Flavonoids from Nelumbo nucifera Gaertn., a Medicinal Plant: Uses in Traditional Medicine, Phytochemistry and Pharmacological Activities

Abstract

Nelumbo nucifera Gaertn. has been used as an important ingredient for traditional medicines since ancient times, especially in Asian countries. Nowadays, many new or unknown phytochemical compounds from N. nucifera are still being discovered. Most of the current research about pharmacological activity focus on nuciferine, many other alkaloids, phenolic compounds, etc. However, there is no current review emphasizing on flavonoids, which is one of the potent secondary metabolites of this species and its pharmacological activities. Therefore, following a taxonomic description, we aim to illustrate and update the diversity of flavonoid phytochemical compounds from N. nucifera, the comparative analysis of flavonoid compositions and contents in various organs. The uses of this species in traditional medicine and the main pharmacological activities such as antioxidant, anti-inflammatory, anti-diabetic, anti-obesity, anti-angiogenic and anti-cancer activities are also illustrated in this works.

Keywords: Nelumbo nucifera; flavonoids; pharmacological activities; traditional medicine.

Figure 1

Nelumbo nucifera Gaertn.: (A) natural habitat; (B) flower; (C) perianth; and (D) dtamen. The photos were taken by D.T. Bar scale = 1 cm.

Figure 2

The herbal tea product from stamens of Nelumbo nucifera Gaertn. are sold in local markets. The photo was taken by D.T.

Figure 3

The chemical structures and names of the mains flavonoid O- (starting by O), C-glycosides (starting by C) and quercetin (Quer) and Diosmetin (Dio) aglycones from Nelumbo nucifera tissues. Flavonoid abbreviations used: Myr, myrycetin; Quer, quercetin; Kae, kaempferol; Iso, isorhamnetin; Syr, syringetin; Dio, diosmetin; Api, apigenin; Lut, luteolin. Sugar abbreviations used: Glc, glucoside; Gal, galactoside; Ara, arabionoside; Gln, glucuronide; Rut, rutinoside; Hex, hexoside; Xyl, xylose; Rha, rhamnose; Pen, pentose. ¹ rutin, quercetin 3-O-rhamnopyranosyl-(1→6)-glucopyranoside; ² hyperoside, quercetin 3-O-galactoside; ³ isoquercitrin, quercetin 3-O-glucoside; ⁴ Astragalin, kaempferol 3-O-glucoside; ⁵ orientin, luteolin 8-C-β-D-glucopyranoside; ⁶ isoorientin, luteolin 6-C-β-D-glucopyranoside; ⁷ vitexin, apigenin 8-C-β-D-glucopyranoside; ⁸ isovitexin, apigenin 6-C-β-D-glucopyranoside. Adapted from Chen et al. [25] and Li et al. [35].

Figure 4

Comparative analysis of flavonoid contents and compositions different tissues of Nelumbo nucifera. Data were compiled from Chen et al. [33] and Li et al. [35]. (A) Comparative analysis of flavonoids aglycones and FOGs in 11 different tissues. (B) Comparative analysis of FCGs in 12 tissues and/or developmental stages including embryo (the major accumulation site of FCGs in Nelumbo nucifera) at five maturation stages. The names and structures of the flavonoids are presented in Figure 3. * Contents are expressed in mg.100 g⁻¹ FW for all tissues except for seed embryo for which contents are expressed in mg.100 g⁻¹ DW in (A)).

Figure 5

Proposed biosynthetic sequence of FOGs (orange) and FCGs (purple) derived flavonoids from Nelumbo nucifera adapted from Li et al. (2014). CHS, chalcone synthase; CHI, chalcone isomerase; FNS, flavone synthase; F3H, flavanone 3 hydroxylase; F3′H, flavonoid 3′ hydroxylase; F3′5′H, flavonoid 3′,5′ hydroxylase; FLS, flavonol synthase; OGT, O-flavonoid glycosyltransferase; CGT, C-flavonoid glycosyltransferase; Api, apigenin; DHM, dihydromyricetin; DHK, dihydrokaempferol; Myr, myricetin; Kae, kaempferol; Quer, quercetin; Iso, isorhamnetin; Dio, diosmetin; Lut, luteolin; Syr, syringetin; Gly, glycoside(s).