Shrimp is an important traded fishery commodity. When subjected to stress, shrimp usually suffers from oxidative stress, which leads to cell injury, senescence, and death. To maintain shrimp good health, performance and production, antioxidant and immune systems are important. Natural antioxidants found in microalgae may be used to increase the cell protection against oxidative damage, being a promising alternative to the carcinogenic synthetic antioxidants. In this study, Tetraselmis chuii was evaluated for its effect on survival, growth and oxidative stress biomarkers on Litopenaeus vannamei postlarvae (PL). The antioxidant properties of the formulated feed with T. chuii inclusion were determined using four antioxidant chemical assays. Meanwhile, the oxidative stress biomarkers on PL were analyzed by hydrogen peroxide, membrane stability and lipid peroxidation assays. Results showed that PL reared on diets supplemented with 50% T. chuii had a significantly higher (P B 0.05) survival (97.6 ± 1.4%) and lower oxidative stress in terms of hydrogen peroxide content (10.08 ± 0.4 mM g -1 FW) and electrolyte leakage (10.8 ± 0.3%). The result of this study also showed that shrimp PL reared on diets supplemented with microalgal, T. chuii have high resistance to reverse salinity stress test (76.7-100%). However, no significant differences (P C 0.05) were found in the growth and lipid peroxidation. Due to the positive effect on oxidative stress status, survival and resistance to salinity stress, the feeding of L. vannamei PL with diet containing at least 50% of T. chuii is recommended as a natural source of antioxidant for PL.

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Microalgae are rich in natural antioxidants, with occurrence and quality depending primarily on the species of microalgae and the conditions of cultivation. Light and photoperiod affect microalgae accumulation of antioxidants. This study examined the growth, biomass, and antioxidant responses of microalgae Chlorella vulgaris (UMT-M1), Isochrysis galbana (CB), and Tetraselmis chuii (CT) grown in 30 ppt F/2-enriched seawater and exposed to 12:12 and 24:0 hours light/dark cycles at 24°C ± 2°C. Overall cell density, wet biomass, chlorophyll a, chlorophyll b, carotenoids, and ascorbic acid content of UMT-M1, CB, and CT increased upon continuous light exposure for 8 days (p < 0.05). Constant light exposure induced α-tocopherol accumulation in UMT-M1 and CT microalgae but not CB. Results indicated that as a response to continuous light treatment, UMT-M1, CB, and CT may exert natural antioxidant protection mechanism.

Growth of plants that reflects water stress can be measured through many different parameters, such as fresh weight, stem diameter and leaf area. A previous study by Chartzoulakis et al. (2002) demonstrated that the total plant leaf area and its dry weight were reduced by more

Chlorella vulqaris is a unicellular microorganism that offers health benefits due to its concentrated antioxidant production. This microalga has received huge attention due to its natural antioxidative property as an alternative antioxidant source because of its rapid growth, easy and flexible culture. Research to date only focuses on the growth and antioxidant production in a selected growth phase, especially exponential and stationary phases; however, so far, limited reports on the production of antioxidants in all growth phases of C. vulgaris. Thus, this study determines the growth, the enzymatic (Catalase, CAT; Ascorbate Peroxidase, APX; and guaiacol peroxidase, gPOD) specific activities and the amount of the non-enzymatic antioxidants (a-tocopherol, ascorbic acid and carotenoids) of C. vulgaris in five growth phases. Chlorella vulgaris was cultured in F/2 medium at 25±2 °C under laboratory conditions. CAT specific activities were the highest at the exponential phase (1.50±0.08 units/mg protein), whereas APX and gPOD were induced at the lag phases of 37.13±4.93 units/mg protein and 1.31±0.03 units/mg protein, respectively. The amount of a-tocopherol was accumulated at the stationary phase (97.3±4.18 µg/g.fwt), whereas the highest amount of ascorbic acid (266.67±22.22 µg/g.fwt) and carotenoids (8.16±2.52 µg/g.fwt) were at the decline phase. Production of enzymatic and non-enzymatic antioxidants in the microalgae cells indicated that they efficiently scavenged reactive oxygen species (ROS) and converted them into less harmful substances. In addition, the production of these antioxidants in different growth phases can be used as a guideline to produce massive antioxidants, which can be commercialized in the food and pharmaceutical industries.

A study was conducted on the chemical and biological properties of three different species of Mangifera i.e. Mangifera pajang, M. indica L., and M. kemanga leaves obtained from Pitas, Sabah. The aims of this study were to determine the presence of secondary metabolites as well as the antioxidative activities especially the catalase (CAT) and guiacol peroxidase specific activities (gPOD) in the leaves part of these three species. The extraction of these samples was carried out using three different polarities of solvents: hexane, ethyl acetate, and methanol. The total percentage of the crude extract of is 7.30% for M. pajang, 12.87% for M. indica and 7.98% for M. kemanga. Phytochemical screening was performed with various tests for each of the crude extracts. The results showed that these three species gave positive results for alkaloids, saponins, flavonoids, phenols, carbohydrates, phytosterols, and tannins metabolites. Based on the tests, CAT specific activities were significantly higher in the leaves of M. pajang with 4.35 ± 1.18 units/mg protein compared to M. indica L. and M. kemanga. The guaiacol peroxidase (gPOD) specific activities showed that M. indica L. has the highest activity with the value of 0.0047 ± 0.0004 units/mg protein.

Sansevieria is an ornamental plant that has many hybrids and varieties make them difficult to distinguish. The most common varieties used for medicinal purposes are Sansevieria trifasciatam which is known for cure of many diseases. However, little attention is given to this plant in proving it medicinal worth and capability as an antioxidant agent. This study was initiated to set up a metabolite classes profile and the potential enzymatic antioxidant of the variations of these plants. Crude extracts of S. trifasciata var. Laurentii and S. trifasciata var. Zeylanica were prepared from their leaves, and solvent used has different polarities. Qualitative phytochemical analysis was carried out using the extracts. Phytochemical screening suggested both of these samples contain carbohydrates in all extracts. It also show that flavonoid was found in hexane and ethyl acetate extracts while did not observed in the methanol extracts for both samples. However, alkaloid, phenol and tannin were positive in all of the methanol extracts except for hexane and ethyl acetate extracts. For the biological activity, all extracts were selected for the determination of enzymatic antioxidant activity test using catalase (CAT) assay and guaiacol peroxidase (gPOD) assay using UV-VIS spectrophotometer. Based on the results, CAT specific activity was the highest in methanol extract of S. trifasciata var. Laurentii (3.15 ± 0.50 units/mg protein) compared to S. trifasciata var. Zeylanica (2.20 ± 0.05 units/mg protein). For gPOD specific activity, ethyl acetate extract of S. trifasciata var. Laurentii shows the highest activity which is 1.46 × 10-2 ± 0.02 units/mg protein compared to the other crude extracts.

Euphorbiaceae plants had been traditionally used in healing various diseases. This study was designed to determine the secondary metabolites that exist in Malaysian Euphorbia milii (Euphorbiaceae) and it’s potential in antioxidant activities. Dried leaves and flowers of E. milii were extracted using hexane, ethyl acetate, and methanol. The qualitative and quantitative phytochemical analysis was performed toward the crude extracts. The outcomes showed that alkaloids, flavonoids, quinones, carbohydrates, and reducing sugar were mainly present in all of the samples extracted by the three solvents. For quantitative analysis, methanolic leaves extract contained the highest amount of flavonoids, given as 0.0867 ± 0.005 mg QE/g of the sample compared to other extracts. Meanwhile, the determination of antioxidant activities of each extract showed that methanol leaves extract consists of the highest antioxidant activity due to the presence of phytochemical compounds. This significant data provides preliminary findings that may lead to further development as a potential source of herbal medicine.