Background:
Antiplatelet, anticoagulant and fibrinolytic activities of stem bromelain
(EC 3.4.22.4) are well described, but more studies are still required to clearly define its usefulness
as an antithrombotic agent. Besides, although some effects of bromelain are linked to its proteolytic
activity, few studies were performed taking into account this relationship.
Objective:
We aimed at comparing the effects of stem bromelain total extract (ET) and of its major
proteolytic compounds on fibrinogen, fibrin, and blood coagulation considering the proteolytic
activity.
Methods:
Proteolytic fractions chromatographically separated from ET (acidic bromelains, basic
bromelains, and ananains) and their irreversibly inhibited counterparts were assayed. Effects
on fibrinogen were electrophoretically and spectrophotometrically evaluated. Fibrinolytic activity
was measured by the fibrin plate assay. The effect on blood coagulation was evaluated by the prothrombin
time (PT) and activated partial thromboplastin time (APTT) tests. Effects were compared
with those of thrombin and plasmin.
Results:
Acidic bromelains and ananains showed thrombin-type activity and low fibrinolytic activity,
with acidic bromelains being the least effective as anticoagulants and fibrinolytics; while basic
bromelains, without thrombin-like activity, were the best anticoagulant and fibrinolytic proteases
present in ET. Procoagulant action was detected for ET and its proteolytic compounds by the
APTT test at low concentrations. The measured effects were dependent on proteolytic activity.
Conclusion:
Two sub-populations of cysteine proteases exhibiting different effects on fibrin
(ogen) and blood coagulation are present in ET. Using well characterized stem bromelain regarding
its proteolytic system is a prerequisite for a better understanding of the mechanisms underlying the
bromelain action.
