On the chemistry of indian orchidaceae plants—II

Abstract: 5-[2′-(3″-Hydroxy-5″-methoxyphenyl)-ethyl]-1,3-benzodioxole and 7-hydroxy-2-methoxy-1,4-phenanthrenedione, along with 16 known compounds were identified from the stems of Dendrobium densifiorum Lindl. ex Wall. (Orchidaceae). The structure of a previously reported compound dendroflorin obtained from the plant was revised on the basis of spectroscopic analysis. Among the identified compounds, five were found to exhibit anti-platelet aggregation activity in vitro.

Abstract: The fresh or dried stems of many Dendrobium species are well known as one of the most expensive tonics in traditional Chinese medicine Documented as a “superior grade” herbal medicine in the ancient text “Shen Nong’s Herbal Classic”, Dendrobium has been used for thousands of years and is now a popular health food worldwide The main chemical components of Dendrobium are alkaloids, aromatic compounds, sesquiterpenoids and polysaccharides, with multiple biological activities, including immunomodulatory, neuroprotective and anti-tumor effects, etc Various qualitative and quantitative methods have been developed for the quality evaluation of Dendrobium In this review, the research progress since the 1930s relating to the chemistry, bioactivity and quality control of Dendrobium is summarized, existing problems and prospects are also discussed

Abstract: Novel procedures for the [Pd]/[Ag]/TFA system catalyzed cascade reactions of nitrile directed remote C-H and dual C-H bond activation with insertion of nitrile were developed, which afforded variously polysubstituted fluorenones in moderate to good yields with tolerance of a wide variety of substrates.

Abstract: A bibenzyl compound that possesses antimutagenic activity was isolated from the storage stem of Dendrobium nobile. The isolated compound suppressed the expression of the umu gene following the induction of SOS response in Salmonella typhimurium TA1535/pSK1002 that have been treated with various mutagens. The suppressive compound was mainly localized in the n-hexane extract fraction of the processed D. nobile. This n-hexane fraction was further fractionated by silica gel column chromatography, which resulted in the purification and subsequent identification of the suppressive compound. EI-MS and (1)H and (13)C NMR spectroscopy were then used to delineate the structure of the compound that confers the observed antimutagenic activity. Comparison of the obtained spectrum with that found in the literature indicated that moscatilin is the secondary suppressive compound. When using 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide) as the mutagen, moscatilin suppressed 85% of the umu gene expression compared to the controls at <0.73 micromol/mL, with an ID(50) value of 0.41 micromol/mL. Additionally, moscatilin was tested for its ability to suppress the mutagenic activity of other well-known mutagens such as 4-nitroquinoline-1-oxide (4NQO), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), UV irradiation, 3-amino-1,4-dimethyl-5H-pyrido[4,3b]indole (Trp-P-1), benzo[a]pyrene (B[a]P), and aflatoxin B(1) (AFB(1)). With all of the aforementioned chemicals or treatments, moscatilin showed a dramatic reduction in their mutagenic potential. Interestingly, moscatilin almost completely suppressed (97%) the AFB(1)-induced SOS response at concentrations <0.73 micromol/mL, with an ID(50) of 0.08 micromol/mL. Finally, the antimutagenic activities of moscatilin against furylfuramide and Trp-P-1 were assayed by the Ames test using the S. typhimurium TA100 strain. The results those experiments indicated that moscatilin demonstrated a dramatic suppression of the mutagenicity of only Trp-P-1 but not furylfuramide.

Abstract: A methanol extract from Dendrobium nobile showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract from D. nobile was re-extracted with n-hexane, dichloromethane, 1-butanol, and water, respectively. A suppressive compound in the n-hexane extract fraction was isolated by SiO2 column chromatography and chemical fractionation and was identified as gigantol by EI-MS and 1H and 13C NMR spectroscopy. Gigantol suppressed the SOS-inducing activity of furylfuramide in the umu test. Gene expression was suppressed 90% at <0.73 μmol/mL, and the ID50 value was 0.35 μmol/mL. Gigantol was also assayed with the mutagen 3-amino-1,4-dimethyl-5H-pyrido[4,3b]indole (Trp-P-1), which requires liver metabolizing enzymes, and it suppressed the SOS-inducing activity of Trp-P-1 in the umu test. Gene expression was suppressed 91% at <0.73 μmol/mL, and the ID50 value was 0.32 μmol...

Abstract: The position and relative orientation of OMe groups in methoxyflavones can be inferred from benzene-induced solvent shifts of the OMe resonances. OMe groups at C-5, C-7, C-10 and C-12 exhibit large positive Δ values (Δ = δCDC13 - δC6H6 ⋍ 0·5 to 0·8 ppm) in the absence of substituents ortho to these groups. In contrast, OMe groups at C-3, or those flanked by two ortho-OMe functions (or one ortho-OH and one orthoOMe function) show small positive or negative Δ values. An OMe at C-5 suffers a drastic algebraic decrease in solvent shift upon the introduction of an OMe group at C-6. Electronic and conformational factors which may account for these differences are considered.

Abstract: Pongaglabol, a new hydroxyfuranoflavone, and aurantiamide acetate, a rarely occurring modified phenylalanine dipeptide, have been isolated together with 4 furanoflavones, karanjin, lancheolatin B, kanjone and pinnatin, a simple flavone, kanugin, a chromenoflavanone (−)-isolonchocarpin, two furanodiketones pongamol and ovalitenone, and β-sitosterol from the petrol and chloroform extracts of the flowers of Pongamia glabra . The structure of pongaglabol has been established as 5-hydroxyfurano(8,7-4″,5″)flavone on the basis of spectral and chemical evidence.

Abstract: The synthesis of 1, 3-dimethoxyfluoren-9-ones (7a-f) from ethyl 2-aryl-4, 6-dihydroxybenzoates (4a-d), prepared by the reaction of diketene with ethyl 3-aryl-3-oxopropionates (3a-d), is described. Reaction of diketene with 3a-d in the presence of sodium hydride in tetrahydrofuran gave 4a-d. Methylation of 4a-d with methyl iodide, followed by treatment with alcoholic sodium hydroxide, gave 2-aryl-4, 6-dimethoxybenzoic acids (6a-d). Cyclization of 6a-d with trifluoroacetic anhydride gave 7a-f.