Occurrence of Benzoic Acid Esters as Putative Catabolites of Prunasin in Senescent Leaves of Prunus laurocerasus

Abstract

Prunus laurocerasus is an evergreen shrub containing large quantities of the cyanogenic glycoside prunasin (1) in its leaves, which decomposes to prunasin amide (2) or glucose-1-benzoate (4) when the leaves become chlorotic as a result of senescence or pseudosenescence. This study was aimed at the systematic identification of senescence-associated metabolites to contribute further insight into the catabolism of 1. LC-ESIMS profiles of senescent and green leaves were analyzed by principal component analysis. In senescent leaves, the concentrations of 36 compounds were increased significantly including several benzoic acid derivatives, of which prunasin amide-6'-benzoate (5) and prunasin acid-6'-benzoate (6) were isolated and identified. The observed metabolic changes were also induced by treatment of P. laurocerasus shrubs with exogenous ethylene. The data presented support an oxidative catabolism of 1 without release of hydrogen cyanide and the remobilization of its nitrogen in the course of senescence. The results are discussed in the context of functional diversification and drug discovery, where senescent plant material represents a widely unexplored source for the discovery of natural products.

Cyanogenic Glucosides and Derivatives in Almond and Sweet Cherry Flower Buds from Dormancy to Flowering

“…In all studied cultivars, the peak of prunasin amide coincided with a decrease in prunasin levels, indicating turnover of prunasin into its amide. The conversion of prunasin to prunasin amide may occur non-enzymatically via the Radziszewski reaction in the presence of hydrogen peroxide (Sendker et al, 2016). Hydrogen peroxide is produced during flower development (Kuroda et al, 2002).…”

“… Proposed turnover pathways (1, 2, 3, and R) for prunasin without the release of hydrogen cyanide (after Pičmanová et al, 2015; Sendker et al, 2016). In pathway 1, prunasin is sequentially converted into its amide and/or acid and anitrile; moreover, β- D -glucose-1-benzoate may be formed from prunasin acid.…”

“…In senescent leaves of P. laurocerasus L., novel benzoic acid esters have recently been reported as formed from prunasin (Sendker et al, 2016). This inspired us to investigate the possible presence of benzoic acid derivatives in almond and sweet cherry flower buds.…”

“…A compound identified as β- D -glucose-1-benzoate was indeed found to be present in high amounts compared to prunasin in the flower buds of all studied almond cultivars as well as in the cherry cultivar ( Figures 5C , 6B ). β- D -Glucose-1-benzoate was suggested to be formed as a novel extension of the oxidative catabolism of prunasin (Sendker et al, 2016). The amount of accumulated β- D -glucose-1-benzoate is high compared to the prunasin level implying that β- D -glucose-1-benzoate might also be synthesized by a different route in the flower buds.…”

Antidiabetic Activities of an LC/MS Fingerprinted Aqueous Extract of Fagonia cretica L. in Preclinical Models

“…The TM was prepared as a tea using freshly dried aerial parts as described by traditional healers [15]. The lyophilised powder was analysed using a modification of the methods described by Sendker et al [34]. The corresponding LC/MS chromatographic fingerprint shows the main components of the extract (Fig.…”