Steroidal Alkaloids from Veratrum dahuricum (Turcz.) Loes. f. with Genotoxicity on Brain Cell DNA in Mice

Two new steroidal alkaloids, 2β‐hydroxyverdine ( 1 ) and tomatillidine 3‐O‐β‐D ‐glucopyranoside ( 2 ), were isolated from the root and rhizome of Veratrum dahuricum (Turcz .) Loes . f., together with four known compounds, i.e., 16‐O‐(2‐methylbutyroyl)germine ( 3 ), veramitaline ( 4 ), jervine ( 5 ), and veratroylzygadenine ( 6 ). Their structures were established by extensive spectroscopic analysis, as well as by comparison with data in literature. Compounds 1 – 6 exhibited genotoxicity on brain cell DNA of the cerebellum and cerebral cortex in mice, evaluated by using single‐cell gel electrophoresis (comet assay).     

Two New Steroidal Alkaloids from Veratrum nigrum L.

Phytochemical studies on Veratrum nigrum L., collected in Shanxi, P. R. China, resulted in the isolation of two new steroidal alkaloids, 23‐methoxycyclopamine ( 1 ) and 15‐O‐(2‐methylbutanoyl)‐3‐O‐veratroylprotoverine ( 2 ). The structures of the two new compounds were established by means of extensive NMR spectroscopic studies.     

Three New Pregnane Alkaloids from Veratrum taliense

Three new alkaloids, 3‐O‐acetylveralkamine ( 1 ), veralkamine 3‐(β‐D ‐glucopyranoside) ( 2 ), and 6,7‐epoxyverdine ( 3 ), together with five known alkaloids, veramitaline, veralkamine ( 4 ), angeloylzygadenine, veratroylzygadenine, and veramiline 3‐(β‐D ‐glucopyranoside), were isolated from the whole plants of Veratrum taliense. Their structures were elucidated on the basis of spectroscopic analysis, and the NMR data of veralkamine ( 4 ) are given for the first time. In addition, the cytotoxic activities of all isolated compounds, except for veramitaline, were tested.     

Steroidal Alkaloids from the Roots and Rhizomes of Vertrum nigrum L.

Two new steroidal alkaloids, neoverapatuline ( 1 ) and (1β,3α,5β)‐1,3‐dihydroxyjervanin‐12‐en‐11‐one ( 2 ), together with the four known compounds, veratramine ( 3 ), rubijervine ( 4 ), veratrosine ( 5 ), and veratroylzygadenine ( 6 ), were isolated from the roots and rhizomes of Veratrum nigrum L. Their structures were established through combined analyses of physicochemical properties and spectroscopic evidence. All compounds 1 – 6 were tested for their cytotoxicities in vitro against the human glioma cell line SF188.     

New Bisabolane Sesquiterpenes from the Rhizomes of Curcuma xanthorrhiza Roxb. and Their Inhibitory Effects on UVB‐Induced MMP‐1 Expression in Human Keratinocytes

Two new bisabolane sesquiterpenoids, 1 and 2 , along with five known ones, 13‐hydroxyxanthorrhizol ( 3 ), 12,13‐epoxyxanthorrhizol ( 4 ), xanthorrhizol ( 5 ), β‐curcumene ( 6 ), and β‐bisabolol ( 7 ), were isolated from the rhizomes of Curcuma xanthorrhiza Roxb . The chemical structures of the new compounds were determined to be (7R,10R)‐10,11‐dihydro‐10,11‐dihydroxyxanthorrhizol 3‐O‐β‐D ‐glucopyranoside ( 1 ) and (?)‐curcuhydroquinone 2,5‐di‐O‐β‐D ‐glucopyranoside ( 2 ) on the basis of 1D‐ and 2D‐NMR spectroscopic analyses and optical‐rotation characteristics. Compounds 2 and 3 decreased MMP‐1 expression in UVB‐treated human keratinocytes by ca. 8.9‐ and 7.6‐fold at the mRNA level, and by ca. 9.2‐ and 6.6‐fold at the protein level, respectively. The results indicate that the isolated compounds may have anti‐aging effects through inhibition of MMP‐1 expression in skin cells.     

Development and validation of an ultra high‐performance liquid chromatographic method for the determination of a diastereomeric impurity in (+)‐pinoresinol diglucoside chemical reference substance

(+)‐Pinoresinol 4,4′‐di‐O‐β‐D ‐glucopyranoside ((+)‐PDG) is one of the major lignans with various pharmacological activities which could be isolated from Duzhong and other plant species. In this study, a diastereomeric impurity, (?)‐pinoresinol 4,4′‐di‐O‐β‐D ‐glucopyranoside ((?)‐PDG), the main impurity was identified in (+)‐PDG chemical reference substance (CRS) and a reliable chromatographic method for rapid purity determination of (+)‐PDG CRS was firstly developed. The optimal chromatographic condition was found to be using ACN/1,4‐dioxane–water (2.5:6:91.5, v/v/v) as mobile phase on a Waters Acquity UPLC HSS T3 column (2.1 mm×100 mm, 1.8 μm) with column temperature of 37°C. The method was validated and applied to determine the chromatographic purity of five (+)‐PDG CRS samples. The content of (?)‐PDG in four commercial (+)‐PDG CRS was 8.47–20.30%, whereas no (?)‐PDG was detected in our in‐house prepared (+)‐PDG CRS in which purity was confirmed to be 99.80%. The above results confirmed that this method is fast and highly efficient for purity determination of the (+)‐PDG CRS.     

Two New Lycopodine Alkaloids from Huperzia serrata

Two new lycopodine alkaloids, (12β)‐12‐hydroxyhuperzine G ( 1 ) and (5β,6β,15α)‐15‐methyllycopodane‐5,6‐diol ( 2 ), were isolated from the whole plants of Huperzia serrata, together with six known compounds, huperzines A, B, and G, phlegmariurine B, (8β)‐8‐hydroxyphlegmariurine B, and lycoposerramine D. Their structures were elucidated on the basis of spectroscopic analysis, including HR‐ESI‐MS, ¹H‐ and ¹³C‐NMR, DEPT, ¹H,¹H‐COSY, HSQC, HMBC, and NOESY data.     

Two New Lycodine Alkaloids from Lycopodiastrum casuarinoides

Two new lycodine alkaloids, 11β‐methoxyhuperzine B ( 1 ) and 16‐oxohuperzinine ( 2 ), together with seven known ones, huperzinine N‐oxide, huperzine D, casuarinine A, huperzine B, casuarinine B, huperzinine, and N‐methyllycodine, were isolated from whole plants of Lycopodiastrum casuarinoides. Their structures were elucidated by spectroscopic methods, including NMR and MS experiments.     

Pinacol Rearrangement of 3,4‐Dihydro‐3,4‐dihydroxyquinolin‐2(1H)‐ones: An Alternative Pathway to Viridicatin Alkaloids and Their Analogs

3‐Alkyl/aryl‐3‐hydroxyquinoline‐2,4‐diones were reduced with NaBH₄ to give cis‐3‐alkyl/aryl‐3,4‐dihydro‐3,4‐dihydroxyquinolin‐2(1H)‐ones. These compounds were subjected to pinacol rearrangement by treatment with concentrated H₂SO₄, resulting in 4‐alkyl/aryl‐3‐hydroxyquinolin‐2(1H)‐ones. When a benzyl (Bn) group was present in position 3 of the starting compound, its elimination occurred during the rearrangement, and the corresponding 3‐hydroxyquinolin‐2(1H)‐one was formed. The reaction mechanisms are discussed for all transformations. All compounds were characterized by IR, ¹H‐ and ¹³C‐NMR spectroscopy, as well as mass spectrometry.     

Five New β‐Carboline‐Type Alkaloids from Stellaria dichotoma var. lanceolata

Five new β‐carboline‐type alkaloids, dichotomines F–J ( 1 – 5 , resp.), along with nine known compounds, dichotomides I, III, V, and VII ( 6 – 9 , resp.), stellarines A and C ( 10 – 11 , resp.), dichotomine B ( 12 ), glucodichotomine B ( 13 ), and 1‐acetyl‐3‐carboxy‐β‐carboline ( 14 ), were isolated from the roots of Chinese medicinal plant Stellaria dichotoma L. var. lanceolata. Their structures were determined by chemical and spectroscopic means. Compounds 12 and 13 exhibited moderate cytotoxicity.     

Xanthone O‐Glycosides from the Roots of Pteris Multifida

Two new xanthone glycosides and six known compounds were isolated from the roots of Pteris multifida. Based on spectroscopic and chemical methods, the structures of the new compounds were elucidated as 1‐hydroxy‐4,7‐dimethoxy‐8‐(3‐methyl‐2‐butenyl)‐6‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐[β‐D‐glucopyranosyl‐(1→3)]‐β‐D‐glucopyranosylxanthone ( 1 ), and 1,3‐dihydroxy‐7‐methoxy‐8‐(3‐methyl‐2‐butenyl)‐6‐O‐α‐L‐rhamnopyranosyl‐(1 →2)‐[β‐D‐glucopyranosyl‐(1→3)]‐β‐D‐glucopyranosylxanthone ( 2 ), respectively.     

Two New Lycopodium Alkaloids from Lycopodium obscurum

Two new Lycopodium alkaloids, (+)‐cermizine D N‐oxide ( 1 ) and (8β)‐8‐(acetyloxy)obscurumine A ( 2 ), along with five known compounds, were isolated from the crude alkaloid portion of Lycopodium obscurum. Their structures were elucidated on the basis of spectroscopic data and chemical correlation. All of these alkaloids were tested in an assay for acetylcholine esterase (AChE) inhibitory activity.     

Prenylated Indole Alkaloid Derivatives from Marine Sediment‐Derived Fungus Penicillium paneum SD‐44

Three new prenylated indole alkaloids, including two β‐carbolines, penipalines A and B ( 1 and 2 , resp.), and one indole carbaldehyde derivative, penipaline C ( 3 ), as well as two known indole derived analogs, 4 and 5 , were isolated from the deep‐sea‐sediment derived fungus Penicillium paneum SD‐44 cultured in a 500‐l bioreactor. The structures of the new compounds were determined on the basis of 1D‐ and 2D‐NMR spectroscopy, as well as by high‐resolution mass spectrometry. The new compounds 2 and 3 showed potent cytotoxic activities against A‐549 and HCT‐116 cell lines.     

Four New Nor‐Diterpenoid Alkaloids from Aconitum brachypodum

Four new C₁₉‐nor‐diterpenoid alkaloids, named brachyaconitines A–D ( 1 – 4 ), were isolated from the roots of Aconitum brachypodum Diels. Their structures were elucidated as 3‐O‐acetyl‐20‐deethyl‐20‐formylaconitine ( 1 ), 3‐O‐acetyl‐19,20‐didehydro‐20‐deethylaconitine ( 2 ), 3‐O‐acetyl‐8‐de(acetyloxy)‐7,8,17,20‐tetradehydro‐20‐deethyl‐7,17‐secoaconitine ( 3 ), and 1‐O‐methylflavaconitine ( 4 ) by means of MS, IR, 1D‐ and 2D‐NMR analyses. The structure of compound 1 was confirmed by an X‐ray diffraction experiment.     

Monoterpenoid Indole Alkaloids from Alstonia mairei

Three new monoterpenoid indole alkaloids, (14α,15α)‐14,15‐epoxyaspidofractinine ( 1 ) and maireines A and B ( 2 and 3 , resp.), together with 19 known alkaloids, were isolated from the leaves and twigs of Alstonia mairei. The structures of the new compounds were elucidated by 1D‐ and 2D‐NMR spectroscopic methods in combination with MS experiments.     

Novel and Stereospecific Synthesis of (2S)‐3‐(2,4,5‐Trifluorophenyl)propane‐1,2‐diol from D‐Mannitol

A stereospecific synthesis of (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol from D ‐mannitol has been developed. The reaction of 2,3‐O‐isopropylidene‐D ‐glyceraldehyde with 2,4,5‐trifluorophenylmagnesium bromide gave [(4R)‐2,2‐dimethyl‐1,3‐dioxolan‐4‐yl](2,4,5‐trifluorophenyl)methanol in 65% yield as a mixture of diastereoisomers (1 : 1). The Ph₃P catalyzed reaction of the latter with C₂Cl₆ followed by reduction with Pd/C‐catalyzed hydrogenation gave (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol with >99% ee and 65% yield.     

Insights into the Synthesis of Steroidal A‐Ring Olefins

The classical synthesis, followed by purification of the steroidal A‐ring Δ¹‐olefin, 5α‐androst‐1‐en‐17‐one ( 5 ), from the Δ¹‐3‐keto enone, (5α,17β)‐3‐oxo‐5‐androst‐1‐en‐17‐yl acetate ( 1 ), through a strategy involving the reaction of Δ¹‐3‐hydroxy allylic alcohol, 3β‐hydroxy‐5α‐androst‐1‐en‐17β‐yl acetate ( 2 ), with SOCl₂, was revisited in order to prepare and biologically evaluate 5 as aromatase inhibitor for breast cancer treatment. Surprisingly, the followed strategy also afforded the isomeric Δ²‐olefin 6 as a by‐product, which could only be detected on the basis of NMR analysis. Optimization of the purification and detection procedures allowed us to reach 96% purity required for biological assays of compound 5 . The same synthetic strategy was applied, using the Δ⁴‐3‐keto enone, 3‐oxoandrost‐4‐en‐17β‐yl acetate ( 8 ), as starting material, to prepare the potent aromatase inhibitor Δ⁴‐olefin, androst‐4‐en‐17‐one ( 15 ). Unexpectedly, a different aromatase inhibitor, the Δ^3,5‐diene, androst‐3,5‐dien‐17‐one ( 12 ), was formed. To overcome this drawback, another strategy was developed for the preparation of 15 from 8 . The data now presented show the unequal reactivity of the two steroidal A‐ring Δ¹‐ and Δ⁴‐3‐hydroxy allylic alcohol intermediates, 3β‐hydroxy‐5α‐androst‐1‐en‐17β‐yl acetate ( 2 ) and 3β‐hydroxyandrost‐4‐en‐17β‐yl acetate ( 9 ), towards SOCl₂, and provides a new strategy for the preparation of the aromatase inhibitor 12 . Additionally, a new pathway to prepare compound 15 was achieved, which avoids the formation of undesirable by‐products.     

Three New Indole‐Containing Diketopiperazine Alkaloids from a Deep‐Ocean Sediment Derived Fungus Penicillium griseofulvum

Three new indole‐containing diketopiperazine alkaloids, named variecolorins M–O ( 1 – 3 ), together with the eight known analogues 4 – 11 , were isolated from a deep‐ocean sediment‐derived fungus, Penicillium griseofulvum. Their structures were determined by analysis of the spectroscopic data. The 2,2‐diphenyl‐1‐picrylhydrazinyl (DPPH) radical‐scavenging activities and the cell‐proliferation inhibitory activities of the three new compounds 1 – 3 were investigated.     

Pharmacokinetics of methyl salicylate‐2‐O‐β‐D‐lactoside,a novel salicylic acid analog isolated from Gaultheria yunnanensis,in dogs

Methyl salicylate‐2‐O‐β‐D‐lactoside (MSL), a natural salicylate derivative of Gaultheria yunnanensis (Franch.) Rehder (G. yunnanensis), has been shown to provide a beneficial anti‐inflammatory effect in animal models. Studies on the pharmacokinetics and bioavailability of MSL can provide both a substantial foundation for understanding its mechanism and empirical evidence to support its use in clinical practice. A simple and sensitive high‐performance liquid chromatography (HPLC) method, coupled with ultraviolet analyte detection, was developed for determining the concentration of MSL and its metabolite in beagle plasma. Chromatographic separation was achieved on a Agilent Zorbax SB‐C₁₈ column (5 μm ,4.6 × 250 mm). The mobile phase consisted of aqueous solution containing 0.1% phosphoric acid and acetonitrile (82:90, v/v), at a flow rate of 1 mL/min. Validation of the assay demonstrated that the developed HPLC method was sensitive, accurate and selective for the determination of MSL and its metabolite in dog plasma. After orally administering three doses of MSL, it could no longer be detected in dog plasma and its metabolite, salicylic acid, was detected. Salicylic acid showed a single peak in the plasma concentration–time curves and linear pharmacokinetics following the three oral doses (r² > 0.99). In contrast, only MSL was detected in plasma following intravenous administration. These results will aid in understanding the pharmacological significance of MSL. The developed method was successfully used for evaluation of the oral and intravenous pharmacokinetic profile of MSL in dogs. Copyright © 2013 John Wiley & Sons, Ltd.     

Bioassay Guided Isolation and Identification of a Cytotoxic Compound from Azadirachta indica Leaves

This study aimed to investigate the structural features of the isolated flavonol glycoside, which might behave as a cytotoxic compound. The hexane, chloroform, ethyl acetate, and aqueous fractions of an 80% methanol solution of Neem (Azadirachta indica) (Family: Meliaceae) leaves were subjected to a cytotoxicity bioassay against brine shrimp, Artemia salina. The ethyl acetate fraction exhibited the highest cytotoxic effect, supported by the lowest lethal concentration, a LC₅₀ value of 1.35±0.40 ppm. A compound, Quercetin 3‐O‐β‐D‐glucopyranoside, was isolated from the most toxic fraction of the ethyl acetate via preparative liquid chromatography and then identified via ultraviolet‐visible (UV‐Vis), infrared (IR), mass spectrum (MS) and nuclear magnetic resonance (NMR) analyses. The compound was further confirmed by physical state, color, solubility, and melting point determination. The cytotoxic results suggest that the leaf ethyl acetate fraction consists of toxic compounds, which point towards the isolation of Quercetin 3‐O‐β‐D‐glucopyranoside.