Genactin® begins as kiwifruit. Kiwifruit is unusual among common fruits for its combination of vitamin C, potassium, dietary fibre and a set of polyphenols, and it has been studied in nutrition research for some decades.
From fruit to ingredient
Fruit is selected and prepared, the target fraction is extracted, and the extract is then concentrated and dried into a powder that can be measured, stored and dosed. Each of those steps is a place where a batch can drift, which is why the specification is defined at the end and tested against.
The work is not extracting something. It is extracting the same thing, twice.
Why a fruit-derived ingredient at all
Because the starting material has a long record of ordinary dietary use, and because a defined fraction of it can be characterised and reproduced in a way a whole fruit cannot. That is a formulation argument, not a health one.