Material Agreement, Financial Obligation (Form 8-K)

Item 1.01 Entry into a Material Definitive Agreement.

On November 4, 2026, Protagenic Therapeutics, Inc. (the "Company" or the "Borrower") issued a promissory note (the "Note") to Patness LLC (the "Lender"), pursuant to which the Borrower agreed to pay to the order of the Lender the principal sum of $250,000 (the "Principal"). The Note bears simple interest at a rate equal to 1.0% per annum, calculated on the basis of a 365-day year and the actual number of days elapsed, and payable on the Maturity Date (as defined below). The unpaid Principal, together with all accrued but unpaid interest (if any) and all other amounts payable under the Note (collectively, the "Obligations"), is due and payable upon the earliest to occur of (i) the closing of any equity capital raise of any type by the Borrower for gross cash proceeds of at least $1,000,000, and (ii) the date that is 180 days from the date of the Note (the "Maturity Date"); provided, that if all Obligations are paid in full prior to the date that is 365 days after the date of the Note, all accrued but unpaid interest shall be forgiven and no interest shall be due or payable.

The Note contains customary events of default, including (i) the Borrower's failure to pay any amount due under the Note within five business days after the date due, (ii) the Borrower's breach of any other material covenant in the Note that remains uncured for ten business days after written notice from the Lender, and (iii) certain bankruptcy and insolvency events. Upon the occurrence and during the continuance of an event of default described in clause (i) or (ii), the Lender may, by written notice to the Borrower, declare all Obligations immediately due and payable. Upon the occurrence of an event of default described in clause (iii), all Obligations shall automatically and immediately become due and payable without any action by the Lender. If the Note is placed in the hands of an attorney for collection following an event of default, the Borrower shall pay the Lender's reasonable out-of-pocket costs and expenses (including reasonable attorneys' fees) incurred in enforcing the Note. The Borrower may prepay the Note, in whole or in part, at any time and from time to time without premium or penalty. Any partial prepayment made under the Note is applied first to reasonable out-of-pocket fees and expenses then due thereunder (if any), next to accrued but unpaid interest (if any), and then to outstanding Principal.

A copy of the Note is filed as Exhibit 10.1 to this Current Report on Form 8-K. The foregoing summary of the terms of the Note is subject to, and qualified in its entirety by, the Note, which is incorporated herein by reference.

The Note was issued in reliance on the exemption from registration provided by Section 4(a)(2) of the Securities Act of 1933, as amended (the "Securities Act"), as a transaction by an issuer not involving a public offering. The Note has not been registered under the Securities Act or any state or other applicable jurisdiction's securities laws, and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements of the Securities Act and applicable state or other jurisdiction's securities laws.

This current report on Form 8-K shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

Item 2.03. Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

The information set forth in Item 1.01 of this Current Report on Form 8-K is incorporated by reference into this Item 2.03 in its entirety.