A new depside and two new diphenyl ether compounds from the lichen Ramalina farinacea (L.) Ach

The chemical investigation of the Vietnamese lichen Ramalina farinacea (L.) Ach. led to the isolation and the structure elucidation of eight compounds (1–8), including one new depside, formulated as methyl homosekikate (1) and two new diphenyl ethers, 3-(2-carboxy-5-methoxy-3-propylphenoxy)-2-hydroxy-4-methoxy-6-propylbenzoic acid, namely ramalinic acid A (2), and 3-(2-carboxy-5-methoxy-3-propylphenoxy)-2-hydroxy-4-methoxy-6-pentylbenzoic acid, namely ramalinic acid B (3). Their chemical structures were unambiguously determined by analysis of 1D and 2D NMR and high resolution ESI mass spectroscopic data, as well as by comparison with literature data. We also proposed a possible biosynthetic route for the formation of the two new diphenyl ethers (2) and (3) via an enzymatically induced intramolecular Smiles rearrangement of the depsides sekikaic acid and homosekikaic acid, respectively.     

Biotransformation of capsaicin by Penicillium janthinellum AS 3.510

Biocatalysis of capsaicin (1) was performed by Penicillium janthinellum AS 3.510. Nine metabolites including four new compounds were afforded, and their structures were elucidated as (8S)-trans-8-hydroxy-8-hydroxymethyl-N-vanillyl-6-nonenamide (2), 6-hydroxy-8-methyl-N-vanillyl-7-nonenamide (3), trans-8-methoxy-8-methyl-N-vanillyl-6-nonenamide (4), 6-methoxy-8-methyl-N-vanillyl-7-nonenamide (5), dihydrocapsaicin (6), ω-1-hydroxydihydrocapsaicin (7), ω-1-hydroxycapsaicin (8), ω-hydroxycapsaicin (9), N-(4-hydroxy-3-methoxybenzyl)-5-[3-(propan-2-yl)oxiran-2-yl]pentanamide (10) by 1D and 2D NMR and HRESIMS spectra. The biotransformation processes include hydroxylation, methylation, reduction, and epoxylation.     

Xanthones from the bark of Garcinia pedunculata

Three new xanthones, pedunxanthones A–C (1–3), together with five known compounds, 1,5-dihydroxy-3-methoxy-6′,6′-dimethyl-2H-pyrano(2′,3′:6,7)-4-(3-methylbut-2-enyl)xanthone, 1,5-dihydroxy-3-methoxy-4-(3-methylbut-2-enyl)xanthone, dulxanthone A, garbogiol and oleanolic acid, were obtained from a petroleum ether extract of the bark of Garcinia pedunculata. The new structures were elucidated using spectroscopic methods, mainly 1-D and 2-D NMR.     

Difuranonaphthoquinones from Plumbago zeylanica roots

The naphthoquinones, lapachol (1), plumbagin (2), 2-isopropenyl-9-methoxy-1,8-di-oxa-dicyclopenta[b,g]naphthalene-4,10-dione (3), 9-hydroxy-2-isopropenyl-1,8-dioxa-dicyclopenta[b,g]naphthalene-4,10-dione (4), 2-(1-hydroxy-1-methyl-ethyl)-9-methoxy-1,8-dioxa-dicyclopenta[b,g]naphthalene-4,10-dione (5) and 5,7-dihydroxy-8-methoxy-2-methyl-1,4-naphthoquinone (6) were isolated isolated from roots of Plumbago zeylanica. The new constituents (3–5) in addition to known compounds (1, 2 and 6) were characterized by spectral analysis (UV, IR, 1D & 2D NMR and MS).     

New derivatives from the aerial parts of Boerhaavia diffusa L. (Nyctaginaceae)

Boerhaavia diffusa L. is used in the traditional medicine of several Asian countries. The isolation and identification of five new compounds, together with 11 known compounds, from the ethyl acetate extract of the aerial part of B. diffusa grown Vietnam is reported. The structure of the new compounds was established by 1D and 2D NMR spectroscopy, and high resolution ESI-MS analysis. New compounds are two rotenoids: 9,11-dihydroxy-6,10-dimethoxy[1]benzopyrano[3,4-b][1]benzopyran-12(6H)-one (boeravinone P, 3) and 3-[2-(β-d-glucopyranosyloxy)-3-hydroxyphenyl]-5-hydroxy-2-hydroxymethyl-7-methoxy-6-methyl-4H-1-benzopyran-4-one (boeravinone Q, 9), an atropisomeric mixture of two rotenoid glycosides (3′,5-dihydroxy-2-hydroxymethyl-7-methoxy-6-methylisoflavone 2′-O-β-d-glucopyranoside, 11), a sesquiterpene lactone (4,10-dihydroxy-8-methoxyguai-7(11)-en-8,12-olide, 5) and a new phenylpropanoid glycoside (boerhaavic acid, 15).     

Enhancement of pancreatic lipase inhibitory activity of curcumin by radiolytic transformation

The naturally occurring yellow dietary diarylheptanoid curcumin (1) was converted by γ-ray to two new γ-lactones, curculactones A (2) and B (3), as well as four known transformates, erythro-1-(3-methoxy-4-hydroxy-phenyl)-propan-1,2-diol (4), threo-1-(3-methoxy-4-hydroxy-phenyl)-propan-1,2-diol (5), vanillic acid (6), and vanillin (7). The structures of the two new γ-lactone derivatives were elucidated on the basis of spectroscopic methods. The steroisomeric phenylpropanoids 4 and 5 exhibited significantly enhanced inhibitory activity against pancreatic lipase when compared to parent curcumin.     

Chemical constituents from the fresh flower buds of Musa nana and their chemotaxonomic significance

Phytochemical study on the fresh flower of Musa nana Lour. provided seventeen known compounds including two alkaloids, 3-(hydroxyacetyl)-indole (1), bi-indol-3-yl (2), two terpenoids, 5-[(1R)-1-hydroxy-2,6,6-trimethyl-4-oxo-2-cyclohexen-1-yl]-3-methyl-, (2Z, 4E) −2, 4-pentadienoic acid (Valdes), 5, 6(S), 7, 7a(R)-tetrahydro-6-hydroxy-4,4-dimethyl-2(4H)-benzofuranone (4), seven phenols (5–11), three phenylphenalenones, 2-hydroxy-4-(4-methoxyphenyl)-1H-phenalen-1-one (12), 2-methoxy-9-phenyl-1H-phenalen-1-one (13), 2-methoxy-9-(4-methoxyphenyl)-1H-phenalen-1-one (14), and three lipids (15–17). In the present study, all the compounds were isolated for the first time from the species M. nana. Ten compounds including 1-8 and 15-16 have never been previously encountered in the Musaceae family. Furthermore, the chemotaxonomic significance of these isolates was also discussed.     

Anti-tobacco mosaic virus phenylpropanoids from the stems of Nicotiana tabacum

Three new phenylpropanoids, 3-(6-methoxy-3-oxo-1, 3-dihydroisobenzofuran-5-yl)-3-oxopropyl acetate (1), 3-hydroxy-1-(6-methoxy-1, 3-dihydroisobenzofuran-5-yl)propan-1-one (2), and 3-hydroxy-1-(6- methyl-1, 3-dihydroisobenzofuran-5-yl)propan-1-one (3), together with three known phenylpropanoids (4–6) were isolated from the stems of Nicotiana tabacum. Their structures were examined using different spectroscopic techniques, including extensive 1D- and 2D NMR. Compounds 1–6 were also evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The anti-TMV results demonstrated that compounds 1 and 6 exhibited high anti-TMV activities, with inhibition rates of 34.6 and 35.4%, both of which were higher than the positive control (32.5%). The other compounds (2–5) also had anti-TMV activities, with inhibition rates between 16.8 and 28.6%.     

Three new arylbenzofurans from Lavandula angustifolia and their bioactivities

Three new arylbenzofurans, 2-(7-methoxy-2-(4-methoxyphenyl)-3-methylbenzofuran-5-yl)ethanol (1), 4-(5-(2-hydroxyethyl)-7-methoxy-3-methylbenzofuran-2-yl)phenol (2), and 2-(6-methoxy-2-(4- methoxyphenyl)-3-methylbenzofuran-5-yl)ethanol (3), together with three known ones (4–6) were isolated from the whole plant of Lavandula angustifolia. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1–3 and 5 were tested for their anti-tobacoo mosaic virus (TMV) activities, and Compounds 1–6 were tested for their cytotoxicity activities. In our assay, Compounds 1–3 showed high anti-TMV activity with inhibition rate of 38.2, 35.2, and 34.0%, which superior to positive control Ningnanmycin. Compounds 1–6 also showed weak inhibitory activities against some tested human tumor cell lines with IC50 values in the range of 2.2–8.2 μM.     

Diarylheptanoids from Curcuma comosa

Three new diarylheptanoids, designated 1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-(6E)-6-hepten-3-ol (1), 1-(3-hydroxyphenyl)-7-(3,4-dihydroxyphenyl)-3-methoxy-(6E)-6-heptene (2), (3R, 5R)-1-(3,4-dihydroxyphenyl)-7-phenyl-heptane-3,5-diol (3) and three known compounds, were isolated from rhizomes of Curcuma comosa. Structures of the compounds were determined by spectroscopic data analysis.     

(2S)-Prenylflavanones and taraxerane triterpenoids from Mallotus mollissimus

Three prenylflavanones, (2S)-5,7-dihydroxy-4′-methoxy-8-(3″,3″-dimethylallyl)flavanone (3), (2S)-5,4′-dihydroxy-7-methoxy-6-(3″,3″-dimethylallyl)flavanone (6), 8-prenylnaringenin (11), and a new epimeric pair (2″S/2″R)-(2S)-5,7-dihydroxy-4′-methoxy-6-(2″-hydroxy-3″-methylbut-3″-enyl)flavanones (4a/4b) were isolated together with taraxerone, taraxerol, epitaraxerol, β-sitosterol, oleanolic acid, 1-O-docosanoyl glycerol, apigenin, and apigenin 7-O-β-D-glucopyranoside from the MeOH extract of the leaves of Mallotus mollissimus. The structures of the isolated compounds were determined on the basis of 1D/2D NMR and HR-MS spectroscopic data; the 2S configuration of the prenylflavanones 3, 4, and 6 was deduced from CD spectroscopic data. The presence of three taraxerane triterpenoids reinforces the inclusion of M. mollissimus (syn. Croton mollissimus) in Mallotus genus. Among species of Mallotus the occurrence of the (2S)-prenylflavanones 3, 4, and 6 is confined to M. mollissimus.     

The isolation of two new lanostane triterpenoid derivatives from the edible mushroom Astraeus asiaticus

Two lanostane triterpenoid derivatives, astrasiaone (2), (22S, 25R, 26R)-26-methoxy-22-26-epoxylanost-8-en-3-one, and astrasiate (3), (3α, 22S, 25R)-3, 22-dihydroxylanost-8-en-26 -oate, together with six known compounds, astraodorol (1), artabotryol B (4), artabotryol C1 (5), 6-dehydrocerevisterol (6), ergosterol (7) and hypaphorine (8) were isolated from the edible mushroom Astraeus asiaticus. 3 and 4 exhibited weak cytotoxicity against KB and NCI-H187 cancer cell lines. A comparison of the structures of 2 and 3 to that of 1, 4 and 5 suggest that these two new compounds could be the intermediate form that occurs during biogenesis.     

Chromones from the stems of Cassia fistula and their anti-tobacco mosaic virus activities

Three new chromones, 5-methoxy-2,2-dimethyl-7-(2-oxopropyl)-2,3-dihydrochromen-4-one (1), 5-methoxy-2,2-dimethyl-8-(2-oxopropyl)-2,3-dihydrochromen-4-one (2), and 1-(3,4-dihydro-5-methoxy-2,2-dimethyl-2H-chromen-7-yl)propan-2-one (3), together with four known chromones (4–7) were isolated from the stems of Cassia fistula. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D-NMR techniques. Compounds 1–5 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compound 5 exhibited high anti-TMV activity with inhibition rate of 30.8% at a concentration of 20 μM. The other compounds also exhibited potential anti-TMV activities with inhibition rates in the range of 15.6–22.1% at the same concentration.     

Phytochemical and chemotaxonomic study on Ziziphus Jujuba Mill. (Rhamnaceae)

Fourteen compounds were isolated from fruits of Ziziphus jujuba Mill., including two flavonoids (1–2), one phenolic glycosides (3), one lignan (4), four phenols (5–8), three alkaloid (9–10, 14), three sesquiterpenoid (11–13). The structures of all the compounds were established by the NMR techniques, as well as by comparison with previously reported data in literature. Compounds 2″-glucosyl-8-C-glucosyl-4′-O-methylapigenin (1), 3′, 4′, 5′-trimethoxycinnamyl alcohol (5), 2-{4-[(1E)-3-Hydroxyprop-1-en-1-yl]-2, 6-dimethoxy-phenoxy}propane-1, 3-diol (6), 1-(4-Hydroxyphenyl)ethane-1, 2-diol (8), (1S, 3S)-1-Methyl-l, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (9), (1R, 3S)-1-Methyl-l, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (10), grasshopper ketone (12), methyl (3R, 5R)-5-methoxy-3-phenylisoxazolidine-5-carboxylate (14) were firstly reported from the genus Ziziphus and the family Rhamnaceae. Furthermore, the chemotaxonomic significance of the isolates was discussed.     

New purine alkaloids from the Red Sea marine tunicate Symplegma rubra

Investigation of the Red Sea marine tunicate Symplegma rubra Monniot, 1972 gave three new purine alkaloids namely 6-methoxy-7,9-dimethyl-8-oxoguanine (1), 6-methoxy-9-methyl-8-oxoguanine (2), and 2-methoxy-7-methyl-8-oxoadenine (4) together with seven known compounds: 6-methoxy-7-methyl-8-oxoguanine (3), 9-methyl-8-oxoadenine (5), 7-methyl-8-oxoadenine (6), 8-oxoadenine (7), 3-methylxanthine (8), inosine (9), and homarine (pyridinium-2-carboxylic acid-1-methyl) (10). Compound 6 was reported here for the first time from a natural source. The structure determination of the compounds was accomplished by extensive interpretation of their spectroscopic data including 1D (¹H and ¹³C) and 2D (¹H–¹H COSY, HSQC, and HMBC) NMR and high-resolution mass spectral data. The isolated compounds were evaluated for their protein kinase inhibitory activity against different kinases (CDK5, CK1, DyrK1A, and GSK3) at 10 μg/mL. The compounds showed moderate activity against these kinases.     

Chemical constituents from Mentha canadensis

Phytochemical investigation on Mentha canadensis led to the isolation of two new compounds, 3,4-dihydro-3,6,7-trihydroxy-2(1H)-quinolinone (1), (E)-2-methoxy-2- oxethyl-3-(4-hydroxyphenyl) acrylate (2), along with nine known phenolic compounds, syringic acid (3), p-coumaric acid (4), esculetin (5), methyl rosmarinate (6), nepetoidin B (7), syringaresinol (8), methyl ester of caffeoyl glycollic acid (9), 2″,3″-diacetylmartynoside (10) and bracteanolide A (12). Additionally, cis-3-[2-[1-(3,4-dihydroxyphenyl)-1-hydroxymethyl]-1,3-benzodioxol-5-yl]-(E)-2-propenoic acid (11), which was isolated as a natural product for the first time. All these compounds were reported for the first time from this species, and their structures were elucidated by spectroscopic techniques. Compound 11 may be a useful chemotaxonomic marker for M. canadensis. The p-coumaric acid derivatives identified in the present investigation may have chemotaxonomic significance at the generic level.     

Mycochromone and mycoxanthone: Two new metabolites from Mycosphaerella rosigena

Two new metabolites, dimethyl 2-(2-ethenyl-5-hydroxy-4H-1-benzopyran-4-onyl-3)-malonate (mycochromone 1a) and methyl 2-methoxy-8-hydroxy-9-oxo-9H-xanthene-1-carboxylate (mycoxanthone 6a), have been isolated and identified from the mycelium of Mycosphaerella rosigena grown on potato-agar.     

Phytochemicals from the stem wood of Sorbus lanata (D. Don.) Schauer

Three new phenolic compounds, sorlanin (4-(3-(hydroxymethyl)-5-methoxy-7-phenyl-2,3-dihydrobenzo[b][1,4]dioxin-2-yl)-2-methoxyphenol, 1), sorbanin (2-((3,5-dimethoxy-[1,1′-biphenyl]-4-yl)oxy)-1-(4-hydroxy-3-methoxyphenyl)propane-1,3-diol, 2) and sorbalanin (4-(3-(hydroxymethyl)-5,6-dimethoxy-2,3-dihydrobenzo[b][1,4]dioxino[2,3-g]benzofuran-2-yl)-2-methoxyphenol, 3), together with eight known compounds, polystachyol (4), isolariciresinol (5), dihydrodehydrodiconiferyl alcohol (6), tuberculatin (7), ovafolinin E (8), aucuparin (9), 2′-methoxyaucuparin (10), and tetracosyl-3-(3,4-dihydroxyphenyl)acrylate (11), were isolated from Sorbus lanata. The structures of these phytoconstituents were elucidated through extensive spectroscopic techniques, including UV, IR, 1D and 2D NMR, ESI-MS and HRESI-MS experiments. All the compounds except 9 and 10 were isolated for the first time from the genus Sorbus. The isolated compounds were also tested in DPPH radical scavenging reaction where compounds 6, 7, 10 and 11 showed significant activities with IC₅₀ values of 9.2, 11.7, 23.0 and 33.7 μM, respectively.     

Further constituents of Galianthe thalictroides (Rubiaceae) and inhibition of DNA topoisomerases I and IIα by its cytotoxic β-carboline alkaloids

A new cytotoxic β-carboline alkaloid, 1-methyl-3-(2-hydroxypropan-2-yl)-2-(5-methoxy-9H-β-carbolin-1-yl)-cyclopentanol (1), was isolated from roots of Galianthe thalictroides, together with the alkaloid 1-(hydroxymethyl)-3-(2-hydroxypropan-2-yl)-2-(5-methoxy-9H-β-carbolin-1-yl)-cyclopentanol (2), the anthraquinones 1-methyl-alizarin and morindaparvin-A, the coumarin scopoletin, homovanillic alcohol, (−)-epicatechin, and the steroids stigmast-4-en-3-one, 4,22-stigmastadien-3-one, campest-4-en-3-one, stigmast-4-en-3,6-dione, 6-β-hydroxy-stigmast-4-en-3-one, stigmasterol, campesterol, β-sitosterol, and β-sitosterol-3-O-β-d-glucopyranoside. Among the previously known compounds, homovanillic alcohol is a novel finding in Rubiaceae, while 1-methyl-alizarin, morindaparvin-A, scopoletin, stigmast-4-en-3-one, 4,22-stigmastadien-3-one, campest-4-en-3-one, stigmast-4-en-3,6-dione, and 6-β-hydroxy-stigmast-4-en-3-one is reported for the first time in the genus Galianthe. The cytotoxic β-carboline alkaloids 1 and 2 exhibited potent antitopoisomerase I and IIα activities and strong evidence is provided for their action as topoisomerase IIα poisons and redox-independent inhibitors.     

Two new lignans with their biological activities in Portulaca oleracea L.

Two new lignans, identified as 6,7-dihydroxy-4-(4′’-hydroxy-3′’-methoxyphenyl)-2-naphthoic acid, named Oleralignan C (1), and 4-(3,4-dihydroxyphenyl)-6-hydroxy-7-methoxy-2-naphthoic acid, named Oleralignan D (2), were obtained from Portulaca oleracea L. The structures were determined by spectroscopic methods, including UHPLC-ESI-QTOFMS, ¹D and ²D NMR. Both Oleralignan C (1) and Oleralignan D (2) inhibited the inflammatory factors, IL-1β and TNF-α in RAW 264.7 cells induced by lipopolysaccharide (LPS). Both compounds also could clear 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals indicating their antioxidant potential.