At December 31, 2015, the balance of the convertible notes with adjustable conversion features (“adjustable convertible notes”) was $824,861. During the interim period ended September 30, 2016, the Company repaid $681,738 of note principal, andnote holders converted $143,123 of note principal into shares of the Company’s common stock. At September 30, 2016, the balance of adjustable convertible notes was $0.
At December 31, 2015, the balance of the accrued interest on the adjustable convertible notes was $298,235. During the interim period ended September 30, 2016, the Company paid $189,443 of accrued interest, andnote holders converted $49,560 of accrued interest into shares of common stock. During the interim period ended September 30, 2016, interest expense of $13,278 was accrued, and $71,153 was forgiven and written-off. At September 30, 2016, the balance of accrued interest on adjustable convertible notes was $1,357.
At the option of the holder, the adjustable convertible notes were convertible into shares of common stock of the Company at a price per share discount of 40% of the Company’s common stock trading market price during a certain time period. The Company determined that the conversion feature of the notes were not fixed, and recorded them as a derivative liability. During the interim period ended September 30, 2016, the payment and conversion of the convertible notes resulted in the Company recording a gain of $635,600 related to the extinguishment of the corresponding derivative liability (see Note 6).