This Phase 1 study is designed to determine the safety, tolerability and pharmacokinetics of PN-235 in healthy volunteers. The study will be conducted in three parts: Part 1 is a single ascending dose study, Part 2 is multiple ascending dose study, and Part 3 is a randomized, crossover solid dose comparison and effect of food study.

Part 1: Approximately 40 subjects randomized into 5 cohorts to receive PN-235 or placebo as single doses.

Part 2: Approximately 50 subjects enrolled into 5 cohorts to receive PN-235 or placebo once daily for 10 days.

Part 3: Twelve subjects will receive single doses of PN-235 in a 4-way, randomized, crossover fashion.

In total, approximately 102 subjects will participate.

Key Inclusion Criteria:

• Subjects must have BMI between 18 and 32
• Subjects must be non-smokers or social smokers
• Subjects must comply with contraception requirements
• Subjects must be willing to consume meals provided by the clinical center

Key Exclusion Criteria:

• Subject must not have history of clinically significant endocrine, neurological, cardiovascular, hematological, hepatic, immunological, renal, respiratory, gastrointestinal or genitourinary abnormalities or diseases within previous 10 years
• Subjects must not have history of surgical resection of the stomach, small or large intestine
• Subjects must not have fever or symptomatic viral or bacterial infection within 2 weeks of screening
• Subjects must not have corrected QT greater than 450 msec in males and 470 msec in females
• Subjects must not test positive for Hepatitis C or B at Screening
• Subjects must refrain from use of prescription and non-prescription drugs and herbal remedies prior to initial dose of study drug and throughout the study

Part 1 blinded, Part 2 blinded, Part 3 unblinded