Natural Nitrogenous Sesquiterpenoids and Their Bioactivity: A Review.

Nitrogenous sesquiterpenoids fromnatural sourcesare rare, so unsurprisingly neither the potentially valuable bioactivity nor thebroad structural diversity of nitrogenous sesquiterpenoids has been reviewed before. This report covers the progressduring the decade from 2010 to February 2020 on the isolation, identification, and bioactivity of 391 nitrogen-containing natural sesquiterpenes from terrestrial plant, marine organisms, and microorganisms. This complete and in-depth reviewshouldbe helpful for discovering and developing new drugs of medicinal valuerelated to natural nitrogenous sesquiterpenoids.

Two new daphnane diterpenes from the roots of Stelleropsis tianschanica.

Two new daphnane diterpenes named tianchaterpenes A and B were isolated from the roots of Stelleropsis tianschanica. Their structures were elucidated on the basis of chemical and spectral analysis, including 1D, 2D NMR analyses and HRESIMS. Compounds 1 and 2 were evaluated for their cytotoxic activities against HeLa and HCT-8 cell lines. The results showed that all compounds displayed weak cytotoxicities to the HeLa cells and were inactive to the HCT-8 cells.

[A new naphthalene derivative from bulbs of Eleutherine americana].

A new naphthalene derivative and three known compounds were isolated from the petroleum ether extract of the bulbs of Eleutherine americana by using various chromatographic techniques, such as column chromatography over silica gel and semi-preparative HPLC. Their structures were elucidated by spectroscopic date (MS, UV, IR, NMR), which were identified as eleutherol B (1), 4,8-dihydroxy-3-methoxy-1-methylanthraquinone-2-carboxylic acid methyl ester (2), 8-hydroxy-3,4-dimethoxy-1-methylanthraquinone-2-carboxylic acid methyl ester (3), and isoeleutherine (4). Compound 1 is a new compound. The diastolic blood vessels activity of compound 1 and 2 were potent, reaching 82.5% and 85.3% at the concentration of 10 µmol·L⁻¹, which were basically the same as that of the positive drug tanshinone ⅡA.

Two new sesquiterpenes from the aerial parts of Schizonepeta tenuifolia.

Two new sesquiterpenes named petafolias A-B were isolated from the aerial parts of Schizonepeta tenuifolia. Their structures were elucidated by various spectroscopic techniques (UV, IR, MS, CD, 1D, and 2D NMR).

Cassane-type diterpenes from Caesalpinia minax induce apoptosis in pituitary adenoma: structure-activity relationship, ER stress and Wnt/ß-catenin pathways.

Plant-derived natural products have been the highly significant sources of novel antitumor agents. The cassane-type diterpenes of genus Caesalpinia have been reported to bear antiproliferative activities toward different types of cancer cells. In this study, we evaluated the antineoplasmic activities of 16 natural origin cassane-type diterpenes isolated from the CHCl3 extract of the seeds of C. minax in pituitary adenomas cells and identified caesalpin G (CAG) showed the strongest cytotoxicity. Moreover, we further investigated the structure-activity relationship and molecular mechanism of these derivatives systematically. The results confirmed the unsaturated lactone-type ring, hydroxyl at C-7, and alkenyl at C-11 or C-14 functionality as critical for anticancer activity in this family of natural products. In addition, the mechanism experiments also demonstrated unfolded protein response and ER stress and Wnt/ß-catenin pathway were involved in the CAG-induced apoptosis.

Oleanane triterpene saponins with cardioprotective activity from Clinopodium polycephalum.

Two new triterpene saponins, clinopodiside VI (1) and saikosaponin c (2), along with six known saikosaponins (3-8), were isolated from the plant of Clinopodium polycephalum. Compounds 1-3 showed moderate inhibition against H9c2 cell damage induced by H2O2.

New Cassane Diterpenoids from Caesalpinia sappan and their Antiplasmodial Activity.

One new cassane diterpene possessing an unusual N bridge between C-19 and C-20 named caesalsappanin R (1), as well as another new diterpene caesalsappanin S (2), were isolated from the seeds of Caesalpinia sappanwith methanol extract. Their structures were determined by spectroscopic analysis and examined alongside existing data from prior studies. Their biological activities were profiled by their antiplasmodial activity.

[Studies on chemical constituents of Clinopodium chinense].

Twenty-eight compounds were isolated and purified from Clinopodium chinense by Sephedax LH-20, ODS, MCI and preparative HPLC. Their structures were identified as apigenin (1), apigenin-7-O-ß-D-glucopyranoside (2), apigenin-7-O-ß-D-glucuronopyranoside (3), thellungianol (4), apigenin-7-O-ß-D-rutinoside (5), luteolin (6), luteolin-4'-O-ß-D-glucopyranoside (7), apigenin-7-O-ß-D-pyranglycuronate butyl ester (8), luteolin-7-O-ß-D-rutinoside (9), luteolin-7-O-ß-D-noehesperidoside (10), acacetin (11), acacetin-7-O-ß-D-glucuronopyranoside (12), buddleoside (13), naringenin (14), pruning (15), nairutin (16), isosakuranetin (17), isosakuranin (18), didymin (19), hesperidin (20), kaempferol (21), quercetin (22), kaempferol-3-O-α-L-rahmnoside (23), p-hydroxycinnamic acid (24), caffeic acid (25), cis-3-[2-[1-(3,4-dihydroxy-phenyl)-1 -hydroxymethyl]-1,3-ben-zodioxol-5-yl]-(E)-2-propenoic acid (26), mesaconic acid (27), gentisic acid 5-O-ß-D-(6'-salicylyl)-glucopyranoside (28). Among them, compounds 7, 9-10, 12, 23, 26-28 were isolated from the Clinopodium for the first time. The protective effects of compounds 1-6, 8-17 and 19 against H2O2-induced H9c2 cardiomyocyte injury were tested, compounds 15 exhibited significantly protective effects. Compared with the cell viability of (62.12±6.18)% in the model, pruning exhibited viabilities of (84.25±7.36)% at 25.0 mg•L⁻¹, respectively, using quercetin as a positive control [cell viability of (84.55±8.26)%, 20 mg•L⁻¹].

Diarylpentanol constituents from the aerial part of Stelleropsis tianschanica.

Five diarylpentanol derivatives including two new compounds stellerasme A (1), stellerasme B (2) were isolated from the aerial parts of Stelleropsis tianschanica. Their structures were elucidated by various spectroscopic techniques (UV, IR, MS, CD, 1D and 2D NMR). All compounds were evaluated for their cytotoxicity activity against HeLa and KB cell lines, and compound 1 showed selective activities against HeLa cell line with an IC50 value of 7.4 µM.

The new steroidal glycosides from the aerial parts of Lepidogrammitis drymoglossoides.

Two new steroidal glycosides ponasteroside C (1) and ponasteroside D (2) were isolated from the aerial parts of Lepidogrammitis drymoglossoides. Their structures were elucidated by various spectroscopic techniques (IR, HRESIMS, 1D and 2D NMR). All compounds were evaluated for their cytotoxicity against HeLa and HCT-8 cell lines, and compounds 1 and 2 showed mild activity against all the test cell lines.

[Cassane diterpenes from the seeds of Caesalpinia decapetala].

Four casssane diterpenes were isolated from the ethanol extract of the seeds of Caesalpinia decapetala (Fabaceae), with a combination of various chromatographic approaches, including silica gel, Sephadex LH-20, reverse phase C18 and so on. On the basis of spectroscopic data analysis, they were identified as caesalpinin MQ (1), neocaesalpin N(2), caesalmin F (3) and α-caesalpin (4). Among them, compound 1 is a new diterpene, compounds 2-4 were isolated for the first time from the plant of C. decapetala.

A new drimane sesquiterpenoid and a new triterpene lactone from fungus of Fomes officinalis.

A new sesquiterpenoid fomeffic acid (1) and a new triterpene lactone fomefficinin (2) were isolated from the fungus Fomes officinalis, together with another six known compounds fomitopsin C (3), dehydrosulfurenic acid (4), dehydroeburiconic acid (5), dehydroeburicoic acid (6), 3-keto-dehydrosulfurenic acid (7), and laricinolic acid (8). The structures and stereochemistry of 1 and 2 were determined by NMR and X-ray diffraction analyses. The sesquiterpenoid and five triterpenes were tested for cytotoxicity against HL-60, Bel-7402, and KB cancer lines in vitro, and they appeared to be modestly active.

[Cassae-type diterpenes from seeds of Caesalpinia minax].

Fifteen cassaen-type diterpenes were isolated from the 95% ethanolic extract of the seeds of C. minax through various chromatographic techniques. Their structures were identified on the basis of spectroscopic data as pulcherralpin (1), caesalpinin ML (2), chamaetexane C (3), chamaetexane D (4), 6ß, 18-diacetoxycassan-13, 15-diene (5), neocaesalpin K (6), neocaesalpin MP (7), neocaesalpin M (8), neocaesalpin Q (9), neocaesalpin P (10), neocaesalpin R (11), caesaldekarin D (12), caesaldekarin A (13), caesaldekarin b (14), 3ß,6α-diacetoxyvouacapane (15). Among them, compounds 14, 9-11 were isolated from this plant for the first time.

Two new degradative cassane-type diterpenes isolated from Caesalpinia minax.

Cassane-type diterpenes are main bioactive constituents of Caesalpinia minax HANCE. As a part of our ongoing chemical investigation of C. minax, two new degradative cassane-type diterpenes, named caesalpins I (1) and J (2), were isolated from the EtOAc extract of the seeds of C. minax. The structures were elucidated by means of spectroscopic analysis.

A new ursane-type triterpene, cymosic acid from Rosa cymosa.

A new ursane-type triterpene, cymosic acid (1) together with two known compounds, 3ß,19α-dihydroxy-2-oxo-12-ursen-28-oic acid (2) and 2α,19α-dihydroxy-3-oxo-12-ursen-28-oic acid (3), were isolated from Rosa cymosa Tratt. The structure of compound 1 was elucidated by analyzing its ¹H and ¹³C NMR, ¹H-¹H COSY, HSQC, HMBC, NOESY, and HR-ESI-MS values. The three compounds were found to display moderate inhibitory activities against nitric oxide production in lipopolysaccharide-activated macrophage cell lines, RAW 264.7 cells.

[Triterpene constituents from Rosa cymosa Tratt].

The constituents in 95% ethanol extract of the root of Rosa cymosa Tratt were purified by column chromatography techniques, leading to isolation of eleven triterpenes. Their structures were elucidated by spectroscopic data as pomolic acid (1), fupenzic acid (2), ursolic acid (3), euscaphic acid (4), arjunic acid (5), tomentic acid (6), 3ß-E-feruloyl corosolic acid (7), 1ß-hydroxyeuscaphic acid (8), myrianthic acid (9), cecropiacic acid (10), and ilexoside B (11). Among them, compounds 3, 6-8, 10 and 11 were obtained from this plant for the first time, and compounds 7 and 10 were obtained from this genus for the first time.

Shancigusins E-I, five new glucosides from the tubers of Pleione yunnanensis.

Five new glucosides, shancigusins E-I (1-5) were isolated from the tubers of Pleione yunnanensis (Rolfe) together with 18 known compounds. The structures of these compounds were determined by extensive analyses of their spectroscopic data.

Cassane-type diterpenes from the seeds of Caesalpinia minax with their antineoplastic activity.

Five new cassane-type diterpenes, neocaesalpin AA (1), neocaesalpin AB (2), neocaesalpin AC (3), neocaesalpin AD (4) and neocaesalpin AE (5), were isolated from Caesalpinia minax together with three known compounds, 12α-methoxyl,5α,14ß-dihydroxy-1α,6α,7ß-triacetoxycass-13(15)-en-16,12-olide (6), spirocaesalmin (7) and magnicaesalpin (8). Their structures were elucidated based on 1D and 2D NMR, MS and CD analyses. Compounds 1-6 were tested against Hela, HCT-8, HepG-2, MCF-7 and A549 cancer cells and showed moderate cytotoxicity with IC50 values from 18.4 to 83.9 µM.

The new cassane-type diterpenes from Caesalpinia minax.

Four new cassane-type diterpenes, Neocaesalpin S (1), Neocaesalpin T (2), Neocaesalpin U (3), and Neocaesalpin V (4) were isolated from Caesalpinia minax HANCE together with seven known compounds Neocaesalpin A (5), Neocaesalpin K (6), Neocaesalpin L (7), Neocaesalpin M (8), Neocaesalpin O (9), Neocaesalpin MP (10), and Magnicaesalpin (11). Their structures were elucidated on the basis of 1D- and 2D-NMR, MS, and circular dichroism (CD) analysis. Compounds 1-4 were tested against liver cancer (HepG-2) and breast cancer (MCF-7), and showed mild antiproliferative activity.