This is a randomized, double-blind, placebo-controlled, single ascending dose (SAD) and multi-dose, sequential, bridging study in healthy volunteer using YG1699 .

This is a randomized, double-blind, placebo-controlled, dose-ascending study to evaluate the safety, tolerability, and pharmacokinetics (PK) of YG1699 following single ascending and multiple oral dose administration.

The study consists of 2 parts: Part 1, SAD dose- ascending; Part 2, multi-dose ascending.

Inclusion Criteria:

1. Are capable of giving informed consent and complying with study procedures;

2. Are between the ages of 18 and 55 years, inclusive;

3. Female subjects have a negative urine pregnancy test result at screening and Day 0, and meet one of the following criteria:

   1. Using a medically acceptable form of birth control for at least 1 month prior to screening (3 months on oral contraceptives) [e.g., hormonal contraceptives (oral, patch, injectable or vaginal ring), implantable device (implantable rod or intrauterine device), or a double barrier (e.g., diaphragm, cervical cap, oral, patch or vaginal hormonal contraceptive, condom, spermicide, or sponge)]

   2. Surgically sterile for at least 3 months prior to screening by one of the following means:

      Bilateral tubal ligation Bilateral salpingectomy (with or without oophorectomy) Surgical hysterectomy Bilateral oophorectomy (with or without hysterectomy)

   3. Postmenopausal, defined as the following:

   Last menstrual period greater than 12 months prior to screening Postmenopausal status confirmed by serum Follicle-Stimulating Hormone（FSH） and estradiol levels at screening;

4. Considered healthy by the Investigator, based on subject's reported medical history, full physical examination, clinical laboratory tests, 12-lead ECG, and vital signs;

5. Non-smoker and less than 5 cigarettes/day or nicotine replacement products in last 6 months;

6. Body mass index (BMI) of 18.0 to 30.0 kg/m2 inclusive and body weight not less than 50 kg;

7. Male subjects with female partners of child bearing potential must agree to use condoms for the duration of the study and until 12 weeks after dosing with the study drug and must refrain from donating sperm for this same period.

Exclusion Criteria:

1. Subjects of non-Chinese nationality living or working in China, or persons of non-East Asian descent who are Chinese nationals;
2. Clinically significant history of gastrointestinal, cardiovascular, musculoskeletal, endocrine, hematologic, psychiatric, renal, hepatic, bronchopulmonary, neurologic, immunologic, lipid metabolism disorders, or drug hypersensitivity as determined by the Investigator;
3. History of food or drug allergy;
4. Known or suspected malignancy;
5. History of unexplained syncope, symptomatic hypotension or hypoglycemia;
6. History or family history of long corrective QT interval（QTc） syndrome;
7. History of chronic diarrhea, malabsorption, unexplained weight loss, food allergies or intolerance;
8. Poor venous access;
9. Positive blood screen for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), hepatitis C antibody or treponema pallidum antibody ;
10. Donated or lost >500ml of blood in the previous 3 months;
11. Taken an investigational drug or participated in a clinical trial within 3 months (or 5 half-lives), whichever is longer;
12. Taken any prescription medications within 14 days or 5 half-lives (whichever is longer) of the first dose of study drug;
13. Hospital admission or major surgery within 6 months prior to screening;
14. A history of prescription drug abuse within 9 months prior to screening;
15. A history of alcohol abuse according to medical history within 9 months prior to screening;
16. Female subjects with positive pregnancy test, pregnant or breastfeeding;
17. A positive screen for alcohol, drugs of abuse at screening;
18. An unwillingness or inability to comply with food and beverage restrictions during study participation;
19. Use of over-the-counter (OTC) medication and herbal within 7 days prior to dosing (Note: Use of acetaminophen at < 2 g/day is permitted until 24 hours prior to dosing);
20. Any condition or finding that in the Investigators opinion would put the subject or study conduct at risk if the subject were to participate in the study.

Double Blinded