When tested for possible blocking effect on the cercarial,
serine proteinase,
elastase (CE) activity, an
iridoid mixture extracted from leaves of Citharexylum quadrangular abolished 31% of the
enzyme activity at final concentration 15 microg. When formulated in
jojoba oil and applied to mice tails followed by
infection with Schistosoma mansoni cercariae, the
iridoid mixture blocked cercarial penetration and caused significant reducetion (94%; P < 0.05) in worm burden in treated mice in comparison to controls. Also, immunomodulatory effects of
iridoid mixture,
iridoid-treated S. mansoni worm homogenate on mice were studied by measuring
IgG and
IgM levels against E. coli lysates (ECL), solube S. mansoni worm antigenic preparation (SWAP) and
cancer bladder homogenates (CBH) as
antigens by ELISA. Cellular immune responses were studied by calculating mean percent of CD4+, CD8(+)-T, B-mesenteric lymph node cells (MLNC) and CD4+, CD8(+)-T thymocytes by direct immunofluorescence staining in treated mice as compared to untreated homogenate given mice or untreated mice. Injecting mice with serial dilutions of
iridoid mixture resulted in fluctuation, peaks and troughs, in both
IgG and
IgM responses against the above mentioned
antigens. 1st and 2nd immunizations with
iridoid mixture treated homogenate resulted in significantly elevated (P < 0.05).
IgM and
IgG levels against the 3 used
antigens in comparison with sera from control mice. Immunized mice with homogenate treated with
iridoid mixture showed a significant increase (P < 0.05) in CD4+T thymocytes, a non significant increase in CD8+T thymocytes, a significant increase (P < 0.05) in CD4+T lymphocytes (MLNC) and a non significant increase in CD8+ T- and B-lymphocytes (MLNC) compared with mice immunized with untreated homogenate or non-injected normal mice.