Quinoline, isoquinoline, and indoles are common heterocyclic compounds. They have many biological activities, such as antioxidant, anti-inflammatory, antibacterial, antitumor, anti-virus, anti-rheumatism, immunity regulation, expectorant, and analgesic. Over the past few centuries, traditional natural products have made great contributions to the discovery and development of new therapeutic agents. Many important drugs have been found from these three classes of compounds. In this mini-review, we mainly cover the research progress on antioxidant, anti-inflammatory, antibacterial, analgesic activities of quinoline, isoquinoline, and indole compounds over the past 20 years (2000- 2019). We aim to explore new characteristic groups or structures in the search for active lead compounds and provide a basis for rational drug design.

The purified total sterols and β-sitosterol extracted from Sargassum horneri were evaluated for their antidepressant-like activity using the forced swim test (FST) and tail suspension test (TST) in mice. Total sterols and β-sitosterol significantly reduced the immobility time in the FST and TST. Total sterols were administered orally for 7 days at doses of 50, 100, and 200 mg/kg, and β-sitosterol was administered intraperitoneally at doses of 10, 20, and 30 mg/kg. β-sitosterol had no effect on locomotor activity in the open field test. In addition, total sterols and β-sitosterol significantly increased NE, 5-HT, and the metabolite 5-HIAA in the mouse brain, suggesting that the antidepressant-like activity may be mediated through these neurotransmitters.