Pure Encapsulations Perilla Plus W/ NAC - Helps maintain healthy immune response at the cellular level. Astragalus is used in Herbal Medicine as an adaptogen to help increase energy and resistance to stress, helping to maintain a healthy immune system during periods of occasional physical or mental stress. Quercetin is known for its antioxidant activity, while N-acetyl-l-cysteine (NAC) promotes tissue levels of glutathione, a key component of the antioxidant defence system. Perilla seed offers a high source of polyphenols, rosmarinic acid, luteolin and other beneficial compounds compared to leaf.