Five phenolic glycosides from Alangium chinense

Characterization of key bitter compounds in Idesia polycarpa var. vestita Diels fruit by sensory-guided fractionation

Idesia polycarpa var. vestita Diels (I. vestita) has become a promising oil crop due to its easily digestible and highly nutritious fruit oil. However, the intense bitter taste of its fruit greatly limits its development and promotion in the food industry. Herein, five key bitter compounds from I. vestita fruit were isolated by sensory-guided fractionation and characterized using ultra-high performance liquid chromatography-quadrupole time of flight-mass spectrometer and nuclear magnetic resonance. The bitter taste of the identified compounds was subsequently validated by threshold tests and computational molecular docking. The bitterness threshold in water of idesin was the lowest (12.051 mg/L), and all bitter substances spontaneously bound to the bitter receptors hTAS2R16 and hTAS2R14, with a stronger affinity for the latter (approximately -6.5 - -9.0 kcal/mol). This is the first systematic study of bitter compounds in I. vestita fruit, providing a scientific basis for revealing the mechanism of bitterness formation and bitterness control.

Anti-Inflammatory Salicin Derivatives from the Barks of Salix tetrasperma

The genus Salix L. is traditionally used in folk medicine to alleviate pain caused by various kinds of inflammation. In the present study, 10 undescribed salicin derivatives along with 5 known congeners were isolated from the barks of Salix tetrasperma, and their structures were elucidated by spectroscopic analyses, single-crystal X-ray diffraction, electronic circular dichroism (ECD) calculations, and chemical conversions. Compounds 4-6 significantly inhibited NO production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages, and the most active 4 obviously suppressed the production of IL-1β and IL-6 and decreased iNOS and COX-2 expression in a dose-dependent manner. Further Western blotting analysis revealed that the anti-inflammatory mechanism of 4 is possibly mediated through the MAPK and NF-κB signaling pathways.

Cadinane Sesquiterpenoids and Their Glycosides from Alangium chinense That Inhibit Spontaneous Calcium Oscillations

Nine new cadinane sesquiterpenoids, alanenses A-I (1-9), were isolated from the leaves of Alangium chinense together with three previously reported analogues (10-12). The structures of these molecules were elucidated by interpretation of spectroscopic and spectrometric data. Absolute configurations were established by the comparison of experimental and calculated ECD data, chemical degradation studies for sugar moieties, and a single-crystal X-ray diffraction analysis. Compounds 1 and 2 were isolated as racemates, and enantiopurification was achieved by chiral HPLC. Compounds 3-5 are glycosylated cadinanes bearing a β-d-glucose unit, while compounds 6-9 incorporate a hydroxymethyl group in either the free form or additional ring fusion. The structure of compound 11 was originally misassigned and later revised using additional NMR data. The corrected structure is here supported by X-ray single-crystal analysis. Compounds 1 and 2 inhibit spontaneous calcium channel oscillations at low micromolar concentrations.

Phenolic glycosides from the stems of Homalium stenophyllum

The phytochemical investigation of the stems of Homalium stenophyllum afforded seven new phenolic glycosides (1-5 and 8-9) and two known compounds (6 and 7). Their structures were elucidated by comprehensive analyses of NMR spectroscopic, mass spectrometric data and chemical hydrolysis. Additionally, their anti-inflammatory activities against the NO production in LPS-induced macrophages were evaluated.

New phenylpropanoid-substituted and benzyl-substituted flavonols from Alangium chinense

Two previously undescribed flavonols with phenylpropanoid or benzyl substitution, named alangsine A (1), and alangsine B (2), together with four known compounds (3-6) were isolated from the leaves of Alangium chinense. Alangsine A was a racemic mixture, which was further separated into two enantiomers via high-performance liquid chromatography on a chiral column. The absolute configurations of the enantiomer pairs were deduced from the circular dichroism (CD) spectra. The activity of the isolated compounds towards neuronal excitability was examined.

Genus Alangium - A review on its traditional uses, phytochemistry and pharmacological activities

The species from Alangium have been used as folk medicine to treat rheumatism, skin diseases, diabetes by the people of Southeast Asia. Previous phytochemical studies have shown this genus are rich sources of alkaloids, glycosides, and terpenoids, which have attracted considerable attention of many researchers due to their markedly diverse and complex architecture. The crude extracts as well as the monomeric compounds from the title genus possess anti-tumor, anti-inflammatory, antibacterial, anti-oxidant pharmacological activities. Besides, some isolates from Alangium exhibited the effects on skeletal, smooth muscle and the nervous system. As a large genus of medicinal plants, the medicinal value of Alangium has been widely reported, but there is no review that provide a systematic summary towards its chemical constituents and pharmacological activities, to our knowledge. This work aims to present a comprehensive overview on the traditional uses, phytochemistry, and pharmacological activities of medicinal plants in the genus Alangium, and to explore the evidence supporting its ethnopharmacological effectiveness.

Phenols and γ-Lactams from the Aerial Part of Pseudolysimachion linariifolium subsp. dilatatum

Linariifolioside II (1) and (2S)-2-hydroxy-5-oxoproline methyl ester (2), two new compounds along with 13 known compounds were obtained from the aerial part of Pseudolysimachion linariifolium Holub subsp. dilatatum (Nakai & Kitag.) D.Y. Hong. Their chemical structures were revealed mainly through NMR and MS data. The absolute configuration of 2 was deduced by comparing its experimental CD with the calculated ECD spectra. At a concentration of 1 mm, total antioxidant capacities of compounds 1-15 were measured using a rapid ABTS method in vitro. Compounds 1, 3-5, and 11-14 exhibited approximately equal antioxidant capacity to that of vitamin C (Vc).

Synthesis of Salicaceae Acetyl Salicins Using Selective Deacetylation and Acetyl Group Migration

In the present work, the synthesis of acetylated salicins, which occur naturally in many Salicaceae species, is reported. The preparation of 2-O-acetylsalicin, 2-O-acetylchlorosalicin, and 2-O-acetylethylsalicin from peracetylated bromosalicin with selective acid-catalyzed deacetylation and one-pot nucleophilic substitution of bromine as the key steps is described. The base-catalyzed O-2 → O-6 acetyl migration afforded 6-O-acetylsalicin derivatives in good yields. Thus, the first synthesis of 6-O-acetylsalicin (fragilin) using acetyl group migration is reported as well as the synthesis of 6-O-acetylchlorosalicin and 6-O-acetylethylsalicin. The NaOMe-catalyzed deacetylation of acetylated glycosides gave salicin, chlorosalicin, and ethylsalicin recently reported from Alangium chinense.

Periplanetols A-F, phenolic compounds from Periplaneta americana with potent COX-2 inhibitory activity

Six new compounds, periplanetols A - F (1-4, 6 and 7), a compound isolated from natural origin for the first time (5), and nine known ones (8-16) were isolated from the 70% ethanol extract of the whole bodies of Periplaneta americana. Their structures including absolute configurations were unambiguously identified by comprehensive spectroscopic analyses and computational methods. Biological evaluation toward COX-2 inhibition revealed that compounds 1, 2, and 10 could inhibit COX-2 activity with the IC₅₀ values of 768.0 nM, 617.7 nM, and 599.5 nM respectively, indicating their potential in developping novel agents against inflammation related disorders.

A Review of Common Medicinal Plants in Chin State, Myanmar

Promising sources of novel bioactive compounds include plants growing in several third-world countries where the local flora is still largely uninvestigated. A paradigmatic example is represented by medicinal plants growing in Myanmar, especially in Chin State, in northwestern Myanmar. This is one of the least developed areas of the country where the people still use natural remedies derived from a rich biodiversity. This review mainly covers the investigations done on phytochemical constituents and biological activities of 20 medicinal plants, namely Alangium chinense, Anemone obtusiloba, Anneslea fragrans, Antidesma bunius, Croton oblongifolius, Embelia tsjeriam-cottam, Ficus heterophylla, Gaultheria fragrantissima, Hydnocarpus kurzii, Leea macrophylla, Leucas cephalotes, Millingtonia hortensis, Myrica nagi, Olax scandens, Pimpinella heyneana, Pterospermum semisagittatum, Ruellia tuberosa, Smilax zeylanica, Stemona burkillii, and Tadehagi triquetrum, that have long been used in the Chin State for curing various diseases. These plants have been selected on the basis of their medicinal uses not only in Myanmar but also in the related Ayurvedic healing system. Moreover, besides their medicinal importance, most of them grow in the Chin State more abundantly than in other regions of Myanmar. Although the efficacy of some of these plants have been verified scientifically, the chemical constituents and biological activities of most of them still need to be investigated to confirm the claimed therapeutic effects.

[Diversity of Secondary Metabolites from Some Medicinal Plants and Cultivated Lichen Mycobionts]

 Studies on the structural determination, biosynthesis, and biological activities of secondary metabolites from natural sources are significant in the field of natural products chemistry. This review focuses on diverse secondary metabolites isolated from medicinal plants and cultivated mycobionts of lichens in our laboratory. Monoterpene-tetrahydroisoquinoline glycosides and alkaloids isolated from Cephaelis acuminata and Alangium lamarckii gave important information on the biosynthesis of ipecac alkaloids. A variety of glycosides linked with a secologanin unit and indole alkaloids were obtained from medicinal plants belonging to the families of Rubiaceae, Apocynaceae, and Loganiaceae. Plant species of the four genera Fraxinus, Syringa, Jasminum, and Ligustrum of the family Oleaceae were chemically investigated to provide several types of secoiridoid and iridoid glucosides. The biosynthetic pathway leading from protopine to benzophenanthridine alkaloids in suspension cell cultures of Eschscholtzia californica was elucidated. The structures and biological activities of the bisbenzylisoquinoline alkaloids of Stephania cepharantha and Nelumbo nucifera were also investigated. In addition, the mycobionts of lichens were cultivated to afford various types of metabolites that differ from the lichen substances of intact lichens but are structurally similar to fungal metabolites. The biosynthetic origins of some metabolites were also studied. These findings suggest that cultures of lichen mycobionts could be sources of new bioactive compounds and good systems for investigating secondary metabolism in lichens.

A new dihydrochalcone glycoside from the stems of Homalium stenophyllum

A new dihydrochalcone glycoside, phloretin-4-O-β-D-glucopyranoside (1), together with seven known flavonoids (2-8), were isolated from the stems of Homalium stenophyllum. The structure of 1 was elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data reported in the literature. The known compounds (2-8) were isolated from the genus Homalium for the first time. All compounds were evaluated for their antibacterial activities against six pathogenic bacteria in vitro.

Salicin derivatives from Salix glandulosa and their biological activities

Two new salicin derivatives, saliglandin (1) and 6'-O-(Z)-p-coumaroylsalicin (2), along with fourteen known analogues (3-16) were isolated from the twigs of Salix glandulosa Seemen. The structures of 1-16 were characterized by the use of NMR methods ((1)H and (13)C NMR, (1)H-(1)H COSY, HSQC and HMBC), chemical hydrolysis, and GC/MS. The full NMR data assignment of the known compounds 6, 13, and 14 are reported for the first time. Isolated compounds were evaluated for their nitric oxide (NO) inhibitory efficacy in lipopolysaccharide (LPS)-activated microglial cell (BV-2). Compounds 2, 5, 8-16 significantly inhibited NO production, compound 11 being the most efficacious (IC50 13.57 μM) respectively. Moreover, compound 16 dramatically increased the nerve growth factor (NGF) production (165.24 ± 11.1%) in C6 glioma cells. Taken together, these results revealed that salicin derivatives from Salix glandulosa might have potent effect as anti-neuroinflammatory agents.

New salicin derivatives from the leaves of Populus euphratica

Chemical investigation of the leaves of Populus euphratica Oliv. led to the isolation and identification of 13 compounds for the first time, among which 6'-O-cis-cinnamoylsalicin (1) and 6'-O-benzoylsalicortinol (2) were new compounds. The spectral data of 6'-O-trans-cinnamoylsalicin (3) and salicortinol (4) were reported for the first time. Their structures were elucidated on the basis of detailed spectroscopic analysis and comparisons with literature values.

Sesquiterpenes and alkaloids from the roots of Alangium chinense

Four new sesquiterpenes (1-4), four new alkaloids (5a, 6a, 6b, and 7), and nine known compounds (5b and 8-15) were isolated from an ethanolic extract of roots of Alangium chinense. The structure of 1 was confirmed by X-ray crystallography. The configurations of 5 and 6 were assigned by chiral HPLC analysis and CD spectra. Compounds 3, 4, 8-13, and 15 exhibited antiviral activity against Coxsackie virus B3 with IC50 values of 1.4-15.4 μM. Compounds 2-4, 7, and 9-13 showed antioxidant activities against Fe(2+)-cysteine-induced rat liver microsomal lipid peroxidation, with IC50 values of 3.8-45.7 μM. Compound 5b displayed neuritis inhibitory activity against microglial inflammation factor, with an IC50 value of 6.7 μM. None of the compounds exhibited detectable cytotoxic activity toward any of five tumor cell lines (A549, Be-17402, BGC-823, HCT-8, and A2780) in the MTT assay.

Phenolic glucosides from Alangium plantanifolium

A novel phenolic glucoside alangitanifoliside A (1) together with two known phenolic glucosides 4',6'-O-(S)-hexahydroxydiphenylsalicin (2) and salicin (3), and gallic acid were isolated from stem barks of Alangium plantanifolium. Their structures were determined by spectroscopic and chemical methods. The structure of 1 was elucidated to be 1-O-[2-(1-hydroxy-6-oxocyclohex-2-ene-1-carboxymethyl)-phenyl]-4,6-O-[(S)-,4,4',5,5' 6,6'-hexahydroxydiphenoyl]-beta-D-glucopyranose.

Glycosides of benzyl and salicyl alcohols from Alangium chinense

From the water-soluble fraction of the dried leaves of Alangium chinense, three new glycosides, benzyl alcohol beta-D-glucopyranosyl-(1 --> 2)-[beta-D-xylopyranosyl-(1 --> 6)]-beta-D-glucopyranoside, 2'-O-beta-D-glucopyranosylsalicin, and 2'-O-beta-D-glucopyranosyl-6'-O-beta-D-xylopyranosylsalicin were isolated along with seven known glycosides. The structures of the new compounds were determined by spectroscopic and chemical means.