Abstract:
Natural Rubber Latex (NRL) allergy is an allergic condition caused by the extractable latex
proteins in dipped rubber products. This allergic condition is a major concern for
consumers, mainly for those who are sensitive to the allergenic extractable proteins in
products such as NRL gloves. The objective of this research is to investigate the extractable
protein levels in a range of dipped rubber goods and to develop an economical method to
reduce the extractable protein quantities in dipped natural latex products. In our
investigation of products, it was found that the NRL glove samples available in the Sri
Lankan market belonging to different brands and batches contain about 500-4000 μg g-1 of
extractable proteins. For quantification of extractable latex proteins, modified Lowry assay
(ASTM D5712-10) was used, as it was confirmed to be the most suitable through a literature
survey and experimental data. Gloves were selected for further analysis on how this
reduction of extractable latex proteins could be performed. In order to reduce extractable
protein levels, two different natural proteases were extracted and purified; papain from
papaya and bromelain from pineapple. Partial purification of bromelain and papain were
carried out with 40% and 45% saturated (NH4)2SO4 solutions (optimum (NH4)2SO4
percentage according to literature) respectively from crude plant extracts. Activity of the
isolated enzymes was confirmed prior to each trial through an egg white digestion test (2
hours), where the weight reduction of boiled egg white was used as an indicator to prove
protease activity. With papain a weight reduction of 25 (±5)% was recorded for this test and
with bromelain it was 13.5 (±2)%. Different glove samples of the same weight were treated
with each enzyme, within an incubation time period of 2 hours at 60 ºC temperature. Control
experiments were carried out using distilled water in the place of enzyme. Triplicate of
experiments carried out with bromelain, showed a reduction of 51 (±11)% of the extractable
proteins whereas with papain it was 58 (±8)%. These results clearly indicate that the
selected natural proteases – papain and bromelain contribute significantly towards the
reduction of total aqueous extractable proteins in NRL products. This concept can be
further reformed for application on an industrial scale to treat either the product or the
natural rubber latex itself to decrease the health complications that occur due to allergic
conditions in dipped rubber product consumers.
