Pretty straightforward presuming it is just a normal plotted set of lines and wasn't from one of the fancy toolbox specialty plots -- and doesn't look like would have been.
Kinda' tedious, but not difficult --caution -- air code, untested, just the outline of what to do programmatically ---
hF=openfig('yourfigure.fig'); % handle to the figure
hAx=findobj(hF,'type','Axes'); % and to the axes object
hLg=findobj(hF,'type','Legend'); % then the legend also child of figure
hL=findobj(hAx,'type','Line'); % and then the lines
Now just iterate over the line handles -- if legend was used,then
hL(i).DisplayName
will return the legend string.
It's not clear the annotation was done with legend, though, with the disparate locations unless there are two axes; one for each set of plots overlaid over each other.
There's too much ambiguous about how the plot was done to write precise code...moral--save the data when drawing the figures! :)
