Durham-based Know Bio LLC raised an additional $4.68 million from 19 investors, according to a Friday Securities and Exchange Commission filing.

The company had raised $7.2 million from 49 investors, according to a filing Jan. 28 with the commission.

The company was founded in 2015 and develops and produces nitric oxide-based therapies. Know Bio operates as a subsidiary of Novan Inc., a clinical-stage biotechnology company.

Know Bio’s subsidiary Vast Therapeutics Inc. is a pre-clinical stage pharmaceutical company for patients with respiratory diseases. It uses a nitric oxide technology which was developed with Dr. Mark Schoenfisch’s lab at UNC-Chapel Hill.

Former Cree CEO Neal Hunter is managing director of KnowBio, a Research Triangle-based incubator for platform based medical technology and biotechnology companies. Vast Therapeutics and PhotonMD Inc. are two companies that have emerged from Know Bio.

Companies relying on a Reg D exemption do not have to register their offering of securities with the SEC, but they must file what’s known as a Form D electronically with the SEC after they first sell their securities.