Forsythia suspensa (Thunb.) Vahl. (Family Oleaceae) is an ornamental shrub, the fruits of which are used as the well-known TCM “Forsythiae Fructus” (FF) (连翘in Chinese). The TCM characteristics of FF are summarized as bitter in flavor, with a mild cold nature and lung, heart or intestinum meridian distributions (Pharmacopoeia Commission of PRC, 2015), those characteristics are parallel to the characterisation of anti-inflammatory TCM, according to Chen and Zhang (2014). In Shennong’s herbal, FF was used for the treatment of pyrexia, inflammation, gonorrhea, carbuncle and erysipelas (Cho et al., 2011). Two forms of FF are available, the greenish fresh ripe fruit called “Qingqiao” and the yellow fully ripe one called “Laoqiao”. Both of them serve as official sources of FF, nevertheless, Qingqiao is used more frequently in TCM prescriptions (Jia et al., 2015). The major producing areas of FF are Hebei, Shaanxi, Shanxi, Shandong, Anhui, Henan, Hubei, Jiangsu (cultivated) and Sichuan Provinces (Editorial Board of Flora of China, 1978).
In the 2015 edition Chinese Pharmacopoeia, 114 Chinese medicinal preparations containing FF are listed, such as Shuanghuanglian oral solution, Yinqiao Jiedu tablet, Niuhuang Shangqing tablets, etc (Pharmacopoeia Commission of PRC, 2015). Modern researches reveal its anti-inflammatory (Kim et al., 2003), antioxidant (C.C. Chen et al., 1999), antibacterial (Han et al., 2012), anti-cancer (Hu et al., 2007), anti-virus (Ko et al., 2005), anti-allergy (Hao et al., 2010), neuroprotective (S. Zhang et al., 2015) effects, etc. Although only the fruit is used as TCM, some studies reported the phytochemistry and pharmacological effects of leaves (Ge et al., 2015, Zhang et al., 2015), flowers (Takizawa et al., 1981) and seeds (Zhang et al., 2002) of F. suspensa. Therefore, we now provide a systematic overview of the available information of F. suspensa, including traditional uses, botany, phytochemistry, pharmacology, toxicity, pharmacokinetics and quality control. Also, the possible future directions of research are discussed.