Macrosphyra longistyla (Cultivated)

Very fragrant, white flowers seen at Lalbagh on 29th March.
Cultivated bushes.
Flowers turning black on drying.
Could be some Species very close to Gardenia or Tarenna.
Yes most likely a Rubiaceae.. Tarenna a possibility but i am not much up on flora of tropical east africa... this seems definitely from that region
some one knowledgeable in african flowers can help
I think I have found the id of these flowers. 
Macrosphyra longistyla, Rubiaceae