Benzopyran Derivatives and an Aliphatic Compound from a Mangrove Endophytic Fungus Penicillium citrinum QJF‐22

Two new benzopyran derivatives, (2R,4S)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol and (2S,4R,2′S,4′R)‐4,4′‐oxybis(5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran), and a new aliphatic compound, (3E,5Z,8S,10E)‐8‐hydroxytrideca‐3,5,10,12‐tetraen‐2‐one, together with three known benzopyran derivatives, were obtained from a mangrove endophytic fungus Penicillium citrinum QJF‐22 collected in Hainan island. Their structures were determined by analysis of spectroscopic data and the relative configuration of (2R,4S)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol was also confirmed by single‐crystal X‐ray diffraction. The absolute configurations of four compounds were established by comparison of ECD spectra to calculations. The configuration of (3E,5Z,8S,10E)‐8‐hydroxytrideca‐3,5,10,12‐tetraen‐2‐one was confirmed by comparison of optical value to the similar compound. The configurations of the compounds (2S,4S)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol and (2R,4R)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol were first determined. (3R,4S)‐3,4,8‐Trihydroxy‐3,4‐dihydronaphthalen‐1(2H)‐one exhibited moderate inhibitory effects on LPS‐induced NO production in RAW264.7 cells with IC₅₀ of 44.7 μM, and without cytotoxicity to RAW264.7 cells within 50 μM.     

Cytotoxic Compounds from the Leaves of Garcinia polyantha

A new compound, named banganxanthone C (=12‐(1,1‐dimethylprop‐2‐en‐1‐yl)‐5,10‐dihydroxy‐9‐methoxy‐2‐methyl‐2‐(4‐methylpent‐3‐en‐1‐yl)‐2H,6H‐pyrano[3,2‐b]xanthen‐6‐one; 4 ), together with five known compounds, were isolated from the leaves of Garcinia polyantha. The structures of the compounds were elucidated on the basis of 1D‐ and 2D‐NMR spectroscopy. Among the known compounds, two were xanthones, one was a pentacyclic triterpene, one sterol, and one benzophenone derivative. Isoxanthochymol ( 2 ) and 4‐[(2E)‐3,7‐dimethylocta‐2,6‐dien‐1‐yl]‐1,5,8‐trihydroxy‐3‐methoxy‐9H‐xanthen‐9‐one ( 3 ) exhibited significant antiproliferative activity against the leukemia cell line TPH‐1 with IC₅₀ inhibition values of 1.5 and 2.8 μg/ml, respectively. The cytotoxic activity was found to be related to apoptosis induction.     

Novel Neolignan from Penthorum chinense

A new neolignan （7＇E）-2＇,4,8-trihydroxy-3-methoxy-2,4＇-epoxy-8,5＇-neolign-7＇-en-7-one （1） was isolated from the whole plants of Penthorum chinense Pursh, along with Iupeol （2）, betulinic acid （3）, glyceryl monopalmitate （4）, β-sitosterol （5）, palmitic acid （5）, ursolic acid （7）, 2β,3β,23-trihydroxy-urs-12-ene-28-oic acid （8）, glyceryl monolaurate （9）, scopoletin （10）, （-）syringaresinol （11）, 9,9＇-O-diferuIoyl-（-）-secoisolariciresionl （12）, pinocembrin （13）, apigenin （14）, kaempferol （15）, Iuteolin （16）, β-daucosterol （17）, quercetin （18）, 1-O-（β-D-glucopyranosyl）-（2S, 2＇R, 3R,4E,8E）-2-（2＇-hydroxyhexadecanoy- lamino）-4,8-octdecadiene-1,3-diol （19）, gallic acid （20）, pinocembrin-7-O-β-D-glucoside （21）, and quercetin-3-O-β-D- glucoside （22）. The structures of these compounds were elucidated on the basis of chemical and spectral evidence.     

Iridoid Derivatives with Cytotoxic Activity from Pedicularis uliginosa Bunge

Three new iridoids, rel‐(4aR,7S,7aS)‐7‐hydroxy‐7‐methyl‐1,4a,5,6,7,7a‐hexahydrocyclopenta[c]pyran‐4‐carbaldehyde ( 1 ), 1‐methoxy‐7‐methyl‐1,3,5,6‐tetrahydrocyclopenta[c]pyran‐4‐carbaldehyde ( 2 ), and rel‐(1R,4S,4aS,7R,7aR)‐7‐methylhexahydro‐1,4‐(epoxymethano)cyclopenta[c]pyran‐3(1H)‐one ( 3 ), together with seven known analogues, were isolated from the 95 % EtOH extract of the whole plants of Pedicularis uliginosa Bunge . Their structures were elucidated via extensive NMR spectroscopy and mass spectral data. In terms of inhibitory effects on human tumor cells, compounds 1 , 2 , 6 , 7 , and 8 exhibited better inhibitory activities against ACHN cells than the positive control (vinblastine).     

Structural Modification of Stilbenoids from Acanthopanax leucorrhizus and Their Cytotoxic Activity

A new cis‐stilbenoid, 1,9‐dihydroxy‐10‐methoxy‐6H‐dibenzo[b,f]oxocin‐6‐one ( 2 ) was isolated from the AcOEt extract of the stem barks of Acanthopanax leucorrhizus, along with three known stilbenoids, 9‐hydroxy‐10‐methoxy‐6H‐dibenzo[b,f]oxocin‐6‐one ( 1 ), 5‐O‐methyl‐(E)‐resveratrol 3‐O‐β‐d ‐glucopyranoside ( 3 ), and (E)‐resveratrol 3‐O‐β‐d ‐xylopyranoside ( 4 ). Two derivatives ( 2a and 2b ) were synthesized by the structural modification of compound 2, which exhibited certain cytotoxic activities against HT‐29 and HeLa cell lines in vitro. All compounds were structurally characterized by comprehensive analysis of their spectroscopic data and comparison with literature information, and evaluated for their cytotoxic activities against three human tumor cell lines (HL‐60, HT‐29, and HeLa) by the standard MTT assay in vitro. The results showed that derivatives 2a and 2b exhibited strong activities than compounds 2 against HT‐29 and HeLa cell lines.     

New Metabolites from Endolichenic Fungus Pleosporales sp.

Eight new metabolites were obtained from the culture of an endolichenic fungus, Pleosporales sp. Their structures were determined as three terphenyl derivatives, cucurbitarins A–C ( 1 – 3 , resp.), two structurally related compounds, cucurbitarins D and E ( 4 and 5 , resp.), two benzocoumarins, 3,10‐dihydroxy‐4,8‐dimethoxy‐6‐methylbenzocoumarin ( 6 ) and 3,8,10‐trihydroxy‐4‐methoxy‐6‐methylbenzocoumarin ( 7 ), as well as one cyclohexenone, (5R)‐5‐hydroxy‐2,3‐dimethylcyclohex‐2‐en‐1‐one ( 8 ), based on the spectroscopic data.     

Four New Chromone Derivatives from Colletotrichum gloeosporioides

Four previously unreported chromones, 5‐hydroxy‐2‐(hydroxymethyl)‐8‐methoxy‐4H‐chromen‐4‐one ( 1 ), (5R,7S)‐5,7‐dihydroxy‐2‐propyl‐5,6,7,8‐tetrahydro‐4H‐chromen‐4‐one ( 2 ), (5R,7S)‐5,7‐dihydroxy‐2‐methyl‐5,6,7,8‐tetrahydro‐4H‐chromen‐4‐one ( 3 ), and (5R,7S)‐5,7‐dihydroxy‐2‐[(E)‐prop‐1‐en‐1‐yl]‐5,6,7,8‐tetrahydro‐4H‐chromen‐4‐one ( 4 ), as well as one known analogue 5‐hydroxy‐2‐methyl‐4H‐chromen‐4‐one ( 5 ) were isolated from the fermentation broth of the endophytic fungus Colletotrichum gloeosporioides derived from the mangrove Ceriops tagal. Their structures were elucidated based on extensive spectroscopic analyses. The absolute configurations of 2 – 4 were determined by comparison the experimental and calculated electronic circular dichroism (ECD) spectra. Compound 2 showed cytotoxic activity against A549 cell line with the IC₅₀ value of 0.094 mm .     

A fluorescence study of differently substituted 3‐styrylindoles and their interaction with bovine serum albumin

Interaction of 3‐styrylindoles 1–8 viz. 3‐(2‐phenylethenyl‐E)‐NH‐indole (1), 3‐[2‐(4‐nitrophenyl)ethenyl‐E]‐NH‐indole (2), 5‐bromo‐3‐[2‐(4‐nitrophenyl)ethenyl‐E]‐NH‐indole (3), 5‐methoxy‐3‐[2‐(4‐nitrophenyl)ethenyl‐E]‐NH‐indole (4), 3‐[2‐(4‐cyanophenyl)ethenyl‐E]‐NH‐indole (5), 3‐[2‐(4‐cyanophenyl)ethenyl‐E]‐N‐ethylindole (6), 5‐bromo‐3‐[2‐(4‐chlorophenyl)ethenyl‐E]‐NH‐indole (7) and 5‐methoxy‐3‐[2‐(4‐chlorophenyl)ethenyl‐E]‐NH‐indole (8) with bovine serum albumin (BSA) was examined by UV–vis and steady‐state fluorescence spectroscopy. The fluorescence intensity of 1–8 increases with the increasing BSA concentration. Upon binding with BSA, while 1 and 5–8 show a blue shift in their λ_{f max}, 2–4 do not exhibit such behavior. Compounds 1–8 also quench the 345 nm fluorescence of BSA in phosphate buffer (λ_ex, 280 nm). These compounds intercalate in the hydrophobic regions of BSA, as evidenced by the determination of BSA binding site micropolarity using compounds 2–8. As evidenced by the estimation of energy transfer efficiency and distance between the donor (BSA‐Trp‐212) and the acceptor (3‐styrylindoles), the halo‐substituted compounds 3 and 7 interact with BSA more effectively than the other 3‐strylindoles. These compounds have potential for use as neutral and hydrophobic fluorescence probes for examining the microenvironments in proteins, polymers, micelles, etc. Copyright © 2008 John Wiley & Sons, Ltd.     

Chemical constituents of Papulaspora immersa, an endophyte from Smallanthus sonchifolius (Asteraceae), and their cytotoxic activity

Papulaspora immersa H. H. Hotson was isolated from roots and leaves of Smallanthus sonchifolius (Poepp. and Endl. ) H. Rob. (Asteraceae), traditionally known as Yacon. The fungus was cultured in rice, and, from the AcOEt fraction, 14 compounds were isolated. Among them, (22E,24R)‐8,14‐epoxyergosta‐4,22‐diene‐3,6‐dione ( 4 ), 2,3‐epoxy‐1,2,3,4‐tetrahydronaphthalene‐c‐1,c‐4,8‐triol ( 10 ), and the chromone papulasporin ( 13 ) were new secondary metabolites. The spectral data of the known natural products were compared with the literature data, and their structures were established as the (24R)‐stigmast‐4‐en‐3‐one ( 1 ), 24‐methylenecycloartan‐3β‐ol ( 2 ), (22E,24R)‐ergosta‐4,6,8(14),22‐tetraen‐3‐one ( 3 ), (?)‐(3R,4R)‐4‐hydroxymellein ( 5 ), (?)‐(3R)‐5‐hydroxymellein ( 6 ), 6,8‐dihydroxy‐3‐methylisocoumarin ( 7 ), (?)‐(4S)‐4,8‐dihydroxy‐α‐tetralone ( 8 ), naphthalene‐1,8‐diol ( 9 ), 6,7,8‐trihydroxy‐3‐methylisocoumarin ( 11 ), 7‐hydroxy‐2,5‐dimethylchromone ( 12 ), and tyrosol ( 14 ). Compound 4 showed the highest cytotoxic activity against the human tumor cell lines MDA‐MB435 (melanoma), HCT‐8 (colon), SF295 (glioblastoma), and HL‐60 (promyelocytic leukemia), with IC₅₀ values of 3.3, 14.7, 5.0 and 1.6 μM , respectively. Strong synergistic effects were also observed with compound 5 and some of the isolated steroidal compounds.     

An Efficient Route to Novel 4,5‐Di‐ and 2,4,5‐Tri Substituted Imidazoles from Imidazo[1,5‐a]‐1,3,5‐triazine (5,8‐Diaza‐7,9‐dideazapurine) Derivatives

Two new types of imidazole derivatives: N‐(2‐R¹‐5‐R²‐1H‐imidazol‐4‐yl) thioureas 7a–g and N‐(2‐R¹‐5‐R²‐1H‐imidazol‐4‐yl) formamides 8b,c,g were obtained in high yields by the hydrolytic degradation of 6‐R¹‐8‐R²‐2‐thioxo‐2,3‐dihydroimidazo[1,5‐a]‐1,3,5‐triazin‐4(1H)‐ones 5a–g and 6‐R¹‐8‐R²‐imidazo[1,5‐a]‐1,3,5‐triazin‐4(3H)‐ones 6b,c,d, respectively. The tautomeric preferences of the new imidazoles were determined.     

Melanogenesis‐Inhibitory and Cytotoxic Activities of Limonoids,Alkaloids, and Phenolic Compounds from Phellodendron amurense Bark

Four limonoids, 1  –  4 , five alkaloids, 5  –  9 , and four phenolic compounds, 10  –  13 , were isolated from a MeOH extract of the bark of Phellodendron amurense (Rutaceae). Among these, compound 13 was new, and its structure was established as rel‐(1R,2R,3R)‐5‐hydroxy‐3‐(4‐hydroxy‐3‐methoxyphenyl)‐6‐methoxy‐1‐(methoxycarbonylmethyl)indane‐2‐carboxylic acid methyl ester (γ‐di(methyl ferulate)) based on the spectrometric analysis. Upon evaluation of compounds 1  –  13 against the melanogenesis in the B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), four compounds, limonin ( 1 ), noroxyhydrastinine ( 6 ), haplopine ( 7 ), and 4‐methoxy‐1‐methylquinolin‐2(1H)‐one ( 8 ), exhibited potent melanogenesis‐inhibitory activities with almost no toxicity to the cells. Western blot analysis revealed that compound 6 inhibited melanogenesis, at least in part, by inhibiting the expression of protein levels of tyrosinase, TRP‐1, and TRP‐2 in α‐MSH‐stimulated B16 melanoma cells. In addition, when compounds 1  –  13 were evaluated for their cytotoxic activities against leukemia (HL60), lung (A549), duodenum (AZ521), and breast (SK‐BR‐3) cancer cell lines, five compounds, berberine ( 5 ), 8 , canthin‐6‐one ( 9 ), α‐di‐(methyl ferulate) ( 12 ), and 13 , exhibited cytotoxicities against one or more cancer cell lines with IC₅₀ values in the range of 2.6 – 90.0 μm . In particular, compound 5 exhibited strong cytotoxicity against AZ521 (IC₅₀ 2.6 μm ) which was superior to that of the reference cisplatin (IC₅₀ 9.5 μm ).     

Taraxerol 4‐Methoxybenzoate,an in vitro Inhibitor of Photosynthesis Isolated from Pavonia multiflora A. St‐Hil. (Malvaceae)

A phytochemical study of Pavonia multiflora A. St ‐Hil . (Malvaceae) led to the isolation through chromatographic techniques of 10 secondary metabolites: vanillic acid ( 1 ), ferulic acid ( 2 ), p‐hydroxybenzoic acid ( 3 ), p‐coumaric acid ( 4 ), loliolide ( 5 ), vomifoliol ( 6 ), 4,5‐dihydroblumenol A ( 7 ), 3‐oxo‐α‐ionol ( 9 ), blumenol C ( 10 ), and taraxerol 4‐methoxybenzoate ( 8 ), the latter being a novel metabolite. Their structures were identified by ¹H‐ and ¹³C‐NMR, using one‐ and two‐dimensional techniques, and X‐ray crystallography. In this work, we report the effect of compounds 5 and 8 on several photosynthetic activities in an attempt to search for new compounds as potential herbicide agents that affect photosynthesis. Both compounds inhibited the electron flow from H₂O to methyl viologen; therefore, they act as Hill reaction inhibitors. Using polarographic techniques and studies of the fluorescence of chlorophyll a, the interaction sites of these compounds were located at photosystem II.     

Triterpenoids and Flavonoids from the Leaves of Astragalus membranaceus and Their Inhibitory Effects on Nitric Oxide Production

Four new cycloartane triterpenes, named huangqiyegenins V and VI and huangqiyenins K and L ( 1 – 4 , resp.), together with nine known triterpenoids, 5 – 13 , and eight flavonoids, 14 – 21 , were isolated from a 70%‐EtOH extract of Astragalus membranaceus leaves. The structures of the new compounds were elucidated by detailed spectroscopic analyses, and the compounds were identified as (9β,11α,16β,20R,24S)‐11,16,25‐trihydroxy‐20,24‐epoxy‐9,19‐cyclolanostane‐3,6‐dione ( 1 ), (9β,16β,24S)‐16,24,25‐trihydroxy‐9,19‐cyclolanostane‐3,6‐dione ( 2 ), (3β,6α,9β,16β,20R,24R)‐16,25‐dihydroxy‐3‐(β‐D ‐xylopyranosyloxy)‐20,24‐epoxy‐9,19‐cyclolanostan‐6‐yl acetate ( 3 ), and (3β,6α,9β,16β,24E)‐26‐(β‐D ‐glucopyranosyloxy)‐16‐hydroxy‐3‐(β‐D ‐xylopyranosyloxy)‐9,19‐cyclolanost‐24‐en‐6‐yl acetate ( 4 ). All isolated compounds were evaluated for their inhibitory activities against LPS‐induced NO production in RAW264.7 macrophage cells. Compounds 1 – 3, 14, 15 , and 18 exhibited strong inhibition on LPS‐induced NO release by macrophages with IC₅₀ values of 14.4–27.1 μM .     

Rubrolides as Model for the Development of New Lactones and Their Aza Analogs as Potential Photosynthesis Inhibitors

Natural phytotoxins and their synthetic analogs are a potential source of new bioactive compounds for agriculture. Analogs of rubrolides, a class of γ‐alkylidene‐γ‐lactones isolated from different ascidians, have been shown to interfere with the photosynthetic electron‐transport chain, yet their activity needs to be improved. With this aim, ten 5‐aryl‐6‐benzyl‐4‐bromopyridazin‐3(2H)‐ones were prepared in yields ranging from 44 to 88% by reaction of their correspondent γ‐alkylidene‐γ‐lactones with NH₂NH₂. The structures of these rubrolide analogs were determined by ¹H‐ and ¹³C‐NMR, 2D‐NMR (COSY and HETCOR), NOE difference, and MS techniques. These compounds were evaluated for their abilities of interfering with the light‐driven reduction of ferricyanide by isolated spinach chloroplasts. Lactones with electron‐withdrawing substituents in the para‐position of the benzylidene ring were the most effective inhibitors. Characterization of the activity of 11b / 11b′ suggested a mechanism based on the interaction with the plastoquinone binding site of photosystem II. Addition of several compounds to the culture medium of a cyanobacterial model strain was found to inhibit algal growth. However, the relative effectiveness was not consistent with their activity in vitro, suggesting the occurrence of multiple targets and/or detoxyfication mechanisms. Indeed, the compounds showed differential effects on the heterotrophic growth of some crop species, Cucumis sativus and Sorghum bicolor. Pyridazin‐3(2H)‐ones 12e, 12i , and 12j , which have been found poorly active against the photosynthetic electron transport, were the most effective in inhibiting the growth of some weeds, Ipomoea grandifolia and Brachiaria decumbens, under greenhouse conditions.     

Naphthalenones and Naphthols Isolated from the Saussurea laniceps Endophytic Fungus Didymella glomerata X223

One new naphthalenone, didymelol A, and three new naphthols, didymelol B–D, together with three known naphthalenones, (3S,4R)‐3,4,6‐trihydroxy‐3,4‐dihydronaphthalen‐1(2H)‐one, (4S)‐4,6‐dihydroxy‐3,4‐dihydronaphthalen‐1(2H)‐one, (4S)‐4‐hydroxy‐3,4‐dihydronaphthalen‐1(2H)‐one, were isolated from the Saussurea laniceps endophytic fungus Didymella glomerata X223. The structures of the isolates were elucidated based on extensive spectroscopic data analysis. The absolute configuration of didymelol A was established through single‐crystal X‐ray diffraction data and didymelols B–D were identified through comparisons of experimental and calculated ECD spectra. All compounds were evaluated for cytotoxic activity against human non‐small cell lung cancer A549 cells and human breast carcinoma MDA‐MB‐435 cells.     

Synthesis and nootropic activity of some 2,3-dihydro-1H-isoindol-1-one derivatives structurally related with piracetam

Three 2,3‐dihydro‐1H‐isoindol‐1‐ones structurally related with piracetam (=2‐oxopyrrolidine‐1‐acetamide) have been synthesized and tested for their nootropic effects in the passive avoidance test in mice. Compounds (RS)‐ 2 , (R,R)‐ 3 , and (R,S)‐ 3 were obtained in good yields in only two steps starting from methyl dl ‐phthaloylalanine. Compound (RS)‐ 2 exhibited nootropic activity at lower doses than piracetam, used as reference drug, but it showed lower efficacy. Whereas diastereoisomers (R,R)‐ 3 and (R,S)‐ 3 were as potent as piracetam to revert amnesia induced by scopolamine, (R,S)‐ 3 showed lower efficacy than (R,R)‐ 3 . Only (R,R)‐ 3 showed myorelaxant effect at doses of 10 and 30 mg/kg; other compounds did not exhibit any anticonvulsant, sedative, myorelaxant, or impaired motor‐coordination effect in mice. These synthesized 2,3‐dihydro‐1H‐isoindol‐1‐one derivatives constitute a new kind of nootropic compounds.     

Oplopane Sesquiterpenes from Ligularia knorringiana and Their Anti‐Complementary Activity

Three new oplopane sesquiterpenes, knorringianalarins D – F ( 1 – 3 , respectively), and five known analogues ( 4 – 8 , respectively), were isolated from the roots and rhizomes of Ligularia knorringiana. The structures of three new compounds were identified as 4‐acetoxy‐11α,12‐epoxy‐2β‐hydroxy‐3β‐(2‐methylbutyryloxy)‐9α‐(4‐methylsenecioyloxy)oplop‐10(14)‐ene ( 1 ), 3β,4‐diacetoxy‐9α‐(4‐acetoxy‐4‐methylsenecioyloxy)‐11α,12‐epoxy‐8α‐(2‐methylbutyryloxy)oplop‐10(14)‐ene ( 2 ), and (1R,5R,6R,7R,9R)‐5,9,11‐trihydroxy‐4,15‐dinoroplop‐10(14)‐en‐3‐one ( 3 ) based on spectroscopic methods including 1D‐ and 2D‐NMR, mass spectrometry, and CD spectroscopy techniques. All compounds were evaluated for their anti‐complementary activity on the classical pathway of the complement system in vitro. Among which, three oplopane sesquiterpenes ( 3 , 7 , and 8 ) exhibited better anti‐complementary effects with CH₅₀ values ranging from 0.33 to 0.89 mm , which are plausible candidates for developing potent anti‐complementary agents.     

Two New Butenolides Produced by an Actinomycete Streptomyces sp.

Two new butenolides, (4S)‐4,10‐dihydroxydodec‐2‐en‐1,4‐olide ( 1 ) and (4S)‐4,8,10‐trihydroxy‐10‐methyldodec‐2‐en‐1,4‐olide ( 2 ), together with three known compounds, MKN‐003B ( 3 ), MKN‐003C ( 4 ), and cyclo(Ala‐Leu) ( 5 ), were isolated from the culture broth of a bacterium of the genus Streptomyces derived from soil environment. The structures of these compounds were elucidated on the basis of spectroscopic analysis. The inhibitory activities of the butenolides against eight pathogenic fungi were evaluated. All of the butenolides showed moderate‐or‐weak antifungal activities in a broth microdilution assay.     

α-Glucosidase Inhibition by Usnic Acid Derivatives

This study investigated a set of new potential antidiabetes agents. Derivatives of usnic acid were designed and synthesized. These analogs and nineteen benzylidene analogs from a previous study were evaluated for enzyme inhibition of α-glucosidase. Analogs synthesized using the Dakin oxidative method displayed stronger activity than the pristine usnic acid (IC₅₀>200 μM). Methyl (2E,3R)-7-acetyl-4,6-dihydroxy-2-(2-methoxy-2-oxoethylidene)-3,5-dimethyl-2,3-dihydro-1-benzofuran-3-carboxylate ( 6b ) and 1,1′-(2,4,6-trihydroxy-5-methyl-1,3-phenylene)di(ethan-1-one) ( 6e ) were more potent than an acarbose positive control (IC₅₀ 93.6±0.49 μM), with IC₅₀ values of 42.6±1.30 and 90.8±0.32 μM, respectively. Most of the compounds synthesized from the benzylidene series displayed promising activity. (9bR)-2,6-Bis[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one ( 1c ), (9bR)-3,7,9-trihydroxy-8,9b-dimethyl-2,6-bis[(2E)-3-phenylprop-2-enoyl]dibenzo[b,d]furan-1(9bH)-one ( 1g ), (9bR)-2-acetyl-6-[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one ( 2d ), (9bR)-2-acetyl-6-[(2E)-3-(3-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one ( 2e ), (6bR)-8-acetyl-3-(4-chlorophenyl)-6,9-dihydroxy-5,6b-dimethyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione ( 3e ), (6bR)-8-acetyl-6,9-dihydroxy-5,6b-dimethyl-3-phenyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione ( 3h ), (6bR)-3-(2-chlorophenyl)-8-[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-6,9-dihydroxy-5,6b-dimethyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione ( 4b ), and (9bR)-6-acetyl-3,7,9-trihydroxy-8,9b-dimethyl-2-[(2E)-3-phenylprop-2-enoyl]dibenzo[b,d]furan-1(9bH)-one ( 5c ) were the most potent α-glucosidase enzyme inhibitors, with IC₅₀ values of 7.0±0.24, 15.5±0.49, 7.5±0.92, 10.9±0.56, 1.5±0.62, 15.3±0.54, 19.0±1.00, and 12.3±0.53 μM, respectively.     

Iridoids from Pedicularis verticillata and Their Anti‐Complementary Activity

Three new iridoids named as pediverticilatasin A – C ( 1 – 3 , resp.), together with five known iridoids ( 4 – 8 , resp.) were isolated from the whole plants of Pedicularis verticillata. The structures of three new compounds were identified as (1S,7R)‐1‐ethoxy‐1,5,6,7‐tetrahydro‐7‐hydroxy‐7‐methylcyclopenta[c]pyran‐4(3H)‐one ( 1 ), (1S,4aS,7R,7aS)‐1‐ethoxy‐1,4a,5,6,7,7a‐hexahydro‐7‐hydroxy‐7‐methylcyclopenta[c]pyran‐4‐carboxylic acid ( 2 ), (1S,4aS,7R,7aS)‐1‐ethoxy‐1,4a,5,6,7,7a‐hexahydro‐7‐hydroxy‐7‐methylcyclopenta[c]pyran‐4‐carbaldehyde ( 3 ). Their structures were elucidated on the basis of spectroscopic methods and compared with the NMR spectra data in the literature. All compounds were evaluated for their anti‐complementary activity on the classical pathway of the complement system in vitro. Among which, compounds 1 , 3 , and 6 exhibited anti‐complementary effects with CH₅₀ values ranging from 0.43 to 1.72 mm , which are plausible candidates for developing potent anti‐complementary agents.