Hopeafuran and a C-glucosyl resveratrol isolated from stem wood of Hopea utilis

Phytochemistry and pharmacological activities of Arundina graminifolia (D.Don) Hochr. And other common Orchidaceae medicinal plants

ETHNOPHARMACOLOGICAL RELEVANCE

Arundina graminifolia (Orchidaceae) has been widely used for heat clearance and detoxification, anti-inflammatory diuretic, and anti-microbes for two thousand years in national minorities, especially among the Dai people. It was known as "Zhuyelan" (Chinese: ), "Wenshanghai" (Chinese: ) and "Baiyangjie" (Chinese: ) in the Dai nationality, and mainly used as antidote, which is characterized by "relieving the poison before getting sick and treating illness". Therefore, it has been typically applied in the treatment of food poisoning, snake bites, rheumatism, stomachache and traumatic injuries. It is also used to treat bronchitis, tuberculosis and pneumonia in the Bulang and the Wa ethnic people.

AIM OF THIS REVIEW

This review aims to provide up-to-date information about the botanical characterization, traditional uses, phytochemistry, and pharmacology of A. graminifolia, and the related importantly medicinal plants (e.g. Bletilla striata, Cremastra appendiculata, and Dendrobium officinale) of the same Orchidaceae family. Our work aims to further promote scientific cognition, basic research and in-depth discovery of potential drug candidates for Minority Medicine of our nation.

MATERIALS AND METHODS

Relevant information was obtained via piles of resources including classic books about Chinese herbal medicine, and worldwide accepted scientific databases including Web of Science, Pubmed, Google Scholar, SciFinder, Elsevier, Springer, NCBI, ACS Publications, CNKI and Wanfang data.

RESULTS

Phytochemical investigations have been intensively performed for these two decades, over 134 compounds, mainly include stilbenoids, phenanthrenes, quinones, ketones, phenolic acids, and glycosides, have been isolated and identified from A. graminifolia. The literature surveys exhibited that the ethnomedicinal uses of A. graminifolia, such as detoxification, anti-inflammation and the ability to cure trauma and pain associated with infections, are correlated with its modern pharmacological activities, including antibacterial, anti-oxidation, anti-lipid peroxidation. Stilbenoids and phenanthrenes have been regarded as the main active substances, among which stilbenoids with open ring style have superior antitumor activity. Furthermore, phytochemical investigations, biological activities, as well as the main molecular mechanism involved the coexisted stilbenoids and phenanthrenes from other most common used medicinal plants of the same Orchidaceae family were presented, compared and discussed together.

CONCLUSIONS

This review presents the current research findings of A. graminifolia and three other related medicinal plants of the same family. Some of the traditional uses of A. graminifolia have been assessed by pharmacological studies. Despite A. graminifolia is used as an antidote and anti-aging dote, a few unsolved problems including the molecular mechanism underlying biological activities, pharmacokinetics, and in vivo detoxification tests still need to be settled extensively. Therefore, it is necessary to conduct a comprehensive survey and collect investigation information on A. graminifolia.

Resveratrol oligomer structure in Dipterocarpaceaeous plants

Oligostilbenoids are a group of natural products derived from the oxidative coupling of C6-C2-C6 units found in some plant families. A structurally diverse chemical pool is produced after the successive regioselective and stereoselective oligomerization of resveratrol. This review describes the current status and knowledge of the structure of resveratrol oligomers (ROs) in Dipterocarpaceaeous plants (DPs). Beginning with the recently validated formation of ROs in DPs, each downstream conversion is described from the perspective of the resveratrol coupling mode. Particular emphasis is placed upon the regioselectivity of monomer- and dimer-derived radical-radical coupling processes, which are responsible for producing dimers, trimers, and tetramers with various cyclic frame skeletons, as well as related processes that result in highly condensed scaffolds, such as hexamers and octamers. Trimers in oxidized, dearomatized, and rearranged forms are also summarized, as well as the biogenic relationship between the compounds. Furthermore, emphasis is placed on the O- and C-glucosides of ROs, as well as on the hetero-coupled ROs. In addition, several stereoisomers that originate from asymmetric carbons and the stereochemistry with respect to the conformation due to the chiral axis are described. Besides, NMR spectroscopic properties such as coalescence and anisotropy are briefly described. Approaches to determine absolute configuration are also summarized.

One-pot, three-component approach to diarylacetonitriles

Described herein is a novel one-pot, three-component reaction where aldehydes, electron-rich arenes, and TMSCN in the presence of BF₃-OEt₂ allowed direct access to a number of diarylacetonitriles under mild reaction conditions in good to excellent yields.

Total synthesis of natural products containing benzofuran rings

In this review, various approaches for the construction of benzofurans as an important moiety in different natural products during the total synthesis of the natural of products are underscored.

Expanding the Strained Alkyne Toolbox: Generation and Utility of Oxygen-Containing Strained Alkynes

We report synthetic methodology that permits access to two oxacyclic strained intermediates, the 4,5-benzofuranyne and the 3,4-oxacyclohexyne. In situ trapping of these intermediates affords an array of heterocyclic scaffolds by the formation of one or more new C-C or C-heteroatom bonds. Experimentally determined regioselectivities were consistent with predictions made using the distortion/interaction model and were also found to be greater compared to selectivities seen in the case of trapping experiments of the corresponding N-containing intermediates. These studies demonstrate the synthetic versatility of oxacyclic arynes and alkynes for the synthesis of functionalized heterocycles, while further expanding the scope of the distortion/interaction model. Moreover, these efforts underscore the value of harnessing strained heterocyclic intermediates as a unique approach to building polycyclic heteroatom-containing frameworks.

Diversity, pharmacology and synthesis of bergenin and its derivatives: potential materials for therapeutic usages

Bergenin, a natural secondary metabolite, has been isolated from different parts of a number of plants. It is one of active ingredients in herbal and Ayurvedic formulations. It exhibits antiviral, antifungal, antitussive, antiplasmodial, antiinflammatory, antihepatotoxic, antiarrhythmic, antitumor, antiulcerogenic, antidiabetic and wound healing properties. It has been analyzed and estimated in different plant extracts, blood and drug samples using chromatographic techniques, and pharmacokinetic studies have been made. Several bergenin derivatives were isolated and/or synthesized and were found to possess pharmacological activities. Total synthesis of bergenin and its derivatives were reported. This review article covers literature on bergenin and its derivatives until 2013. Ethnomedicinal value of bergenin containing plant materials is also highlighted. This comprehensive review provides information on the potentiality of bergenin and its derivatives for therapeutic usages.

Isolation and identification of lignans from Caulis Bambusae in Taenia with antioxidant properties

Caulis Bambusae in Taenia is a medicinal preparation from Bambusa tuldoides Munro consisting of skinless slices of the stem (bamboo shavings) and used as a traditional health food in tea, wine, and soup in Asia. Three novel lignans, (-)-7'-epi-lyoniresinol 4,9'-di-O-β-D-glucopyranoside (7), (-)-lyoniresinol 4,9'-di-O-β-D-glucopyranoside (8), bambulignan A (10), and seven known lignan compounds (1-6 and 9) were isolated from Caulis Bambusae in Taenia. The structures of the lignans were determined by detailed spectroscopic analysis (HRESIMS, HSQC, HMBC, NOE). All the isolated lignans were tested for antioxidant activities by DPPH and FARP assays. The results showed that the compounds (+)-lyoniresinol 9'-O-β-D-glucopyranoside (1) and (-)-7'-epi-lyoniresinol 9'-O-β-D- glucopyranoside (9) have strong free radical scavenging activity and reducing power.

[Structures of oligostilbenoids in dipterocarpaceaeous plants and their biological activities]

Stilbenoids such as resveratrol (3,5,4'-trihydroxystilbene) have drawn much attention due to the diversity of structures and biological activities. These compounds are typically found as oligomers in a few plant families, such as Dipterocarpaceae, Vitaceae, Leguminosae, Cyperaceae, and Gnetaceae. The rich structural variation and multifunctional bioactivity make stilbenoid oligomers interesting targets for detailed phytochemical investigations. The oligomeric stilbenoids in Dipterocarpaceaeous plants have been my main focus of extensive structural investigation for the past decade. The tetramers of a resveratrol such as (-)-hopeaphenol, vaticanol B, and vaticanol C are widespread and present in large quantities in Dipterocarpaceaeous plants. These are of special interest due to the large number of stereoisomers resulting from many asymmetric carbons and the various frameworks when a resveratrol is homogeneously oligomerized. The structural variations in Vatica, Vateria, Upuna, Cotylelobium, Dipterocarpus, Shorea, and Hopea genera have been examined and about 120 new resveratrol oligomers isolated to date. A detailed structural determination based on comprehensive spectral study has solved the difficulties in elucidation caused by the complicated stereochemistry that comprises diastereomers, epimers, enantiomers, and rotamers. The isolates bear a structural variation of fused cyclic frameworks including heterocyclic and bicyclo ring systems, and have been developed as a chemical library for drug discovery and chemical biology probes for the first time.

Chemical constituents in the leaves of Vateria indica

Comprehensive re-investigation of the chemical constituents in the leaves of Vateria indica (Dipterocarpaceae) resulted in the isolation of a novel resveratrol dimeric dimer having a C(2)-symmetric structure, vateriaphenol F (1), and two new O-glucosides of resveratrol oligomers, vateriosides A (2) (resveratrol dimer) and B (4) (resveratrol tetramer), along with a new natural compound (3) and 33 known compounds including 26 resveratrol derivatives. The absolute structures were elucidated by spectroscopic analysis, including two dimensional NMR and circular dichroism (CD) spectra.

Modular synthesis of polyphenolic benzofurans, and application in the total synthesis of malibatol a and shoreaphenol

A modular strategy for the synthesis of hexacyclic dimeric resveratrol polyphenolic benzofurans is reported. The developed synthetic technology was applied to the total synthesis of malibatol A, shoreaphenol, and other biologically relevant poly-phenols.

A 2-Arylbenzofuran Derivative from Hopea Mengarawan

A new 2-arylbenzofuran derivative (diptoindonesin G) (1), along with nine known oligostilbenes, have been isolated and identified from the acetone extract of the tree bark of Hopea mengarawan. The structures of these compounds were determined based on spectroscopic data, including 2D NMR and HREIMS spectra. On cytotoxic evaluation of the isolated compounds against murin leukemia P-388 cells, compound 1 was the strongest in inhibiting the growth of the cells.

Stilbene C-glucosides from Cissus repens

Four new stilbene C-glucosides, namely trans-3-O-methyl-resveratrol-2-C-beta-glucoside (1), cis-3-O-methyl-resveratrol-2-C-beta-glucoside (2), trans-3-O-methyl-resveratrol-2-(2-p-coumaric)-C-beta-glucoside (cissuside A) (3), and trans-3-O-methyl-resveratrol-2-(3-p-coumaric)-C-beta-glucoside (cissuside B) (4), were isolated from the aerial parts of Cissus repens, along with known trans-resveratrol (5), trans-resveratrol-2-C-beta-glucoside (6) and cis-resveratrol-2-C-beta-glucoside (7). Their structures were established by spectroscopic methods. Stilbene C-glucosides were found in the genus Cissus for the first time.

Inhibitory Activity of Plant Stilbene Oligomers against DNA Topoisomerase II

The inhibitory activity of 40 stilbene oligomers isolated from six plant species against topoisomerase II was evaluated, of which nine compounds showed a potent inhibitory effect, stronger than daunorubicin, a topoisomerase II inhibitor, used as an anti-cancer drug. The specificity of active stilbene oligomers on topoisomerase II was assessed by their effect on DNA restriction enzyme. In particular, specific inhibitory activity was observed in alpha-viniferin 13-O-beta-glucopryranoside (2) and hemsleyanol C (13).

Two Novel Trimeric Resveratrol Derivatives fromCotylelobium lanceolatum

Two new resveratrol (= 5-[(E)-2-(4-hydroxyphenyl)ethenyl]benzene-1,3-diol) trimers, cotylelophenols A (1) and B (2), were isolated from the stem of Cotylelobium lanceolatum (Dipterocarpaceae), together with ten known resveratrol oligomers (3-12). The structures of the isolates were established on the basis of spectroscopic analyses, including a detailed NMR spectroscopic investigation of 1 under different conditions. Compound 1 is the first resveratrol trimer with a rearranged 4-hydroxyphenyl group. Four possible biogenetic pathways towards resveratrol oligomers are proposed (Scheme).

Two oligostilbenes, cis- and trans-diptoindonesin B, from Dryobalanops oblongifolia

Two oligostilbenes, cis- and trans-diptoindonesin B, have been isolated from the tree bark of Dryobalanops oblongifolia (Dipterocarpaceae). The structures and relative configurations of both compounds were determined on the basis of spectroscopic evidence, including 2D-NMR spectroscopic analysis.

Inhibitory effects of resveratrol derivatives from dipterocarpaceae plants on tyrosinase activity

Stilbene derivatives, which are resveratrol (3,4',5-trihydroxy-trans-stilbene) oligomers ranging from monomer to tetramer, isolated from Dipterocarpaceae plants were tested for their inhibitory effects against murine tyrosinase activity. The structure-activity relationships obtained in this study suggest that the double bond in the stilbene skeleton is critical for the inhibition, and also that molecular size is important for inhibitory potency.

Vaticanol C, a novel resveratrol tetramer, inhibits cell growth through induction of apoptosis in colon cancer cell lines

A novel resveratrol tetramer, vaticanol C, isolated from the stem bark of Vatica rassak markedly suppressed cell growth through induction of apoptosis, which was characterized by nuclear changes and DNA ladder formation, in three different human colon cancer cell lines.