Bibenzyl Derivatives of Arundina graminifolia and their Cytotoxicity

Arundinosides I-IX and graminifolosides A-B: 2R-benzylmalate and 2R-isobutylmalates derivatives from Arundina graminifolia (D.Don) Hochr. with antioxidant, cytocompatibility and cytoprotective properties

Phytochemical investigation of the underground parts of Arundina graminifolia D.Don Hochr was conducted leading to the isolation of nine new glucosyloxybenzyl 2R-benzylmalate and two new glucosyloxybenzyl 2R-isobutylmalate derivatives. The compounds were purified using chromatographic techniques and their structures were deduced based on spectroscopic techniques including nuclear magnetic resonance and high-resolution mass spectrometry as well as comparing with previous literature. The antioxidant activities of the isolated compounds were also evaluated. The compounds showed potent antioxidant activities in the ABTS radical scavenging, DPPH radical scavenging and FRAP activities. Furthermore, the isolated compounds were observed to exert minimal cytotoxic effects against RAW 264.7 cell, suggesting biocompatibility as well as cytoprotective effects against hydrogen peroxide induced cell toxicity.

The Transcriptome Profiling of Flavonoids and Bibenzyls Reveals Medicinal Importance of Rare Orchid Arundina graminifolia

Orchids are very important flowering plants that spend long juvenile phases before flowering. Along with aesthetic importance, they are rich sources of medicinal components. However, their long reproductive cycle is the major hurdle to study the medicinal efficacy. Arundina graminifolia is a rare orchid that grows fast, unlike other orchids, and this characteristic makes it an ideal plant to study the medicinal enrichment of orchids. Therefore, this study presents the identification of important medicinal components in various parts of A. graminifolia. Transcriptome analysis was performed for five stages (FD1-FD5) of flower development and four tissue types (mature flower, silique, root, and leaf) to ascertain genetic regulators of flavonoids and bibenzyls. Most of the genes showed the highest expression in roots as compared with other tissues. Weighted gene coexpression network analysis (WGCNA) was performed to identify the coexpression modules and the candidate genes involving biosynthesis pathways of these chemicals. MEyellow module contained the highly coexpressed genes. Moreover, the concentrations of phenylpropanoid, bibenzyls, and flavone were ascertained through high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Phenylpropanoid and bibenzyl were comparatively high in the leaf, while flavone showed a high concentration in the stem. The selected candidate genes [bibenzyl biosynthesis (BIBSY212), CYP84A1, CYP73A4, 4CLL7, UGT88B1, UGT73C3, anthocyanin synthase (ANS), phenylalanine ammonia-lyase (PAL), flavanone synthase FLS, and CHS8] were validated through quantitative real-time PCR (qRT-PCR). Most of these genes showed high expression in leaf and root as compared with other tissue. Therefore, the presence of bibenzyls and flavonoids in different parts of A. graminifolia and their molecular regulators can provide a quick source to decipher the medicinal efficacy of orchids.

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.

Arundinosides A-G, new glucosyloxybenzyl 2R-benzylmalate derivatives from the aerial parts of Arundina graminifolia

Seven new glucosyloxybenzyl 2R-benzylmalate derivatives, arundinosides A-G (1-7) were isolated from the aerial parts of the bamboo orchid Arundina graminifolia. This is the first occurrence of this class of compounds in the genus Arundina. Their planar structures and absolute configuration were determined by extensive NMR spectroscopic data as well as chemical conversion. Their neuroprotective properties were also evaluated on their potential ability to reduce the beta amyloid damage on PC12 cell model.

A practical protocol for the synthesis of bibenzyls via C(sp3)–H activation of methyl arenes under metal-free conditions

A variety of bibenzyl derivatives have been synthesized with excellent atom economy via C(sp³)–H–C(sp³)–H coupling of readily available methyl arenes using K₂S₂O₈ under metal-free and environmentally benign conditions.

Two New Stilbenoids from the Aerial Parts of Arundina graminifolia (Orchidaceae)

Two new phenanthrene derivatives, a phenanthrenequinone named arundiquinone (1) and a 9,10-dihydrophenanthrene named arundigramin (2) together with a known lignin dimer (3) and seven known stilbenoids (4–10) were isolated from the aerial parts of the Asian orchid Arundina graminifolia. The structures of the isolated compounds were elucidated by spectroscopic methods, including extensive 1D, 2D NMR (heteronuclear single quantum coherence (HSQC), heteronuclear multiple-bond correlation spectroscopy (HMBC), and HR-ESI-MS techniques, as well as comparison with respective literature reports. The cytoprotective activity of the isolated compounds were evaluated for their ability to reduce beta amyloid induced toxicity on undifferentiated PC12 cells. Compound 8 showed moderate cytoprotective activity at 0.5 µmol/L (71% of cell viability) while the other compounds showed no significant activity at the highest concentration tested.