Antibacterial activities in each part of watercress(Oenanthe javanica D.C.) grown under different culture conditions were measured to determine the possibility to use watercress as a resource to develop the antibacterial substance. The leaves of watercress were extracted with methanol and the methanol extract was further fractionated with various organic solvents. Antibacterial activities against Shigella dysenteriae ATCC 9361 in all fractions were determined according to the agar diffusion method using paper disc. Methanol extract of watercress leaves was more effectively inhibited the growth of the tested bacteria than the extracts of roots or stems at the concentration of 0.5 g eq./disc, and the extract of watercress from Hwasoon was the most effective one as compared to others. Phenolic and neutral fractions fractionated from methanol extract of watercress had a considerable inhibiting activity on the growth of the bacteria, but acidic and basic fractions did not show any inhibitory effect. Minimum inhibitory concentrations of phenolic and neutral fractions against Shigella dysenteriae ATCC 9361 were 400 μg/disc and 550 μg/disc, respectively.

Chemical properties of the different parts of watercress(Oenanthe javanica D.C.) grown and harvested from the culture fields under different cultivating methods were studied. In proximate analyses of watercress in parts, moisture contained more in stem than in root or in leaf, but crude protein and crude lipid contents were lower in stem than in root or in leaf. Crude ash in root contained up to about double amount in leaf or stem. Major mineral elements detected in watercress were Fe, Mg, Ca, and K, and their contents in root was higher than those in stem or leaf. Especially, Fe in root was significantly higher than that in stem or in leaf. Total free sugar composed mainly with fructose and glucose, was the highest in watercress from Hwasoon and followed the watercress from Jeonju and Donggok in order. Free sugar content was highest in leaf and the lowest in root. Major water-soluble vitamins were vitamin C, thiamin and biotin and the content of vitamin C was higher than others. These vitamins contained more in leaf than in stem or root. Niacin contained 6.09 mg/100 g in leaf of watercress from Hwasoon, which was much higher than others, but it was not detected in stem of watercress from Jeonju. Organic acids detected were oxalic acid, citric acid and malic acid and other 12 organic acids were not detected. In fatty acid composition, there were significant differences among watercresses from different parts and different culture fields. Linoleic acid, linolenic acid and palmitic acid were major fatty acids contained in watercress and it took about 80% of the total content. Amino acid content in leaf was higher than that in root and in stem. Glutamic acid and proline were major amino acids in stem of watercress from Jeonju and in stem of watercresses from Hwasoon and Donggok, respectively. In leaves of all three watercresses glutamic acid content was the highest.