vels suggest other potentially important molecular mechanisms underlying the observed effects of these compounds that remain to INNO-406 Bafetinib be further elucidated. Recently, PPARγ has been shown to regulate IDE expression levels in rat primary neurons.54 This, taken together with the current data, suggests that 1 may have some effect on PPARγ leading to the upregulation in IDE protein levels. Furthermore, it remains to be seen if compounds 1 and 2 have any affect on activities of one or more of the A related targets studied here. In this context, the computational docking studies that were conducted indicate the occurrence of favorable interaction complexes between the natural product 1 and the active sites of all four targets indicating its possible direct effect on the levels and the activities of these enzymes.
Patil et al. Page 5 J Nat Prod. Author manuscript, available in PMC 2011 July 23. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript The synergistic, multi target activity demonstrated here by 1 and 2 is in line with a recent shift in the AD drug discovery focus from one target molecules to finding multi target ligands.13,55 This type of multi functional Cuscutin 477-90-7 activity may prove advisable for any novel therapeutic molecule to be effective in modifying the complex pathology of AD. With this in mind, an anti A multi target therapeutic index is proposed, defined simply as the ratio of the fractional up regulation in anti amyloid targets to the fractional downregulation in pro amyloid targets, as shown below: This index may serve as a potentially important criterion for determining the effectiveness of a therapeutic molecule in modulating multiple targets that synergistically affect cerebral Alevels, the higher the index value, the higher the anti amyloid, multi targeting activity of the test compounds.
With a minimum number of targets equal to two, at least one anti amyloid and one pro amyloid target, and minimum 35% up regulation and 35% down regulation, respectively, for biological significance, the following evaluation is obtained: Thus, a minimum index value for any therapeutic molecule to have a significant, multitarget anti A activity is 2.10. From the present data, for 1 at the highest concentration of 100 M, equation can be written as follows by using values from Figures 2 and 5: Similarly, for 2 at the highest concentration of 10 M, the following is obtained: Thus, comparing these anti A MTTI values for 1 and 2 with the minimum index value of 2.
10, both 1 and 2 seem to possess excellent multi targeted, anti A activities. In summary, it has been shown for the first time that withanolide A and asiatic acid positively modulate multiple targets associated with A pathways and thus, may be beneficial in attenuating A levels in the AD brain by both decreasing A production and also by increasing A degradation. Therapies based on modulating secretases will act locally to affect A production, while therapies based on increasing A degradation may prove essential in acting at sites that are widely separated from the A production sites.
43 This kind of multi functional and multi level activity in a given therapeutic molecule may prove highly effective against AD, providing multiple mechanisms to alter amyloid pathology in the AD brain. Finally, in addition to the A related activities established in the present study, both 1 and 2 have been shown to induce significant regeneration of neurites and dendrites, which may help in reconstructing neuronal networks Patil et al. Page 6 J Nat Prod. Author manuscript, available in PMC 2011 July 23. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript damaged in AD.56,57 Thus, these two natural products may serve as lead compounds for the development of novel thera