Suhaila Mohamed

Antioxidant activities and phenolics content of eight species of seaweeds from North Borneo

The antioxidant activity of eight edible species of Malaysian North Borneo seaweeds obtained from Sabah waters (Kudat, Tanjung Aru and Semporna) consisting of three red seaweeds (Eucheuma cottonii, E. spinosum and Halymenia durvillaei), two green seaweeds (Caulerpa lentillifera and C. racemosa) and three brown seaweeds (Dictyota dichotoma, Sargassum polycystum and Padina sp.) were determined. Methanol and diethyl ether were used as extraction solvent. The antioxidant activities were determined by two methods, TEAC (trolox equivalent antioxidant capacity) and FRAP (ferric reducing antioxidant power) assays. The total phenolic content of the extract was determined according to the Folin–Ciocalteu method and results were expressed as phloroglucinol equivalents. The methanolic extracts of green seaweeds, C. lentillifera and C. racemosa, and the brown seaweed, S. polycystum showed better radical-scavenging and reducing power ability, and higher phenolic content than the other seaweeds. The TEAC and FRAP assays showed positive and significantly high correlation (R2 = 0.89). There was a strong correlation (R2 = 0.96) between the reducing power and the total phenolic content of the seaweeds methanolic dry extracts. These seaweeds could be potential rich sources of natural antioxidants.

Antimicrobial, antioxidant, antitumour-promoting and cytotoxic activities of different plant part extracts of Garcinia atroviridis griff. ex T. anders.

Crude extracts (methanol) of various parts, viz. the leaves, fruits, roots, stem and trunk bark, of Garcinia atroviridis were screened for antimicrobial, cytotoxic, brine shrimp toxic, antitumour-promoting and antioxidant activities. The crude extracts exhibited predominantly antibacterial activity with the root extract showing the strongest inhibition against the test bacteria at a minimum inhibitory dose (MID) of 15.6 microg/disc. Although all the extracts failed to inhibit the growth of most of the test fungi, significant antifungal activity against Cladosporium herbarum was exhibited by most notably the fruit (MID: 100 microg), and the leaf (MID: 400 microg) extracts. None of the extracts were significantly cytotoxic, and lethal towards brine shrimps. The root, leaf, trunk and stem bark extracts (except for the fruits) showed strong antioxidant activity exceeding that of the standard antioxidant, alpha-tocopherol. Antitumour-promoting activity (>95% inhibition) was shown by the fruit, leaf, stem and trunk bark extracts.

Nutritional values of chironomid larvae grown in palm oil mill effluent and algal culture

Copyright (c) 1997 Elsevier Science B.V. All rights reserved. Chironomid larvae were grown in nine 70-l tanks containing palm oil mill effluent (POME) and algal culture. The algal culture was obtained by inoculating 200 ml pure culture of Chlorella vulgaris Beijerinck initially in 20-l tap water containing inorganic fertilizer N:P:K (1:0.2:0.2). Each treatment was done in triplicate. Dissolved oxygen, pH, total nitrogen, total ammonia nitrogen, ortho-phosphate, chemical oxygen demand (COD), total suspended solids and total dissolved solids of the media in each tank were analyzed. Protein, lipid, ash, amino acids, fatty acids, total carotene and minerals were determined for POME, chironomid larvae, and algae. The culture was terminated after 25 days and chironomid production was determined. The production of chironomid larvae was significantly (P<0.01) higher in POME tanks (580 g/20 l POME) than in algal culture (35 g/20 l algal culture). Raw palm oil mill effluents contained significantly higher (P<0.05) arginine, methionine, isoleucine and phenylalanine than algae grown in fertilizer. The essential amino acids of chironomid larvae grown in POME such as histidine, arginine, methionine, isoleucine, phenylalanine and lysine were significantly (P<0.05) higher than in chironomid larvae grown on algal culture. The polyunsaturated fatty acids (PUFA) with the exception of Υ-linolenic acid (18:3n−6), were higher in chironomid larvae grown in POME than those grown on algal culture. Twenty seven minerals were detected by electron microscope but 23 minerals were analyzed and quantified in POME, algae, and chironomid larvae grown in POME and algal culture. The quantity of sulfur was significantly higher (P<0.05) in POME than algae, which probably induced the synthesis of methionine, a S-containing essential amino acid in chironomid larvae cultured in POME. Experiments showed that POME did not only induce high production of chironomid larvae, but also produced high quality live food for the aquaculture industry.

Antiviral, Cyototoxic And Antimicrobial Activities Of Anthraquinones Isolated From The Roots Of Morinda Elliptica

2-Formyl-1-hydroxyanthraquinone, along with ten other known anthraquinones (1-hydroxy-2-methylanthraquinone, nordamnacanthal, damnacanthal, lucidin-?-methyl ether, rubiadin, rubiadin-1-methyl ether, soranjidiol, morindone, morindone-5-methyl ether and alizarin-1-methyl ether), isolated from the roots of Morinda elliptica , were assayed for anti-HIV, cytotoxic and antimicrobial activites. Only damnacanthal showed moderate activity against HIV. It was cytotoxic towards the MCF-7 (breast carcinoma) and CEM-SS (T-lymphoblastic leukaemia) cell line. Nordamnacanthal was very cytotoxic against the CEM-SS cell lines. Other anthraquinones that showed strong cytotoxicity towards the cell lines tested were lucidin-?-methyl ether (CEM-SS and MCF-7) and rubiadin (CEM-SS). Three anthraquinones viz., nordamnacanthal, damnacanthal and morindone, were found to have strong antimicrobial activity.

Food components affecting the oil absorption and crispness of fried batter

Frying batters are used to add value to a product by improving texture, flavour, weight and volume and reducing water loss during frying which, in turn, lessens oil absorption. The physical characteristics of fried batters were studied using model systems based on rice flours. Crispness was positively correlated with amylose content, while oil absorption was negatively correlated with amylose content. Addition of pregelatinised rice flour improved crispness but resulted in increased oil absorption because of the porous nature of the fried product. Amongst the proteins (egg yolk, gluten, skimmed milk, whey and ovalbumin) studied, ovalbumin was able to reduce oil absorption and improve the crispness of the fried batter. Addition of calcium chloride also reduced oil absorption and improved crispness, while a little oil reduced the oil content of the fried batter and improved its taste. Addition of ovalbumin, oil or calcium chloride beyond the optimal levels reduced crispness and increased oil absorption in a linear manner. Modified tapioca starch and diglyceride emulsifiers improved crispness but increased oil absorption. The amount of water added to the formulation affected the physical characteristics of the fried batter. The optimal formulation for a crisp frying batter with reasonably low oil absorption was an amylose/amylopectin ratio of about 18: 67; with (g kg−1) 850 pregelatinised rice flour; up to 150 modified tapioca starch; 30 ovalbumin; 1 calcium chloride; 20 oil; 20 emulsifier and a water/flour ratio of 2:1.

Hypoglycaemic effect of Parkia speciosa seeds due to the synergistic action of β-sitosterol and stigmasterol

Oral administration of the chloroform extracts of Parkia speciosa seeds (petai papan) to alloxan-induced diabetic rats produced a significant depression in blood glucose levels. Extraction, isolation and structure elucidation of the hypoglycaemic fraction (S-9·4) gave a mixture of β-sitosterol (66%) and stigmasterol (34%). Fraction S-9·4 produced 83% hypoglycaemic activity at 100 mg/kg body weight (BW) compared with 111% activity of glibenclamide at 5 mg/kg BW dosages. The minimum effective dose which produced statistically significant hypoglycaemic effect was 25 mg seeds/kg BW. When tested individually β-sitosterol and stigmasterol showed no hypoglycaemic effects, indicating that synergism between β-sitosterol and stigmasterol was necessary to effect the hypoglycaemic activity. The hypoglycaemic effect was not observed in healthy rats. The synergism of β-sitosterol and stigmasterol to produce hypoglycaemic activity and their occurrence in Parkia speciosa Hassk has never been reported.

Antioxidative properties of Pandanus amaryllifolius leaf extracts in accelerated oxidation and deep frying studies.

The potential uses of Pandanus amaryllifolius leaf extract as a natural antioxidant were evaluated in refined, bleached and deodorized (RBD) palm olein, using accelerated oxidation and deep frying studies at 180°C from 0 to 40h. The extracts (optimum concentration 0.2%) significantly retarded oil oxidation and deterioration (P<0.05), comparably to 0.02% BHT in tests such as peroxide value, anisidine value, iodine value, free fatty acid, oxidative stability index (OSI), polar and polymer compound contents. In sensory evaluation studies, different batches of French fries were not significantly different (P<0.05) from one another for oiliness, crispiness, taste and overall acceptability when the same oil was used for up to the 40th hour of frying. P. amaryllifolius leaf extract, which had a polyphenol content of 102mg/g, exhibited an excellent heat-stable antioxidant property and may be a good natural alternative to existing synthetic antioxidants in the food industry.

Antioxidative and antimycotic effects of turmeric, lemon-grass, betel leaves, clove, black pepper leaves and Garcinia atriviridis on butter cakes

Turmeric, lemon-grass, Garcinia atriviridis and clove were found to be effective in retarding mould growth in butter cakes. Betel leaves and black pepper leaves showed no antimycotic activity and may even promote mould growth in butter cakes. Turmeric, betel leaves and clove effectively retarded the rancidity of butter cakes and extended their storage life from 2 weeks (control) to more than 4 weeks. Lemon-grass, G atriviridis and butylated hydroxy toluene (BHT) extended the butter cake storage life to 4 weeks, while butylated hydroxy anisole (BHA) was only able to extend the storage life to 3 weeks. The thiobarbituric acid value (TBAV), peroxide value (PV) and anisidine value (AV) of cakes containing these extracts (0.1% w/w butter) and control cakes were significantly different (p < 0.05) during the 4 weeks of storage. Turmeric and betel leaves had the best antioxidative activities (TBAV = 0.62f, 0.64f; PV = 10.2cde, 15.29bc; AV = 3.05e, 3.63e; Totox V = 23.55b, 34.21b respectively), performing better than BHA or BHT (TBAV = 1.62c, 1.21cde; PV = 9.77de, 5.46ef; AV = 12.52c, 15.16b; Totox V = 32.06b, 26.08b respectively). Same letters superscripted on the mean values of samples indicate insignificant difference between them. The oxidative values of BHA and BHT in cakes were insignificantly different (p < 0.05) except in AV analysis, but significantly lower than control cakes (TBAV = 2.43b; PV = 23.09a; AV = 23.10a; Totox V = 69.27a). Clove and lemon-grass were also better than BHA/BHT and had the next strongest antioxidant activity (TBAV = 0.81ef, 0.98def; PV = 15.45b, 12.50bcd; AV = 3.11e, 7.20d; Totox V = 34.03b, 32.20b respectively). The AVs of cakes containing G atriviridis (25.03a) were similar to control cakes (23.10a) but the PVs were low (0.94f) throughout the storage period, indicating that G atriviridis increased the rate of conversion of hydroperoxides to aldehydes. Black pepper leaves appeared to be pro-oxidative (TBAV = 2.91a; PV = 10.45bcde; AV = 8.52d; Totox V = 29.40b). © 1999 Society of Chemical Industry

Comparison of Cardiovascular Protective Effects of Tropical Seaweeds, Kappaphycus alvarezii, Caulerpa lentillifera, and Sargassum polycystum, on High-Cholesterol/High-Fat Diet in Rats

This study was designed to investigate the comparative in vivo cardiovascular protective effects of red, green, and brown tropical seaweeds, namely, Kappaphycus alvarezii (or Eucheuma cottonii), Caulerpa lentillifera, and Sargassum polycystum, in rats fed on high-cholesterol/high-fat (HCF) diets. Male Sprague-Dawley rats (weighing 260-300 g) on the HCF diet had significantly increased body weight, plasma total cholesterol (TC), plasma low-density lipoprotein cholesterol (LDL-C), plasma triglycerides (TG), lipid peroxidation, and erythrocyte glutathione peroxidase (GSH-Px) and superoxide dismutase levels after 16 weeks. Supplementing 5% seaweeds to HCF diet significantly reduced plasma TC (-11.4% to -18.5%), LDL-C (-22% to -49.3%), and TG (-33.7% to -36.1%) levels and significantly increased HDL-C levels (16.3-55%). Among the seaweeds, S. polycystum showed the best anti-obesity and blood GSH-Px properties, K. alvarezii showed the best antihyperlipemic and in vivo antioxidation effects, and C. lentillifera was most effective at reducing plasma TC. All seaweeds significantly reduced body weight gain, erythrocyte GSH-Px, and plasma lipid peroxidation of HCF diet rats towards the values of normal rats.

Antimycotic screening of 58 Malaysian plants against plant pathogens

Ethanolic extracts of 58 Malaysian plants belonging to 24 different families were screened for antifungal activity against seven plant pathogens using the filter paper disc diffusion technique. Two varieties of Piper betle, showed strong activity against all the pathogens tested (Colletotrichum capsici, Fusarium pallidoroseum, Botryodiplodia theobromae, Alternaria alternata, Penicillium citrinum, Phomopsis caricae-papayae and Aspergillus niger), with inhibition diameters significantly (P<0·01) bigger than 2·5 mg ml−1 prochloraz or 10 mg ml−1 clotrimazole. The minimum inhibitory concentrations of the ethanolic extracts of P. betle against these plant pathogens ranged between 0·01 mg ml−1 and 1 mg ml−1. Thirty-four other plants (Kucing gala, Limau batik, Bertholletia excelsa, Bixa orellana, Caesalpinia pulcherrima, Cerbera odollam (fruits and leaves), Colocasia gigantea, Curcuma domestica, Curcuma manga, Derris eliptica, Elephantopus scaber, Eleusine indica, Eugenia polyantha, Euphorbia hirta, Euphorbia tirucalli, Gardenia florida, Hedyotis auricularia, Hibiscus rosa-sinensis, Juniperus chinensis (three varieties), Lawsonia inermis, Lecythis ollaria, Mentha arvensis, Mimusops elengi, Ocimum sanctum, Phyllanthus niruri, Piper nigrum, Piperomia pellucida, Pedilanthus tithymaloides, Polygonum minus, Spondias dulcis, Solanum nigrum, Tinospora tuberculata) showed selective antifungal activity, while 21 species were inactive.