Triterpenoid saponins from Piptadeniastrum africanum (Hook. f.) Brenan

One new triterpenoid saponin, named piptadeniaoside (1), along with two known saponins (2–3) have been isolated from the stem bark of Piptadeniastrum africanum. After previous isolation of flavone derivatives from this plant, new phytochemical investigations were performed for its saponin content. Their structures were established by direct interpretation of their spectral data, mainly HRESIMS, 1D NMR (¹H, ¹³C NMR, DEPT) and 2D NMR (COSY, NOESY, HSQC and HMBC), and by comparison with the literature data.     

Pro-apoptotic activity of acylated triterpenoid saponins from the stem bark of Albizia chevalieri harms

As a continuation of our interest in apoptosis-inducing triterpenoid saponins from Albizia genus, phytochemical investigation of the stem bark of Albizia chevalieri led to the isolation of three new oleanane-type saponins, named chevalierosides A–C (1–3). Their structures were established on the basis of extensive analysis of 1D and 2D NMR (¹H-, ¹³C NMR, DEPT, COSY, TOCSY, ROESY, HSQC and HMBC) experiments, HRESIMS studies, and by chemical evidence. The pro-apoptotic effect of the three saponins was evaluated on two human cell lines (pancreatic carcinoma AsPC-1 and hematopoietic monocytic THP-1). Cytometric analyses showed that saponins 1–3 induced apoptosis of both human cell lines (AsPC-1 and THP-1) in a dose-dependent manner.     

Chemical constituents from Celastrus aculeatus Merr.

Phytochemical investigation of Celastrus aculeatus Merr. led to the isolation of nine compounds. Their structures were identified to be dulcitol (1), β-sitosterol (2), n-tritriacontane (3), nimbidiol (4), pristimerin (5), p-hydroxybenzoic acid (7), vanillic acid (8), 3, 5-dimethoxy-4-hydroxybenzoic acid (9) and a new compound named pristimerol (6) on the basis of mass and NMR spectra. This is the first report of phenolic acids (compounds 7–9) from C. aculeatus Merr. We present the HR-MS, 1D NMR (¹H, ¹³C NMR, DEPT) and 2D NMR (HMBC) data of the new compound (6).     

Accumulation of alpha-Tocopherol in Senescing Organs as Related to Chlorophyll Degradation

α-Tocopherol (α-T) has been identified, using gas chromatography-mass spectroscopy and ¹H- and ¹³C-nuclear magnetic resonance, in senescing leaves of Melia azedarach L. The content of α-T increased concomitantly with the breakdown of chlorophyll in senescing Vinca and Melia leaves. An increase in α-T was found also in detached Melia leaves, senescing in either light or darkness and in senescing, ethylene-treated orange leaves and fruit. The possibility that phytol, which is released from chlorophyll by chlorophyllase is utilized for the biosynthesis of α-T is discussed. Senescing leaves of the low chlorophyllase plants, parsley and tobacco, did not contain α-T in measureable amounts.     

Chemical constituents from Alnus mandshurica (Callier) Hand.-Mazz. and their chemotaxonomic significance

A new phenol compound, (9S)-9-hydroxy-9-[(2-hydroxyphenyl)methoxy]-nonanoic acid methyl ester (1) was isolated from the stem bark of Alnus mandshurica (Callier) Hand.-Mazz., along with eight known compounds (2–9). The structure of compound 1 was determined by spectral analyses, including HR-ESI-MS, 1D and 2D NMR (COSY, HMQC and HMBC) experiments. All the isolated compounds were reported for first time from A. mandshurica. Furthermore, compounds 3–9 were found in the family Betulaceae for the first time.     

An unusual lanostane-type triterpenoid,spiroinonotsuoxodiol, and other triterpenoids from Inonotus obliquus

An unusual lanostane-type triterpenoid, spiroinonotsuoxodiol (1), and two lanostane-type triterpenoids, inonotsudiol A (2) and inonotsuoxodiol A (3), were isolated from the sclerotia of Inonotus obliquus. Their structures were determined to be (3S,7S,9R)-3,7-dihydroxy-7(8 → 9)abeo-lanost-24-en-8-one (1), lanosta-8,24-dien-3β,11β-diol (2), and (22R)-3β,22-dihydroxylanosta-8,24-dien-11-one (3) on the basis of NMR spectroscopy, including 1D and 2D (¹H–¹H COSY, NOESY, HMQC, HMBC) NMR, and FABMS. Compounds 1–3 showed moderate activity against cultured P388, L1210, HL-60 and KB cells.     

A new triterpenoid and other constituents from Lepidogrammitis drymoglossoides

Phytochemical investigation of a Chinese fern Lepidogrammitis drymoglossoides led to the isolation of five compounds, including one triterpenoid, two lignans and two glycosides. Their structures were determined to be filic-3-ene-28-oic acid (1), (−)-syringaresinol-4-O-beta-d-glucopyranoside (2), lyoniresinol (3), 4-O-beta-d-glucopyranosyl caffeic acid (4) and n-butyl-O-beta-d-fructopyranoside (5) on the basis of mass and NMR spectra and chemical and physical properties. Filic-3-ene-28-oic acid (1) is a new triterpenoid, while compounds 2–5 were isolated from the genus Lepidogrammitis for the first time. Chemotaxonomic significance of this investigation is summarized.     

Five new C19-diterpenoid alkaloids from Aconitum carmichaeli

Five new aconitine-type C₁₉-diterpenoid alkaloids, namely, carmichaenine A–E (1–5), and six known diterpenoid alkaloids, namely, 14-benzoylneoline (6), neoline (7), 10-hydroxyneoline (8), neolinine (9), songoramine (10), and songorine (11), were isolated from the aerial parts of Aconitum carmichaeli. Their structures were determined by extensive spectroscopic methods, especially 2D NMR analyses. Compounds 8 and 9 were isolated for the first time from A. carmichaeli.     

Steroidal Saponins from the Rhizomes of Aspidistra typica

Eleven new furostanol saponins, typaspidosides B-L (1–11), one new spirostanol saponin, typaspidoside M (12), and five known spirostanol saponins, 25S-atropuroside (13), neoaspidistrin (14), (25S)-pratioside D₁ (15), 25S-aspidistrin (16) and 25S-neosibiricoside (17) were isolated from the rhizomes of Aspidistra typica Baill. The structures of the new compounds were established using 1D and 2D NMR (¹H-¹H COSY, HMQC, HMBC and ROESY) spectroscopy, high resolution mass spectrometry, and chemical methods. The aglycones of 1–3 (unusual furostanol saponins with opened E ring type), 9 and 10 (the methoxyl substituent at C-23 position) were found, identified from natural products for the first time. Moreover, the anti-HIV activities of the isolated steroidal glycosides were assessed, and compounds 13, 14, 16 and 17 exhibited high active against HIV-1.     

Antimicrobial phenolic metabolites from the aerial parts of Orthosiphon aristatus

Two new compounds oraristatin A (1) and oraristatinoside A (2), one new natural compound (2 S)-methyl-6,7-dihydroxytropate (3), and 11 known phenolic metabolites were isolated from the aerial parts of Orthosiphon aristatus. Their chemical structures were identified by 1D- and ²D NMR and HRESIMS spectroscopic analyses. The absolute configurations of 1 and 3 were determined by TD-DFT ECD spectroscopic analyses. Of the isolates, compound 2 weakly inhibited both Gram-positive and -negative bacteria (MIC = 150–300 μM), while 6 and 7 suppressed the growth of three Gram-positive bacteria and a yeast (MIC = 75–150 μM). This is the first report of the isolation of 6 − 9, 12, and 14 from the genus Orthosiphon and the antimicrobial effects of compounds 3, 7, 9, 12, and 14.     

Triterpenoid saponins from the aerial parts of Trifolium argutum Sol. and their phytotoxic evaluation

Four triterpenoid saponins (1–4) were isolated from the aerial parts of Trifolium argutum Sol. (sharp-tooth clover) and their structures were elucidated by comprehensive spectroscopic analysis, including 1D and 2D NMR techniques, mass spectrometry and chemical methods. Two of them are new compounds, characterized as 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-galactopyranosyl-(1→2)-β-d-glucuronopyranosyl]-3β,24-dihydroxyolean-12-ene-22-oxo-29-oic acid (1) and 3-O-[β-d-galactopyranosyl-(1→2)-β-d-glucuronopyranosyl]-3β,24-dihydroxyolean-12-ene-22-oxo-29-oic acid (2). The occurrence of 3β,24-dihydroxyolean-12-ene-22-oxo-29-oic acid (melilotigenin) in its natural form is reported for the first time as a triterpenoid aglycone within Trifolium species. The phytotoxicity of compounds was evaluated on four STS at concentration 1 μM to 333 μM. Compound 1 was the most active, showing more than 60% inhibition on the root growth of L. sativa at the higher dose, with IC₅₀ (254.1 μM) lower than that of Logran^® (492.6 μM), a commercial herbicide used as positive control. The structure–activity relationships indicated that both aglycones and glycosidic parts may influence the phytotoxicity of saponins.     

Bioactive oleanane-type saponins from the rhizomes of Anemone taipaiensis

Investigation of the n-BuOH extract of the rhizomes of Anemone taipaiensis led to the isolation of five new oleanane-type triterpenoid saponins (1–5), together with seven known saponins (6–12). Their structures were determined by the extensive use of ¹D and ²D NMR experiments along with ESIMS analyses and acid hydrolysis. The aglycone of 1, 2 and 4 was determined as siaresinolic acid, which was reported in this genus for the first time. The cytotoxicities of the saponins 1–12, prosapogenins 4a, 5a, 10a–12a and sapogenins siaresinolic acid (SA), oleanolic acid (OA), hederagenin (HE) were evaluated against five human cancer cell lines, including HepG2, HL-60, A549, HeLa and U87MG. The monodesmosidic saponins 6–8, 5a, 10a–12a and sapogenins SA, OA, HE exhibited cytotoxic activity toward all cancer cell lines, with IC₅₀ values ranging from 2.25 to 57.28 μM. Remarkably, the bisdesmosidic saponins 1–4 and 9 showed selective cytotoxicity against the U87MG cells.     

Identification of cardiac glycosides in fractions from Periploca forrestii by high-performance liquid chromatography/diode-array detection/electrospray ionization multi-stage tandem mass spectrometry and liquid chromatography/nuclear magnetic resonance

Cardiac glycosides are a class of naturally occurring compounds that are characterized by some interesting biological activities and are widely distributed in the plant kingdom and can also be found in some animals. There is an interest in the chemical characterization of these molecules due to their toxicity and their use in medicines. In the study reported here, a combination of electrospray ionization tandem mass spectrometry with high-performance liquid chromatography equipped with diode-array detector (HPLC-DAD/ESI-MSⁿ), and hyphenation to both liquid chromatography and nuclear magnetic resonance spectroscopy (HPLC/NMR) were utilized for the on-line analyses of cardiac glycosides from Periploca forrestii. The fragmentation patterns and ¹H NMR spectra of nine isolated cardiac glycosides were investigated; their fragmentation rules and ¹H NMR spectral characteristics were summarized and applied to the structural identification of similar constituents in fractions from P. forrestii. As a result, a total of nine trace cardiac glycosides were tentatively determined by analyses of accurate molecular masses, representative fragment ions and characteristic ¹H NMR signals provided by HPLC/high-resolution mass spectrometry (HRMS), HPLC-DAD/ESI-MSⁿ and HPLC/¹H NMR experiments, respectively. Of these, eight (2–9) are new compounds and one (1) is reported from P. forrestii for the first time. Results of the present study can benefit the rapid identification and targeted isolation of new cardiac glycosides from crude plant extracts.     

6β-Hydroxy-4-stigmasten-3-one and 6β-hydroxy-4-campesten-3-one

The first naturally occurring 6-hydroxylated Δ⁴-3-oxo steroids with intact sterol side chains have been isolated as a molecular complex from the bark extracts of Melia azedarach L. The complex has been characterized by UV, IR, NMR and MS analyses to consist of 6β-hydroxy-4-stigmasten-3-one and 6β-hydroxy-4-campesten-3-one, and these structures confirmed by partial synthesis.     

Chemical constituents from Ficus natalensis hochst (Moraceae) and their chemophenetic significance

Phytochemical investigation of the stem bark of Ficus natalensis afforded eleven compounds including one ceramide (1), two anthraquinones (2, 3), four triterpenes (4–7), two polyols (8, 9) and two steroids (10, 11). The structures of the compounds were determined by spectroscopic analyses including IR, UV, MS, 1D- and 2D- NMR (¹H, ¹³C, ¹H–¹H COSY, HMQC, HMBC and NOESY), as well as by comparison with literature data. The antibacterial activity and the cytotoxicity of the extract, fractions and some isolated compounds (3, 5, 8 and 9) were evaluated. Some fractions and sub-fractions from various column chromatography displayed moderate antibacterial activity with diameter zone of inhibition (DZI) ranging from 7 to 10 mm. None of the compounds tested had activity. In the present study, all the compounds are isolated for the first time from the species F. natalensis. Compounds 2, 4–7, 10 and 11 were previously reported from the genus Ficus. The chemophenetic significance of the isolated compounds is discussed.     

Chemical constituents from the seeds of Raphanus sativus L. and their chemotaxonomic significance

The phytochemical investigations on the seeds of Raphanus sativus L. led to the isolation and identification of 15 compounds, including eleven sinapoyl derivatives (1–11), two terpenes (12–13), and two phenolic acids (14–15). All chemical structures were elucidated via ¹H NMR and ¹³C NMR spectroscopic methods, and further supported by comparison with literature data. Compound 11 was isolated from the genus Raphanus for the first time. Notably, Compounds 7, 9, and 12–14 were reported in the Brassicaceae family for the first time. The chemotaxonomic significance of these compounds is discussed.     

Dimeric antioxidant and cytotoxic triterpenoid saponins from Terminalia ivorensis A. Chev.

Three saponins, including two dimeric triterpenoid glucosides possessing an unusual skeleton, ivorenosides A and B, and a monomeric triterpenoid saponin (ivorenoside C), together with the known sericoside, were isolated from the bark of Terminalia ivorensis. Their structures were established on the basis of 1D and 2D NMR data, chemical methods and tandem MS–MS spectrometry as a dimer of β-d-glucopyranosyl-18,19-seco-2α,3β,19,19,24-pentahydroxyolean-12-en-28-oate and β-d-glucopyranosyl-2α,3β,19α,24-tetrahydroxyolean-12-en-28-oate (ivorenoside A, 1), a dimer of β-d-glucopyranosyl-18,19-seco-24-carboxyl-2α,3β,19,19-tetrahydroxyolean-12-en-28-oate and β-d-glucopyranosyl-2α,3β,19α,24-tetrahydroxyolean-12-en-28-oate (ivorenoside B, 2) and β-d-glucopyranosyl-2α,3β,19β,24-tetrahydroxyolean-11-oxo-olean-12-en-28-oate (ivorenoside C, 3). Ivorenosides A and B are the first examples in nature of dimeric triterpenoid saponins with a 18,19-seco E ring of one of the two units. These isolated compounds were evaluated for their antioxidant properties and further for their cytotoxic activity against four human cancer cell lines. Ivorenoside B and C exhibited scavenging activity against DPPH and ABTS⁺ radicals with IC₅₀ values comparable with that of the standard drug Trolox and ivorenoside A showed antiproliferative activity against MDA-MB-231 and HCT116 human cancer cell lines with IC₅₀ values of 3.96 and 3.43 μM, respectively.     

Chemical constituents from Cyclocarya paliurus (Batal.) Iljinsk

A novel triterpenoid, cyclocarioside K, together with fifteen known compounds, including seven triterpenoids (2–8), five flavonoids (9–13), three phenolic derivatives (14–16), was obtained from the leaves of Cyclocarya paliurus (Batal.) Iljinsk (Juglandaceae). Their structures were elucidated by spectroscopic methods, including two-dimensional NMR experiments (HSQC DEPT and HMBC). The chemotaxonomic relationships were also discussed. As a result, 3, 4-secodammarane triterpenoids and kaempferol glycosides may represent phytochemical fingerprints for C. paliurus, and C. paliurus has close relationships with other species of Juglandaceae.     

Chemical constituents from the rhizome of Menispermum dauricum DC. and their chemotaxonomic significance

The phytochemical investigations on the rhizome of Menispermum dauricum DC. led to the isolation of 18 compounds, including eleven alkaloids (1–11), four amides (12–15) and three fatty acids (16–18). All chemical structures were established on the basis of NMR (¹H NMR and ¹³C NMR) spectroscopic data. Meanwhile, compounds 5–6, 9–10 and 13–18 are reported for the first time from Menispermum genus, as well as the rhizome of Menispermum dauricum DC. Notably, this is the first study to report compounds 10, 15–18 from the family Menispermaceae. These compounds laid the foundation for the chemical classification of this species.     

Three New and Other Limonoids from the Hexane Extract of Melia azedarach Fruits and Their Cytotoxic Activities

A defatted fraction obtained from the hexane extract of the fruits of Melia azedarach L. (chinaberry tree; Meliaceae) exhibited cytotoxic activities against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK‐BR‐3) cancer cell lines with IC₅₀ values in the range of 2.9–21.9 μg/ml. Three new limonoids, 3‐deacetyl‐4′‐demethylsalannin ( 5 ), 3‐deacetyl‐28‐oxosalannin ( 14 ), and 1‐detigloylohchinolal ( 17 ), along with 16 known limonoids, 1 – 4, 6 – 13, 15, 16, 18 , and 19 , and one known triterpenoid, 20 , were isolated from the fraction. The structures of new compounds were elucidated on the basis of extensive spectroscopic analyses and comparison with literature. These compounds were evaluated for their cytotoxic activities against the four cancer cell lines mentioned above. 3‐Deacetyl‐4′‐demethyl‐28‐oxosalannin ( 16 ), which exhibited potent cytotoxicity against AZ521 (IC₅₀ 3.2 μM ) cells, induced typical apoptotic cell death in AZ521 cells upon evaluation of the apoptosis‐inducing activity by flow cytometry. This work provided, furthermore, valuable information on the structural features of limonoids of the fruits and/or seeds of Melia azedarach and related Meliaceae plants, M. toosendan and Azadirachta indica.