New Tyrosinase Inhibitory Sesquiterpenes fromChloranthus henryi

Structurally diversified sesquiterpenoids from Chloranthus henryi and their neuroprotective activities on H2O2 damaged PC12 cells

Fifteen undescribed sesquiterpenoid monomers, including six pairs of sesquiterpenoid enantiomers (1a/1b-3a/3b and 5a/5b-7a/7b) and three analogues (4, 8, and 9), together with two known sesquiterpenoid dimers (10 and 11) were isolated from the whole plant of Chloranthus henryi Hemsl. Their structures were characterized by spectroscopic data analysis, ECD calculations, and single crystal X-Ray diffractions. Compounds 1a and 1b were highly aromatic cadinane-type sesquiterpenoids. At a concentration of 10 μM, compounds 8, 10, and 11 exhibited potent neuroprotective activity against H2O2-induced PC12 cell damage. Compounds 10 and 11 significantly decreased the level of ROS. In addition, compound 11 increased the levels of p-AMPK, p-SIRT1, and SIRT3 in the H2O2-induced PC12 cell damage via activated the AMPK/SIRT signaling pathway.

Constituents from Chloranthus multistachys and their cytotoxic activities against various human cancer cell lines

Two new furanoeremophilane sesquiterpenoids, namely, 6,9-dioxo-1α,4α-dihydroxy-furanoeremophilane (1) and 4α,5α-epoxy-6,9-dioxo-1α-hydroxyl-furanoeremophilane (2), and 10 known compounds were isolated from the whole plant of Chloranthus multistachys, and compound 3 was converted to derivative 3a. Their structures were determined based on extensive spectroscopic analysis. All compounds were evaluated by using five cancer cell lines: PC3, LNcap, A549, K562, and HEL. The derivative 3a exhibited excellent cytotoxic activities, with the IC₅₀ against HEL cells being the lowest at 1.322 ± 0.08 μM, which was comparable to that of the positive control (doxorubicin). Mechanism studies showed that the anticancer activity of 3a may be associated with cell cycle regulation.

Sesquiterpenes from Myrrh and Their ICAM-1 Inhibitory Activity In Vitro

By using various chromatographic steps (silica flash, CPC, preparative HPLC), 16 sesquiterpenes could be isolated from an ethanolic extract of myrrh resin. Their chemical structures were elucidated by 1D and 2D NMR spectroscopy and HRESIMS. Among them, six previously unknown compounds (1-6) and another four metabolites previously not described for the genus Commiphora (7, 10, 12, 13) could be identified. Sesquiterpenes 1 and 2 are novel 9,10-seco-eudesmanes and exhibited an unprecedented sesquiterpene carbon skeleton, which is described here for the first time. New compound 3 is an 9,10 seco-guaian and the only peroxide isolated from myrrh so far. Compounds 1, 2, 4, 7-9, 11, 13-16 were tested in an ICAM-1 in vitro assay. Compound 7, as well as the reference compound furanoeudesma-1,3-diene, acted as moderate inhibitors of this adhesion molecule ICAM-1 (IC50: 44.8 and 46.3 μM, respectively). These results give new hints on the activity of sesquiterpenes with regard to ICAM-1 inhibition and possible modes of action of myrrh in anti-inflammatory processes.

Neuroprotective racemic germacranolides from the roots of Chloranthus henryi

Three pairs of new germacranolides, (+)/(-)-chlogermacrones A-C, along with two known analogues were obtained from the roots of Chloranthus henryi. Spectroscopic techniques and single-crystal X-ray crystallographic analyses were used for the structure elucidation of the compounds. All of the isolated compounds were tested for their neuroprotective effects on H₂O₂ damaged PC12 cells, compounds 3 and 5 increased cell viability from 43.4 ± 1.3% to 99.6 ± 8.7 and 68.1 ± 4.8% at 10 μM, respectively.

Secondary metabolite profiling, cytotoxicity, anti-inflammatory potential and in vitro inhibitory activities of Nardostachys jatamansi on key enzymes linked to hyperglycemia, hypertension and cognitive disorders

ETHNOPHARMACOLOGICAL RELEVANCE

Nardostachys jatamansi (D. Don) DC., 'Spikenard' or 'Jatamansi', a highly valued, aromatic herb from alpine Himalayas has a long history of use as ethnomedicine and dietary supplements in Ayurveda, Unani and Chinese system of medicine since Vedic ages (1000-800 BC). In Ayurveda and traditional system of medicine, the species is used as stimulant, sedative, brain tonic or mind rejuvenator, antidiabetic, cardio tonic, and in the treatment of various neurological disorders such as insomnia, epilepsy, hysteria, anxiety and depression. It is considered as Sattvic herb in Ayurveda and is now commercially marketed either as single or poly-herbal formulations by many companies in national and international markets.

AIM OF THE STUDY

The species has become threatened in its natural habitats due to over exploitation and illegal trade of its rhizomes for drug preparation in herbal and pharmaceutical industries. Considering the increasing demand and tremendous medicinal importance of this threatened plant species, a detailed study was undertaken to evaluate its antioxidant potential, secondary metabolite profiling, cytotoxicity, anti-inflammatory potential and in vitro enzyme inhibitory activities on key enzymes linked to hyperglycemia, hypertension and cognitive disorders in different plant parts of wild and in vitro-raised plants with respect to different solvent systems for its sustainable utilization.

MATERIALS AND METHODS

Anti-cholinesterase activity of leaves and rhizome of wild and cultured plant extracts was investigated against both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. In vitro anti-hyperglycemic (α-amylase and PTP1B), anti-hypertensive (angiotensin-converting enzyme), anti-tyrosinase and anti-inflammatory potential (5-lipoxygenase and hyaluronidase) of different plant parts of wild and in vitro-raised plants with respect to different solvent systems were also evaluated. In vitro cytotoxic effect of rootstock extracts of wild and in vitro-derived plants were against cancer (HCT-116, MCF-7 and OE33) and two normal (HEK and MEF) cell lines. Secondary metabolite profiling of rhizome segments of wild and in vitro-derived plants was carried out by quantitative gas chromatography-mass spectrometry (GC-MS).

RESULTS

In vitro-raised plantlets showed comparative higher yield of various secondary metabolites with a significantly high antioxidant activity as compared to the wild plants. Methanolic rootstock extracts of both wild and in vitro-derived plants of N. jatamansi exhibited significant AChE (IC₅₀ 36.46 ± 2.1 and 31.18 ± 2.6 µg/ml, respectively) and BuChE (IC₅₀ 64.6 ± 3.5 and 60.12 ± 3.6 µg/ml, respectively) inhibitory potential as compared to standard inhibitor galanthamine (IC₅₀ 0.94 ± 0.03 and 4.45 ± 0.5 µg/ml). Methanolic rootstock extract of in vitro-derived plants showed significant α-amylase (IC₅₀ 90.69 ± 2.1 µg/ml), PTP1B (IC₅₀ 24.56 ± 0.8 µg/ml), angiotensin-converting enzyme (IC₅₀ 42.5 ± 3.6 µg/ml) and tyrosinase (IC₅₀ 168.12 ± 3.6 µg/ml) inhibitory potential as compared to standard acarbose (IC₅₀ 52.36 ± 3.1 µg/ml), ursolic acid (IC₅₀ 5.24 ± 0.8 µg/ml), captopril (IC₅₀ 32.36 ± 2.5 µg/ml) and kojic acid (IC₅₀ = 54.44 ± 2.3 µg/ml). Both the methanolic rootstock and leaf extracts of tissue culture-derived plants exhibited promising anti-5-LOX and anti-hyaluronidase activities against the known inhibitor of 5-LOX and hyaluronidase. Furthermore, methanolic rootstock extracts of both wild and in vitro-derived plants exhibited promising cytotoxic effects to HCT-116, MCF-7 and OE33 cell lines as compared to the normal HEK and MEF after 12 h of treatment. Secondary metabolite profiling of wild and in vitro-derived plants by quantitative GC-MS analysis revealed the presence of different classes of terpenoids and phenolic acids might be responsible for its effective biological activities.

CONCLUSION

In vitro-derived plants revealed a substantial anti-cholinesterases, anti-hyperglycemic anti-inflammatory, anti-hypertensive and anti-tyrosinase potential with higher yield of various bioactive metabolites and significantly higher antioxidant activity which substantially explain medicinal importance of N. jatamansi in traditional medicine, used for centuries in different Ayurvedic formulations. The present findings suggest that cultured plants could be a promising alternative for the production of bioactive metabolites with comparative biological activities to the wild plants.

(+)/(-)-Phaeocaulin A-D, four pairs of new enantiomeric germacrane-type sesquiterpenes from Curcuma phaeocaulis as natural nitric oxide inhibitors

Germacrane-type sesquiterpenes, with a flexible 10-membered ring unit as the structural and conformational features, play a central role in the biosynthesis and synthesis of other sesquiterpenes. In this report, two pairs of new sesquiterpene alkaloids, (+)/(−)-phaeocaulin A [(+)-1/(−)-1] and B [(+)-2/(−)-2], and two pairs of new sesquiterpenes, (+)/(−)-phaeocaulin C [(+)-3/(−)-3] and D [(+)-4/(−)-4], along with one related known analog (5), were isolated from the rhizomes of Curcuma phaeocaulis. The absolute configurations of (+)-1/(−)-1, (+)-2/(−)-2, (+)-3/(−)-3 and (+)-4/(−)-4 were unambiguously determined by analysis of single-crystal X-ray diffractions and quantum chemical electronic circular dichroism (ECD) method. It is noteworthy that (+)/(−)-phaeocaulin A [(+)-1/(−)-1] and B [(+)-2/(−)-2] are two pairs of rare N-containing germacrane-type sesquiterpenes. A possible biogenetic pathway for 1–5 was postulated. All of the isolated compounds were tested for their inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages.

Sesquiterpenoids from the Rhizomes of Curcuma phaeocaulis and Their Inhibitory Effects on LPS-Induced TLR4 Activation

Two new guaiane-type (2, 6) and one new furanogermacrane-type (11) sesquiterpenoids have been isolated along with twelve known compounds from an EtOAc-soluble extract of Curcuma phaeocaulis rhizomes. The structures of the isolated compounds were elucidated using a combination of NMR, MS, and circular dichroism (CD) spectra. The inhibitory effects of each compound on lipopolysaccharide (LPS)-induced Toll-like receptor 4 (TLR4) activation in THP-1-Blue cells were assessed, and compound 4 showed more potent inhibitory activity against LPS-stimulated TLR4 activation.

Constituents from Chloranthaceae plants and their biological activities

The Chloranthaceae is a small family with only four genera (

Bioactive ent-Pimarane and ent-Abietane Diterpenoids from the Whole Plants of Chloranthus henryi

Two new ent-pimarane (1 and 2), eight new ent-abietane (3-10) diterpenoids, and eight known analogues (11-18) were isolated from the whole plants of Chloranthus henryi. The absolute configuration of 1 was determined on the basis of single-crystal X-ray diffraction data. Compound 8 represents a class of rare naturally occurring C-14 norabietanes, and compounds 9 and 10 feature rare 13,14-seco-abietane skeletons. Compounds 5, 12, 13, and 15 inhibited the yeast-to-hyphae transition of Candida albicans with IC50 values between 97.3 and 738.7 μM.

Phytochemical and biological studies of Chloranthus medicinal plants

The plants of genus Chloranthus have been investigated in many chemical and pharmacological laboratories due to their complex secondary metabolites and diverse bioactivities. The aim of this review is to provide an up-to-date overview on the chemistry and bioactivity of the compounds isolated, mainly sesquiterpenoids and diterpenoids, from the genus Chloranthus over the past few decades.

Terpenoids from Chloranthus elatior

Two new eudesmane-type sesquiterpenoid lactones, named chlorelactone A (1) and chlorelactone B (2), and one new labdane-type diterpenoid, named elatiorlabdane (3), along with seven known sesquiterpenoids and one known disesquiterpenoid were isolated from the whole plants of Chloranthus elatior. Their structures and relative configurations were established on the basis of extensive spectroscopic analysis.

New lignan glucosides with tyrosinase inhibitory activities from exocarp of Castanea henryi

Three novel lignan glycosides, 1-[4-(β-glucopyranosyl (1→2)-[β-glucopyranosyl (1→6)]-β-glucopyranosyloxy)-3-methoxyphenyl]-2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-1,3-propanediol (1), 2,3-dihydro-2-[4-(β-glucopyranosyl (1→2)-[β-glucopyranosyl (1→6)]-β-glucopyranosyloxy)-3-methoxyphenyl]-3-(hydroxymethyl)-7-methoxy-5-benzofuranpropanol (2), 7-hydroxy-9'-β-glucopyranosyloxyl secoisolariciresinol (3) and two known lignans were isolated from exocarp of Castanea henryi. Their structures were established by spectroscopic means, and their tyrosinase inhibitory potentials were evaluated in vitro using mushroom tyrosinase.

An unusual stress metabolite induced by CuCl(2) and other constituents from the leaves of Chloranthus anhuiensis

A 6-eremophilene derivative 2 with an unusual pendant was produced as phytoalexin in the fresh leaves of Chloranthus anhuiensis K. F. Wu in response to abiotic stress elicitation by CuCl(2). The phytoalexin was characterized as a sesquiterpene with a (2,6-dimethoxy-4-hydroxy)benzyl moiety pendant. Two new sesquiterpenes, (3R,4S,5R,10S,11S)-3-hydroxy-8-oxo-6-eremophilen-12-oic acid (1) and (3R,4S,5R,6R,8R,10S)-3,6,8-trihydroxy-7(11)-eremophilen-12,8-olide (3), one new sesquiterpene glycoside, anhuienoside A (4), one new caffeoyl phenylethanoid diglycoside with an unusual cyclic structure, anhuienoside B (5), and one new tyramine derivative, N-acetyltyramine 1-O-beta-d-glucoside (6), and three known compounds were also isolated. Their structures and relative configurations were established by spectroscopic means. The absolute configurations of 1-3 were defined mainly by comparison of quantum chemical TDDFT calculated and experimental ECD spectra.

Antifungal activity of CHE-23C, a dimeric sesquiterpene from Chloranthus henryi

An antifungal compound was isolated from methanol extracts of stems and roots of Chloranthus henryi Hemsl. using ethyl acetate extraction and various chromatographic techniques. On the basis of spectroscopic analyses including mass and various NMR, the structure of the compound was identified as a dimeric sesquiterpene, CHE-23C. The compound showed potent antifungal activities (MICs = 1-32 microg/mL) in vitro against various phytopathogenic fungi such as Alternaria kikuchiana , Botrytis cinerea , Colletotrichum lagenarium , Magnaporthe grisea , Pythium ultimum , and Phytophthora infestans . In particular, it exhibited 91 and 100% disease-control activity in vivo against tomato late blight (P. infestans) and wheat leaf rust ( Puccinia recondita ) at concentrations of 33 and 100 microg/mL, respectively. The disease-control activity of this compound was stronger than that of the commercially available fungicide chlorothalonil, but weaker than that of dimethomorph. Therefore, the compound might serve as an interesting lead to develop effective antifungal agents.

An updated review of tyrosinase inhibitors

Tyrosinase is a multifunctional, glycosylated, and copper-containing oxidase, which catalyzes the first two steps in mammalian melanogenesis and is responsible for enzymatic browning reactions in damaged fruits during post-harvest handling and processing. Neither hyperpigmentation in human skin nor enzymatic browning in fruits are desirable. These phenomena have encouraged researchers to seek new potent tyrosinase inhibitors for use in foods and cosmetics. This article surveys tyrosinase inhibitors newly discovered from natural and synthetic sources. The inhibitory strength is compared with that of a standard inhibitor, kojic acid, and their inhibitory mechanisms are discussed.

Sesquiterpenoids and phenylpropanoids from Chloranthus serratus

Seven new sesquiterpenoids, chlorantenes A-G (1-7), two new phenylpropanoids (8 and 9), and six known sesquiterpenoids were isolated from the whole plants of Chloranthus serratus. Their structures were elucidated on the basis of spectroscopic analyses. Chlorantene A (1) was a sesquiterpene with a unique C-4 and C-10 linkage, and chlorantene B (2) possessed a nitro group at C-1. The structure of a eudesmane-type sesquiterpene previously isolated from Chloranthus henryi was revised as its 4-epimer (3a).