Embryogenic callus induction, cell suspension culture, and spectrum-effect relationship between antioxidant activity and polyphenols composition of Siraitia grosvenorii cultured cells

Siraitia grosvenorii (S. grosvenorii), a perennial vine of Cucurbitaceae family, has been widely used in medicine and food products. However, its application is hindered due to the limited output of natural and cultivated plants. Thus, to expand plant resource and application of S. grosvenorii, the current research study comprises embryogenic callus induction, development of suspension culture, and analysis on the spectrum-effect relationship between antioxidant activity and polyphenols composition of S. grosvenorii cultured cells. Adding 0.5 g·L−1 ascorbic acid and 1.0 g·L−1 choline could increase the induction rate from 0.75% to 68% and enhances the antioxidant enzyme activities of loose embryogenic calluses. A total of 15 polyphenols (14 flavonols and 1 phenolic acid) in the callus extracts were identified via liquid chromatography-mass spectrometry. Through Plackett-Burman's design and response surface methodology, optimal proportionings of plant growth regulator (PGRs) for cell suspension culture were obtained. With the optimized PGRs, the obtained cell biomass and polyphenols content were 32.18% and 13.86%, respectively, more than PGRs proportioning before optimization. Furthermore, a homogeneous and rapidly grown suspension cell culture was developed with a maximum biomass and polyphenols content of 25.5 g·L−1 DW and 30.75 mg·g−1 DW, respectively. The results of spectrum-effect relationships analysis indicated a strong linear correlation between 15 above-identified polyphenols and the antioxidation activity of the extracts. In addition, the partial least square method result revealed that all 15 polyphenols positively contributed to antioxidant capacity, including 3,4-di-p-coumaroyl, 5-tri-hydroxycoumaroyl quinic acid and kaempferol-3-O-Glc-7-O-Rha with vital roles. Our results indicated that the extracts from S. grosvenorii cell have excellent antioxidant activity, and therefore have potential applications in healthy food and daily cosmetics.