Research Article: Screening and Identifying Antioxidative Components in Ginkgo biloba Pollen by DPPH-HPLC-PAD Coupled with HPLC-ESI-MS2

Date Published: January 17, 2017

Publisher: Public Library of Science

Author(s): Jiying Qiu, Xiangyan Chen, A. I. Netrusov, Qingxin Zhou, Danyang Guo, Xiaoyong Liu, Hailun He, Xue Xin, Yifen Wang, Leilei Chen, Gabriel Agbor.

http://doi.org/10.1371/journal.pone.0170141

Abstract

The Ginkgo biloba is one of ancient trees that exists from billions of years ago, its leaf and nut are used as herbs and foods in China, while so far its pollen does not have any application except pollination. In order to evaluate the antioxidant activity of Ginkgo biloba pollen, and rapidly screen its antioxidative components, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, total flavonoid, total phenol, and proanthocyanidin of Ginkgo biloba pollen were determined and compared with those of Ginkgo biloba leaf and nut, and the off-line DPPH-HPLC-PAD and HPLC-ESI-MS2 were applied for screening and identifying the antioxidant flavonoids in Ginkgo biloba pollen. The results showed that the DPPH scavenging ability of Ginkgo biloba pollen was much higher than Ginkgo biloba nut, but lower than Ginkgo biloba leaf, while the total content of flavonoid in Ginkgo biloba pollen was approximately 4.37 times higher than in Ginkgo biloba leaf. Further studies found that the major flavonol aglycone in Ginkgo biloba pollen was kaempferol, which accounted for 96.71% of the total aglycones (includes quercetin, kaempferol and isorhamnetin), and the main flavonoid components in Ginkgo biloba pollen were flavonoid glycosides. Finally, ten antioxidant peaks were screened and identified to be flavonoids (including kaempferol and nine flavonoid glycosides), so flavonoids were likely to be the main antioxidant components in GP, and among them, three novel kaempferol glycosides (peaks 1, 2, and 3) were found in Ginkgo biloba pollen for the first time, which had never been found in Ginkgo biloba.

Partial Text

The Ginkgo biloba is one of ancient trees that exists from billions of years ago, which is well-known as a “living fossil” in the worldwide area. It was firstly discovered in China, and then rapidly spread into Korea, Japan, Netherlands and other countries and regions [1–2]. As the birthplace of Ginkgo biloba, China is one of leading manufacturers of Ginkgo biloba medicines [3]. Ginkgo biloba leaf (GL) is known for a wide variety of medicinally active chemicals, such as flavonoids (glycosides of kaempferol, quercetin, isorhamnetin, etc.) and terpenoids (ginkgolides and bilobalide) [4–6]. It can be taken internally for the treatment of cerebral and peripheral vascular diseases, ailments associated with ageing (dizziness and ringing in the ears) and short-term memory deterioration, as mentioned in Chinese Pharmacopoeia [7]. However, a few side effects have also been reported, such as intracerbral hemorrhage, gastrointestinal disturbances, headaches, dizziness and allergic skin reactions [8]. Dry Ginkgo biloba nut (GN), which contains roughly 60 mg/g sucrose, 680 mg/g starch, 130 mg/g protein and 30 mg/g fat [2], has been widely used as a traditional Chinese medicine to treat asthma, bronchitis, kidney and bladder disorders. The effects, dosages and other useful information of GN can also be found in Chinese Pharmacopoeia [7]. GN also has some toxicity, so it should be eaten according to a certain amount of dosage.

Flavonoids, phenols, and proanthocyanidins are the major antioxidant components existing in plants. In this article, the antioxidant capacity and the contents of total flavonoid, total phenol, and proanthocyanidin of Ginkgo biloba pollen (GP) was qualitatively analyzed. A technique that combining off-line DPPH-HPLC-PAD and HPLC-ESI-MS2 was used for the first time for antioxidants screening and identifying from GP. The results showed that flavonoids were very important active compounds present in GP, they possibly can be the main components that generate the antioxidant effect. Moreover, the flavonoids species of GP were found significantly different from GL and GN, kaempferol was the major flavonol aglycone in GP, and flavonoid glycosides were its main flavonoids. Meanwhile, ten antioxidant compounds were screened out and mainly identified as flavonoid glycosides. Among them, three novel kaempferol glycosides (peaks 1, 2, and 3) were discovered for the first time, which had never been found in Ginkgo biloba leaf and nut. It seemed that Ginkgo biloba pollen (GP) is rich in antioxidant flavonoids, especially water-soluble flavonoid glycosides, we considered that the Ginkgo biloba pollen (GP) has greater potential for the market of healthy foods when compared with Ginkgo biloba leaf (GL) and Ginkgo biloba nut (GN).

 

Source:

http://doi.org/10.1371/journal.pone.0170141