Cytotoxic activities of flavonoids from a traditional Mongolian medicinal herb Clematis aethusifolia Turcz

A novel flavonol glycoside and six derivatives of quercetin and kaempferol from Clematis flammula with antioxidant and anticancer potentials

Clematis flammula leaves are traditionally used in Algeria to treat rheumatoid arthritis. Our aim was to identify the main compounds in this plant in order to characterize its antioxidant and anticancer activities. A new flavonol compound, kaempferol 3-O-[(6-O- caffeoyl)- glucosyl(1 → 2)]-(6-Ocaffeoyl) glucoside-7-O-rhamnoside (6) along with six known flavonol molecules were isolated from an ethanolic extract of Clematis flammula leaves. The chemical structures of these flavonols were elucidated using NMR and high resolution-MS spectroscopies. Antioxidant activities of the extract were revealed through its elimination of superoxide radical (O2.-) produced enzymatically (49.7 ± 1.52% at 50 μg/ml) and non-enzymatically (34 ± 1.2% at 100 μg/ml), probably related to its inhibition of the xanthine oxidase form of the xanthine oxidoreductase (XOR) enzyme (25.05 ± 2.33 μg/mL at 100 μg/mL), but mostly to that of the NADH oxidase form of the enzyme (69.16 ± 4.0%). Cytotoxicity tests of the extract on human hepatoma cell line HepG2 and ovarian cancer cell lines A2780 and OVCAR3 were promising especially regarding A2780 cell line (IC50: 77.0 μg/mL), which was comparable to taxol (IC50:76.9 μg/mL).

Comparative transcriptome analysis of heat stress responses of Clematis lanuginosa and Clematis crassifolia

BACKGROUND

Clematis species are attractive ornamental plants with a variety of flower colors and patterns. Heat stress is one of the main factors restricting the growth, development, and ornamental value of Clematis. Clematis lanuginosa and Clematis crassifolia are large-flowered and evergreen Clematis species, respectively, that show different tolerance to heat stress. We compared and analyzed the transcriptome of C. lanuginose and C. crassifolia under heat stress to determine the regulatory mechanism(s) of resistance.

RESULTS

A total of 1720 and 6178 differentially expressed genes were identified from C. lanuginose and C. crassifolia, respectively. The photosynthesis and oxidation-reduction processes of C. crassifolia were more sensitive than C. lanuginose under heat stress. Glycine/serine/threonine metabolism, glyoxylic metabolism, and thiamine metabolism were important pathways in response to heat stress in C. lanuginose, and flavonoid biosynthesis, phenylalanine metabolism, and arginine/proline metabolism were the key pathways in C. crassifolia. Six sHSPs (c176964_g1, c200771_g1, c204924_g1, c199407_g2, c201522_g2, c192936_g1), POD1 (c200317_g1), POD3 (c210145_g2), DREB2 (c182557_g1), and HSFA2 (c206233_g2) may be key genes in the response to heat stress in C. lanuginose and C. crassifolia.

CONCLUSIONS

We compared important metabolic pathways and differentially expressed genes in response to heat stress between C. lanuginose and C. crassifolia. The results increase our understanding of the response mechanism and candidate genes of Clematis under heat stress. These data may contribute to the development of new Clematis varieties with greater heat tolerance.

Two new terpenes from the aerial parts of Clematis chinensis Osbeck

Two new acyclic sesquiterpenoids (1-2) and fourteen known monocyclic monoterpenoids (3-16) were isolated from the aerial parts of Clematis chinensis Osbeck. All compounds were isolated from C. chinensis for the first time. The structures of all compounds were characterized by spectroscopic methods (1 D, 2 D NMR and HRESIMS). In-vitro cytotoxic activity against two human cancer cell lines (MGC-803 and Ishikawa) of all the compounds were evaluated by CCK-8 assay.

The antifeedant, insecticidal and insect growth inhibitory activities of triterpenoid saponins from Clematis aethusifolia Turcz against Plutella xylostella (L.)

BACKGROUND

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a global insect pest of crops, leading to a reduction of agricultural products in productivity and quality. Plant saponins are rich sources for the discovery of candidates to control insect pests. This study focused on discovery of triterpenoid saponins from Clematis aethusifolia Turcz and evaluation of their antifeedant, insecticidal and insect growth inhibitory activities against the 3rd instar larvae of P. xylostella.

RESULTS

Seven triterpenoid saponins (1-7) were isolated for the first time from the n-BuOH extract of C. aethusifolia. Monodesmosides 1, 2, and 5 with a free 28-COOH group showed much higher antifeedant activity (DC₅₀ were 733.67-844.77 μg mL^-1 at 24 h, and 737.19-748.28 μg mL^-1 at 48 h) than bidesmosides 3-4 and 6-7 (DC₅₀ were 1284.35-2053.98 μg mL^-1 at 24 h, and 1183.72-1990.96 μg mL^-1 at 48 h). Similarly, monodesmosides 1, 2, and 5 (LC₅₀ were 1462.78-1785.96 μg mL^-1 ) showed stronger insecticidal activity than bidesmosides 3-4 and 6-7 (LC₅₀ were 2219.22-3050.51 μg mL^-1 ) against P. xylostella at 72 h. These results suggest the 28-COOH group is an important functional group for their antifeedant and insecticidal activity. Besides, monodesmosides 1, 2, and 5 showed insect growth inhibitory activity against P. xylostella through reduction of larval growth and percentage of pupation, associated with prolongation of larval and pupal stages.

CONCLUSION

The present results provide evidence that triterpenoid saponins from C. aethusifolia, particularly those monodesmosidic saponins with a free 28-COOH group, have the potential to be developed as pesticides to control P. xylostella.

Effect of Non-Volatile Constituents of Elsholtzia ciliata (Thunb.) Hyl. from Southern Vietnam on Reactive Oxygen Species and Nitric Oxide Release in Macrophages

The extract of Elsholtzia ciliata aerial parts was subjected to bio-guided isolation using the intercellular ROS reduction in J774A.1 macrophages to monitor the anti-oxidative activity. Fifteen compounds were isolated from the active fractions including eleven flavonoids (vitexin, pedalin, luteolin-7-O-β-d-glucopyranoside, apigenin-5-O-β-d-glucopyranoside, apigenin-7-O-β-d-glucopyranoside, chrysoeriol-7-O-β-d-glucopyranoside, 7,3'-dimethoxyluteolin-6-O-β-d-glucopyranoside, luteolin, 5,6,4'-trihydroxy-7,3'-dimethoxyflavone, 5-hydroxy-6,7-dimethoxyflavone (compound 13), 5-hydroxy-7,8-dimethoxyflavone); three hydroxycinnamic acid derivatives (caffeic acid, 4-(E)-caffeoyl-l-threonic acid, 4-O-(E)-p-coumaroyl-l-threonic acid) and one fatty acid (α-linolenic acid). The biological evaluation of these compounds (10-2.5 μm) indicated that all of them exerted good antioxidant and anti-inflammatory activities, in particular compound 13.

Sesquiterpenoids, phenolic and lignan glycosides from the roots and rhizomes of Clematis hexapetala Pall. and their bioactivities

Approximately 17 compounds were isolated from a 60% EtOH aqueous extract of the roots and rhizomes of Clematis hexapetala Pall., including three new guaianolide sesquiterpenoids with 5/7/5-fused rings and 3S-configuration (1-3), five new prenylated tetra-substituted phenolic glycosides (4-8) with 6/6-fused 9H-benzopyran skeleton (5) and 6/7-fused 7,10-dihydro-benzoxepin skeleton (6-8), one new isoferulyl glucoside (9), two new furofuran lignan diglucosides (10-11), and six known compounds. The chemical structures of the new compounds were elucidated via spectroscopic data and electronic circular dichroism (ECD) analyses in combination with a modified Mosher's method. The possible biosynthetic relationships of prenylated tetra-substituted phenols were postulated. In the in vitro assays, compound 16 exhibited moderate TNF-α secretion inhibitory activity with IC₅₀ value of 3.419 μM. Compounds 14-16 displayed potent PTP1B enzymatic inhibitory activities with inhibition ratios of 48.30-86.00%. And compound 16 showed significant PTP1B enzymatic inhibition with IC₅₀ value of 4.623 μM.

Chemical Constituents of the Leaves of Peltophorum pterocarpum and Their Bioactivity

Two new sesquiterpenoids peltopterins A and B (compounds 1 and 2) and fifty-two known compounds were isolated from the methanol extract of P. pterocarpum and their chemical structures were established through spectroscopic and mass spectrometric analyses. The isolates 40, 43, 44, 47, 48, 51 and 52 exhibited potential inhibitory effects of superoxide anion generation or elastase release.

A new indole-type alkaloid from the roots of Clematis florida var. plena

One new indole-type alkaloid, α-L-rhamnopyranosyl-(1→6)-β-D- glucopyranosyl 6-methoxy-3-indolecarbonate (1), together with three known alkaloids (2-4), one aromatic acid (5) and five known saponins (6-10), was isolated from the roots of Clematis florida var. plena. Their structures were established by NMR spectroscopic analysis and acid hydrolysis. In in vivo anti-inflammatory activity, n-butanol extract was found to be potent against ear edema in mice, with inhibition rate of 48.7% at a dose of 800 mg/kg. Furthermore, compounds 8 and 9 obtained from the n-butanol extract exhibited significant anti-inflammatory activities with inhibition rates of 50.9% and 54.7% at a dose of 200 mg/kg.

Apigenin-7-O-β-d-(-6″-p-coumaroyl)-glucopyranoside pretreatment attenuates myocardial ischemia/reperfusion injury via activating AMPK signaling

AIMS

Apigenin-7-O-β-d-(-6″-p-coumaroyl)-glucopyranoside (APG) was considered as the major active compound derived from Clematis tangutica. Though we have demonstrated that APG exerts cardioprotective effects, the mechanism of APG-mediated cardioprotection remains largely unknown. Numerous studies indicate that endoplasmic reticulum stress (ERS) is a vital injury factor in myocardial ischemia reperfusion (MI/R). In this study, we mainly investigated whether modulation of the ERS and AMPK were involved in the cardioprotective action of APG during MI/R injury.

MAIN METHODS

The perfused isolated rat heart or primary neonatal rat cardiomyocytes which exposed to APG with or else without the AMPK inhibitor Compound C was then subject to MI/R. After reperfusion, the degree of myocardial injury was assessed by using lactate dehydrogenase (LDH) release, creatine kinase (CK) release, histological examination, and TTC staining. The protein expressions of p-AMPK, AMPK, p-PERK, PERK, p-eIF2α, eIF2α, CHOP, Bax, Bcl2 and Cleaved Caspase 3 were analyzed by western blot. The cell viability was assessed by CCK-8 kit while apoptosis assessed by using TUNEL assay.

KEY FINDINGS

Pretreatment of APG significantly improved cardiac function and suppressed ERS through activating the AMPK signaling pathway, which could simultaneously improve cardiac function, alleviate myocardial injury, increase the cell viability and decrease apoptosis.

SIGNIFICANCE

To conclude, APG ameliorates MI/R injury by activating the AMPK signaling pathway and relieving endoplasmic reticulum stress. APG may be a natural product with pharmacological preconditioning activity, which could do us a favor to develop more novel therapy methods to against MI/R injury in the future.

Synthesis and antiproliferative activities of aminoalkylated polymethoxyflavonoid derivatives

A series of novel aminoalkylated polymethoxyflavonoid derivatives 3-11 was synthesised from 5-hydroxy-3,7,3',4'-tetramethoxyflavonoid (1) through extending alkoxy chain at the 5-position, and introducing amine hydrogen bond receptor at the end of the side chain. Their antiproliferative activities were evaluated in vitro on a panel of three human cancer cell lines (Hela, HCC1954 and SK-OV-3). The results showed that all the target compounds exhibited antiproliferative activities against investigated cancer cells with IC₅₀ values of 9.51-53.33 μM. Compounds 5, 7, 8, 11 on Hela cells and compounds 4-9, 11 on HCC1954 exhibited more potency as compared to positive control cis-Platin.

Antioxidant potential assessment of phenolic and flavonoid rich fractions of Clematis orientalis and Clematis ispahanica (Ranunculaceae)

The antioxidant activities of crude extract fractions using Hexane, Chloroform, Ethyl Acetate, Butanol and Water of Clematis orientalis and Clematis ispahanica were investigated. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay and the ferric reducing/antioxidant potential (FRAP) were used to evaluate the antioxidant capacity. The total phenolics were found to be 4.37-9.38 and 1.32-11.37 mg gallic acid equivalents (GAE)/g in different fractions for C. orientalis and C. ispahanica, respectively. The ethyl acetate fraction of C. orientalis and chloroform fraction of C. ispahanica showed the highest DPPH and FRAP activities at a concentration of 300 μg/mL. The predominant phenolic compounds identified by HPLC in C. orientalis were Resorcinol (603.5 μg/g DW) in chloroform fraction and Ellagic acid (811.7 μg/g DW) in chloroform fraction of C. ispahanica.