Ten cyclopentanoid monoterpenes from the whole plant of Rehmannia piasezkii maxim.

Ten new cyclopentanoid monoterpenes (1-10) were isolated from the whole plant of Rehmannia piasezkii. The structures of these compounds were elucidated based on spectroscopic data analysis. In in-vitro assays, compounds 3, 7, and 9 exhibited weak hepatoprotective activities against APAP-induced HepG2 cell damage. Compound 9 exhibited protective effect on hapassocin carbon tetrachloride model.

[Chemical constituents from leaves of Craibiodendron yunnanense].

The present study investigated the chemical constituents from the leaves of Craibiodendron yunnanense. The compounds were isolated and purified from the leaves of C. yunnanense by a combination of various chromatographic techniques including column chromatography over polyamide, silica gel, Sephadex LH-20, and reversed-phase HPLC. Their structures were identified by extensive spectroscopic analyses including MS and NMR data. As a result, 10 compounds, including melionoside F(1), meliosmaionol D(2), naringenin(3), quercetin-3-O-α-L-arabinopyranoside(4), epicatechin(5), quercetin-3'-glucoside(6), corbulain Ib(7), loliolide(8), asiatic acid(9), and ursolic acid(10), were isolated. Compounds 1 and 2 were two new compounds, and compound 7 was isolated from this genus for the first time. All compounds showed no significant cytotoxic activity by MTT assay.

[A new lignan glucoside from stems and branches of Rhododendron ovatum].

Ten lignans were isolated from the ethanol extract of stems and branches of Rhododendron ovatum through column chromatography over silica gel, ODS, Sephadex LH-20, and MCI-gel resin and semi-preparative RP-HPLC. The structures of all compounds were elucidated by extensive spectroscopic data analysis(UV, IR, HR-ESI-MS, ECD and NMR) as(-)-4-epi-lyoniresinol-9'-O-α-L-rhamnopyranoside(1),(+)-lyoniresinol-3α-O-α-L-rhamnopyranoside(2),(+)-5'-methoxyisolariciresinol-9'-O-α-L-rhamnopyranoside(3),(-)-lyoniresinol-3α-O-ß-D-glucopyranoside(4),(+)-lyoniresinol-3α-O-ß-D-glucopyranoside(5),(-)-4-epi-lyoniresinol-9'-O-ß-D-glucopyransoide(6), racemiside(7), neociwujiaphenol(8),(+)-syringaresinol(9), and homohesperitin(10). Among them, compound 1 was a new aryltetralin-type lignan. All the isolated lignans were tested for antioxidant activities in Fe~(2+)-cysteine induced rat liver microsomal lipid peroxidation in vitro, and compounds 8 and 9 showed antioxidant activities on the formation of malondiadehyde(MDA) in rat liver microsomes at 1×10~(-5) mol·L~(-1), with significant inhibitory rates of 75.20% and 91.12%, respectively.

[A new sesquiterpene from stems of Buddleja lindleyana].

The present study investigated the chemical constituents from the stems of Buddleja lindleyana. Ten compounds were isolated from the 95% EtOH extract of B. lindleyana stems by means of some techniques including polyamide, silica gel, MCI, Sephadex LH-20 column chromatography, and semi-preparative high-performance liquid chromatography(HPLC). Their structures were identified by spectral analysis and single-crystal X-ray diffraction as buddledin F(1), 6-O-4″-hydroxy-3″-methoxy-benzoyl ajugol(2), negundoin G(3),(+)-dihydrocubebin(4), 7-O-ethylguaiacylglycerol(5),(-)-jatrointelignan B(6), threo-1,2-bis-(4-hydroxy-3-methoxyphenyl)-propane-1,3-diol(7), vomifoliol(8), hinokinin(9), and isovanillic acid(10). Compound 1 was a new sesquiterpene named buddledin F. Compounds 3-8 were isolated from the Buddleja plant for the first time. The anti-inflammatory activities of compounds 1-10 in vitro were investigated, and the results failed to show the inhibitory activities of these compounds on the production of inflammatory factor NO.

Six new sesquiterpenoids from the fruits of Xanthium italicum.

Four new germacrane-type sesquiterpenoids (1-4) and two new guaiane-type sesquiterpenoids (5-6) were isolated from the fruits of Xanthium italicum Moretti. The structures of the new compounds were elucidated on the basis of spectroscopic analysis and X-ray diffraction experiment. Compounds 1, 2 and 6 showed the anti-inflammatory effects against the activation of NF-κB induced by lipopolysaccharide (LPS) with IC50 values of 20.12, 22.89 and 68.66 µM, respectively.

Chromosome-scale genome assembly of Rhododendron molle provides insights into its evolution and terpenoid biosynthesis.

BACKGROUND: Rhododendron molle (Ericaceae) is a traditional Chinese medicine, which has been used to treat rheumatism and relieve pain since ancient times. The characteristic grayanoids of this plant have been demonstrated to be the chemical basis for the analgesic activity. Moreover, unlike morphine, these diterpenoids are non-addictive. Grayanoids mainly distribute in the leaves, flowers, roots, and fruits of R. molle, with low content. Currently the research on the biosynthesis of grayanoids is hindered, partially due to lack of the genomic information. RESULTS: In the present study, a total of 744 Mb sequences were generated and assembled into 13 chromosomes. An ancient whole-genome duplication event (Ad-ß) was discovered that occurred around 70 million years ago. Tandem and segmental gene duplications led to specific gene expansions in the terpene synthase and cytochrome P450 (CYP450) gene families. Two diterpene synthases were demonstrated to be responsible for the biosynthesis of 16α-hydroxy-ent-kaurane, the key precursor for grayanoids. Phylogenetic analysis revealed a species-specific bloom of the CYP71AU subfamily, which may involve the candidate CYP450s responsible for the biosynthesis of grayanoids. Additionally, three putative terpene biosynthetic gene clusters were found. CONCLUSIONS: We reported the first genome assembly of R. molle and investigated the molecular basis underpinning terpenoids biosynthesis. Our work provides a foundation for elucidating the complete biosynthetic pathway of grayanoids and studying the terpenoids diversity in R. molle.

[Chemical constituents from seeds of Hydnocarpus anthelminthica].

The present study investigated the chemical constituents from the dry seeds of Hydnocarpus anthelminthica. The compounds were isolated and purified from the dry seeds of H. anthelminthica by various chromatographic techniques including column chromatography over silica gel and Sephadex LH-20 and reversed-phase HPLC. Their structures were identified by spectroscopic analysis. The in vitro cytotoxic activities were determined by MTT assay. Ten compounds were isolated and identified as 2-(4-hydroxy-3,5-dimethoxyphenyl)-3-(2-hydroxy-5-methoxyphenyl)-3-oxo-1-propanol(1), threo-1,2-bis-(4-hydroxy-3-methoxyphenyl)-propane-1,3-diol(2), erythro-1,2-bis-(4-hydroxy-3-methoxyphenyl)-propane-1,3-diol(3), 2-(4-hydroxy-3-methoxyphenyl)-3-(2-hydroxy-5-methoxyphenyl)-3-oxo-1-propanol(4), 3-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one(5), chrysoeriol(6), evofolin B(7), apigenin-3'-methoxy-7-O-rutinoside(8), luteolin(9), and vitexin(10). Compound 1 is a new compound. Compounds 4 and 5 were isolated from this genus for the first time. All compounds showed no significant cytotoxic activity.

Five new Erythrina alkaloids from the stems of Erythrina corallodendron.

Five new Erythrina alkaloids and five known E. alkaloids were isolated from a 95% ethanol extract of the stems of Erythrina corallodendron L. Their chemical structures were elucidated by UV, IR, HRESIMS, NMR and X-ray. Furthermore, the analgesic activities of E. alkaloids 1, 2 and 6 were evaluated by using an acetic acid-induced writhing test in mice, and their writhing inhibition rates were 67.9%, 64.6% and 70.3% at doses of 20 mg/kg, respectively.

New lignans and diterpenoid glycosides from the fruits of Xanthium italicum Moretti.

A pair of new lignans [(+)- 1 and (-)- 1] and three new compounds (2-4), together with a known compound 5, were isolated from the fruits of Xanthium italicum Moretti. The structures of these compounds were determined on the basis of spectroscopic analysis, particularly HR-ESI-MS and 1 D and 2 D NMR. Compounds 2 and 3 showed antinociceptive effects in an acetic acid-induced writhing test in mice with the writhe inhibition rates of 80.50% and 67.89% at the dose of 20 mg/kg, respectively.

[Research advances in methods of cyclezation mechanism of sesquiterpenes].

Terpenes are the largest group of natural products and contain the widest assortment of structural types. Terpene cyclization is also the most complex reaction found in nature. For a long time, terpenoids with diverse structures have attracted natural product chemists to explore their biosynthesis mechanism. Such a large number of terpene skeletons are catalyzed by enzymes called terpene synthase. Sesquiterpene synthase is a kind of terpene synthase, which can catalyze the cyclization of linear precursor farnesyl pyrophosphate(FPP) to sesquiterpene skeletons. Sesquiterpene synthase cyclize a single precursor FPP into many sesquiterpene skeletons. With the continuous discovery of sesquiterpene synthase, the cyclization mechanism of sesquiterpene synthase has been studied deeply. In recent years, with the development and improvement of isotope labeling of substrate FPP and structural analysis of sesquiterpene synthase, the structure and cyclization mechanism of sesquiterpene synthase have been studied more systematically and accurately. In this review, we reviewed the progress of the research methods on the mechanism of sesquiterpene cyclization by substrate isotope labeling and protein structure, as well as the summary and prospect of sesquiterpene synthase research.

[Erythrina alkaloids from stems of Erythrina corallodendron].

This study aims to investigate Erythrina alkaloids from the stems of Erythrina corallodendron. Eighteen Erythrina alkaloids were isolated from the 95% ethanol extract of the stems of E. corallodendron by silica gel,octadecyl silica( ODS),Sephadex LH-20 column chromatography and preparative HPLC. With nuclear magnetic resonance( NMR) spectroscopy and mass spectrometry( MS),their structures were identified as crstanine A( 1),erytharbine( 2),cristamine C( 3),( +)-erystramindine( 4),10,11-dioxoerythraline( 5),8-oxoerythraline( 6),8-oxo-11ß-methoxyerythradine( 7),11-methoxyerythradine( 8),( ±)-11-epi-methoxyerythraline( 9),( +)-erythraline( 10),crystamidine( 11),8-oxoerythrinine( 12),( +)-11α-hydroxyerysotrine( 13),erythrinine( 14),erysodine( 15),erysotrine-N-oxide( 16),( +)-erythratidine( 17),erythratine( 18). Compounds 1-4,7,9,11,13,16 and 17 were isolated from E. corallodendron for the first time. Furthermore,the cytotoxic activities of these Erythrina alkaloids were screened by MTT assay. The results showed that all compounds had no obvious cytotoxic activity. The analgesic activities of compounds1,6 and 8 were evaluated using an acetic acid-induced writhing test in mice. The writhing inhibition rates of compounds 1,6 and 8 at20 mg·kg~(-1)( ip) were 69%,70% and 62%,respectively( P<0. 01),indicating they have significant analgesic activity.

Humulane-type and germacrane-type sesquiterpenoids from the fruits of Xanthium spinosum Linn.

Eight undescribed humulane-type sesquiterpenoids (xanthspinol A-E, I, J and N), three undescribed germacrane-type sesquiterpenoids (xanthspinol F, G and O) and twelve known compounds were isolated from the fruits of Xanthium spinosum. The structures of the undescribed compounds were elucidated by analyses of spectroscopic data, electronic circular dichroism (ECD) calculations, dimolybdenum tetraacetate [Mo2(OAc)4]-induced circular dichroism (ICD) spectra, a CD exciton chirality method and the modified Mosher's method. Xanthspinol A and B featured a humulane skeleton containing a 2,5-dihydrofuran fragment. Putative biosynthetic pathways for the undescribed compounds are proposed. Xanthspinol N, 8-epi-isoxanthanol and deacetyl-4-epixanthanol showed moderate activity against Coxsackie virus B3 (CVB3) with IC50 values of 8.70, 3.70 and 3.70 µM, respectively.

Recent advances in natural anti-HIV triterpenoids and analogs.

The human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic is one of the world's most serious health challenges. Although combination antiretroviral therapy provides effective viral suppression, current medicines used against HIV cannot completely eradicate the infectious disease and often have associated toxicities and severe side effects in addition to causing drug resistance. Therefore, the continued development of new antiviral agents with diverse structures and novel mechanisms of action remains a vital need for the management of HIV/AIDS. Natural products are an important source of drug discovery, and certain triterpenes and their analogs have demonstrated potential as pharmaceutical precursors for the treatment of HIV. Over the past decade, natural triterpenoids and analogs have been extensively studied to find new anti-HIV drugs. This review discusses the anti-HIV triterpenoids and analogs reported during the period of 2009-2019. The article includes not only a comprehensive review of the recent anti-HIV agent development from the perspective of medicinal chemistry, but also discusses structure-activity relationship analyses of the described triterpenoids.

[Chemical compositions from roots of Erythrina corallodendron].

This project is to investigate chemical compositions from the roots of Erythrina corallodendron. Through the methods of silica gel,ODS,Sephadex LH-20 column chromatography and preparative HPLC,15 compounds were isolated from the 95% ethanol extract of the roots of E. corallodendron. Based on spectroscopic techniques,the structures of these compounds were identified as 10,11-dioxoerythraline( 1),erythrinine( 2),erythraline( 3),11-methoxyerythraline( 4),cristanines B( 5),erythratine( 6),erysotrine( 7),medioresinol( 8),( ±)-ficusesquilignan A( 9),( +)-pinoresinol( 10),nicotinic acid( 11),dibutyl phthalate( 12),vanillic acid( 13),3-hydroxy-1-( 4-hydroxy-3-methoxyphenyl)-1-propanone( 14),and syringic acid( 15). Compounds 8-10 are isolated from genus Erythrina for the first time and all compounds are isolated from E. corallodendron for the first time. Furthermore,this paper screened the antioxidant and cytotoxic activities of the compounds using models of liver microsomal oxidation inhibition and MTT.

[Lignans from seed of Hydnocarpus anthelminthica].

This project is to investigate lignans from the seed of Hydnocarpus anthelminthica. Thirteen lignans were isolated from the 95% ethanol extract of the seed of H. anthelminthica, by polyamide resin, Sephadex LH-20, ODS column chromatography and preparative HPLC. Their structures were elucidated as(+)-syringaresinol(1), lirioresinol A(2),(+)-medioresinol(3),(7R,8R,8'R)-4'-guaiacylglyceryl-evofolin B(4), leptolepisol C(5),(-)-(7R,7'R,7″R,8S,8'S,8″S)-4',4″-dihydroxy-3,3',3″,5,5',5″-hexamethoxy-7,9':7',9-diepoxy-4,8″-oxy-8,8'-sesquineolignan-7″,9″-diol(6),(-)-(7R,7'R,7″R,8S,8'S,8″S)-4',4″-dihydroxy-3,3',3″,5,5'-pentamethoxy-7,9':7',9-diepoxy-4,8″-oxy-8,8'ses-quineolignan-7″,9″-diol(7), ceplignan(8), hydnocarpusol(9), isohydnocarpin(10),(-)-hydnocarpin(11), hydnocarpin(12), and hydnocarpin-D(13) by spectroscopic data analysis. Compounds 1-8 were obtained from the genus Hydnocarpus for the first time.

Diverse epoxy grayanane diterpenoids with analgesic activity from the roots of Pieris formosa.

In our on-going study to investigate components with analgesic activity, eight new grayanane diterpenoids, epoxypieristoxins A-H (1-8), along with one known compound (9) were isolated from the roots of Pieris formosa. Their structures with absolute configurations were characterized by a series of spectroscopic methods and X-ray diffraction. Notably, compounds 1-5 represented the first example of natural grayanane diterpenoids possessed a 10,14-epoxy group. Whereas, compounds 6-7 were the first example of grayanane diterpenoid with a 7,10-epoxy group. Biological assays showed that compounds 1-3 and 5-8 displayed significant analgesic activity at a dose of 5.0 mg/kg (ip) compared to the vehicle tests (p < .05).

Minor Nortriterpenoids from the Twigs and Leaves of Rhododendron latoucheae.

A hyphenated NMR technique (analytical HPLC with a DAD connected to MS, SPE, and NMR) has proven effective for the full structural analysis and identification of minor natural products in complex mixtures. Application of this hyphenated technique to the CH2Cl2-soluble fraction of Rhododendron latoucheae led to the identification of 15 new minor ursane-type 28-nortriterpenoids (1-15). Compounds 1 and 12 inhibited HSV-1 with IC50 values of 6.4 and 0.4 µM, respectively.

[A new dimeric xanthanolide from fruits of Xanthium chinense].

Through the methods of polyamide resin， Sephadex LH-20， ODS column chromatography and preparative HPLC etc.， 7 compounds were isolated from the 70% ethanol extract of the fruits of Xanthium chinense. Based on ESI-MS and NMR data， the structures of these compounds were identified as pungiolide O(1)， grasshopper ketone(2)， icariside F2(3)， 7-[(ß-D-apiofuranosyl-(1→6)-ß-D-glucopyranosyl)oxymethy]-8，8-dimethyl-4，8-dihydrobenzo[1，4]thiazine-3，5-dione(4)，(6R，9S)-3-oxo-α-ionol ß-D-glucopyranoside(5)， cryptochlorogenic acid methyl ester(6)， and chlorogenic acid methyl ester(7). Among them， compound 1 is a new compound.

3-Hydroxy-3-methylglutaryl flavone glycosides from the leaves of Turpinia arguta.

Three new 3-hydroxy-3-methylglutaryl (HMG) flavone 7-O-diglycosides, argutosides A-C (1-3); two new flavone 7-O-triglycosides, argutosides D-E (4-5); and one known apigenin 7-O-triglycoside (6), were isolated from the leaves of Turpinia arguta. The structures of these compounds were elucidated by spectroscopic and chemical techniques. The NO inhibitory activities of compounds 1-6 were evaluated using lipopolysaccharide-induced RAW264.7 cells. Only compound 2 showed a moderate inhibitory effect on NO production with an IC50 value of 25.74µM. Compounds 1-6 were not cytotoxic to RAW264.7 cells at 10µM.

Sesquiterpenes from the Endophyte Glomerella cingulata.

From the cultured endophytic fungus Glomerella cingulata isolated from a toxic plant, Gelsemium elegans, one new phenanthrene (1), four new sesquiterpenes (2-5), and three known sesquiterpenes (6-8) were isolated. Their structures were elucidated using spectroscopic methods. Based on the ECD calculations, the absolute configurations of the new compounds were determined. Compounds 2, 4, and 5 inhibited lipopolysaccharide (LPS)-induced NO production in BV2 cells by 50.6, 36.1, and 29.4%, respectively, at 1 µM (positive control curcumin, IC50 = 4.0 µM).