Raktika or Rati, seed of Gunja vine, was used in ancient India as a unit of weight for weighing the precious metals like Gold. The seeds have the quality of having almost identical weights. It is generally taken as 0.118 grams but the consistency over the different times is doubtful. The standard varied from time to time and place.
The botanical name of Gunja is Arbus Precatorious. It is vine which spirals on the trunks of the trees. The seed is bright red with black spots like ladybirds. The seeds contain a potent toxin called which is called abrin and consists of proteins which are dimers and called abrin A and abrin B respectively. It is very lethal. The unit B attaches itself to the cell. Once inside the cell, the A chain deactivates the 26S subunit of Ribosome. One moelcule is enough to deactivate up to 1,500 ribosome.
Manu defined the weight units in ancient India as follows:
5 Raktikas = 1 masa
16 masas = 1 tola or suvarna.
4 tolas =1 pala
10 palas =1 dharana.
Thus Raktika or Ratti was the smallest weight unit.
Besides, the Raktikas were used to make beads and ornaments.
The seed is also known as Jequirity, Crab’s Eye, Rosary Pea, John Crow Bead, Precatory bean, Indian Licorice, Akar Saga, Giddee Giddee or Jumbie Bead in different parts of the world. It is, as one of its names suggests, used as rosary beads. The seeds are used in Andhra and Tamil Nadu in the medicine called Siddha medicine. For this purpose, the toxin arbin has to be deactivated. It is done by boiling the seeds with milk which helps in peptization of the proteins.