Antibacterial activity of Parankipaddal Kudineer (decoction) and its component plants

Abstract

Decoction, a hot water extract, is an internal medicine in the Siddha medical system. Parankipaddaikudineer (PPK) consists of 13 plant parts from 12 medicinal plants and is used to treat skin diseases. The antimicrobial activity of PPK has not been reported previously. The study of the decoction as well as its component plants is timely as there is a rapidly increasing demand for novel antimicrobial agents from plant sources, particularly for the treatment of infections by bacteria resistant pathogens. Staphylococcus aureus NCTC 6571, Escherichia coli NCTC 10418, Pseudomonas aeruginosa NCTC 10662 and 5 clinical isolates of Methicillin-Resistant S. aureus were used in this study. The decoction was prepared according to the method in Siddha literature. Antibacterial screening at 1/10, 1/20, 1/40, 1/80 and 1/160 dilutions of decoction was performed using a well diffusion method. Plates were incubated at 37 °C for 24 h and the zone of inhibition (ZOI) measured. The Minimum inhibitory concentration (MIC) was determined by the agar dilution method. Ten μL of the 1/10 dilution of each test strain was used. After 24 hours incubation, the growth of pathogens was compared with the control. PPK decoction has inhibitory activity (ZOI: 15.3±2.5-16.0±1.0 mm) against S. aureus NCTC 6571 and 5 MRSA strains at 1/10 dilution. Out of 12 individual plant decoctions, 10 were shown to have inhibitory activity, 9 of which showed activity against S. aureus NCTC and 5 strains of MRSA. Three replicates were carried out for the entire procedure. Results show that PPK decoctions and its individual plants S. aromaticum, E. ribes, C. angustifolia, I. aspalathoides and M. fragrans leaf possess inhibitory activity against both sensitive and resistant strains of S. aureus at a high dilution which indicates the potential of using them as antimicrobial agents.