Minor Hydroxylated Triterpenoids Produced in Engineered Yeast by the Enzymes OSC and CYP716s from the Plant Enkianthus chinensis and Their Anti-Inflammatory and Hepatoprotective Activities.

Triterpenoids are a type of specialized metabolites that exhibit a wide range of biological activities. However, the availability of some minor triterpenoids in nature is limited, which has hindered our understanding of their pharmacological potential. To overcome this limitation, heterologous biosynthesis of triterpenoids in yeast has emerged as a promising and time-efficient production platform for obtaining these minor compounds. In this study, we analyzed the transcriptomic data of Enkianthus chinensis to identify one oxidosqualene cyclase (EcOSC) gene and four CYP716s. Through heterologous expression of these genes in yeast, nine natural pentacyclic triterpenoids, including three skeleton products (1-3) produced by one multifunctional OSC and six minor oxidation products (4-9) catalyzed by CYP716s, were obtained. Of note, we discovered that CYP716E60 could oxidize ursane-type and oleanane-type triterpenoids to produce 6ß-OH derivatives, marking the first confirmed C-6ß hydroxylation in an ursuane-type triterpenoid. Compound 9 showed moderate inhibitory activity against NO production and dose-dependently reduced IL-1ß and IL-6 production at the transcriptional and protein levels. Compounds 1, 2, 8, and 9 exhibited moderate hepatoprotective activity with the survival rates of HepG2 cells from 61% to 68% at 10 µM.

Diverse prenylated C6-C3 derivatives from the stems and branches of Illicium ternstroemioides A. C. Smith with anti-inflammatory and antiviral activities.

Fifteen unreported prenylated C6-C3 derivatives (1-15) were isolated from the stems and branches of Illicium ternstroemioides A. C. Smith, including one bis-prenylated C6-C3 derivative (1), three prenylated C6-C3 derivative-shikimic acid ester hybrids (2-4) and 11 prenylated C6-C3 monomers (5-15). The structures of compounds 1-15 were elucidated by spectroscopic analysis (UV, IR, 1D and 2D NMR, and HRESIMS). The absolute configurations of the compounds were determined using electronic circular dichroism (ECD), induced circular dichroism (ICD), and the modified Mosher's method. Among the isolates, compounds 11, 12, and 15 exhibited significant anti-inflammatory activities by inhibiting the nitric oxide with IC50 values ranging from 1.89 to 24.83 µM in lipopolysaccharide-stimulated murine RAW 264.7 macrophages and murine BV2 microglial cells; compounds 2, 3, and 7 exhibited antiviral activitives against Coxsackievirus B3 with an IC50 value of 33.3, 25.9, and 27.8 µM, respectively.

Minor terpenoids from the leaves of Craibiodendron yunnanense.

One new taraxastane-type triterpenoid, three new grayanane-type diterpenoids (2 - 4), and 12 known compounds (5 - 16) were isolated from the leaves of Craiobiodendron yunnanens W. W. Smith. The structures of these compounds were elucidated on the basis of their spectroscopic data and chemical evidence. Compounds 1 and 8 exhibited partly anti-inflammatory activity based on the inhibition of NF-κB activity in SW480 cells at 10 µM with inhibition ratios of 60.53 and 59.20%, respectively. Compounds 10 and 13 showed excellent cytotoxicity against human leukemia cell (MV4-11) at 10 µM with inhibition ratios of 43.02 and 49.11%, respectively.

Minor terpenoids from the stems and twigs of Rhododendron ovatum.

Four minor undescribed terpenoids, including a monoterpenoid (1) and three triterpenoids (3, 6 and 7), together with 26 known terpenoids were isolated from the stems and twigs of Rhododendron Ovatum. Their structures were identified by extensive spectroscopic analyses and electronic circular dichroism (ECD) techniques. Compound 10 showed excellent cytotoxicity against human colon cancer cell (HCT-116) with IC50 value of 2.56 µM. Compounds 9 and 19 exhibited partly inhibitory effects on nitric oxide production stimulated by lipopolysaccharide-induced neuroinflammation in microglia cells at 10 µM with inhibition ratios of 39.70% and 28.08%, respectively.

Oxygenated pentacyclic triterpenoids from the stems and branches of Enkianthus chinensis.

Thirty new pentacyclic triterpenoids, including five oleanane-type (1-5), twenty-three ursane-type (9-23, 26-33) and two taraxerane-type (24 and 25), along with fourteen known triterpenoids, were isolated from the stems and branches of Enkianthus chinensis. Their structures were elucidated by extensive spectroscopic analyses, X-ray crystallographic data and electronic circular dichroism (ECD) techniques. Sixteen compounds (1-5, 9-13, 20, 22, 32, 34-36) bearing a gem-hydroxymethyl group at C-4 represent rare examples of pentacyclic triterpenoids. In the in vitro biological activity evaluation, compounds 8, 9, 12-14, 17, 24, and 44 exhibited potent hepatoprotective effects at 10 µM. Moreover, compound 25 showed latent activity against HSV-1 with an IC50 value of 6.4 µM.

New hexalactone derivatives and a pair of new oxaspiro-carbon epimeric glycosides from the fruits of Illicium lanceolatum.

Five new compounds (1-5), including three hexalactone derivatives (1-3) and a pair of new oxaspiro-carbon epimeric glycosides (4 and 5), and six known compounds (6-11) were obtained from the fruits of Illicium lanceolatum. The structures of the new compounds were elucidated using extensive spectroscopic data. The absolute configurations of compounds 1-3 were determined by an analysis of their CD spectra. It was determined that compounds 4 and 5, which are epimeric at C-5, possess the same 1-oxaspiro[4,5]decane-7α,8α,9ß-triol moiety. Plausible biogenetic pathways for 4 and 5 derived from the key precursor shikimic acid were proposed. Compounds 1-11 were all assayed on monosodium glutamate-induced human neuroblastoma SH-SY5Y cell damage. The results demonstrated that compounds 4, 5, and 8-10 possess potential neuroprotective effects. The anti-inflammatory, antiviral, and cytotoxic activities of 1-11 were also evaluated.

Two azafluoranthene alkaloids and a phytoecdysone from the stems of Cyclea barbata.

Two new azafluoranthene alkaloids (1 and 2), and a new phytoecdysone (3), were isolated from the stems of Cyclea barbata Miers, together with six known compounds (4-9). Their structures were elucidated by spectroscopic data analysis and comparison with published data. This is the first report of azafluoranthene alkaloids (1 and 2) and phytoecdysones (3, 8, and 9) from Cyclea genus. In in vitro bioassay, four isolates (3, 5, 6, and 9) showed moderate hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced toxicity in HepG2 cells.

Bioactive megastigmane glucosides and monoterpenes from Lyonia ovalifolia.

Three new megastigmane glucosides (1-3) and two new monoterpenes (4-5), together with 14 related known compounds (6-19) were isolated from the twigs and leaves of Lyonia ovalifolia. The structures of the new compounds were determined by extensive MS, NMR, CD experiments and chemical methods. Compounds 2, 6, and 18 displayed potent antiviral activity against Coxsackie B3, with IC50 values between 6.4 and 14.6 µM. Additionally, compounds 6, 10, and 11 exhibited noteworthy anti-inflammatory activities, with inhibition rates ranging from 54.55% to 83.33% under the concentration of 10-5 M.

New C-2 diastereomers of flavanone glycosides conjugated with 3-hydroxy-3-methylglutaric acid from the pericarp of Citrus grandis (L.) Osbeck.

Two new 3-hydroxy-3-methylglutaryl (HMG) flavanone 7-O-diglycosides, cigranosides A and B (1 and 2), the known naringenin 7-(2''-α-rhamnosyl-6''-(3''''-hydroxy-3''''-methylglutaryl)-glucoside (melitidin, 3), their common biosynthetic precursor flavanone 7-O-diglycoside (naringin, 4), and one known flavone 7-O-diglycoside (rhoifolin, 5) were isolated from the pericarp of Citrus grandis (L.) Osbeck. The structures of these compounds were elucidated by spectroscopic and chemical techniques. The relative ratios and absolute configurations of the C-2 diastereomers of compounds 1, 2 and 4 were determined by online normal-phase HPLC-CD using a Chiralcel column. The absolute configuration of the HMG fragment in compounds 1-3 was assigned to be S through spectroscopic analysis of the mevalonamide obtained by amidation and reduction of the HMG moiety. The NO inhibitory activities of compounds 1-5 were evaluated using lipopolysaccharide-induced RAW264.7 cells. Compounds 1-5 were not cytotoxic to RAW264.7 cells at 10 µM.

A novel and practical synthesis of CAT3: a phenanthroindolizidine alkaloid with potential in treating glioblastoma.

CAT3, one of the (+)-deoxytylophorinine-based phenanthroindolizidine alkaloids, is a promising therapeutic agent for the treatment of hedgehog (Hh)-driven glioblastoma and is currently being evaluated in preclinical studies. In this paper, a novel and practical synthetic route for CAT3 was firstly demonstrated with 10% overall yield in 11 steps and has been successfully validated for pilot-plant scale preparation. Investigation of the substitution at the 3-position of phenanthrene revealed that the electron-donating functionality can well preserve the S configuration. In particular, the excellent enantiomeric excess of CAT3 (≥99% ee) was achieved by introducing the strongly electron-donating tert-butyldimethylsilyl (TBS) group.

Pierisketolide A and Pierisketones B and C, Three Diterpenes with an Unusual Carbon Skeleton from the Roots of Pieris formosa.

Pierisketolide A (1) and pierisketones B and C (2 and 3), three diterpenes with an unusual A-homo-B-nor-ent-kaurane carbon skeleton, were isolated from the roots of Pieris formosa. Their structures were characterized by a series of spectroscopic methods, X-ray diffraction, and electronic circular dichroism (ECD). Pierisketolide A (1) exhibited an analgesic effect with a 45% writhe inhibition rate at a dose of 10.0 mg/kg. The plausible biosynthetic pathways of 1-3 are proposed.

Artaboterpenoids A and B, Bisabolene-Derived Sesquiterpenoids from Artabotrys hexapetalus.

Artaboterpenoids A and B (1 and 2), two novel bisabolene-derived sesquiterpenoids, were isolated from the roots of Artabotrys hexapetalus. Their structures with absolute configurations were elucidated by spectroscopic methods, and electronic circular dichroism (ECD) analyses. Notably, 1 featured a novel carbon skeleton with a new C-2-C-10 linkage, and 2a and 2b, a pair of enantiomers, represented the first examples of 1,2-seco-bisabolene-type sesquiterpene lactones. 2a exhibited cytotoxic effects against HCT-116, HepG2, A2780, NCI-H1650, and BGC-823 cell lines with IC50 values of 1.38-8.19 µM. Plausible biogenetic pathways for artaboterpenoids A and B were proposed.

A new thiophene and two new monoterpenoids from Xanthium sibiricum.

Three new compounds (1-3), together with six known compounds (4-9), were isolated from the fruits of Xanthium sibiricum. The structures and the absolute configurations of sibiricumthionol (1), (+)-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [(+)-2], ( - )-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [( - )-2], (2E,4E,1'S, 2'R, 4'S, 6'R)-dihydrophaseic acid (3), (+)-xanthienopyran [(+)-4] and ( - )-xanthienopyran [( - )-4] were established by extensive spectroscopic analyses, X-ray crystallographic analysis, ECCD analysis and ECD calculations. Caffeic acid (7) and caffeic acid ethyl ester (8) weekly inhibited α-glucosidase enzymatic activity by 44.5% and 40.2%, respectively, at 40 µM. Protocatechuic acid (9) selectively exhibited cytotoxicity against HepG2 cell lines, with an IC50 value of 2.92 µM.

Bioactive Sesquiterpenes and Lignans from the Fruits of Xanthium sibiricum.

Seven new sesquiterpenes (1, 3-8), a new sesquiterpene natural product (2), and two new lignans (9 and 10), together with 15 known compounds, were isolated from the fruits of Xanthium sibiricum. The structures of the new compounds were established by NMR spectroscopic analysis, ECD calculations, and Mo2(OAc)4-induced circular dichroism, with the structures of 1 and 4 confirmed by single-crystal X-ray diffraction. Compound 1 is the first example of a 3/5/6/5 tetracyclic eudesmane sesquiterpene lactone formed at C-6 and C-7. In turn, compound 4 is the first example of a natural xanthane tetranorsesquiterpene, while compounds 5-8 are the first xanthane trinorsesquiterpenes found to date. Compounds 8, 11-15, 17, and 24 exhibited indirect anti-inflammatory activity by suppressing the lipopolysaccharide-induced proinflammatory factors in BV2 microglial cells, with IC50 values between 1.6 and 8.5 µM. Furthermore, compounds 13 and 17 exhibited anti-inflammatory activity against ear edema in mice produced by croton oil, with inhibition rates of 46.9% and 37.7%, respectively. Compounds 8, 11, 12, 23, and 24 exhibited potent activity against influenza A virus (A/FM/1/47, H1N1) with IC50 values between 3.7 and 8.4 µM.

[Chemical constituents from stems of Brucea mollis and their cytotoxic activity].

Ten compounds were isolated from the stems of Brucea mollis by various chromatographic techniques such as column chromatography on silica gel and Sephadex LH-20, and preparative HPLC, and their structures were elucidated as deacetylated isobrucein B (1), indaquassin X (2), cleomiscosin A (3), cleomiscosin B (4), (+)-lyoniresinol (5), (+)-epipinoresinol(6), (+)-pinoresinol (7), (+)-syringaresinol (8), 4,5-dihydroblumenol A (9) and adenosine (10) on the basis of spectroscopic data analysiS. All compounds were obtained from this plant for the first time, moreover, compound 1 was a new natural product. Compound 2 showed significant cytotoxic activities against the human cell lines HT-29, HepG2, BGC-823 and SKOV3 with IC50 values of 0.84-3.97 micromol x L(-1).

Novel sesquiterpenoid glycosides and sesquiterpenes from the roots of Illicium henryi.

Seven new sesquiterpenoid glycosides, consisting of one thapsan-type (1), two capnellane-type (2 and 3), four floridanolide sesquiterpene glycosides (4-7), and one new azulene-type sesquiterpene (8), along with six known sesquiterpenes (9-14) were isolated from the roots of Illicium henryi. The structures of 1-8 were elucidated by extensive spectroscopic analyses and chemical methods. The absolute configurations of 1, 2, and 8 were determined based on Rh2(OCOCF3)4-induced CD, Mo2(OAc)4-induced CD data, and calculated electronic circular dichroism (ECD), respectively. Compound 1 was found to exhibit weak neurotoxicant activity.

Sesquiterpenes and alkaloids from the roots of Alangium chinense.

Four new sesquiterpenes (1-4), four new alkaloids (5a, 6a, 6b, and 7), and nine known compounds (5b and 8-15) were isolated from an ethanolic extract of roots of Alangium chinense. The structure of 1 was confirmed by X-ray crystallography. The configurations of 5 and 6 were assigned by chiral HPLC analysis and CD spectra. Compounds 3, 4, 8-13, and 15 exhibited antiviral activity against Coxsackie virus B3 with IC50 values of 1.4-15.4 µM. Compounds 2-4, 7, and 9-13 showed antioxidant activities against Fe(2+)-cysteine-induced rat liver microsomal lipid peroxidation, with IC50 values of 3.8-45.7 µM. Compound 5b displayed neuritis inhibitory activity against microglial inflammation factor, with an IC50 value of 6.7 µM. None of the compounds exhibited detectable cytotoxic activity toward any of five tumor cell lines (A549, Be-17402, BGC-823, HCT-8, and A2780) in the MTT assay.

Tirucallane triterpenoids from the stems of Brucea mollis.

Three new tirucallane triterpenoids, brumollisols A-C (1-3, resp.), together with five known analogues, (23R,24S)-23,24,25-trihydroxytirucall-7-ene-3,6-dione (4), piscidinol A (5), 24-epipiscidinol A (6), 21α-methylmelianodiol (7), and 21ß-methylmelianodiol (8), were isolated from an EtOH extract of the stems of Brucea mollis. Their structures were elucidated by means of spectroscopic methods including 1D- and 2D-NMR techniques and mass spectrometry. In the in vitro assays, compound 6 exhibited significant cytotoxic activity against A549 and BGC-823 cancer cells with IC50 values of 1.16 and 3.01 µM, respectively. At a concentration of 10 µM, compounds 1-5, 7, and 8 were found to inhibit NO production in mouse peritoneal macrophages with inhibitory ratios ranging from 39.8±7.7 to 68.2±4.5%.

Diterpenoids and sesquiterpenoids from the twigs and leaves of Illicium majus.

Four new abietane diterpenes (1-4) and two new cycloparvifloralone-type sesquiterpenoids (5-6) have been isolated from the twigs and leaves of Illicium majus, together with three known sesquiterpenoids and five known diterpenoids. Their structures were determined by spectroscopic analysis and chemical methods. The absolute configuration of the 15,16-diol moiety in 2 is confirmed by Snatzke's method, observing the induced circular dichroism after the addition of dimolybdenum tetraacetate in DMSO. Compound 2 exihibited significant anti-inflammatory activity with an IC50 value of 0.26 ± 0.03 µM, while compounds 10, 11, and 13 showed good anti-inflammatory activities with IC50 values ranging from 1.94 ± 0.56 to 2.60 ± 0.48 µM.

Sesquiterpenes and neolignans from the roots of Illicium dunnianum.

Two new sesquiterpenes, dunnianoside I (1) and 8'-oxo-6-hydroxy-dihydrophaseic acid methyl ester (2), a new glycoside, dunnianoside J (3), two new neolignans, dunnianeolignans A-B (4, 5), together with 10 known compounds (6-15), were isolated from the roots of Illicium dunnianum. The structures of these new compounds were elucidated by spectroscopic methods including 1D and 2D NMR, HR-ESI-MS, and chemical methods. Compounds 7, 8, and 13-15 exhibited potent antioxidant activities against Fe²âº-cystine-induced rat liver microsomal lipid peroxidation, with IC50 values ranging from 4.2 ± 0.4 to 38.4 ± 2.6 µM.