The purpose of this study is to evaluate the safety, tolerability, pharmacokinetic (PK), and pharmacodynamic (PD) effects of SGB-3908 in healthy subjects and mildly hypertensive subjects. The study will be a single ascending dose (SAD) phase.

Inclusion Criteria:

• Has body mass index (BMI) ≥18 and ≤30 kg/m^2 and has bodyweight ≥ 50 kg;
• Has Systolic blood pressure (SBP) ≥100 mmHg and ≤150 mmHg and diastolic blood pressure (DBP) ≥65 mmHg and ≤95 mmHg at screening;

Exclusion Criteria:

• Has mental illness, liver and kidney disease, gastrointestinal disease, nervous system disease, or other related systemic diseases that affect the trial;

• Has a history of hospitalization or other clinically significant diseases within 1 month before screening, major surgery within 6 months before screening, or other unstable conditions judged by the investigator;

• Has a history of orthostatic hypotension or syncope;

• Patients with clinically significant abnormalities confirmed by physical examination, 12-lead electrocardiogram, laboratory tests, etc., or those who meet any of the following conditions during screening need to be excluded:

  1. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin higher than 1.5× upper limit of normal (ULN)
  2. Serum creatinine (Cr) higher than ULN
  3. Serum potassium higher than 5 mmol/L
  4. QT/QTc interval prolongation during screening (QTcF>450 ms)