A New Phenolic Compound from Dendrobium longicornu

Abstract

The stems of several Dendrobium species (Orchidaceae) are used as "Shi-Hu" in traditional Chinese medicine mainly for the good of throat and immune ability.1-3 D. longicornu belongs to Sect. Formosae of Dendrobium species and mainly distributed in southwest of China, 1 and chemical research of this Sect. plant is not common. First chemical report of this species at 2004 4 described five new phenolic compounds, and continual experiments of the species lead to the isolation of an interesting new phenolic compound (1) having an oxepine parent nucleus, together with three known compounds, trigonopol A (2), β-sitosterol and daucosterol. To the best of our knowledge, it is the first time for the isolation of this kind of compound from Dendrobium species. This paper describes the isolation and structural elucidation of the new compound 1.Compound 1 A proton signal at δ 9.93 correlated with the carbon signal at δ 187.6 (C-12) in the HSQC spectrum indicated an aldehyde group. The aldehyde group was linked to a quaternary carbon (C-10), which in turn was connected to another quaternary carbon (C-11), as appreciated by their correlations [H-12/C-10, C-11] in the HMBC spectrum. These two quaternary carbons, two 1,3,4-trisubstituted aromatic rings and an oxygen constituted an oxepine nucleus. The observed correlations [H-12/C-9a, H-1/C-4a, C-11, H-9/C-5a, C-10] in the HMBC spectrum of 1 was in perfect agreement with the proposed structure. Therefore, compound 1 was determined as (Z)-7,11-dihydroxy-3-methoxy-10,11-dihydrodibenzo [b,f] oxepine-10-carbaldehyde and named as longicornuol B.The structure of compound 2 was confirmed to be trigonopol A, 5 a bibenzyl which was first reported from Dendrobium species by us recently. Other two known compounds, β-sitosterol and daucosterol, were elucidated by comparing with authentic compound by TLC means. Experimental SectionGeneral procedures. Melting points were measured on a XRC-1 micro-melting point apparatus (Beijing, China) and were uncorrected. Optical rotations were measured with a Horiba SEAP-300 spectropolarimeter. UV spectra were measured on a Hitachi UV-3210 spectrophotometer (Shanghai, China). IR spectra were measured with a Bio-Rad FTS-135 IR spectrometer (Richmond, CA) with KBr pellets. FABMS was obtained on a VG Auto Spec-3000 mass spectrometer (VG, Manchester, England). 1D and 2D NMR spectra were recorded on Bruker AM-400 MHz and DRX-500 spectrometers (Karlsruhe, Germany), with chemical shifts (δ) in ppm relative to trimethylsilane (TMS) as internal standard and coupling constants in hertz (Hz). Column chromatography was carried out on silica gel (200 -300 mesh) and TLC was carried out on plates precoated with silica gel (10 -40 µm, Qindao Marine Chemical Ltd., Qingdao, PRC). Sephadex LH-20 was purchased from Amersham Biosciences.Plant material. Extraction and isolation. Extraction of the plant material (4.5 kg) with 95% EtOH and evaporated under reduced pressure and then fractionated successively into CHCl3 soluble (76 g) and n-BuOH soluble (73 g) fractions were repor...

Cytotoxic Activity of Antioxidant-Riched Dendrobium longicornu

“…1 Variety of its chemical constituents such as bibenzyls, phenanthrenes, lignin glycoside and phenolic compounds have been reported. 2,3 Besides these, biological activities of this plant have not been reported yet. Reactive oxygen species and reactive nitrogen species, including singlet oxygen, hydrogen peroxide, superoxide anion, hydroxyl radical and nitrous oxide are often generated in the living organisms as byproducts of biological reaction, are known to play a vital role in oxidative cellular damaged.…”

Antioxidant, anticancer and antimicrobial effects of In vitro developed protocorms of Dendrobium longicornu

“…During cell and tissue culture, the release of bioactive compound derivatives is very common as reported in much previous literature [ [26] , [27] , [28] ]. Many phytochemicals such as alkaloids, flavonoids, phenolic derivatives have been previously reported from its wild counterparts [ [4] , [5] , [6] , [7] , 29 ]. However, phytochemicals synthesized in the tissue cultured plant material (protocorms) are reported first time in this paper.…”

“…Dendrobium longicornu exhibits the DPPH free radical scavenging capacity as it has many antioxidant-rich secondary metabolites [ [4] , [5] , [6] , [7] , 29 ]. We have already evaluated the antioxidant, cytotoxic and antimicrobial capacity of its wild counterparts [ 8 , 9 ].…”

“…Dendrobium longicornu is widely used in traditional medicine for the treatment of fever and cough, as well as in tonic to produce the body fluid and nourish stomachache [ [1] , [2] , [3] ]. The whole plant of D. longicornu largely contains bibenzyl and phenanthrene, as well as minimal amounts of monoaromatics, steroid and flavonoid derivatives [ [4] , [5] , [6] , [7] ]. Due to the presence of such compounds, its extract has been shown the antioxidant, antimicrobial and cytotoxic effects [ 8 , 9 ].…”

Antibacterial activity of selected Dendrobium species against clinically isolated multiple drug resistant bacteria

“…Several Dendrobium species are used in traditional medicine as tonics to nourish the stomach, promote the production of body fluids and decrease fever (Ng et al, 2012;Xu et al, 2013). They produce a variety of secondary metabolites, such as phenolic compounds (Hu et al, 2010;Li et al, 2009a;Zhao et al, 2003), bibenzyl derivatives (Bi et al, 2004;Chen et al, 2010;Hu et al, 2008;Li et al, 2009bLi et al, , 2009cLi et al, , 2014Majumder et al, 1999;Majumder and Chatterjee, 1989), lignin glycosides and phenanthrenes (Hu et al, 2008), and alkaloids (Elander et al, 1973;Kierkegaard et al, 1970;Li et al, 2008;Venkateswarlu et al, 2002). Such metabolites are responsible for these species' wide variety of medicinal properties (Chand et al, 2016;Paudel et al, 2015Paudel et al, , 2017.…”