Differences in in vivo absorption of flavone glycosides, flavone aglycones and terpene lactones under different dosage forms and physiological conditions

Highlights

• An UPLC-MS method was developed, which can simultaneously determine the contents of 12 compounds in vitro or in vivo samples.

• The differences of oral absorption of different compounds in different dosage forms of GBE preparations were compared.

• The differences in oral absorption of 12 compounds in GBE preparation under different physiological conditions were explored.

• After oral administration, high content of prototype flavonoid glycosides could be measured in plasma.

Abstract

Ethnopharmacological relevance

Ginkgo biloba L. extract (GBE) oral preparations have been used for many years in the prevention and treatment of cardiovascular and cerebrovascular diseases, and the main active ingredients are flavonoids and terpene lactones. Among them, the oral absorption of the prototype components of flavonoid glycosides into the blood needs to be further clarified, and the differences in the oral absorption of different components in GBE by different dosage forms and physiological conditions are not clear yet.

Aim of the study

To clarify the oral absorption of the prototype flavonoid glycosides in vivo, and to further explore the differences in the oral absorption of various active compounds under different oral dosage forms and dietary conditions.

Materials and methods

Firstly, the target compounds were selected based on the characteristic chromatogram of GBE and literature. Then, the content differences of three different oral GBE preparations were studied, and their pharmacokinetics (PK) were compared. Finally, the PK differences of the preparations with better oral absorption under different dietary conditions were studied.

Results

Five flavonoid glycosides, three aglycones and four terpene lactones were selected as the research objects. The content determination results of GBE tablets, guttate pills and tinctures showed that the content of several components especially flavonoid glycosides in the tincture was higher than that of the other two preparations. After oral administration of these three preparations, the PK study showed different results from previous studies. The PK behavior of flavonoid glycosides was also determined at the same time as flavonoid glycosides and terpene lactones. and the bioavailability of flavonoid glycosides in the tincture was higher than that of the other two preparations. PK results of fasting and non-fasting showed that taking GBE tincture on an empty stomach increased the absorption of various compounds, especially flavonoid glycosides. However, due to the existence of food residues in the gastrointestinal tract, the oral bioavailability of flavonoid glycosides was significantly improved.

Conclusions

This study discussed the differences in the content and oral absorption of active compounds in different oral preparations of GBE, clarified the in vivo absorption of flavonoid glycosides prototype, as well as the influence of diet on the PK of active compounds, which has certain guiding significance for the clinical application of GBE oral preparations.

Introduction

Ginkgo biloba L. (http://www.theplantlist.org), is among the oldest seed plants. Its place of origin is believed to be eastern China in Yangtze River Valley (Jaggy and Koch, 1997; Singh et al., 2008). Ginkgo biloba L. leaf is included in the Chinese Pharmacopoeia 2020, and has functions such as activating blood circulation and removing blood stasis, clearing collaterals and relieving pain, etc. Ginkgo biloba L. extract (GBE) oral preparation plays an important role in the clinical application of cardiovascular and cerebrovascular diseases (Shaito et al., 2020). Pharmacological researches show that it has the functions of scavenging oxygen free radicals, resisting lipid peroxidation, reducing microvascular permeability, relaxing arterioles, improving microcirculation, etc. (Hoffman et al., 2004; Niederhofer, 2010; Shu et al., 2019; Tian et al., 2017). The main active components of GBE are flavonoids and terpene lactones. More than 95% of flavonoids exist in the form of glycosides (Mahadevan and Park, 2008). Flavonoids have the functions of antioxidation, immune regulation, blood lipid lowering, liver protection, blood glucose lowering, etc (Liu et al., 2018a, 2018b; Nishida and Satoh, 2004; Šamec et al., 2022). Terpene lactones are strong platelet activating factor antagonists, which have a protective effect on central nervous system and ischemic injury (Liu et al., 2018a, 2018b; Nakanishi, 2005). After oral administration, one of the main prerequisites for effective ingredients to exert their effects in the body is to absorb them into the blood and maintain a high concentration in the plasma. Therefore, the oral absorption of effective ingredients with high content, such as flavonoid glycosides, cannot be ignored.

Flavonoid aglycones (Chen et al., 2010) and ginkgo terpene lactones (Ude et al., 2013) have low polarity and good oral bioavailability. However, in previous studies, on the one hand, due to the lack of advanced technology and methods, the prototype of flavone glycosides was almost undetectable in blood or urine (van Beek and Montoro, 2009). On the other hand, due to the large polarity of flavonoid glycosides, it is considered difficult to cross biofilms. Therefore, for many years, flavonoid glycosides were considered difficult to be absorbed into the blood through the small intestine as prototypes (Tao et al., 2022). However, in recent years, with the continuous improvement of scientific and technological level, some significant progress has been made in the study of oral absorption of flavonoid glycosides. Studies have proved that rutin, quercetin-3-O-glucoside and quercetin-3-O-rhamnoside in natural plants can be absorbed into the blood by oral administration (Hu et al., 2022; Qu et al., 2022; Wang et al., 2016). This puts forward higher scientific requirements for further elucidating the absorption of active ingredients such as flavonoid glycosides in natural plant medicine represented by ginkgo biloba L. leaves.

Oral medication is the most commonly used route of administration in clinical. Most of the drugs are absorbed in the gastrointestinal tract after oral administration and then enter the blood circulation to exert their effects. Among them, the physicochemical properties and dosage forms of the drugs (Debotton and Dahan, 2017), as well as the physiological conditions in the gastrointestinal tract, etc. (Everts et al., 2020), will affect the oral absorption of the drugs. The indications of most drugs with the same name are the same or similar. However, the dosage forms prepared by different preparation methods or different excipients may change the disintegration or dissolution time of oral drugs, which may have some impact on the efficacy (Chen et al., 2021; Osterberg et al., 2006; Sunkara et al., 2014). In clinical application, most of the drugs are taken orally after meals, but the food may change the pH in the gastrointestinal tract and the gastric emptying time of the drugs, or combine with drug molecules, etc., which may affect the absorption of drugs in vivo, and may affect the efficacy of drugs ultimately (Lebkowska-Wieruszewska et al., 2015; Malhotra et al., 2009; Ochoa et al., 2020). In the existing researches, the absorption of drugs in vivo by different oral dosage forms and foods is mainly western medicine or single component, while there are few related studies on traditional Chinese medicine or extracts.

Therefore, this study will take flavonoid glycosides, flavonoid aglycones and terpene lactones as the research objects, compare the content of compounds in three different GBE oral preparations, and explore the differences of pharmacokinetics (PK) of compounds under different oral preparations and physiological conditions, so as to provide more reasonable and comprehensive guidances for the clinical application of GBE oral preparations.