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HERDIN Record #: R07-USC-14102406345039 Submitted: 24 October 2014 Modified: 27 October 2014

Determination of the antibacterial activity of the tannin extract from fresh leaves of Psidium guajava linn. (Bayabas)

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This research dealt with the determination of the antibacterial activity of the tannin extract from fresh guava leaves. Decoction was employed in the preparation of extractive and was saturated with sodium chloride (table salt) to obtain tannin constituent. The tannin isolate was made into 250 mh/ml test to solution. Gentamicin Sensi Disc 10 ug was used as the protective control. Distilled water was the negative control.

The antibacterial activity was determined by Kirby Bauer Disc Diffusion Method using three test organisms namely Escherichia coli, Psedomonas aeruginosa and Staphylococcus aureus. After sixteen hours of incubation, the zone produced by the positive control, negative control  and test solution was measured.

The 250 mg/ml and 500 mg/ml test solution showed antibacterial activity against Staphylococcus aureus but no antibacterial activity to Escherichia coli and Pseudomonas aeruginosa. The 500 mg/ml test solution showed a larger antibacterial activity against Staphylococcus aureus. The percent antibacterial activity was 41.05% in trial 1, 38.57% in trial 2 and 36.76%in trial 3. While the 250 mg/ml percent antibacterial activity was 37.51% in trial 1, 31.41% in trial 2 and 30.89% in trial 3 against Staphylococcus.

The 250 mg/ml and 500 mg/ml produced no zone of inhibition, indicating that two solution did not inhibit the growth of both Escherichia coli and Staphylococcus aureus.

The researchers recommends to test the tannin to other microorganism. A statistical treatment should be done to determine the significance of the antibacterial activity of the plant.

Publication Type
Thesis Degree
Publication Date
March 2007


The goal of the study is to determine the antibacterial activity of tannins from Psidium guajava Linn.

Specifically, this study sought to:

1. determine the diameter of zone of inhibition around the disk impregnated with the tannin extract from Psidium guajava linn.

2. identify which bacteria (Escherichia coli, Staphylococcus aureus or Pseudomonas aureginosa) was most inhibited by the tannin extract.

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