You can find various PDF tools that should be capable of recovering the original documents and saving them in their original format. So programs, such as Able2Extract can help you in exporting MS Publisher documents (.pub) from PDF documents (.pdf). This will of course only work on PDFs that were made in Publisher.
Convert Adobe Portable document format to Microsoft Publisher document.
We found one software available in the database for this conversion.
Multiplatform software - convert pdf to pub on any platform
A dedicated PDF conversion solution
Convert from pdf file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.