Effect of pH and temperature on antioxidant enzymes activities in Morinda citrifolia L. (Mengkudu) leaves extract

Mohd Zin Z., . and Azman S.N.S., . and Yahya F., . and Hasmadi M., . and Zainol M.K., . (2022) Effect of pH and temperature on antioxidant enzymes activities in Morinda citrifolia L. (Mengkudu) leaves extract. Food Research (Malaysia), 6. pp. 60-67. ISSN 2550-2166

Morinda citrifolia L. (Mengkudu) leaf is not well-known for its benefits compared to M. citrifolia fruit. It can be considered a good source in healing disease and anti-cancer properties due to the high content of antioxidant enzymes. The objective of this study was to determine the antioxidative activities of M. citrifolia leaves extracted at different Ph (pH 3 to pH 9) and temperatures (20°C to 80°C), based on four types of antioxidant enzymes test, namely catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO) and superoxide dismutase (SOD). Another analytical test is the protein determination of M. citrifolia leaves using Bovine Serum Albumin as standard. All of the tests were conducted using spectroscopy methods. Catalase (CAT) activity was monitored by reduction of absorbance due to the decomposition of hydrogen peroxide and peroxidase (POD) activity was observed by an increment of absorbance caused by the oxidation of 4-methylcatechol by hydrogen peroxide. Polyphenol oxidase (PPO) was monitored by an increment of absorbance due to the oxidation of 4-methylcatechol and superoxide dismutase (SOD) activity was determined using the NBT-based method, which monitors the amount of enzyme causing 50% inhibition of photochemical reduction of NBT. Results indicated that CAT activity and POD activity were significantly highest (p<0.05) at pH6, 0.51 U/mg for CAT, 2.58 U/mg for POD, while SOD activity was significantly higher at pH7, 0.47 U/ mg. However, no significant difference (p>0.05) was observed for PPO activity in pH treatment. For different temperature treatments, CAT activity was significantly highest (p<0.05) at 50°C, 0.36 U/mg, while PPO activity and SOD activity were found to be significantly highest (p<0.05) at 30°C, 0.64 U/mg for PPO and 0.43 U/mg for SOD. However, all-temperature treatments given did not significantly affect POD activity. Morinda citrifolia leaves have a good antioxidant potential and can be practised in the treatment of diseases associated with oxidative stress.

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Abstract

Morinda citrifolia L. (Mengkudu) leaf is not well-known for its benefits compared to M. citrifolia fruit. It can be considered a good source in healing disease and anti-cancer properties due to the high content of antioxidant enzymes. The objective of this study was to determine the antioxidative activities of M. citrifolia leaves extracted at different Ph (pH 3 to pH 9) and temperatures (20°C to 80°C), based on four types of antioxidant enzymes test, namely catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO) and superoxide dismutase (SOD). Another analytical test is the protein determination of M. citrifolia leaves using Bovine Serum Albumin as standard. All of the tests were conducted using spectroscopy methods. Catalase (CAT) activity was monitored by reduction of absorbance due to the decomposition of hydrogen peroxide and peroxidase (POD) activity was observed by an increment of absorbance caused by the oxidation of 4-methylcatechol by hydrogen peroxide. Polyphenol oxidase (PPO) was monitored by an increment of absorbance due to the oxidation of 4-methylcatechol and superoxide dismutase (SOD) activity was determined using the NBT-based method, which monitors the amount of enzyme causing 50% inhibition of photochemical reduction of NBT. Results indicated that CAT activity and POD activity were significantly highest (p<0.05) at pH6, 0.51 U/mg for CAT, 2.58 U/mg for POD, while SOD activity was significantly higher at pH7, 0.47 U/ mg. However, no significant difference (p>0.05) was observed for PPO activity in pH treatment. For different temperature treatments, CAT activity was significantly highest (p<0.05) at 50°C, 0.36 U/mg, while PPO activity and SOD activity were found to be significantly highest (p<0.05) at 30°C, 0.64 U/mg for PPO and 0.43 U/mg for SOD. However, all-temperature treatments given did not significantly affect POD activity. Morinda citrifolia leaves have a good antioxidant potential and can be practised in the treatment of diseases associated with oxidative stress.

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Item Type:	Article
AGROVOC Term:	Morinda citrifolia
AGROVOC Term:	leaf extracts
AGROVOC Term:	enzyme activity
AGROVOC Term:	extraction
AGROVOC Term:	pH
AGROVOC Term:	temperature
AGROVOC Term:	catalase
AGROVOC Term:	peroxidases
AGROVOC Term:	superoxide dismutase
AGROVOC Term:	spectroscopy
Geographical Term:	Malaysia
Depositing User:	Mr. Khoirul Asrimi Md Nor
Date Deposited:	20 Feb 2026 07:07
Last Modified:	20 Feb 2026 07:07
URI:	http://webagris.upm.edu.my/id/eprint/3462

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