N-hydroxysuccinimide is a synthetic ingredient used in cosmetics as an ester to soften and condition skin. It’s also a reagent, a substance used to trigger a reaction that leads to a new substance, such as peptides and polymers. N-hydroxysuccinimide activates the elimination of blood originated pigments responsible for dark color and inflammation that causes under eye circles.

N-Hydroxysuccinimide (Wikipedia)

N-Hydroxysuccinimide (NHS) is an organic compound with the formula (CH₂CO)₂NOH. It is a white solid that is used as a reagent for preparing active esters in peptide synthesis. It can be synthesized by heating succinic anhydride with hydroxylamine or hydroxylamine hydrochloride.

N-Hydroxysuccinimide

Names
Preferred IUPAC name 1-Hydroxypyrrolidine-2,5-dione
Other names HOSu, HSI.
Identifiers
CAS Number	6066-82-6 Y
3D model (JSmol)	Interactive image
ChemSpider	72416 N
ECHA InfoCard	100.025.456
PubChem CID	80170
UNII	MJE3791M4T N
CompTox Dashboard (EPA)	DTXSID7064102
InChI InChI=1S/C4H5NO3/c6-3-1-2-4(7)5(3)8/h8H,1-2H2 N Key: NQTADLQHYWFPDB-UHFFFAOYSA-N N InChI=1/C4H5NO3/c6-3-1-2-4(7)5(3)8/h8H,1-2H2 Key: NQTADLQHYWFPDB-UHFFFAOYAM
SMILES O=C1N(O)C(=O)CC1
Properties
Chemical formula	C4H5NO3
Molar mass	115.09 g/mol
Appearance	Colourless solid
Melting point	95 °C (203 °F; 368 K)
Related compounds
Related imides	Succinimide N-Bromosuccinimide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references