Conduct in Chinese healthy adult subjects:1.To observe the safety and tolerability of multiple-dose oral administration of different doses of PNA;2.By measuring the changing drug concentration in the plasma and urine after a single oral administration of different doses of PNA on the condition of fasting, the pharmacokinetic parameters of the single dose are estimated;3.By measuring the changing drug concentration in the plasma of PNA after a multiple-dose oral administration on the condition of fasting, the pharmacokinetic parameters of multiple-dose are estimated, and a basis for dosage regimens of the clinical research phase Ⅱ is provided;4.To study the effects of diet on the pharmacokinetic parameters via the changes of concentration of PNA in plasma after high-fat and high-calorie food.