Antioxidant and antibacterial properties of tuhau (etungera punicae)

Chia, Kah Fei (2006) Antioxidant and antibacterial properties of tuhau (etungera punicae). Universiti Malaysia Sabah. (Unpublished)


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Etlingera punicae (tuhau), of the Zingiberaceae family, is an indigenous plant in Sabah which has been used as food and condiment. Phenolic extracts from different parts of tuhau, including rhizome, stem, bud and leaf were screened for potential antioxidant properties. These properties Included DPPH (2,2-diphenyl-1-picylhydrazyl hydrate) scavenging activity, metal chelation, and β- carotene bleaching. The content of total phenolics was also measured in all parts of tuhau extracts. The leaf extract showed the highest phenolics oontent of 49.76 mg/g of extract in GAE and good correlated with DPPH scavenging activity (IC₅₀) in regression analysis. Tuhau leaf exhibited high radical scavenging activity that was not significantly (P<0.05) different from butylated hydroxyl toluene (BHT). On the other hand, the extract of stem parts of tuhau exhibited significant metal cheIating activity, which is comparable to BHT. Similar trends of antioxidant activity were observed using β-carotene bleaching method for stem extract. Interesting that the tuhau leaf with high DPPH scavenging activity showed a poor antioxidative activity tested against metal chelating and f β-carotene methods. The results suggested that several different phytochemical compounds contribute to antioxidative activity of different parts of tuhau. Four parts of tuhau extracts were screened for their antimicrobial activities against Bacillus cereus, Staphylococcus aureus, Salmonella typhimurfum and Pseudomonas aeruginosa by discs diffusion assay. All the extracts showed effective inhibition against selected Gram positive bacteria. No activity was detected against selected Gram negative. Staphylococcus aureus was most susceptible bacteria tested against all parts of tuhau extract using disc diffusion assay. In time-kill curve assay, population of S. aureus inhibited (killing the bacteria) by rhizomes, stem, bud and leaf extract of E.punicae and fell below the detection limit after 24 hour of incubation. No further growth was detected In this study for up to 36 hours. The extract with the lowest MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) was the stem extract of tuhau (17.2 mg and 18.8 mg respectively).

Item Type: Academic Exercise
Uncontrolled Keywords: tuhau, indigenous plant, phenolic extracts, antioxidant, total phenolics, leaf extract, extract of stem
Subjects: T Technology > TX Home economics > Nutrition. Foods and food supply
Divisions: SCHOOL > School of Food Science and Nutrition
Depositing User: Unnamed user with email
Date Deposited: 09 Mar 2015 06:05
Last Modified: 25 Oct 2017 06:07

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