Contribution of phenolamides to the quality evaluation in Lycium spp

ETHNOPHARMACOLOGICAL RELEVANCE

Goji berry is a general term for various plant species in the genus Lycium. Goji has long been historically used in traditional Chinese medicines. Goji is a representative tonic medicine that has the effects of nourishing the liver and kidney and benefiting the essence and eyesight. It has been widely used in the treatment of various diseases, including tinnitus, impotence, spermatorrhea and blood deficiency, since ancient times.

AIM OF THE REVIEW

This study aims to comprehensively summarize the quality evaluation methods of the main compounds in goji, as well as the current research status of the phenolamides in goji and their pharmacological effects, to explore the feasibility of using phenolamides as quality control markers and thus improve the quality and efficacy in goji.

MATERIALS AND METHODS

Relevant literature from PubMed, Web of Science, Science Direct, CNKI and other databases was comprehensively collected, screened and summarized.

RESULTS

According to the collected literature, the quality evaluation markers of goji in the Pharmacopoeia of the People's Republic of China are Lycium barbarum polysaccharide (LBP) and betaine. As a result of its structure complexity, only the total level of LBP can be determined, while betaine is not prominent in the pharmacological action of goji and lacks species distinctiveness. Neither of them can well explain the quality of goji. KuA and KuB are commonly used as quality evaluation markers of the Lycii cortex because of their high levels and suitable pharmacological activity. Goji is rich in polyphenols, carotenoids and alkaloids. Many studies have used the above compounds to establish quality evaluation methods but the results have not been satisfactory. Phenolamides have often been neglected in previous studies because of their low single compound levels and high separation difficulty. However, in recent years, the favorable pharmacological activities of phenolamides have been gradually recognized, and studies on goji phenolamides are greatly increasing. In addition, phenolamides have higher species distinctiveness than other compounds and can be combined with other compounds to better evaluate the quality of goji to improve its average quality.

CONCLUSIONS

The phenolamides in the goji are rich and play a key role in antioxidation, anti-inflammation, neuroprotection and immunomodulation. As a result of their characteristics, it is suitable to evaluate the quality by quantitative analysis of multi-components by single-marker and fingerprint. This method can be combined with other techniques to improve the quality evaluation system of goji, which lays a foundation for their effectiveness and provides a reference for new quality evaluation methods of similar herbal medicines.

New insights into bee pollen: Nutrients, phytochemicals, functions and wall-disruption

Bee pollen is hailed as a treasure trove of human nutrition and has progressively emerged as the source of functional food and medicine. This review conducts a compilation of nutrients and phytochemicals in bee pollen, with particular emphasis on some ubiquitous and unique phenolamides and flavonoid glycosides. Additionally, it provides a concise overview of the diverse health benefits and therapeutic properties of bee pollen, particularly anti-prostatitis and anti-tyrosinase effects. Furthermore, based on the distinctive structural characteristics of pollen walls, a substantial debate has persisted in the past concerning the necessity of wall-disruption. This review provides a comprehensive survey on the necessity of wall-disruption, the impact of wall-disruption on the release and digestion of nutrients, and wall-disruption techniques in industrial production. Wall-disruption appears effective in releasing and digesting nutrients and exploiting bee pollen's bioactivities. Finally, the review underscores the need for future studies to elucidate the mechanisms of beneficial effects. This paper will likely help us gain better insight into bee pollen to develop further functional foods, personalized nutraceuticals, cosmetics products, and medicine.

Phenolamide and flavonoid glycoside profiles of 20 types of monofloral bee pollen

This study aimed at investigating phenolamides and flavonoid glycosides in 20 types of monofloral bee pollen. The plant origins of pollen samples were determined by DNA barcoding, with the purities to over 70 %. The 31 phenolamides and their 33 cis/trans isomers, and 25 flavonoid glycosides were identified; moreover, 19 phenolamides and 14 flavonoid glycosides as new-found compounds in bee pollen. All phenolics and flavonoids are present in the amidation or glycosylation form. The MS/MS cleavage modes of phenolamides and flavonoid glycosides were summarized. Isorhamnetin-3-O-gentiobioside presented the highest levels 23.61 mg/g in apricot pollen. Phenolamides in 11 types of pollen constituted over 1 % of the total weight, especially 3.9 % in rose and 2.8 % in pear pollen. Tri-p-coumaroyl spermidine and di-p-coumaroyl-caffeoyl spermidine respectively accounted for over 2.6 % of the total weight in pear and rose pollen. The richness in phenolamides and flavonoid glycosides can offer bee pollen more bioactivities as functional foods.

Widely targeted metabolomics analysis reveals the effect of fermentation on the chemical composition of bee pollen

Microbial fermentation can break the bee pollen wall. However, the global profiling of bee pollen metabolites under fermentation remains unclear. This study aims to comprehensively elucidate the changes in the composition of bee pollen after microbial fermentation. Ultra-performance liquid chromatography-electron spray ionization-mass spectrometry (UPLC-ESI-MS) based on widely targeted metabolomics analysis was used to compare the chemical composition of unfermented bee pollen (UBP) and fermented bee pollen (FBP). Among the 890 metabolites detected, a total of 668 differential metabolites (classified into 17 categories) were identified between UBP and FBP. Fermentation significantly increased the contents of primary metabolites such as 74 amino acids and derivatives, 42 polyunsaturated fatty acids and 66 organic acids, as well as some secondary metabolites such as 38 phenolic acids, 80 flavone aglycones and 22 phenolamides. The results indicate that fermentation is a promising strategy to improve the nutritional value of bee pollen.

Immobilized lipase catalytic synthesis of phenolamides and their potential against α-glucosidase

Although coumaroyltyramine (CT) derivatives are one kind of phenolamides with remarkable biological activities, the low content in plants would inhibit their potential use in food and pharmaceutical industries. Therefore, it is necessary to screen an efficient method to produce CT derivatives. A green and efficient method by using lipase as catalyst to synthesize a series of CT derivatives, was thus proposed. To obtain optimum reaction conditions, the effects of various parameters on conversion rate were firstly evaluated. An in vitro α-glucosidase inhibitory assay of synthesized compounds was then carried out, and the structure-activity relationship of these compounds was conducted. Under the optimum conditions (MTBE, Nu/S: 2/1, E/S: 20/1, 50 °C and 24 h), the conversion rates of synthesized compounds were above 65 %. The bioassay results indicated that N-trans-caffeoyltyramine and N-trans-feruloyltyramine had potent activities against α-glucosidase with IC₅₀ of 30.08 μM and 31.94 μM, respectively. The structure-activity relationship results showed that the presence of -OH or -OCH₃ group at C-3 position could boost the activities of CT derivatives. Meanwhile, the presence of -OH group at C-4 position and double bound on caffeoyl moiety as well as the presence of -OH group at C-4' position was essential for the activities of CT derivatives.

Phenolamides: Plant specialized metabolites with a wide range of promising pharmacological and health-promoting interests

Phenolamides constitute a family of metabolites, widely represented in the plant kingdom, that can be found in all plant organs with a predominance in flowers and pollen grains. They represent a large and structurally diverse family, resulting from the association of phenolic acids with aliphatic or aromatic amines. Initially revealed as active compounds in several medicinal plant extracts, phenolamides have been extensively studied for their health-promoting and pharmacological properties. Indeed, phenolamides have been shown to exhibit antioxidant, anti-inflammatory, anti-cancer and antimicrobial properties, but also protective effects against metabolic syndrome and neurodegenerative diseases. The purpose of this review is to summarise this large body of literature, including in vitro and in vivo studies, by describing the diversity of their biological properties and our actual knowledge of the molecular mechanisms behind them. With regard to their considerable pharmacological interest, the question of industrial production is also tackled through chemical and biological syntheses in engineered microorganisms. The diversity of biological activities already described, together with the active discovery of the broad structural diversity of this metabolite family, make phenolamides a promising source of new active compounds on which future studies should be focused.

An improved method for a fast screening of α-glucosidase inhibitors in cherimoya fruit (Annona cherimola Mill.) applying effect-directed analysis via high-performance thin-layer chromatography-bioassay-mass spectrometry

α-glucosidase inhibitors (AGIs) are very attractive bioactive compounds due to their therapeutic profile that includes beneficial effects over glycemic control in type 2 diabetes mellitus and viral infections. Its detection and identification in plants and fruits has gained growing attention, and certainly requires efficient screening methodologies. The objective of the present work was to develop a fast methodology to detect and identify AGIs in cherimoya fruit (Annona cherimola Mill.) applying effect-directed analysis via high-performance thin layer-chromatography (HPTLC) linked with bioassay and mass spectrometry (MS). Both, HPTLC and bioassay conditions, were optimized accomplishing 50% and 83% reduction on enzyme concentration and incubation time respectively, compared to the original method. Additionally, the contrast between inhibitory bands and purple background was also enhanced by enzyme substrate impregnation on HPTLC plate. The optimized detection conditions established were the following: 5.0 U mL^-1 of enzyme solution, 1.0 mg mL^-1 of 2-naphthyl-α-D-glucopyranoside substrate, 1.0 mg mL^-1 of Fast Blue B salt solution and 10 min as incubation time. Applying this methodology, coupled to HPTLC-MS and ultra-high-performance liquid chromatography (UHPLC)-diode array detector (DAD)-MS/MS, it was possible for the first time to detect and identify three AGIs in cherimoya peel and seeds. Compounds were tentatively assigned as phenolamides (phenylethyl cinnamides): N-trans-feruloyl tyramine (m/z 314 [M+H]⁺; UV λ_max 293 and 316 nm), N-trans-p-coumaroyl tyramine (m/z 284 [M+H]⁺; UV λ_max 296 nm) and N-trans-feruloyl phenethylamine (m/z 298 [M+H]⁺; UV λ_max 288 nm). To the best of our knowledge, the presence of latter compound is reported for the first time in cherimoya.

Accumulation of secondary metabolites in healthy and diseased barley, grown under future climate levels of CO2, ozone and temperature

Plants produce secondary metabolites promoting adaptation to changes in the environment and challenges by pathogenic microorganisms. A future climate with increased temperature and CO2 and ozone levels will likely alter the chemical composition of plants and thereby plant-pathogen interactions. To investigate this, barley was grown at elevated CO2, temperature and ozone levels as single factors or in combination resembling future climatic conditions. Increased basal resistance to the powdery mildew fungus was observed when barley was grown under elevated CO2, temperature and ozone as single factors. However, this effect was neutralized in the combination treatments. Twenty-five secondary metabolites were putatively identified in healthy and diseased barley leaves, including phenylpropanoids, phenolamides and hydroxynitrile glucosides. Accumulation of the compounds was affected by the climatic growth conditions. Especially elevated temperature, but also ozone, showed a strong impact on accumulation of many compounds, suggesting that these metabolites play a role in adaptation to unfavorable growth conditions. Many compounds were found to increase in powdery mildew diseased leaves, in correlation with a strong and specific influence of the climatic growth conditions. The observed disease phenotypes could not be explained by accumulation of single compounds. However, decreased accumulation of the powdery mildew associated defense compound p-coumaroylhydroxyagmatine could be implicated in the increased disease susceptibility observed when barley was grown under combination of elevated CO2, temperature and ozone. The accumulation pattern of the compounds in both healthy and diseased leaves from barley grown in the combination treatments could not be deduced from the individual single factor treatments. This highlights the complex role and regulation of secondary metabolites in plants' adaptation to unfavorable growth conditions.

Phenolic characterization and variability in leaves, stems and roots of Micro-Tom and patio tomatoes, in response to nitrogen limitation

Phenolics are implicated in the defence strategies of many plant species rendering their concentration increase of putative practical interest in the field of crop protection. Little attention has been given to the nature, concentration and distribution of phenolics within vegetative organs of tomato (Solanum lycopersicum. L) as compared to fruits. In this study, we extensively characterized the phenolics in leaves, stems and roots of nine tomato cultivars using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-MS(n)) and assessed the impact of low nitrogen (LN) availability on their accumulation. Thirty-one phenolics from the four sub-classes, hydroxycinnamoyl esters, flavonoids, anthocyanins and phenolamides were identified, five of which had not previously been reported in these tomato organs. A higher diversity and concentration of phenolics was found in leaves than in stems and roots. The qualitative distribution of these compounds between plant organs was similar for the nine cultivars with the exception of Micro-Tom because of its significantly higher phenolic concentrations in leaves and stems as compared to roots. With few exceptions, the influence of the LN treatment on the three organs of all cultivars was to increase the concentrations of hydroxycinnamoyl esters, flavonoids and anthocyanins and to decrease those of phenolamides. This impact of LN was greater in roots than in leaves and stems. Nitrogen nutrition thus appears as a means of modulating the concentration and composition of organ phenolics and their distribution within the whole plant.