CHEMICAL MODIFICATION OF BROMELAIN WITH DEXTRAN ALDEHYDE AND ITS POTENTIAL MEDICAL APPLICATION.

The aim of this study was to obtain a more stable and less allergic form of bromelain, an enzyme complex derived from the stem of Pineapple plant (Ananas comosus L. Merr.), via chemical modification with a polysaccharide. In order to obtain purified bromelain (enriched with protein) from comercial bromelain, protein precipitation method by alcohol was used. According to our results the protein concentration after the purification was increased by about 20%. In this work, we examine the method of bromelain's chemical modification with a water-soluble, biocompatible and biodegradable natural polysaccharide - dextran, oxidized to dextran aldehyde. For the determination of the degree of bonding gel-filtration of bromelain and modified bromelain on sephadex G-75 was performed. After gel filtration of bromelain only one fraction-peak was obtained, whereas after gel filtration of modified bromelain with dextran two fraction-peaks were obtained and the degree of protein bonding with dextran was 65±5%. The method was developed both with and without the addition of cysteine. The addition of cysteine increased the activity of modified bromelain from 50±5% to 70±5%. the pH optimum for native bromelain was 7.5, whereas for modified bromelain it was shifted towards 8.5, while the temperature optimum in both cases was 60˚C. Taking into consideration the obtained results and comparing them with literary data we suggest that modified bromelain will have much potential in medical application than currently available native product. Further research is required to test the effect of this modification on bromelain's specific pharmacological and allergic properties.