Metabolomic and chemometric analyses of St. John's wort and related Asian Hypericum species linked to bioactivity.

ETHNOPHARMACOLOGICAL RELEVANCE: Plants in the genus Hypericum (Hypericaceae), include more than 500 species worldwide, and many are valued for their medicinal properties, and are used as traditional herbal medicines. However, only H. perforatum is officially recognized as herbal drug in several pharmacopoeias, and used as an antidepressant clinically. Hypericum perforatum had been used as an herbal medicine since the Han Dynasty (206 B.C. -220 A.D.) in China. It taxonomically belongs to the section Hypericum in the genus Hypericum. There are about 42 species in the section Hypericum, with six species occurring in China. All six are recorded as traditional herbal medicines for treating aliments, including hepatitis, malaria, traumatic hemorrhage, irregular menstruation, wounds, and bruises. AIM OF THE STUDY: The study aimed to characterize the chemical profiles of five phylogenetically related Hypericum species, and compare their metabolites with three H. perforatum products. Informed by ethnobotanical use, the extracts prepared from the five species were further investigated into anticancer, anti-inflammatory and antiplasmodial activity. This study tested the hypothesis that systematic metabolomic and bioactivity characterization of species in section Hypericum will help to validate their phytotherapeutic use and reveal potential drug lead compounds. MATERIALS AND METHODS: Targeted and non-targeted metabolic analyses coupled with chemometrics were conducted on H. perforatum and four medicinal species, H. attenuatum, H. enshiense, H. erectum, and H. faberi, native to China from section Hypericum. UPLC-QTOF-MS/MS and UPLC-TQD-MS/MS were used for non-targeted and targeted metabolic analyses, respectively. Cytotoxicity bioassays on four cancer cell lines, anti-inflammation tests and anti-plasmodial activity on Plasmodium falciparum 3D7, selected based on traditional medicinal use, were evaluated on extracts from Hypericum species. Progenesis QI and EZinfo were used for chemometrics analysis to link the chemical profile and bioassay activity to aid in the identification of bioactive compounds. RESULTS: In total, 58 compounds were identified from the five species, including compounds with well-characterized bioactivity. Hypericum attenuatum, H. erectum, and H. perforatum, displayed the highest cytotoxicity, and contain the cytotoxic compounds petiolin A, prolificin A, and hypercohin G, respectively. Hypericum faberi and H. perforatum showed the highest anti-inflammatory activity, with pseudohypericin, quercetin and chlorogenic acid being observed at higher concentrations. Hypericum perforatum and H. erectum showed anti-plasmodial activity, with higher hyperforin and xanthones in these species that may account for the anti-plasmodial activity. CONCLUSIONS: This study characterized the chemical differences among five Hypericum species using metabolomics. These ethnomedically important species were tested for their biological activities in three distinct in vitro assays. The ethnobotanical data were useful for identifying bioactive Hypericum species. Hypericum attenuatum, H. erectum and H. faberi are promising phytotherapeutic species, although they are much less studied than H. perforatum, St. John's wort. Combining ethnobotanical surveys with chemometric analyses and bioactivity screening can greatly enhance the discovery of promising active constituents.

Chromosome-level genome assembly of Amomum tsao-ko provides insights into the biosynthesis of flavor compounds.

Amomum tsao-ko is an economically important spice plant in the ginger family (Zingiberaceae). The dried ripe fruit has been widely used as spice and medicine in Southeast Asia due to its distinct flavor metabolites. However, there is little genomic information available to understand the biosynthesis of its characteristic flavor compounds. Here, we present a high-quality chromosome-level genome of A. tsao-ko with a total length of 2.08 Gb assembled into 24 chromosomes. Potential relationships between genetic variation and chemical constituents were analyzed by a genome-wide association study of 119 representative A. tsao-ko specimens in China. Metabolome and transcriptome correlation analysis of different plant organs and fruit developmental stages revealed the proposed biosynthesis of the characteristic bicyclononane aldehydes and aromatic metabolites in A. tsao-ko fruit. Transcription factors of 20 families may be involved in the regulatory network of terpenoids. This study provides genomic and chemical insights into the biosynthesis of characteristic aroma and flavor constituents, which can be used to improve the quality of A. tsao-ko as food and medicine.

Differences in Leaf Chemistry and Glandular Trichome Density between Wild Southwestern American Hop (Humulus neomexicanus) and Commercial Hop Cultivars.

The female flowers ("cones") of the hop plant (Humulus L.) produce compounds that contribute to the flavor and other properties of beer. Hop leaves and cones produce many of the same compounds, which also confer agronomic traits such as insect and disease resistance. Targeted and untargeted ultraperformance liquid chromatography-quadrupole time-of-flight-mass spectrometry with Waters MSE technology (UPLC-QTof-MSE) metabolomics were used to compare leaf phytochemical compositions of greenhouse-grown southwestern American wild Humulus neomexicanus (A. Nelson and Cockerell) Rydb. against a group of commercial hop cultivars consisting of both pure European Humulus lupulus L. and European-North American hybrids. Principal component analysis showed a clear distinction in chemical profiles between the two groups. H. neomexicanus leaves had a significantly higher content of total α acids (p = 4.4 × 10-9), total bitter acids (p = 2.6 × 10-6), cohumulone (p = 1.0 × 10-13), humulone + adhumulone (p = 9.1 × 10-4), and the prenylflavonoids xanthohumol (p = 0.013) and desmethylxanthohumol (p = 0.029) as well as significantly higher densities of glandular trichomes (p = 1.3 × 10-6), the biosynthetic site of those compounds. Most flavonol glycosides measured were also significantly more abundant in H. neomexicanus (p = 1.5 × 10-22 to 0.0027), whereas phenolic acids were consistently, but generally nonsignificantly (p > 0.05), more abundant in the cultivars. The higher bitter acid, prenylflavonoid, and flavonol glycoside content of H. neomexicanus leaves may help to confer more favorable insect and disease-resistance properties.

Gaultheria longibracteolata, an alternative source of wintergreen oil.

Gaultheria longibracteolata (Ericaceae) has been traditionally used by different linguistic groups in Yunnan Province, China, but it has not been well studied. Through our ethnobotanical study in Lüchun County of Yunnan, we found that this species has multiple traditional uses including food, medicine, and worship. The essential oils from the root, stem, and leaf were investigated by both GC-MS and anti-bacterial assays. The GC-MS study showed that methyl salicylate is the main (>90%) component of the essential oil, and the oil composition extracted from different plant parts showed some similarities. The oil of G. longibracteolata displayed antimicrobial activity against Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus, which is likely due to its methyl salicylate content. Gautheria longbracteolata appears to be a useful natural wintergreen oil substitute, but further studies are needed to develop this product.

UPLC-QTof-MSE Metabolomics Reveals Changes in Leaf Primary and Secondary Metabolism of Hop (Humulus lupulus L.) Plants under Drought Stress.

The hop (Humulus lupulus L.) is an important specialty crop used in beer production. Untargeted UPLC-QTof-MSE metabolomics was used to determine metabolite changes in the leaves of hop plants under varying degrees of drought stress. Principal component analysis revealed that drought treatments produced qualitatively distinct changes in the overall chemical composition of three out of four genotypes tested (i.e., Cascade, Sultana, and a wild var. neomexicanus accession but not Aurora), although differences among treatments were smaller than differences among genotypes. A total of 14 compounds consistently increased or decreased in response to drought stress, and this effect was generally progressive as the severity of drought increased. A total of 10 of these marker compounds were tentatively identified as follows: five glycerolipids, glutaric acid, pheophorbide A, abscisic acid, roseoside, and dihydromyricetin. Some of the observed metabolite changes likely occur across all plants under drought conditions, while others may be specific to hops or to the type of drought treatments performed.

Identification of tandem repeat families from long-read sequences of Humulus lupulus.

Hop (Humulus lupulus L.) is known for its use as a bittering agent in beer and has a rich history of cultivation, beginning in Europe and now spanning the globe. There are five wild varieties worldwide, which may have been introgressed with cultivated varieties. As a dioecious species, its obligate outcrossing, non-Mendelian inheritance, and genomic structural variability have confounded directed breeding efforts. Consequently, understanding the hop genome represents a considerable challenge, requiring additional resources. In order to facilitate investigations into the transmission genetics of hop, we report here a tandem repeat discovery pipeline developed using k-mer filtering and dot plot analysis of PacBio long-read sequences from the hop cultivar Apollo. From this we identified 17 new and distinct tandem repeat sequence families, which represent candidates for FISH probe development. For two of these candidates, HuluTR120 and HuluTR225, we produced oligonucleotide FISH probes from conserved regions of and demonstrated their utility by staining meiotic chromosomes from wild hop, var. neomexicanus to address, for example, questions about hop transmission genetics. Collectively, these tandem repeat sequence families represent new resources suitable for development of additional cytogenomic tools for hop research.

Hop (Humulus lupulus L.) terroir has large effect on a glycosylated green leaf volatile but not on other aroma glycosides.

Genetics and environment both influence the content of hop (Humulus lupulus L.) aroma compounds. The effects of these two factors on aroma glycosides, which can change the aroma profile of beer over time, were examined in a preliminary study. Twenty-three hop cultivars were grown in the northwestern United States in two locations with distinct terroirs. UPLC-MS/MS analysis of hop cone extracts revealed that growing location had a large effect on hexyl glucoside levels but only a negligible effect on levels of linalyl, raspberry ketone, and 2-phenylethyl glucoside, which were mostly affected by genetic differences. The large terroir effect on hexyl glucoside, which releases a green leaf volatile with a grassy aroma when hydrolyzed, but not on the other aroma glucosides, which have more desirable aromas when hydrolyzed, could have an impact on beer aroma profiles.

Metabolic Profiling of Different Parts of Acer truncatum from the Mongolian Plateau Using UPLC-QTOF-MS with Comparative Bioactivity Assays.

Acer truncatum is an important ornamental, edible, and medicinal plant resource in China. Previous phytochemical research has focused on the leaf (AL) due to its long history as a tea for health. Other parts such as the branch (ABr), bark (ABa), fruit (AF), and root (AR) have drawn little attention regarding their metabolites and bioactivities. The strategy of an in-house chemical library combined with Progenesis QI informatics platform was applied to characterize the metabolites. A total of 98 compounds were characterized or tentatively identified, including 63 compounds reported from this species for the first time. Principal component analysis showed the close clustering of ABr, ABa, and AR, indicating that they share similar chemical components, while AL and AF clustered more distantly. By multiple orthogonal partial least-squares discriminant analyses (OPLS-DA), 52 compounds were identified as potential marker compounds differentiating these different plant parts. The variable influence on projection score from OPLS-DA revealed that catechin, procyanidins B2 or B3, and procyanidins C1 or C2 are the significant metabolites in ABa extracts, which likely contribute to its antioxidant and cytotoxic activities.

[Studies on volatile oils compounds of Acorus macrospadiceus based on GC-MS, an ethnomedicinal and food plant used by local people in southwest China].

Acorus macrospadiceus is a common medicinal and food plant used different ethnic groups in Guizhou and surrounding areas. In this paper, the leaf and rhizome tissues of A. macrospadiceus were hydro-distilled to extract the volatile oils. The chemical constituents of these oils were analyzed by GC-MS and identified using the NIST 14.0 & NIST 14.0s mass spectral libraries. The relative contents of chemical constituents from the different plant parts were determined by area normalization. The analysis of A. macrospadiceus volatile oils resulted in the identification of 25 compounds from the leaf and 36 compounds from the rhizome. The identified compounds accounted for 97.85% of the leaf essential oil content and 97.18% of the rhizome essential oil content. The main volatile constituent of A. macrospadiceus was identified as estragole (93.56% of total oil content in leaf and 71.62% of total oil content in rhizome). Fourteen compounds were found to be common to essential oils of both leaf and rhizome. However, the relative amounts of these compounds were significantly different between the plant parts; the remaining identified compounds were unique to each part. This comparison of volatile oils from the different parts of A. macrospadiceus can serve as a reference for future development. Because of the higher estragole content and better harvesting sustainability of the leaves compared to rhizomes, the leaves of A. macrospadiceus deserve consideration for sustainable development. However, when we use it as a medical plant, we should draw a distinction between it with A. tatarinowii.