Untargeted metabolite profiling of petal blight in field-grown Rhododendron agastum using GC-TOF-MS and UHPLC-QTOF-MS/MS

The Preliminary Analysis of Flavonoids in the Petals of Rhododendron delavayi, Rhododendron agastum and Rhododendron irroratum Infected with Neopestalotiopsis clavispora

The petal blight disease of alpine Rhododendron severely impacts the ornamental and economic values of Rhododendron. Plant secondary metabolites play a crucial role in resisting pathogenic fungi, yet research on metabolites in alpine Rhododendron petals that confer resistance to pathogenic fungi is limited. In the present study, the secondary metabolites in Rhododendron delavayi, R. agastum, and R. irroratum petals with anti-pathogenic activity were screened through disease index analysis, metabolomic detection, the mycelial growth rate, and metabolite spraying experiments. Disease index analysis revealed that R. delavayi petals exhibited the strongest disease resistance, while R. agastum showed the weakest, both under natural and experimental conditions. UHPLC-QTOF-MS/MS analysis identified 355 and 274 putative metabolites in positive and negative ion modes, respectively. The further antifungal analysis of differentially accumulated baicalein, diosmetin, and naringenin showed their half-inhibitory concentrations (IC50) against Neopestalotiopsis clavispora to be 5000 mg/L, 5000 mg/L, and 1000 mg/L, respectively. Spraying exogenous baicalein, diosmetin, and naringenin significantly alleviated petal blight disease caused by N. clavispora infection in alpine Rhododendron petals, with the inhibition rates exceeding 64%. This study suggests that the screened baicalein, diosmetin, and naringenin, particularly naringenin, can be recommended as inhibitory agents for preventing and controlling petal blight disease in alpine Rhododendron.

In Vitro Antioxidant and Antibacterial Activities of Medicinal Flower Laligurans Rhododendron arboreum Collected from Kathmandu Valley, Nepal

Rhododendron arboreum, known as Nepal's national flower and belonging to the Ericaceae family, thrives throughout the Himalayan region. This study investigates the antioxidant and antimicrobial potential of Rhododendron arboreum flowers. Three different extracts were prepared at concentrations ranging from 10 to 640 μg/mL and assessed for their total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical scavenging activity. Results showed significant accumulation of antioxidant compounds (P < 0.05), with TPC levels of 37.78, 67.29, and 53.46 mg GAE/g and TFC values of 49.46, 67.46, and 65.71 mg QE/g for LGP, LGE, and LGA at 640 μg/mL, respectively. DPPH activity was highest in LGE (96.33%), followed by LGA (87.11%) and LGP (76.59%), compared to the standard (77.38%). The antibacterial properties were significant against Aeromonas hydrophila, Staphylococcus aureus, and Escherichia coli at 100% concentration, with inhibition rates of 15%, 16%, and 17% for LGP, LGE, and LGA, respectively. These findings indicate that Rhododendron arboreum petals, rich in bioactive compounds, possess strong antioxidant and antibacterial properties, making them potential candidates for developing cost-effective therapeutic formulations. Further research should focus on isolating specific bioactive compounds and understanding their molecular mechanisms to enhance therapeutic efficacy.

Exploring the impact of polyphenolic compounds on the chromatic characteristics in flowers of Rhododendron arboreum Sm. collected from different altitudinal locations

INTRODUCTION

Rhododendron arboreum Sm. flowers grow in the Himalayan region and have traditionally been used in beverages and food. These wild edible Himalayan flowers are known for their sweet-sour flavor and beautiful scarlet red color. The primary pigments responsible for the scarlet red color of these flowers are anthocyanins.

OBJECTIVE

In the present study, we conducted chemo-profiling and elucidated the chromatic characteristics of R. arboreum flower petals growing in the wild in different altitudinal areas.

METHODOLOGY

The content of anthocyanins, phenolics, and other flavonoids was determined in R. arboreum flower petals collected from 38 different locations in two provinces in India (Himachal Pradesh and Uttarakhand) to obtain a distinguishable chemical index. A UHPLC method has also been developed and validated for the quantitative analysis. Besides, the color characteristics of each collected floral sample were also analyzed.

RESULTS

Chemometric analysis (principal component analysis [PCA] and heatmap analysis) revealed that floral samples collected from different altitudes exhibited similar chemical diversity, whereas statistical analysis (bivariate linear correlation) revealed a positive correlation between the color parameter a*/b* and cyanidin glycosides. Besides, non-targeted metabolomics analysis was carried out, which resulted in the tentative identification of 150 metabolites.

CONCLUSION

The results revealed that there is a direct influence of accumulated anthocyanins to color parameter a*/b* values in the floral samples irrespective of altitude.

UPLC-Q-TOF-MS profiling of Viola stocksii Boiss. and evaluation of aphrodisiac potential and risk factors associated with erectile dysfunction

ETHNOPHARMACOLOGICAL RELEVANCE

Viola stocksii Boiss. locally known as makhni or makhanr booti, is an important medicinal food plant with multiple therapeutic applications, including erectile dysfunction (ED). It is mixed with butter and used for boosting energy and sexual health in the subcontinent.

AIMS OF THE STUDY

This study was designed to evaluate the chemical composition, aphrodisiac potential and effect of V. stocksii on the risk factors associated with ED.

METHODOLOGY

The hydroethanolic extract of V. stocksii (HEEVS) was prepared through the microwave-assisted extraction (MAE) technique. The chemical composition was evaluated using preliminary phytochemical screening and UPLC-Q-TOF-MS analysis. Metals and minerals analysis was performed by an atomic absorption spectrophotometer. The aphrodisiac activity of HEEVS was evaluated using an in vivo aphrodisiac model established in male albino rats and the effect on various sexual parameters such as mount, intromission, ejaculation frequencies and mount, intromission, ejaculation latencies, postejaculatory interval, penile reflexes and serum hormone concentration were analyzed. The effect of HEEVS on various risk factors associated with ED, including prostate cancer (PC), bacterial infections, diabetes and obesity, was evaluated using various in vitro assays. Moreover, four compounds were selected from the UPLC-Q-TOF-MS profile and evaluated for in silico computational analysis against phosphodiesterase-5 (PDE-5) for possible interaction.

FINDINGS

The phytochemical screening revealed the presence of various secondary metabolites in HEEVS, while 58 compounds were tentatively identified in the UPLC-Q-TOF-MS analysis. Various important minerals and metals such as zinc, calcium, cadmium and magnesium were detected in the atomic absorption spectrometry analysis. The in vivo aphrodisiac evaluation showed a significant (p < 0.05) increase in the mount, intromission and ejaculation frequencies and a decrease in the mount, intromission latencies and post-ejaculatory intervals at a dose of 300 mg/kg. A marked (p < 0.05) increase was observed in the concentration of serum testosterone and luteinizing hormones in HEEVS treated animals with a significant increase in total penile reflexes. The extract displayed significant anti-prostate cancer activity and a potential antibacterial spectrum against E. coli and S. aureus, with MIC50 values of 215.72 μg/mL and 139.05 μg/mL, respectively. Similarly, HEEVS was found active towards pancreatic lipase (67.34 ± 1.03%), α-glucosidase (3.87 ± 0.54 mmol ACAE/g d.w.) and α-amylase (6.98 ± 1.63 mmol ACAE/g d.w.). The in silico docking study presented a potential interaction between the selected compounds and residues of the active site of PDE-5.

CONCLUSION

This report highlights the aphrodisiac potential of V. stocksii and provides experimental support for its traditional use in ED with an attenuative effect on the risk factors associated with ED. Moreover, the chemical composition displayed the presence of functional phytoconstituents and minerals in HEEVS and paves the way for the isolation of compounds with potent aphrodisiac activity.

Early and Late Transcriptomic and Metabolomic Responses of Rhododendron 'Xiaotaohong' Petals to Infection with Alternaria sp

In recent years, petal blight disease caused by pathogens has become increasingly epidemic in Rhododendron. Breeding disease-resistant rhododendron is considered to be a more environmentally friendly strategy than is the use of chemical reagents. In this study, we aimed to investigate the response mechanisms of rhododendron varieties to petal blight, using transcriptomics and metabolomics analyses. Specifically, we monitored changes in gene expression and metabolite accumulation in Rhododendron 'Xiaotaohong' petals infected with the Alternaria sp. strain (MR-9). The infection of MR-9 led to the development of petal blight and induced significant changes in gene transcription. Differentially expressed genes (DEGs) were predominantly enriched in the plant-pathogen interaction pathway. These DEGs were involved in carrying out stress responses, with genes associated with H2O2 production being up-regulated during the early and late stages of infection. Correspondingly, H2O2 accumulation was detected in the vicinity of the blight lesions. In addition, defense-related genes, including PR and FRK, exhibited significant up-regulated expression during the infection by MR-9. In the late stage of the infection, we also observed significant changes in differentially abundant metabolites (DAMs), including flavonoids, alkaloids, phenols, and terpenes. Notably, the levels of euscaphic acid, ganoderol A, (-)-cinchonidine, and theophylline in infected petals were 21.8, 8.5, 4.5, and 4.3 times higher, respectively, compared to the control. Our results suggest that H2O2, defense-related genes, and DAM accumulation are involved in the complex response mechanisms of Rhododendron 'Xiaotaohong' petals to MR-9 infection. These insights provide a deeper understanding of the pathogenesis of petal blight disease and may have practical implications for developing disease-resistant rhododendron varieties.

Evaluation of the anti-inflammatory, antioxidant, and cytotoxic potential of Cardamine amara L. (Brassicaceae): A comprehensive biochemical, toxicological, and in silico computational study

Introduction: Cardamine amara L. (Brassicaceae) is an important edible plant with ethnomedicinal significance. This study aimed at evaluating the phytochemical composition, anti-inflammatory, antioxidant and cytotoxicity aspects of the hydro-alcoholic extract of C. amara (HAECA). Methods: The phytochemical composition was evaluated through total phenolic contents (TPC), total flavonoid contents (TFC) determination and UPLC-QTOF-MS profiling. Anti-inflammatory evaluation of HAECA was carried out through the carrageenan induced paw edema model. Four in vitro methods were applied in the antioxidant evaluation of HAECA. MTT assay was used to investigate the toxicity profile of the species against human normal liver cells (HL7702), human liver cancer cell lines (HepG2) and human breast cancer cell lines (MCF-7). Three major compounds (Gentisic acid, skullcapflavone and conidendrine) identified in UPLC-Q-TOF-MS analysis were selected for in silico study against cyclooxygenase (COX-I and COX-II). Results and Discussion: The findings revealed that HAECA is rich in TPC (39.32 ± 2.3 mg GAE/g DE) and TFC (17.26 ± 0.8 mg RE/g DE). A total of 21 secondary metabolites were tentatively identified in UPLC-Q-TOF-MS analysis. In the MTT cytotoxicity assay, the extract showed low toxicity against normal cell lines, while significant anticancer activity was observed against human liver and breast cancer cells. The carrageenan induced inflammation was inhibited by HAECA in a dose dependent manner and showed a marked alleviation in the levels of oxidative stress (catalase, SOD, GSH) and inflammatory markers (TNF-α, IL-1β). Similarly, HAECA showed maximum antioxidant activity through the Cupric reducing power antioxidant capacity (CUPRAC) assay (31.21 ± 0.3 mg TE/g DE). The in silico study revealed a significant molecular docking score of the three studied compounds against COX-I and COX-I. Conclusively the current study encourages the use of C. amara as a novel polyphenolic rich source with anti-inflammatory and antioxidant potential and warrants further investigations on its toxicity profile.

A holistic comparison of flavor signature and chemical profile in different harvesting periods of Chrysanthemum morifolium Ramat. based on metabolomics combined with bioinformatics and molecular docking strategy

Taiju and Duoju are products of Hangbaiju (HJ) obtained during different collection periods, and they have been commonly used as ingredients in tea beverages and dietary traditional Chinese medicine. This study reports an integrated strategy based on metabolomics, bioinformatics and molecular docking to further explore the effect of the harvesting period on the metabolic profile and clinical efficacy of HJ. Firstly, gas chromatography-mass spectrometry (GC-MS) and ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) were employed for non-targeted metabolomics profiling of essential oils and flavonoids. A sequential window acquisition of all theoretical fragment-ion spectra information-dependent acquisition (SWATH-IDA) bi-directionally verified (SIBDV) method was developed that integrates the advantages of both SWATH and IDA in characterizing flavonoids. Chemometric methods were then used to screen potential chemical markers. Furthermore, HJ is effective in hepatoprotective functions. Therefore, hepatocellular-carcinoma-related differentially expressed genes were obtained using bioinformatics, and the corresponding proteins were molecularly docked with diagnostic chemical markers. In total, 78 volatile oils and 63 flavonoids were tentatively identified. The results allowed the selection of 11 metabolites (5 volatile oils and 6 flavonoids), which are nominated as novel markers for material authentication of Taiju and Duoju. Additionally, two proteins associated with hepatoma were screened using bioinformatics. All six flavonoid markers with binding energies of <-5 kcal mol-1 were considered to be anti-hepatoma biomarkers. Noticeably, in Taiju, the content of hydroxygenkwanin showed a downward trend, but the content of the other five flavonoids and the five flavored volatile difference compounds had an upward trend. This bestows a unique flavor profile on Taiju, leading to differences in sensory aroma and clinical efficacy in Taiju and Duoju. In conclusion, the transformation of secondary metabolites was the dominant trend during HJ growth. These findings lay the foundation for food development and distinguishing clinical applications.

Chemical characterization of the antioxidant and α-glucosidase inhibitory active fraction of Malus transitoria leaves

Chinese Tibetan tea made from the tender leaves of Malus transitoria is a widely consumed health drink, but there are few reports on its chemical composition and biological activity. In this study, we found that a 50% ethanol extract of M. transitoria had good antioxidant and α-glucosidase inhibitory activities in vitro. Guided by in vitro bioassays, chromatographic separation and purification were conducted, and the most active fraction in M. transitoria was determined. UPLC-Orbitrap-MS/MS was used to further quickly and comprehensively characterize the chemical composition. Library searches, MS/MS fragmentation patterns of two isolated reference compounds, and bibliography were used to annotate 81 compounds, of which 2 were new compounds, and 79 were identified from M. transitoria for the first time. This study provides a scientific basis for the development of antioxidant and anti-diabetic functional foods from M. transitoria.

Mass Spectrometry-Based Metabolomics of Phytocannabinoids from Non-Cannabis Plant Origins

Phytocannabinoids are isoprenylated resorcinyl polyketides produced mostly in glandular trichomes of Cannabis sativa L. These discoveries led to the identification of cannabinoid receptors, which modulate psychotropic and pharmacological reactions and are found primarily in the human central nervous system. As a result of the biogenetic process, aliphatic ketide phytocannabinoids are exclusively found in the cannabis species and have a limited natural distribution, whereas phenethyl-type phytocannabinoids are present in higher plants, liverworts, and fungi. The development of cannabinomics has uncovered evidence of new sources containing various phytocannabinoid derivatives. Phytocannabinoids have been isolated as artifacts from their carboxylated forms (pre-cannabinoids or acidic cannabinoids) from plant sources. In this review, the overview of the phytocannabinoid biosynthesis is presented. Different non-cannabis plant sources are described either from those belonging to the angiosperm species and bryophytes, together with their metabolomic structures. Lastly, we discuss the legal framework for the ingestion of these biological materials which currently receive the attention as a legal high.

LC-ESI-MS/MS Characterization of Concentrated Polyphenolic Fractions from Rhododendron luteum and Their Anti-Inflammatory and Antioxidant Activities

The high biological potential of polyphenols encourages the search for new natural sources of and biomedical applications for these compounds. Rhododendron luteum Sweet was previously reported to contain pharmaceutically active polyphenols. The present research investigates the polyphenolic fractions in R. luteum leaves, including a determination of the free and bound phenolic acid and flavonoid contents and their anti-inflammatory and antioxidant activities. LC-ESI-MS/MS (liquid chromatography/electrospray ionization triple quadrupole mass spectrometry) analysis revealed a great abundance of free (e.g., 5-O-caffeoylquinic acid, ferulic acid, protocatechuic acid, catechin, and dihydromyricetin) and bound (e.g., caffeic acid, p-coumaric, protocatechuic acid, myricetin, quercetin) phenolics. The R. luteum samples exhibited high anti-inflammatory potential in lipoxygenase (IC50: 0.33 ± 0.01-2.96 ± 0.06 mg dry extract (DE)/mL) and hyaluronidase (IC50: 78.76 ± 2.09 - 429.07 ± 31.08 µg DE/mL) inhibition capacity assays. Some samples also had the ability to inhibit cyclooxygenase 1 (IC50: 311.8 ± 10.95 µg DE/mL) and cyclooxygenase 2 (IC50: 53.40 ± 5.07; 608.09 ± 14.78 µg DE/mL). All fractions showed excellent antioxidant activity in the Oxygen Radical Absorbance Capacity (ORAC) assay (5.76-221.81 g Trolox/g DE), ABTS•+ radical scavenging ability (0.62 ± 0.03 - 5.09 ± 0.23 g Trolox/g DE), and moderate ion (Fe2+) chelating power. This paper expands our knowledge of the phytochemistry and pharmacological activity of R. luteum polyphenols. It reveals, for the first time, the presence of dihydromyricetin, afzelin, and laricitrin in the plant material. It indicates biologically active polyphenolic fractions that should be further investigated or which could be efficiently used in pharmaceutical, cosmetic, or nutraceutical applications.