Secondary metabolites from pericarp of Juglans regia

Chemical investigation of the pericarps of Juglans regia led to the isolation of sixteen compounds, including five α-tetralone (1-5), five phenolic acids (6-10), two phenylpropanoids (11, 12), one diarylheptanoid (13), one sesquiterpene (14), and two α- tetralone dimers (15, 16). Among them, compounds 2, 4, 5, 11, 12 and 13 were isolated from J. regia for the first time, and compounds 10 and 14 were reported for the first time from Juglandaceae. The chemotaxonomic significance of these compounds was summarized.     

Secondary metabolites from the leaves of Juglans regia L.

One new diarylheptanoid (1) and one previously unknown ascorbic acid derivative (2) along with 48 known compounds including three ascorbic acid derivatives (3-5), three diarylheptanoids (6-8), three juglone derivates (9-11), six racemic α-tetralones (12a/b-17a/b), four anthraquinones (18-21), eight flavonoids (22-29), nine oligomeric proanthocyanidins (30-38), one phenolic aldehyde (39), one aromatic ketone (40), one pyrrole alkaloid (41), one steroid (42), six terpenes (43-48) and two fatty acids (49-50) were isolated from the leaves of Juglans regia. Their chemical structures were elucidated on basis of 1D and 2D NMR techniques, HRESIMS, polarimetry and CD spectroscopy as well as chiral HPLC and literature data. Furthermore, the chemotaxonomic significance is discussed.     

Antioxidative Activities of Galloyl Glucopyranosides from the Stem-Bark of Juglans mandshurica

Two phenolics, 1,2,6-trigalloylglucose (1) and 1,2,3,6-tetragalloylglucose (2), isolated from the stem-bark of Juglans mandshurica were evaluated for their antioxidative activities. The results showed that compounds 1 and 2 exhibited strong scavenging activities against 1,1′-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzenthiazoline-6-sulphonic) acid (ABTS^?+), and superoxide radicals (O₂ ^??), and also had a significant inhibitory effect on lipid peroxidation and low-density lipoprotein (LDL) oxidation. The strong superoxide radical scavenging of 1 and 2 resulted from the potential competitive inhibition with xanthine at the active site of xanthine oxidase (OX). In addition, compounds 1 and 2 displayed significant lipoxygenase inhibitory activity, the mode of inhibition also being identified as competitive. In comparison, the antioxidative activities of compounds 1 and 2, together with gallic acid, indicated that the number of galloyl moieties could play an important role in the antioxidative activity.     

Three new compounds from the roots of Juglans mandshurica Maxim.

A new biflavone glycoside juglbiflavone A (1) along with two new lupane-type triterpenes (2-3) were identified from the roots of Juglans mandshurica Maxim. Their structures and absolute configurations were elucidated by extensive spectroscopic methods including 1D/2D NMR, HRESIMS and CD. Compound 1 is the first example of biflavone glycoside consisted of a flavanol unit and a flavone unit from this genus, which also exhibited moderate cytotoxic activity against SGC-7901 and A549 cell lines in vitro with IC₅₀ values of 10.08 ± 0.52 μM and 12.44 ± 1.21 μM, respectively.     

Three new compounds from the bark of Antiaris toxicaria

Three new compounds, namely (+)-pranferol (1), antiarone M (2), and anticerol A (3), together with 9 known compounds, were obtained from the bark of Antiaris toxicaria. Their chemical structures were elucidated on the basis of spectroscopic methods including UV, IR, (HR) ESI–MS, ¹H, ¹³C NMR, HSQC, ¹H-¹H COSY, HMBC and X-ray crystallographic technique. The absolute configurations of compounds 1 and 2 were determined by modified mosher method and CD spectrum.     

Phytochemical investigation on the roots of Juglans mandshurica and their chemotaxonomic significance

Phytochemical research of the roots of Juglans mandshurica Maxim. (Juglandaceae) verified 37 secondary metabolites, including thirteen diarylheptanoids (1–13), five naphthoquinones (14–18), five tetralones (19–23), three lignans (24–26), three phenols (27–29), two anthraquinones (30–31), two triterpenoids (32–33), two secoiridoids (34–35), one naphthalenyl glycoside (36), and one flavonoid (37). The chemical structures of these constituents were elucidated by NMR spectroscopy and compared with data from the literature. This is the first confirmation of the presence of ten compounds (6, 12, 16, 18, 24–26, 30, 32–33) isolated from the family Juglandaceae, two compounds (1 and 8) from the genus Juglans, and four compounds (27, 31, 34–35) from J. mandshurica. The isolation and chemotaxonomic significance of the metabolites from the roots of J. mandshurica were described in this study.     

Secondary metabolites from Cedrelopsis grevei (Ptaeroxylaceae)

From the hexane extract of the stem bark of Cedrelopsis grevei (Ptaeroxylaceae) was isolated the triterpenoid derivative, cedashnine, and the quassinoid, cedphiline, along with cedmiline, scoparone, beta-amyrin and sitosteryl glucoside.     

Chemical constituents from the bark of Juglans mandshurica Maxim. and their phenol oxidase inhibitory effects

Botanical insecticides investigation led to 21 compounds from the bark of Juglans mandshurica Maxim., in which, compounds 4, 10, 11, 13, 14 and 15 were isolated from Juglans genus for the first time. The inhibitory effect of dihydrokaempferol (6), naringenin (7) and rhoiptelol C (18) on phenol oxidase (PO) are 5–10 times more than arbutin, a well-known tyrosinase inhibitor. Thus, the selective and effective these inhibitors can be expected for using in the development of environment-friendly pesticide.     

New cytotoxic protolimonoids from the stem bark of Aglaia argentea (Meliaceae)

Two new protolimonoid compounds, namely, argentinin A (1) and B (2) along with five known triterpenoid compounds, dammar-24-en-3α-ol (3), 3-epi-cabraleahydroxy lactone (4), (E)-25-hydroperoxydammar-23-en-3β,20-diol (5), mixture of eichlerianic acid and shoreic acid (6a and 6b), and dammar-24-en-3α,20-diol (7), were isolated from the stem bark of Aglaia argentea. The structure of new compounds were elucidated by spectroscopic methods including one and two-dimensional NMR as well as high-resolution mass spectrometric analysis. All of the compounds were tested for their cytotoxic effects against P-388 murine leukemia cells in vitro. Among those isolated compounds, argentinin A (1) showed the strongest activity with an IC₅₀ value of 1.27 μg/mL (3.05 μM).     

Triterpenoid saponins from the stem bark of Caryocar villosum

Five triterpenoid saponins, caryocarosides II-22 (3), III-22 (4), II-23 (5), III-23 (6), and II-24 (7), have been isolated from the methanol extract of the stem bark of Caryocar villosum, along with two known saponins (1-2). The seven saponins are glucuronides of hederagenin (II) or bayogenin (III). Caryocaroside II-24 (7) is an unusual galloyl ester saponin acylated on the sugar chain attached to C-28, the 3-O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-galactopyranosyl-(1-->3)-beta-D-glucuronopyranosyl hederagenin-28-O-[2-O-galloyl-beta-D-glucopyranosyl] ester. The structures of the saponins were established on the basis of extensive NMR ((13)C, (1)H, COSY, TOCSY, HSQC, HMBC and ROESY) and ESI-MS studies. The cytotoxic activity of saponins 2 and 3 was evaluated in vitro against human keratinocytes. The DOPA-oxidase inhibition and the lipolytic activities were evaluated ex vivo using an explant of human adipose tissue.     

Triterpenoid saponins from Pteleopsis suberosa stem bark

Thirteen oleanane saponins (1-13), four of which were new compounds (1-4), were isolated from Pteleopsis suberosa Engl. et Diels stem bark (Combretaceae). Their structures were determined by 1D and 2D NMR spectroscopy and ESI-MS spectrometry. The compounds were identified as 2alpha,3beta,19alpha,23,24-pentahydroxy-11-oxo-olean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl ester (1), 2alpha,3beta,19beta,23,24-pentahydroxy-11-oxo-olean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl ester (2), 2alpha,3beta,19alpha,23-tetrahydroxy-11-oxo-olean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl ester (3), and 2alpha,3beta,6beta,19alpha,24-pentahydroxy-11-oxo-olean-12- en-28-oic acid 28-O-beta-D-glucopyranosyl ester (4). The presence of alpha,beta-unsaturated carbonyl function was not common in the oleanane class and the aglycons of these compounds were not found previously in the literature. Moreover, the isolated compounds were tested against Helicobacter pylori standard and vacA, and cagA clinical virulence genotypes. Results showed that compound 6 has an anti-H. pylori activity against three metronidazole-resistant strains (Ci 1 cagA, Ci 2 vacA, and Ci 3).     

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.     

Uvariastrol,a novel cycloartane triterpene from the stem bark of Uvariastrum zenkeri

Uvariastrol, a cycloartane triterpene with a novel tetrahydrofuran/furanone side-chain, has been isolated from the stem bark of Uvariastrum zenkeri and characterized using spectral characteristics, notably high-field ¹H NMR and ¹³C NMR spectroscopy.     

Secondary metabolites from the roots of Engelhardia roxburghiana and their antitubercular activities

Engelharquinone (1), engelharquinone epoxide (2), engelharolide (3), and engelhardic acid (4), were isolated as naturally occurring products from a plant source, Engelhardia roxburghiana together with 20 previously known compounds, four of which were hitherto not known as plant constituents. Their structures were identified by means of spectroscopic analysis. A biological evaluation showed that three of the previously isolated antitubercular constituents [(-)-4-hydroxy-1-tetralone, 3-methoxyjuglone and engelhardione] and engelharquinone (1) exhibited moderate antitubercular activity against Mycobacterium tuberculosis 90-221387.     

Antioxidative activities of galloyl glucopyranosides from the stem-bark of Juglans mandshurica

Two phenolics, 1,2,6-trigalloylglucose (1) and 1,2,3,6-tetragalloylglucose (2), isolated from the stem-bark of Juglans mandshurica were evaluated for their antioxidative activities. The results showed that compounds 1 and 2 exhibited strong scavenging activities against 1,1'-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzenthiazoline-6-sulphonic) acid (ABTS(*+)), and superoxide radicals (O(2)(*-)), and also had a significant inhibitory effect on lipid peroxidation and low-density lipoprotein (LDL) oxidation. The strong superoxide radical scavenging of 1 and 2 resulted from the potential competitive inhibition with xanthine at the active site of xanthine oxidase (OX). In addition, compounds 1 and 2 displayed significant lipoxygenase inhibitory activity, the mode of inhibition also being identified as competitive. In comparison, the antioxidative activities of compounds 1 and 2, together with gallic acid, indicated that the number of galloyl moieties could play an important role in the antioxidative activity.     

长白山林区核桃楸种群数量动态变化的研究

运用种群年龄结构、存活曲线统计和Leslie模型对长白山核桃楸种群在水胡林、针阔混交林、核桃楸占优杂木林和杂木林4种不同群落类型中种群数量动态变化进行了研究和预测。结果表明,核桃楸种群表现出衰退型的年龄结构特点,幼苗和幼树比例较小,种群在幼年期死亡率较高,反映出核桃楸种群15~20龄在个体经历了比较强烈的环境筛作用;Leslie模型预测显示,核桃楸幼苗数量和种群总数量在今后35年基本呈下降趋势,除在核桃楸占优的林分中种群维持增长外,在其它3中森林类型都表现出衰退趋势。因此,促进核桃楸的天然更新、加强幼苗幼树的抚育工作对长白山地区核桃楸种群的发展至关重要。     

Triterpenoid saponins and C-glycosyl flavones from stem bark of Erythrina abyssinica Lam and their cytotoxic effects.

Six new compounds including two oleanane-type triterpenoid saponins (1, 2) and four C-glycosyl flavones (3–6), along with a known saponin (7), three di-C-glycosyl flavones (8–10) and a glycosyl auronol (11), were isolated from the stem bark of Erythrina abyssinica Lam. The structures of the new compounds, identified as 3-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-galactopyranosyl-(1 → 2)-β-d-glucuronopyranosyl]-22-O-β-d-glucopyranosyl sophoradiol (1), 3-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 2)-β-d-glucuronopyranosyl]-22-O-β-d-glucopyranosyl sophoradiol (2), 6-C-β-glucopyranosyl-8-C-β-quinovopyranosyl apigenin (3), 6-C-β-quinovopyranosyl-8-C-β-glucopyranosyl apigenin (4), 8-C-[6″-O-α-l-rhamnopyranosyl-(1‴ → 6″)]-β-glucopyranosyl 7,4′-dihydroxyflavone (5) and 8-C-[6″-O-β-d-xylopyranosyl-(1‴ → 6″)]-β-glucopyranosyl 7,4′-dihydroxyflavone (6), were determined by comprehensive spectroscopic analysis, including 1D and 2D NMR techniques, mass spectrometry and acid hydrolysis. These new compounds together with the known saponins 7 were evaluated for their cytotoxic activity against MCF-7 (estrogen dependent) and MDA-MB-231 (estrogen independent) cell lines. The new saponin 2 exhibited the highest cytotoxic activity among tested compounds, exerting a selective inhibitory effect against the proliferation of MCF-7 cells, with lower IC₅₀ value (12.90 μM) than that of the positive control, resveratrol (13.91 μM). Structure–activity relationship of these compounds is also discussed.     

The different responses of Batocera horsfieldi adults to Juglans regia bark and leaf volatile compounds

Batocera horsfieldi (Hope) (Coleoptera: Cerambycidae) is an important pole borer pest. It causes serious harm to various hosts, particularly Juglans regia L. (Juglandaceae). In this study, headspace solid-phase microextraction (HS-SPME), gas chromatography–mass spectrometry (GC–MS), and electroantennogram (EAG) responses were combined to examine the mechanism by which B. horsfieldi adults locate their host, J. regia. The results showed that J. regia contained 65 volatile compounds in all, with 36 and 42 volatile substances in bark and leaves, respectively. Moreover, terpenes accounted for the largest relative content among the volatile compounds of bark and leaves, 43.4 and 78.9%, respectively. Ten of 19 selected volatile components elicited significant EAG responses in adult B. horsfieldi, which indicated that the pest may prefer certain volatile compounds when selecting a host. Sex and volatile concentration affected the responses of B. horsfieldi. Male adults had the strongest EAG responses to 1-octen-3-ol, whereas female adults had the strongest EAG responses to linalool. Host selection in B. horsfieldi was somewhat positively associated with the concentrations of the effective volatile compounds in the host. Furthermore, B. horsfieldi showed varying preferences for isomers. This work provided data support for the development of insect attractants, and laid a theoretical foundation for the ecological protection of local forestry.     

Cytotoxic triterpenoid saponins from the stem bark of Antonia ovata

Phytochemical investigation of the MeOH extract of the stem bark of Antonia ovata led to the isolation of four triterpenoid saponins, along with eleven known compounds. Their structures were established by extensive 1D and 2D NMR, as well as HR-MS analysis and acid hydrolysis. All isolated saponins contained the same tetrasaccharide chain O-β-d-xylopyranosyl-(1 → 2)-O-β-d-glucopyranosyl-(1 → 3)-O-[β-d-glucopyranosyl-(1 → 2)]-β-d-glucuropyranoside linked to C-3 of esterified derivatives of R₁-barrigenol, A₁-barrigenol, barringtogenol C, or camelliagenin. Biological evaluation of the compounds against KB cell line revealed a potent cytotoxic activity with IC₅₀ values ranging from 3.1 to 6.6 μM. The known compounds were found to be inactive at 10 μg/ml concentration.