Is there any way (software) to defrag NTFS on Mac?
In short, no, I don't know of a way to do this other than booting into Windows.

That being said, a few things:


Why do you feel that the drive needs to be defragmented? Modern NTFS does a fairly decent job of preventing itself from getting too fragmented, at least when running under Windows 7+.
If you're sharing these disks with Windows machines, any reason you can't defrag when connected to those platforms?
The NTFS implementation on OSX has never really been extremely robust. While I'm not sure if the reason is solely due to how to handle ACLs (file permissions), it is worth pointing out that NTFS write capability isn't enabled by default.
If your primary machine is OSX, then you're probably best served using HFS+ as your file system. NTFS should be "SneakerNet" with the implication that it probably spends a significant amount of its time on a Windows machine anyway.


Probably #3 is the strongest point here, but at least this list is worth some thought?