Cinnamic acid had more greater action intensity than p-hydroxy benzoic acid.

The phenolic acids used were vanillic acid, vanillin and P-hydroxy benzoic acids for studying the effects of phenolic acids on the growth and activities of protective enzymes of muskmelon.

The thermodynamic parameters of carboxylic group and titrable phenolic hydroxyl group of humic acid are similar to that of simple hydroxy-benzoic acid.