compunction

huono omatunto, omantunnon pistos A pricking of conscience or a feeling of regret, especially one which is slight or fleeting.
(RQ:Dickens Little Dorrit):

He would have had no compunction whatever in flinging him out of the highest window in Venice into the deepest water of the city.

I felt no compunction in doing so, for under the circumstances I felt that I should protect myself in every way I could.

But he felt, later, a little compunction. He had been violent, cruel with poor Hermione. He wanted to recompense her, to make it up.

As for average U.S. consumers, they've shown little compunction about buying diamonds that fund bloody militias in Africa.