PH Indicator
The extract of Melastoma malabathricum fruits can be used as pH indicators. Anthrocyanins are the compounds which cause this property of Melastoma malabathricum. It gives dark red colour in acids (pH < 7), black-blue colour in neutral solutions (pH = 7) and dark green colour in Basic/Alkaline Solutions (pH > 7).It can be used as a homemade universal indicator. But it decay approximately after 24 hours due to the reaction between the other particles in the air.
Read more about this topic: Melastoma Affine