Aesculus chinensis seed

Edible Uses:

seed – cooked. It can be dried and ground into a powder and used as a gruel. The seed is quite large, it can be 3cm in diameter, and is easily harvested. Unfortunately it is also rich in saponins, these must be removed before it can be used as a food and this process also removes many of the minerals and vitamins, leaving behind mainly starch. See also the notes above on toxicity. The following notes apply to A. californica, but are probably also relevant here:- The seed needs to be leached of toxins before it becomes safe to eat – the Indians would do this by slow-roasting the nuts (which would have rendered the saponins harmless) and then cutting them into thin slices, putting them into a cloth bag and rinsing them in a stream for 2 – 5 days[213]. 
Medicinal Uses 

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Antirheumatic;  Emetic.

The seed is antirheumatic and emetic[178, 218]. The sweet tasting seed is said to be used in the treatment of contracted limbs that are due to palsy or rheumatism[178, 218]. It is also used in the treatment of stomach aches[218]. 
Other Uses 
Soap;  Wood.

Saponins in the seed are used as a soap substitute[169]. The saponins can be easily obtained by chopping the seed into small pieces and infusing them in hot water. This water can then be used for washing the body, clothes etc. Its main drawback is a lingering odour of horse chestnuts[K].