Sapindus

Sapindus is a genus of about five to twelve species of shrubs and small trees in the lychee family, Sapindaceae, native to warm temperate to tropical regions of the world. The genus includes both deciduous and evergreen species. Members of the genus are commonly known as soapberries[3] or soapnuts because the fruit pulp is used to make soap. The generic name is derived from the Latin words sapo, meaning “soap”, and indicus, meaning “of India”.[4]

The leaves are alternate, 15–40 cm (5.9–15.7 in) long, pinnate (except in S. oahuensis, which has simple leaves), with 14-30 leaflets, the terminal leaflet often absent. The flowers form in large panicles, each flower small, creamy white. The fruit is a small leathery-skinned drupe 1–2 cm (0.39–0.79 in) in diameter, yellow ripening blackish, containing one to three seeds.

The drupes (soapnuts) contain saponins, which have surfactant properties, having been used for washing by ancient Asian people and Native Americans.[5]

Soapnuts have historically been used in folk remedies,[6] but, as the effectiveness of such treatments has not been subjected to scientific scrutiny, there are no confirmed health benefits of using soapnuts to treat any human disease. The soapnut contains saponins, which are under laboratory research for their potential antimicrobial properties.[6]

Sapindus species are used as food plants by the larvae of some Lepidoptera (moths and butterflies) species including Endoclita malabaricus. Kernel extracts of soapnut disrupt the activity of enzymes of larvae and pupae and inhibits the growth of the mosquito Aedes aegypti, an important vector of viral diseases.[7]