Polysaccharides represent quantitatively the most important group of substances in the fruit of L. barbarum. which are estimated to comprise 3–8 % of the dried fruits (Amagase and Farnswoeth 2011). More than 30 polysaccarides have been isolated from the fruit of L. barbarum, L. chinense, and L. ruthenium (Table 1.2). The molecular weight of polysaccharides varies greatly in different species, which might lead to the different pharmacological function.

As to the color regents in wolfberry, the reddish-orange color of L. barbarum and L. chinense is derived from carotenoids and their esters, which are the second major group of metabolites. Twelve carotenoids and their esters were identified in the genus Lycium (Table 1.2.). The highest content of carotenoids in ripen red berry is zeaxanthin dipalmitate which counts for 75 % of total carotenoids (508.90 μg g^− 1 fresh weight (FW) in ripen fresh fruit) (Liu et al. 2014). Although there is very low level of total carotenoid (34.46 μg g^− 1 FW), with 18.01μg g^− 1 FW of β-carotene, in green fruits of L. ruthenicum, the content of total carotenoid in ripen black berry is undetectable (Liu et al. 2014). The zeaxanthin and β-Cryptoxanthin are undetectable both in green and ripen fruits of L. ruthenicum (Liu et al. 2014). As to the black color in ripen fruits of L. ruthenicum, ten anthocyanins were identified using HPLC-DAD-MS/MS (Zheng et al. 2011), with the highest content of pentunidin-3-O-rutinoside (trans-p-coumaroyl)-5-O-glucoside which counts 95 % of total flavonoids (Zeng et al. 2014). Consistent with this, anthocyanin content in L. ruthenicum increased steadily and reached maximum levels (10.37 OD₅₃₄/g) at the ripening stage, while anthocyanin was undetectable at all stages in L. barbarum fruits (Zeng et al. 2014).

Other phytochemicals include flavonoids, alkaloids, amides, peptides, anthraquinones, coumarins, lignanoids, terpenoids, steroids, and their derivatives, organic acids, and glycolipids are summarized in Table 1.3. Kim et al. (1997c) identified 45 volatile flavor components in L. chinense leaves including four acids, 15 alcohols, seven aldehydes, two esters, three furans, nine hydrocarbons, and three others. Sannai et al. (1983) identified 36 neutral volatile compounds in L. chinense fruits. Fifty-four volatile components including twelve alcohols, twelve esters, seven aldehydes, six acids, five hydrocarbons, eight ketones, one furan, and three pyrazines were detected in the fruit of L. chinense (Yao et al. 2011). Twenty-one compounds from the essential oil of L. barbarum fruits and 18 compounds from the essential oil of L. ruthenicum fruits were identified by GC/MS (Altintas et al. 2006). 1β-Amino-3β, 4β, 5α-trihydroxycycloheptane, digupigan A, and a tryptophane glycoside, were only isolated from the root barks of L. chinense (Asano et al. 1997; Yahara et al. 1989; Wei and Liang 2003). The only one lignin, (+)-Lyoniresinol 3α–O–β–d-glucopyranoside was isolated from the root bark of L. chinense (Han et al. 2002; Lee et al. 2005). Two compounds were newly identified from the acetone extract of dry Goji berry, 3-(3-hydroxy-4-methoxyphenyl)-N-[2-(4-methoxyphenyl)ethyl]-(2E)-Propenamide, and 3-(4-hydroxy-3-methoxyphenyl)-N-[2-(4-hydroxyphenyl)ethyl]-2-Propenamide (Personal communication with Dr. Minghua Qiu).