Phytochemistry and pharmacology of sea buckthorn (Elaeagnus rhamnoides; syn. Hippophae rhamnoides): progress from 2010 to 2021

Abstract

Sea buckthorn (Elaeagnus rhamnoides; syn. Hippophae rhamnoides) is a thorny shrub or a small tree belonging to the Elaeagnaceae family, native to Eurasia. Sea buckthorn fruit is rich in vitamins and minerals, oils from the seeds and fruit flesh find use in medicine and the cosmetic industry or as nutraceutical supplements. Fruit, leaves and other parts of buckthorn have been used in traditional medicine, especially in China, Tibet, Mongolia, and Central Asia countries, and are a rich source of many bioactive substances. Due to its health-promoting and medicinal properties, the plant has been extensively investigated for several decades, and its phytochemical composition and pharmacological properties are well characterized. The years 2010-2021 brought significant progress in phytochemical research on sea buckthorn. Dozens of new compounds, mainly phenolics, were isolated from this plant. Numerous pharmacological studies were also performed, investigating diverse aspects of the biological activity of different extracts and natural products from sea buckthorn. This review focuses on the progress in research on sea buckthorn specialized metabolites made in this period. Pharmacological studies on sea buckthorn are also discussed. In addition, biosynthetic pathways of the main groups of these compounds have been shortly described.

Keywords: Elaeagnus rhamnoides; Hippophae rhamnoides; Pharmacology; Phytochemistry; Sea buckthorn.

Fig. 1

A twig of sea buckthorn (A) and its detail (B). The photo by Luc.T (Creative Commons Attribution 2.0 Generic license)

Fig. 2

Flavonoids isolated from sea buckthorn

Fig. 3

A scheme of biosynthesis of flavonoids and ellagitannins. C4H—cinnamate-4-hydroxylase; 4CL—4-coumarate-CoA ligase; CHS—chalcone synthase; CHI—chalcone isomerase; DHD-SDH—3-dehydroquinate dehydratase/shikimate dehydrogenase; E4P—erythrose 4-phosphate; F3H—flavanone 3-hydroxylase; F3’H—flavonoid 3’-hydroxylase; F3′5H′—flavonoid 3′5′-hydroxylase; FLS—flavonol synthase; OMT—O-methyltransferase; PAL—phenylalanine ammonia lyase; PEP—phosphoenolpyruvate; UGlcT—UDP-glucosyltransferase

Fig. 4

Flavonolignans from the fruit of sea buckthorn continued

Fig. 4

Flavonolignans from the fruit of sea buckthorn continued

Fig. 4

Flavonolignans from the fruit of sea buckthorn continued

Fig. 5

Hippophaenin C

Fig. 6

Other phenolic compounds isolated from sea buckthorn.

Fig. 7

Triterpenoids isolated from sea buckthorn

Fig. 8

Saponins isolated from sea buckthorn

Fig. 9

A scheme of biosynthesis of triterpenoids, sterols, and carotenoids. AAS – α-amyrin synthase; BAS – β-amyrin synthase; CAS – cycloartenol synthase; CHY-B – carotene hydroxylase B; CHY-E—carotene hydroxylase E; DMADP—dimethylallyl diphosphate; DXP—1-deoxy-D-xylulose-5-phosphate; DXS—1-deoxy-D-xylulose-5-phosphate synthase; FDP – farnesyl diphosphate; FDS—farnesyl diphosphate synthase; G3P—glyceraldehyde 3-phosphate; GGPP – geranylgeranyl diphosphate; GGPPS—geranylgeranyl diphosphate synthase; IDP – isopentenyl diphosphate; IDI—isopentenyl diphosphate isomerase; LCYB – lycopene cyclase B; LCYE—lycopene cyclase E; LS – lupeol synthase; PSY—phytoene synthase; SQS – squalene synthase; SQE – squalene epoxidase

Fig. 10

Other aliphatic compounds isolated from sea buckthorn

Fig. 11

Nitrogen-containing compounds isolated from sea buckthorn