Anna was a Lady-in-Waiting to Tsaritsa Elizabeth. Many of her family sided with Peter III when he attempted to push his wife Sophie aside after Tsaritsa Elizabeth died. Peter III did not succeed and Sophie became Tsaritsa Catherine the Great. Anna's life was trending downwards when Antropov painted this portrait in 1763. Her Wikipedia article is here.
Spots in background removed blurring with Photoshop by gogm.