[JoeyBananas]

This is out of the scope of a text editor. Instead, you could write a script to convert your text to HTML.

[gus_massa]

Something like this?

<person>Jhon doe</person> started the <vehicle>car</vehicle>.

[neo_hacker]

It is not just UI highlight. I want to be able to store them for processing later.

[JoeyBananas]

The format proposed by gus_massa would be capable of both of these tasks. You can generate HTML for the visual highlight, and do whatever processing that you wish in a different script.

This is just my 2 cents, I have no idea what your intended application is.