New Acylated Phenolic Glycosides with ROS-Scavenging Activity from Psidium guajava Leaves

Abstract

Reactive oxygen species and subsequent oxidative stress are reported to play important roles in chronic metabolic diseases. Plant-derived polyphenols, especially food-derived phenolics, have attracted a lot of attention due to their potential usage against oxidative stress-related diseases. The leaf of Psidium guajava (known as guava) is regarded as a good resource of polyphenols and its products are commercially available in Japan as functional foods against multiple chronic metabolism disorders. In the course of finding novel polyphenols with antioxidative activities from guava leaf, 11 acylated phenolic glycosides (1–11), including 5 new oleuropeic acid-conjugated phenolic glycosides, named guajanosides A–E (1, 2, and 5–7), along with 17 known meroterpenoides (12–28), were isolated and identified. Their structures were determined by spectroscopic data analysis, chemical degradation, and acid hydrolysis. Compounds 1, 2, and 5–11 displayed potent reactive oxygen species-scavenging activity in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. Western blot revealed that compound 6 markedly increased the expression levels of nuclear factor-erythroid 2-related factor 2 (Nrf2), NAD­(P)H quinone dehydrogenase 1 (NQO1), and the glutamate–cysteine ligase catalytic subunit. The current study revealed the presence of oleuropeic acid-derived phenolic glycosides in guava leaf and highlighted the potential usage of this type of phenolics against oxidative stress-related metabolic diseases via activation of the Nrf2 signaling pathway.

Hitting the sweet spot: A systematic review of the bioactivity and health benefits of phenolic glycosides from medicinally used plants

“…Finally, both of the studies focussing on antioxidant activity several glycosides with significant antioxidative bioactivity (Dissanayake et al, 2017; Li et al, 2019). Furthermore, the level of antioxidant activity shown by some of the isolated glycosides was comparable to or exceeded that of the positive controls (ascorbic acid and minocycline).…”

Chemical Characterization and Hepatoprotective Effects of a Standardized Triterpenoid-Enriched Guava Leaf Extract

“…41 Previous studies, including our group work, has reported that GUB is the major phenolic component present in guava. 18,27 The HPLC−DAD-MS analysis revealed that most phenolics including guavinoside B, flavonoids, 17 and oleuropeic acid-conjugated phenolic glycosides 34 in guava leaves were successfully removed from TGL (see Supporting Information Figure S4). This was supported by the analysis of the ratio (1:29) between total phenolics (2.1%) and total triterpenoids (58.6%) in TGL, which suggested that the enrichment of triterpenoids in guava leaves was achieved.…”

“…guajava leaves with a voucher number No. 1610056 were collected and identified as previous report . Air-dried and powdered P.…”

“…1610056 were collected and identified as previous report. 34 Air-dried and powdered P. guajava leaves (4.0 kg) were defatted with petroleum ether for twice (10 L), and then extracted with aqueous ethanol (75%) at room temperature for three times. The ethanol extract was combined and dried with a rotary evaporator under reduced pressure.…”

NO Release Inhibitory Activity of Flavonoids from Aesculus Wilsonii Seeds through MAPK (P38), NF-κB, and STAT3 Cross-Talk Signaling Pathways

“…-Fig. aeswilflavonoside IID (7) have been found only in four species including Psidium guajava [25], Eucalyptus cypellocarpa [26], E. resinifera [27], E. maideni [28], and E. polybractea [29], all belonging to the family Myrtaceae. Flavonoid glycosides with a 5-[2-(carboxymethyl)-5-oxocyclopent-yl]pent-3-enylate residue like aeswilflavonoside IC (3) appears also quite rare.…”