Comparative Study on Antioxidant Activity, Lycopene Content and Antibacterial Properties of Dragon Fruit (Hylocereus Polyrhizus), Japanese Plum (Prunus Salicina) and Pumpkin (Cucurbita Moschata)

Tan, Kah Yee (2018) Comparative Study on Antioxidant Activity, Lycopene Content and Antibacterial Properties of Dragon Fruit (Hylocereus Polyrhizus), Japanese Plum (Prunus Salicina) and Pumpkin (Cucurbita Moschata). Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Dragon fruit (Hylocereus polyrhizus), Japanese plum (Prunus salicina) and pumpkin (Cucurbita moschata) are the fruits that commonly consumed. This study was conducted to compare their antioxidant activities, lycopene contents and antibacterial activities. All three types of fruits were separated into peel, pulp and seed fractions and were extracted through maceration method by using methanol. The antioxidant activities for each extracts were evaluated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) in order to calculate their radial scavenging activity % (RSA) and vitamin C equivalent antioxidant capacity, VCEAC (mg/g). According to the results, the highest VCEAC and RSA (%) was found in the peels of Japanese plum which are 0.9880 ± 0.0006 mg/g extracts and 93.97 ± 0.0006% whereas the lowest VCEAC and RSA (%) was found in the peels of pumpkin which are 0.0263 ± 0.0015 mg/g extracts and 37.41± 0.0015%. Lycopene was analysed by a simple spectrophotometric method at 503 nm, in hexane:acetone:ethanol extraction. Based on the results, the highest lycopene was detected in the pumpkin peels whereas the lowest lycopene was detected in the dragon fruit pulps which are 0.0540 ± 0.0153% and 0.0016 ± 0.0076%. By conducting simple qualitative phenolic test such as ferric chloride and foam test, phenol compounds or saponin content in each extracts can be detected. The antibacterial activity for each extracts was performed by agar well diffusion method. Gram positive and negative bacteria (Salmonella sp., Escherichia coli, Staphylococcus aureus and Bacillus sp.) were tested for each extracts. Based on the results, most of the bacteria were inhibited by all fractions of the dragon fruits due to high polyphenol contents. All fraction extract of Japanese plum can only inhibited E. coli. Besides, pulps extracts of pumpkin inhibited the E. coli and S. aureus growth. The contamination of Bacillus sp. cannot be used in analysis of antibacterial activity.