Salai guggal and boswellic acids: their effects on the arachidonic acid cascade.
Salai guggal is the gum resin from the tree Boswellia serrata.
Based on studies by G.B. Singh and C.K. Atal showing anti-inflammatory
activity of extracts, we studied the effect of an extract of B. serrata
and a variety of boswellic acids on the formation of products of the
arachidonic acid cascade. Prostaglandins: In human platelets, which
produce only prostaglandins, salai guggal inhibited formation of
6-keto-PGF l[alpha] only at very high concentrations being around 100
[micro]g/ml. When a mixture of acetyl boswellic acids was employed, no
inhibition was found up to 60 [micro]g/rnl. On the other hand,
acetyl-keto-beta-boswellic acid produced inhibition in concentrations
above 10 [micro]M. Leukotrienes: Using polymorphnuclear leukocytes which
can produce only leukotrienes, salai guggal in a sigmoid concentration-dependent manner inhibited production of LT[B.sub.4] and
other 5-LO products. Employing acetyl-boswellic acids, again an
inhibition of LT[B.sub.4] and other 5-LO product formation was observed.
Among several boswellic acids, acety1-11-keto-[beta]-boswellic acid
(AKBA) was the most effective, the [IC.sub.50] was 1.5 [micro]M. As far
as ll-keto-j3-boswellic acid (KBA) is concerned [IC.sub.50] was 4.5
[micro]M. Other boswellic acids have been found to be less or not
effective at all. There was a close structure-activity relationship.
Inhibition of leukotriene synthesis occurred in a nonredox and
noncompetitive manner. In photo-labeling studies with
-azido-boswellic acid, it was found that this compound binds to the
enzyme 5-lipoxygenase and could be removed in the presence of unlabeled
AKBA or other boswellic acids. It is concluded that certain boswellic
acids including AKBA and KBA preferentially inhibit 5-lipoxygenase and
with far less activity cyclooxygenase. This leads to the hypothesis that
chronic inflammatory diseases with increased leukotriene formation may
be a target for the treatment with salai guggal or certain boswellic
acids. Pilot studies so far suggest therapeutic benefit in chronic bowel
diseases, rheumatoid arthritis and bronchial asthma.
Ammon, H.P.T., 2006. Boswellic acids in chronic inflammatory
diseases. Planta Med. 72, 1100-1116.
Department of Pharmacology, Institute of Pharmaceutical Sciences.
University of Tuebingen, 72076 Tuebingen, Germany
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