Synthetic Biologics, Inc. announced that it has entered into a securities purchase agreement for the private placement of 275,000 Series C convertible preferred shares and 100,000 Series D convertible preferred shares at a price of $8 per share for gross proceeds of approximately $3 million with returning investor MSD Credit Opportunity Master Fund, L.P., a fund managed by MSD Partners, L.P. on July 28, 2022. The Series C convertible preferred shares and Series D convertible preferred shares have a conversion price of $1.22. The securities are subject to transfer restrictions.