Quantitative 1H NMR with global spectral deconvolution approach for quality assessment of natural and cultured Cordyceps sinensis.

Cordyceps sinensis is a precious medicinal food which has been successfully cultivated indoors. It remains to be investigated for a simultaneous comparison on aqueous components of natural and cultivated samples. Herein, an approach of quantitative nuclear magnetic resonance (qNMR) analysis combined with global spectral deconvolution (GSD) was established for simultaneous quantification of 26 aqueous components in C. sinensis. Processed by GSD, the distorted baselines of 1H NMR spectra were greatly improved, and overlapped signals were also well separated so as to achieve accurate identification and quantitation of components in C. sinensis. Method validation by UHPLC-QTOF-MS and TOF-SIMS analysis revealed that qNMR combined with GSD is a reliable approach for simultaneous quantification of multiple components including characteristic markers of glutamine, GABA and trehalose in authentic and fake C. sinensis. The well-established qNMR approach can be used for quality assessment of natural and cultivated C. sinensis as well as differentiation from fake ones.

Discrimination of Baphicacanthis Cusiae Rhizoma et radix and its adulterant species and establishment of an assay method for quality control.

BACKGROUND: Baphicacanthis Cusiae Rhizoma et Radix, commonly known as Nan-Ban-Lan-Gen (NBLG), is an essential traditional Chinese medicine that possesses diverse bioactivities, particularly noteworthy for its antiviral properties. Although NBLG has been listed in the Chinese Pharmacopoeia as an independent Chinese medicine, the establishment of a comprehensive quality standard for NBLG remains elusive. The absence of assay for marker compound in its quality standards has led to the lack of corresponding quality control measures for NBLG-containing preparations, and its discrimination from adulterant species in the market which thereby can significantly impact the efficacy and safety of NBLG-containing products. METHODS: Ultra-high performance liquid chromatography (UHPLC) coupled with quadrupole-time-of-flight mass spectrometry (Q-TOF-MS) was employed for comprehensive profiling of the chemical constituents of NBLG, the stem of Baphicacanthus cusia (Nees) Bremek (NBLJ), and the roots of Isatis indigotica Fort. (Bei-Ban-Lan-Gen, BBLG). Additionally, multivariate analysis was conducted to compare the chemical components of NBLG with those of NBLJ and BBLG. Furthermore, we established an optimized and validated HPLC method to obtain the fingerprint of NBLG and quantify the content of 2-benzoxazolinone and acteoside in the samples. RESULTS: A total of 73 compounds belonging to six classes were assigned in NBLG, with alkaloids being the most abundant and diverse species. High compositional similarities with significant differences in content were observed between NBLG and NBLJ. Moreover, the chemical profile of BBLG markedly differed from that of NBLG. An informative high performance liquid chromatography (HPLC) fingerprint of NBLG comprising seven characteristic peaks that can be used for quality assessment was established. Notably, we propose a quality control standard for NBLG, stipulating that the limit of content in dry weight for both 2-benzoxazolinone and acteoside should not be less than 0.010%. CONCLUSION: This study provides the most comprehensive chemical information to date on NBLG, offering valuable insights into its authentication and quality control. Our findings highlight the importance of comprehensive chemical profiling to differentiate potential substitutions and adulterations of herbal medicines, particularly when the original source is scarce or unavailable. These results can aid in the development of quality control measures for NBLG-containing preparations, ensuring their safety and efficacy.

Bioassay-Guided Isolation of Anthelmintic Components from Semen pharbitidis, and the Mechanism of Action of Pharbitin.

Parasitic helminths continue to pose problems in human and veterinary medicine, as well as in agriculture. Semen pharbitidis, the seeds of Pharbitis nil (Linn.) Choisy (Convolvulaceae), is a well-known traditional Chinese medicinal botanical preparation widely used for treating intestinal parasites in China owing to its desirable efficacy. However, the anthelmintic compounds in Semen pharbitidis and their mechanism of action have not been investigated yet. This study aimed to identify the compounds active against helminths from Semen pharbitidis, and to establish the mechanism of action of these active compounds. Bioassay-guided fractionation was used to identify the anthelmintic compounds from Semen pharbitidis. The anthelmintic assay was performed by monitoring Caenorhabditis elegans (C. elegans) motility with a WMicrotracker instrument. Active compounds were identified by high-resolution mass spectrometry. Several (analogues of) fragments of the anthelmintic compounds were purchased and tested to explore the structure-activity relationship, and to find more potent compounds. A panel of C. elegans mutant strains resistant to major currently used anthelmintic drugs was used to explore the mechanism of action of the active compounds. The bioassay-guided isolation from an ethanol extract of Semen pharbitidis led to a group of glycosides, namely pharbitin (IC50: 41.0 ± 9.4 µg/mL). Hit expansion for pharbitin fragments yielded two potent analogues: 2-bromohexadecanoic acid (IC50: 1.6 ± 0.7 µM) and myristoleic acid (IC50: 35.2 ± 7.6 µM). One drug-resistant mutant ZZ37 unc-63 (x37) demonstrated a ~17-fold increased resistance to pharbitin compared with wild-type worms. Collectively, we provide further experimental scientific evidence to support the traditional use of Semen pharbitidis for the treatment of intestinal parasites. The anthelmintic activity of Semen pharbitidis is due to pharbitin, whose target could be UNC-63 in C. elegans.

Structures, biomimetic synthesis, and anti-SARS-CoV-2 activity of two pairs of enantiomeric phenylpropanoid-conjugated protoberberine alkaloids from the rhizomes of Corydalis decumbens.

(±)-Decumicorine A (1) and (±)-epi-decumicorine A (2), two pairs of enantiomeric isoquinoline alkaloids featuring a novel phenylpropanoid-conjugated protoberberine skeleton, were isolated and purified from the rhizomes of Corydalis decumbens. The separation of (±)-1 and (±)-2 was achieved by chiral HPLC to produce four optically pure enantiomers. The structures and absolute configurations of compounds (-)-1, (+)-1, (-)-2, and (+)-2 were elucidated by spectroscopic analysis, ECD calculations, and X-ray crystallographic analyses. The two racemates were generated from a Diels-Alder [4 + 2] cycloaddition between jatrorrhizine and ferulic acid in the proposed biosynthetic pathways, which were fully verified by a biomimetic synthesis. Moreover, compound (+)-1 exhibited an antiviral entry effect on SARS-CoV-2 pseudovirus by blocking spike binding to the ACE2 receptor on HEK-293T-ACE2h host cells.

Antiperspirant effects and mechanism investigation of Mulisan decoction in rats based on plasma metabolomics.

CONTEXT: Mulisan decoction (MLS) is a classic formula of traditional Chinese medicine for treating hyperhidrosis. The mechanism remains unclear. OBJECTIVE: To investigate the antiperspirant effect and underlying mechanisms of MLS. MATERIALS AND METHODS: Fifty rats were divided into control, model, and three doses of MLS intervention groups (n = 10). Rats except for control group were induced diseases features of the applicable scope of MLS via i.p. reserpine (0.5 mg/kg/d) for 10 days. From day 11, MLS groups were administrated orally MLS at 0.6, 3, and 15 g/kg once a day for 14 days, respectively. After the last administration, sweating was induced in all rats via s.c. pilocarpine (25 mg/kg), the right hind foot of rats was stained, and sweat point numbers were observed. Rat serum was collected to detect IL-2, IL-6, IFN-γ, and TNF-α. Rat plasma was collected for endogenous metabolite analysis via UPLC-QE-Focus-MS. RESULTS: Rats treated with MLS presented a significant decrease in sweat point numbers (13.5%), increase in body weight (13.2%), and promotion in the balance of Th1/Th2 cytokine ratio via increasing IL-2 (38.3%), IFN-γ (20.1%), and TNF-α (22.0%) and decreasing IL-6 (24.7%) compared with the model group (p < 0.05). Plasma metabolomics disclosed 15 potential biomarkers related to model rats, of which two could be significantly reversed by MLS (p < 0.05). The involved pathways were pantothenate and CoA biosynthesis, and porphyrin metabolism. CONCLUSIONS: MLS demonstrated a good antiperspirant effect and metabolism improvement. These findings inspire more clinical study validation on immune improvement and antiperspirant effect.

In situ Chemical Profiling and Imaging of Cultured and Natural Cordyceps sinensis by TOF-SIMS.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a sensitive surface analytical technology, which can simultaneously acquire diverse chemical components and their precise locations on the surfaces of samples without any requirements for chemical damage pretreatments or additional matrices. Commonly, the quality control of TCMs (traditional Chinese medicines) is limited by the qualitative and quantitative evaluations of the specifically extractive constituents. In this study, a practical sample preparation strategy named two-layered media embedding sample preparation was developed to obtain ideal freezing sections of dried materials of Cordyceps sinensis. Meanwhile, the well-established sample preparation method was applied for in situ chemical profiling and imaging of natural (NCS) and cultured Cordyceps sinensis (CCS) by using TOF-SIMS. More than 200 components were tentatively identified and imaged in NCS and CCS at the same time. Mass spectrometry imaging revealed that most components have even distributions in caterpillars of Cordyceps sinensis, while TAGs, DAGs, MAGs, and FAs only have distributions outside caterpillars' digestive chambers. This is the first time that components were in situ imaged for Cordyceps sinensis to exhibit the chemical distributions which have never been achieved by other analytical techniques so far. In addition, chemometrics was used to simplify and explain the massive TOF-SIMS mass data sets, which revealed the high chemical similarity between CCS and NCS. Furthermore, the relative quantification of TOF-SIMS data showed that CCS has comparable proportions of amino acids, nucleosides, monosaccharides, sphingolipids, sterols and other principles to NCS except for fatty acids, glycerides and glycerophospholipids. The higher amounts of TAGs and DAGs in CCS were confirmed by quantitative 1H-NMR, indicating reliable relative quantification of TOF-SIMS. In general, our research developed a novel approach of TOF-SIMS for in situ chemical analysis of TCMs, and its successful application in comparative study of CCS and NCS suggested that TOF-SIMS is an advanced and promising analytical technology for the research of TCMs.

The localization of the alkaloids in Coptis chinensis rhizome by time-of-flight secondary ion mass spectrometry.

Background: Understanding the spatial distribution of active compounds can effectively evaluate the quality of decoction pieces of traditional Chinese medicine (TCM). Traditional methods are economical and practical but lack chemical information on the original distribution. Time-of-flight secondary ion mass spectrometry (TOF-SIMS), with the advantage of non-destructive detection of samples, can directly analyze the distribution of chemical compounds on the surface of various samples. Methods: In this study, TOF-SIMS image analysis technology was used to detect TCM for the first time. Taking Coptis rhizome (CR) as an example, a commonly used TCM, the distribution of the compounds in the cross-section of CR was studied. Meanwhile, ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLCQQQ-MS/MS) was used to verify the results of TOF-SIMS. Results: The distribution of nine active compounds: berberine, epiberberine, coptisine, palmatine, columbamine, jatrorrhizine, tetrahydricheilanthifolinium, and oxyberberine, was well imaged in the cross-section of CR by TOF-SIMS. The content of berberine and epiberberine was the highest; Palmatine distribution in the pith was more than that in other parts; Oxyberberine was mainly concentrated in the cork and xylem rays. Normalization analysis showed contents of these compounds increased along with the growth years. The result was consistent with UPLC-QQQ-MS/MS. Conclusion: The TOF-SIMS method can display the spatial distribution status of the active compounds of herbs, providing a basis for selecting the medicine site with non-destructive and fast detection.

Amide Derivatives of Ginkgolide B and Their Inhibitory Effects on PAF-Induced Platelet Aggregation.

Ginkgolides are the most important components of Ginkgo biloba extracts, whose lactone can be hydrolyzed in the aqueous environment. Although the hydrolyzed products have complex structures and their functions are not well-understood, opening the lactone ring is an important strategy in producing novel derivatives of ginkgolide. The preparation of a single pure aminolyzed ginkgolide for the study of its bioactivity and understanding of the process of aminolysis are challenging. To obtain stable aminolyzed products, four amide derivatives (2-5) of ginkgolide B (GB, 1) were prepared via the ring-opening reaction of its lactone with propylamine. These products were purified and fully identified by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) spectroscopy and were further evaluated for their ability to inhibit the PAF-induced platelet aggregation of rabbit platelets in vitro. Compound 2, which was obtained by selective aminolysis of the lactone ring C of GB, showed a much better inhibitory activity of platelet aggregation (IC50, 15 nM) than the parent compound GB (IC50, 442 nM). The other three products (3-5), which were obtained by the aminolysis of lactone rings C and F of GB, did not show platelet aggregation inhibitory activity. The results greatly extended our understanding of the chemistry of GB and provided important structural information for the exploration and development of new drugs based on ginkgolides in G. biloba.

Comprehensive chemical study on different organs of cultivated and wild Sarcandra glabra using ultra-high performance liquid chromatography time-of-flight mass spectrometry (UHPLC-TOF-MS).

To illuminate the similarities and differences between wild and cultivated Sarcandra glabra (S. glabra), we performed a comprehensively study on 26 batches of cultivated S. glabra and 2 batches of wild S. glabra. Chemical constituents and distribution characteristics of roots, stems and leaves in both wild and cultivated S. glabra were investigated through UHPLC-TOF-MS method. The result revealed that there were significant differences between roots, stems and leaves in S. glabra. And the chemical contents in the root part were less or even absence than those in leaf and stem, which suggested the root organ could be excluded as medicine. Meanwhile, the chemical contents of stems and leaves in cultivated S. glabra was sightly higher than that of wild samples. Therefore, cultivated S. glabra may have a high potential for substitution of wild S. glabra without affecting its pharmaceutical properties. In summary, our study could provide important information to the molecular basis for quality control of S. glabra.

Identification of blood-red color formation in edible bird's nests provides a new strategy for safety control.

In order to reveal the color formation mechanism of blood-red edible bird's nests (EBNs) and develop a quick and specific strategy to distinguish the artificial fake one, multiple methods of UPLC-TOF/MS, UV, NMR, FT-IR and 2D IR were used to detect the chemical markers of the reddening reaction, the results showed that the reddening substances were C9H10N2O5 and C9H9NO6, which were verified as products of a phenol-keto tautomerism evolved from l-tyrosine. Moreover, natural and artificial red EBNs with varying degrees of chemical fumigation also can be successfully distinguished using the chemical markers, and the protein variation in SDS-PAGE gel could also support the distinction. This work established a systematic method of chemical identification for both natural and artificial blood-red EBNs, and provided a new identification strategy for food safety control that can promote the development of a healthier market of EBNs.

Isolation of Antimicrobial Compounds From Cnestis ferruginea Vahl ex. DC (Connaraceae) Leaves Through Bioassay-Guided Fractionation.

Different parts of Cnestis ferruginea are used in traditional African medicine for treating infectious diseases such as dysentery, bronchitis, eye troubles, conjunctivitis, sinusitis, gonorrhea, and syphilis. Despite its long traditional use in the treatment of infections, this plant is not well studied for its in vitro antimicrobial properties. Therefore, the present study aims to establish the antimicrobial activity profile of extracts from this plant, as well as to isolate and evaluate the antimicrobial activity of the most abundant bioactive compound in C. ferruginea leaves through bioassay-guided purification, using Staphylococcus aureus as a target organism. Although both methanol and water extracts of the plant leaves proved active against S. aureus, a water extract was pursued, and subjected further to liquid-liquid partitioning (ethyl acetate, butanol, and water). The ethyl acetate fraction was found to be the most potent and was subjected to silica gel chromatography. In total, 250 fractions were obtained, and those with similar TLC profiles were clustered into 22 major groups, of which pooled fraction-F6 (83 mg) was the most potent. Additional purification by HPLC resulted in two active peaks, which were identified, using a combination of NMR and mass spectrometry, as hydroquinone and caffeic acid methyl ester. Their antimicrobial activity was confirmed using a microdilution protocol on S. aureus, where hydroquinone had a stronger activity (MIC50 = 63 µg/mL) compared to caffeic acid methyl ester (>200 µg/mL). Traditionally this plant is used as an aqueous preparation to treat many infections, and the present study also demonstrated antimicrobial activity in the aqueous extract, which appears due mainly to two major water-soluble compounds isolated through bioassay-guided purification. This supports the clinical use of the aqueous extract of C. ferruginea leaves as a phytotherapeutic for bacterial infections.

Bioassay-guided isolation of anti-seizure principles from Semen Pharbitidis using a zebrafish pentylenetetrazol seizure model.

ETHNOPHARMACOLOGICAL RELEVANCE: Semen Pharbitidis, the seeds of Pharbitis nil (Linn.) Choisy (Convolvulaceae) is a well-known traditional Chinese medicinal plant used for treating helminthiasis and epilepsy in China. AIM OF THE STUDY: This study aims to identify the anti-seizure components from Semen Pharbitidis. METHODS: A bioassay-guided isolation of anti-seizure compounds from Semen Pharbitidis was performed using a zebrafish pentylenetetrazol seizure model. The structures of active compounds were elucidated by high resolution mass spectrometry. The fragments of active compounds were tested for anti-seizure activity as well. RESULTS: The bioassay-guided isolation of ethanol extract of Semen Pharbitidis led to a group of resin glucosides, namely pharbitin. One of the fragments of pharbitin, 2-methylbutyric acid, also showed anti-seizure activity. CONCLUSIONS: We provided further experimental scientific evidence to support the traditional use of Semen Pharbitidis for the treatment of epilepsy. Pharbitin was identified to be the main anti-seizure component in Semen Pharbitidis.

Bioassay-guided isolation of active substances from Semen Torreyae identifies two new anthelmintic compounds with novel mechanism of action.

ETHNOPHARMACOLOGICAL RELEVANCE: Semen Torreyae, the seeds of Torreya grandis Fortune ex Lindley (Cephalotaxaceae) is a well-known traditional Chinese medicinal plant recorded in the Chinese Pharmacopeia (2010 version). It is widely used for treating intestinal parasites in China, owing to its desirable efficacy and safety. However, the anthelmintic compounds in Semen Torreyae have not yet been identified. AIM OF THE STUDY: This study aims to identify the compounds active against helminths from Semen Torreyae. In addition, we tested whether C. elegans strains resistant to currently-used anthelmintic drugs showed cross-resistance to these compounds. METHODS: A bioassay-guided isolation of anthelmintic compounds from Semen Torreyae was performed using a Caenorhabditis elegans (C. elegans) testing model. The structures of active compounds were elucidated by a combination of GC-MS, high resolution MS, and NMR. The median-effect method was employed to generate a combination index (CI) to evaluate the synergistic effect of the anthelmintic compounds. A panel of C. elegans mutant strains resistant against the major anthelmintic drug classes was used to study the cross-resistance to currently-used anthelmintic drugs. A panel of transient receptor potential (TRP) channel mutant strains was also tested to explore the possible mechanisms of action of the anthelmintic compounds. RESULTS: The bioassay-guided isolation led to two active compounds, i.e. galangal acetate (IC50: 58.5 ±â€¯8.9 µM) and miogadial (IC50: 25.1 ±â€¯5.4 µM). The combination of galangal acetate and miogadial resulted in a synergistic effect at IC50, IC70, and IC90 levels (CIs < 1). Galangal acetate and miogadial demonstrated similar activity against drug-resistant C. elegans strains compared to the wild-type strain. In addition, none of the TRP mutants was significantly resistant to galangal acetate or miogadial compared to wild type worms. CONCLUSIONS: We identified the bioactive compounds from Semen Torreyae responsible for its anthelmintic activity: galangal acetate and miogadial. The two anthelmintic compounds demonstrated a synergistic effect against C. elegans. Galangal acetate and miogadial are unlikely to act on the targets of currently-used anthelmintics (ivermectin, levamisole, benomyl and aldicarb), and an action on TRP channels appears to be ruled out as well. In summary, galangal acetate and miogadial are promising anthelmintic hits worth further investigation.

Bioassay-Guided Isolation of Anti-Candida Biofilm Compounds From Methanol Extracts of the Aerial Parts of Salvia officinalis (Annaba, Algeria).

Salvia officinalis is frequently used in traditional Algerian medicine to treat diverse microbial infections, including oral and vaginal candidiasis. The aerial parts of S. officinalis collected in Annaba, Algeria were extracted in parallel by maceration with four solvents viz. hexane, acetone, methanol and water. All the extracts were tested in vitro against several Candida species: C. albicans, C. glabrata, and C. parapsilosis. Furthermore, the activity against biofilm-forming C. albicans was investigated using bioassay-guided fractionation. A large-scale extract was prepared via maceration in methanol, followed by fractionation on a silica gel column using increasingly polar mixtures of n-hexane, ethyl acetate, methanol, and acetic acid as mobile phase, to yield a total of 150 fractions. Two major active fractions (F-31 and F-39), were further separated by HPLC, resulting in several active chromatographic peaks. Carnosol and 12-methoxy-trans-carnosic acid were isolated as two major active compounds, and identified by a combination of NMR and mass spectrometry. The biofilm inhibitory concentration showed that 12-methoxy-trans-carnosic acid is more effective than carnosol with BIC50 values of 94 µM (95% confidence interval, 78.9-112.1 µM) and 314 µM (95% confidence interval, 200.7-491.2 µM), respectively. The present study supports the traditional use of sage in the treatment of various fungal infections caused by Candida. Further studies of the bioactive compounds in an in vivo Candida biofilm model are required to validate their clinical potential as antifungals.

Chemical profiling and cytotoxicity assay of bufadienolides in toad venom and toad skin.

ETHNOPHARMACOLOGICAL RELEVANCE: Toad venom and toad skin have been widely used for treating various cancers in China. Bufadienolides are regarded as the main anticancer components of toad venom, but the difference on composition and anticancer activities of bufadienolides between toad venom and toad skin remains unclear. METHODS: Fractions enriched with free and conjugated bufadienolides were prepared from toad venom and toad skin. Bufadienolides in each fraction were comprehensively profiled by using a versatile UHPLC-TOF-MS method. Relative contents of major bufadienolides were determined by using three bufogenins and one bufotoxin as marker compounds with validated UHPLC-TOF-MS method. Furthermore, cytotoxicity of the fractions was examined by MTT assay. RESULTS: Two fractions, i.e., bufogenin and bufotoxin fractions (TV-F and TV-C) were isolated from toad venom, and one bufotoxin fraction (TS-C) was isolated from toad skin. Totally 56 bufadienolides in these three fractions were identified, and 29 were quantified or semi-quantified. Bufotoxins were identified in both toad venom and toad skin, whereas bufogenins exist only in toad venom. Bufalin-3-conjugated bufotoxins are major components in toad venom, whereas cinobufotalin and cinobufagin-3-conjugated bufotoxins are main bufotoxins in toad skin. MTT assay revealed potent cytotoxicity of all the fractions in an order of TV-F>TV-C>TS-C. CONCLUSIONS: Our study represents the most comprehensive investigation on the chemical profiles of toad venom and toad skin from both qualitative and quantitative aspects. Eight bufotoxins were identified in toad skin responsible for the cytotoxicity for the first time. Our research provides valuable chemical evidence for the appropriate processing method, quality control and rational exploration of toad skin and toad venom for the development of anticancer medicines.

Chemical differentiation of two taste variants of Gynostemma pentaphyllum by using UPLC-Q-TOF-MS and HPLC-ELSD.

To differentiate the sweet and bitter taste variants of a Chinese medicinal tea Gynostemma pentaphyllum (GP), a method for the quantitative analysis of ginsenosides Rb(1), Rb(3), Rd, and F(2) in GP by using UPLC-Q-TOF-MS was developed. According to the different contents of the four ginsenosides, chemical differentiation of the two taste variants of GP was achieved by principal component analysis (PCA). A supplementary quantitative analysis method of using HPLC-ELSD for determination of 20(S)-panaxadiol in the hydrolysates of GP was also developed. Similarly, chemical differentiation based on different amounts of 20(S)-panaxadiol was established and the result was well consistent with that based on the analysis of the four ginsenosides. It was found that the amounts of the four ginsenosides and 20(S)-panaxadiol in the sweet taste variant were significantly higher than those in the bitter one. The significant difference between the sweet and bitter taste variants of GP was easily visualized in 3D-PCA score plots. The PCA loading plot also indicated the contributions among the four ginsenosides (Rd > Rb(3) > F(2) > Rb(1)) for distinguishing the two taste variants. This is the first report to describe the use of these two quantitative methods (UPLC-Q-TOF-MS and HPLC-ELSD) for the accurate authentication and quality control of GP.

Immunosuppressive decalin derivatives from red yeast rice.

Five new decalin derivatives (1-5), together with two known compounds (6 and 7), were isolated from the ethyl acetate extract of red yeast rice. Their structures were elucidated by means of NMR and mass spectroscopic analyses. Monascusic lactone A (1) is the first reported naturally occurring decalin derivative possessing a spiro lactone at the C-1 position. The immunosuppressive effects of all these isolates (1-7) on human T cell proliferation were investigated, and all, especially monascusic acids B (2), C (3), D (4), and A (6) and heptaketide (7), suppressed human T cell proliferation in a dose-dependent manner from 10 to 100 µM. This is the first report on the immunosuppressive activity of decalin derivatives.

Cytotoxic dehydromonacolins from red yeast rice.

Two new dehydromonacolins (1 and 3), together with nine known monacolins (4-12), were isolated from red yeast rice. Compounds 4-6 were isolated from a natural resource for the first time. Their structures were elucidated by means of NMR and mass spectroscopic analyses. The structure of dehydromonacolin N (1) was further confirmed by its semisynthesis from monacolin K (lovastatin) (11). Dehydromonacolin J (2), an intermediate in the semisynthesis of 1, was obtained as a new dehydromonacolin. The structure of dehydromonacolin L (3) was also confirmed by an elimination reaction of monacolin L (12). Compound 1, possessing a C2 side chain, is unprecedented in the natural monacolin family and exhibited moderate cytotoxic activity against Hep G2, Caco-2, and MCF-7 cancer cell lines. Dehydromonacolin K (8) demonstrated the most potent cytotoxicity to all three of these cell lines. The structure-activity relationship of natural and synthesized monacolins was discussed. This is the first report on the cytotoxic effects of dehydromonacolins.