Phytochemicals screening for potential antibacterial and antioxidant properties in Sabah pigmented rice

Chong, Pui Lai (2011) Phytochemicals screening for potential antibacterial and antioxidant properties in Sabah pigmented rice. Universiti Malaysia Sabah. (Unpublished)


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The phytochemical contents, antibacterial, antioxidant and free radical scavenging properties of four pigmented rice varieties (black, red, brown and white) in Sa bah were studied. Seven phytochemical groups, which are the alkaloids, phenolic acids, saponins, flavonoids, tocopherols, carbohydrate and proteins were found to be present in all the rice samples. Red rice contains the highest quantity of phenolic acids (329.93 ± 19.17 mg/100 g), saponins (625.33 ± 10.26 mg/100 g), tocopherols (200.33 ± 13.61 mg/100 g), and protein (22.45 ± 0.98%). Black rice has the highest content of flavonoids (23.28 ±0.97 mg/100 g). There are no significant differences in the content of alkaloids and carbohydrate among all four rice varieties. In order to detect the antioxidant activity of the pigmented rice extracts, ferric thiocyanate (FTC) assay was used and compared with the thiobarbituric acid (TBA) method. Scavenging activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. Red rice extract shows the highest activity in all three tests, FTC (0.302), TBA (0.329) and DPPH (65.54% ± 0.57) due to its high content of phenolic acids and tocopherols, followed in descending order by black rice, brown rice and finally white rice. Potential antibacterial activity of the methanolic crude extracts of pigmented rice was screened against Escherichia coli, Pseudomonas sp. and Streptococcus sp. using disc diffusion technique. There are no inhibition zone of bacteria was formed that indicated all the four rice varieties do not have antibacterial properties. This study indicates that pigmented rice varieties has protective effect against hydroperoxide generation and has free radical scavenging activity. The antioxidants capacity of the extract also differs depending on the bran colour of the rice.

Item Type: Academic Exercise
Uncontrolled Keywords: phytochemical contents, antibacterial, antioxidant, free radical scavenging, rice
Subjects: S Agriculture > SB Plant culture
Divisions: FACULTY > Faculty of Sustainable Agriculture
Depositing User: Munira M
Date Deposited: 21 Jun 2017 11:58
Last Modified: 16 Oct 2017 12:18

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