Effects of Tormentic Acid and the Extracts from Callistemon citrinus on the Production of Extracellular Proteases by Staphylococcus aureus

Table 1

Pr values obtained after exposing S aureus to tormentic acid and extracts from C. citrinus.

Sample	Pr value	Measure of protease production
Negative control	0.64	Very strong
Positive control	1	None
Tormentic acid (100 µg/ml)	1	None
DCM : methanol extract (50 µg/ml)	0.92	Weak
Water : ethanolic extract (100 µg/ml)	0.92	Weak
Water : ethanol extract (50 µg/ml)	0.85	Mild

Unexposed cells were used as the negative control and ciprofloxacin was used as the positive control. Protease activity was scored as follows: (1) No protease activity; (0.99–0.9) weak protease activity; (0.89–0.8) mild protease activity; (0.79–0.7) moderately strong protease activity; (<0.69) very strong protease activity.