Research Article

Chemical Composition and Antimicrobial Activity of Two Sri Lankan Lichens, Parmotrema rampoddense, and Parmotrema tinctorum against Methicillin-Sensitive and Methicillin-Resistant Staphylococcus aureus

Table 3

Comparison of zone diameters of the disc diffusion assay performed on P.tinctorum and P. rampoddense against MSSA (ATCC 25923) and 20 clinical isolates of MRSA.

Diameters of the inhibitory zones (mm)
ExtractConcentration (mg/ml)MSSA (ATCC 25923)MRSA#
P. tinctorumP.rampoddenseP. tinctorumP. rampoddense

Ethanol3009.4 ± 0.114.4 ± 0.87.13 (6.2–9.6), n = 179.61 (7.9–11.4), n = 20
3015.3 ± 0.67.11 (6.1–11.1), n = 1610.38 (8.5–12.4), n = 20
316.5 ± 0.47.03 (6.1–8.2), n = 15

Hexane3007.7 ± 0.27.8 ± 0.17.24 (6.3–9.1), n = 186.76 (6.1–7.4), n = 18
307.5 ± 0.16.5 ± 0.16.78 (6.4–7.1), n = 5
36.8 ± 0.3

Aqueous3008.1 ± 0.27.28 (6.1–8.0), n = 13
307.9 ± 0.1
3

Positive control30 μg/disk20.8 ± 0.413.53 ± 0.23

Negative control10%

Data are expressed as mean ± SEM. #Data are expressed as mean (Min-Max) of the 20 clinical isolates of MRSA. n denotes the number of MRSA isolates which gave a measurable diameter. Vancomycin was used as the positive control. 10% DMSO was used as the negative control. – denotes a measurable diameter was not observed.