought to be due to their role as antioxidants. beta-Carotene may have added benefits due its ability to be converted to vitamin A. Additionally, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye. Food sources of these compounds include a variety of fruits and vegetables, although the primary sources of lycopene are tomato and tomato products. Additionally, egg yolk is a highly bioavailable source of lutein and zeaxanthin. These carotenoids are available in supplement form. However, intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.

Effect of the isocoumarin paepalantine on the luminol and lucigenin amplified chemiluminescence of rat neutrophils

Paepalantine (9,10-dihydroxy-5,7-dimethoxy-1H-naphto(2,3c)pyran-1-one), a natural isocoumarin isolated from the capitula of Paepalanthus bromelioides (Eriocaulaceae), was assessed for its effect on the respiratory burst (zymosan-stimulated luminol-enhanced chemiluminescence and PMA-stimulated lucigenin-enhanced chemiluminescence) of polymorphonuclear neutrophils in vitro. Special attention was devoted to establishing the IC(50) for neutrophils. Paepalantine was able to decrease luminol and lucigenin chemiluminescence, reflecting an inhibitory effect on the respiratory burst, with an ED(50) of 0.44+/-0.05 and 0.84+/-0.15 microg/ml, respectively. A cell-free system was performed with paepalantine on myeloperoxidase/H(2)O(2) and myeloperoxidase/H(2)O(2)/Cl(-) systems. Paepalantine inhibited luminol oxidation in both systems. This inhibition was related to the interaction of paepalantine-myeloperoxidase and its scavenger effect on HOCl.