39 cultivars of ginkgo nuts were used to detect the content of ginkgotoxin, and were divided into 4 cultivar groups, including the main nut cultivars in China. The results showed that there was no significant correlation between different cultivars and ginkgotoxin content, however, there were significant differences between the 4 cultivar groups (P<0.05). The ginkgotoxin content of 39 ginkgo cultivars ranged from 330.25 μg∙g^-1 to 525.79 μg∙g^-1. MPN accounts for most of the ginkgotoxin, from 54% to 95%. The ginkgotoxin content of 4 cultivar groups was ranked as Changzi, Fozhi, Zhongzi, Yuanzi. The correlation between ginkgotoxin and different cultivar groups was explored for the first time. Based on this finding, people can preliminarily determine the level of ginkgotoxin, which provides help and convenience for daily consumption.

The nuts of 39 ginkgo cultivars were collected from the National Ginkgo Seed Base of Pizhou, Xuzhou City, Jiangsu Province, China. Excellent cultivars of branches were collected from all parts of China and Japan, and rafted with 5-year-old seedlings 2-3 m high as rootstock in the 1990s. We selected a moderately growing tree from each cultivar to collect nuts in October 2019. The nuts coat was removed after morphology coefficient was measured. The endosperm was freeze-dried at -60 °C, crushed and ground, and then passed through a 50-mesh sieve.

We determined the ginkgotoxin content of nuts by HPLC with reference to the detection method of Liu, Y. et al. Took 0.5 g dry nuts powder, add 20 mL ultrapure water, shocked, 120 min, 10000 rꞏmin^-1 centrifugal supernatant on 10 min after collecting, repeat twice. The twice collected supernatant was passed through 0.22 microns filter membrane and then fixed volume to 50 mL for later use. Liquid chromatography mobile phase A: 5 mM potassium phosphate solution containing 5 mM sodium pentane sulfonate, pH was to 2.5 with phosphoric acid; mobile phase B: acetonitrile. The column temperature was 30 °C, the injection volume was 20 μL, the retention time was 40 min, and the flow rate was 1 mL·min^-1. The detection conditions were: fluorescence emission wavelength 395 nm, excitation wavelength 295 nm.