Articles Vol. 67 No. CĐ8-NCKH 06/07/2026

INVESTIGATION OF THE ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF PSIDIUM GUAJAVA L. LEAVES EXTRACT

Nguyen Quang Tho1,2, Doan Duong Huyen Trinh1,2, Doan Thanh Truc3,4, Tri Kim Ngoc5,6, Le Phuong Thao1,2
1 Faculty of Pharmacy, School of Medicine and Pharmacy, Tra Vinh University
2 Khoa Dược, Trường Y Dược, Đại học Trà Vinh
3 Faculty of Pharmacy and Nursing, Tay Do University
4 Khoa Dược - Điều Dưỡng, Trường Đại học Tây Đô
5 Faculty of Natural Sciences, Can Tho University
6 Khoa Khoa học tự nhiên, Trường Đại học Cần Thơ
DOI: 10.52163/yhc.v67iCD8.5689
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Keywords
Psidium guajava, guava leaves, ethanol extract, antioxidant activity, antimicrobial activity.
Abstract

Objectives: To investigate preliminary phytochemical constituents, determine total phenolic and flavonoid contents, and evaluate the antioxidant and antimicrobial activities of guava leaf ethanol extract.

Subjects and methods: The extract was prepared using 70% ethanol-assisted ultrasonic extraction. Phytochemical constituents were screened qualitatively. Total phenolic and flavonoid contents were determined by Folin-Ciocalteu and AlCl₃ methods, respectively. Antioxidant activity was evaluated by DPPH, ABTS+ and NO assays; antimicrobial activity was assessed by agar well diffusion.

Results: The extraction yield was 17.82%. The extract contained flavonoids, tannins, terpenoids, alkaloids, saponins, and other phytochemical groups. Total flavonoid and phenolic contents were 409.09 ± 8.46 mgQE/g and 295.34 ± 17.25 mgGA/g dry material, respectively. IC₅₀ values for DPPH, ABTS+ and NO assays were 31.87 ± 4.57, 37.42 ± 6.43, and 539.72 ± 5.87 µg/mL, respectively. The extract inhibited MRSA, MSSA, E.coli, P.vulgaris, and C.albicans, with the strongest activity against MRSA.

Conclusions: Guava leaf ethanol extract is rich in polyphenols and flavonoids and exhibits notable antioxidant and antimicrobial activities.

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