Phenolics from Acalypha indica

Two novel hydrolysable tannins, potassium brevifolincarboxylate and acaindinin, together with eight known tannins—1-O-galloyl-β-D -glucose, 1,2,3,6-tetra-D -galloyl-β-D -glucose, corilagin, geraniin, acetonylgeraniin A, euphormisin M₂, repandusinic acid A, and chebulagic acid, as well as two flavonoid glycosides — quercetin 3-O-β-D -glucoside and rutin, were isolated from Acalypha indica. Their structures were elucidated on the basis of chemical and spectroscopic evidence.     

Secondary metabolites from Asperula lutea subsp. rigidula

From the aerial parts of Asperula lutea subsp. rigidula (Halacsy) Ehrend., an endemic plant of south-eastern Greece, nine known compounds, beta-sitosterol, geniposidic acid, deacetyl-asperuloside, scandoside, chlorogenic acid, quercetin, hyperin, isoquercitrin and rutin, were isolated. From the analysis of a non polar fraction of the methanolic extract by means of GC and GC-MS, eighteen compounds were identified, mainly esters of fatty acids. The major components were the ethyl esters ofpalmitic acid (32.7%), linolenic acid (20.1%) and linoleic acid (10.5%).     

Cytotoxic constituents from Vicia monantha subsp. monantha seeds

Chemical investigation of Vicia monantha subsp. monantha Retz. revealed isolation of one new hydroxy- fatty acid (6) identified as (6-Z, 10-E)-9-hydroxy henicosa-6,10-dienoic acid in addition to six known metabolites; hexadecanoic acid (1), β-sitosterol (2), β-amyrin (3), β-sitosterol-glucoside (4), 2,3-dihydroxypropyl tetradecanoate (5) and (Z)-9-hydroxypentadec-6-enoic acid (7). The cytotoxic effect of the isolated compounds was assessed by MTT assay using lung cancer A-549, prostate cancer PC3, breast cancer MCF-7, colon cancer HCT-116 and liver cancer HepG2 cell lines. Only compounds 1, 2, and 4 showed cytotoxic effect on HCT-116 cells where compound 2 was the most active with IC₅₀ value of 22.61 μg/mL. In addition, compounds 1, 2, 3, and 4 showed promising cytotoxic effect on MCF-7 cells with IC₅₀ values of 21.03, 15.42, 10.089, and 11.34 μg/mL, respectively.     

Xanthones from calli of Hypericum perforatum subsp. perforatum

Two new xanthone derivatives, 1-hydroxy-5,6,7-trimethoxyxanthone and 3-O-methylpaxanthone were isolated from callus of Hypericum perforatum subsp. perforatum together with the known paxanthone, cadensin G, 1-hydroxy-6,7-dimethoxyxanthone, 1,3,6,7-tetrahydroxyxanthone, and 1,3,5,6-tetrahydroxyxanthone. The structures of the new compounds were established by spectroscopic methods.     

New Iridoid Glycosides from Lamium eriocephalum subsp. eriocephalum

Two new iridoid glycosides, eriobioside ( 1 ) and lamerioside ( 2 ), were isolated from the aerial parts of Lamium eriocephalum subsp. eriocephalum, along with the two known compounds lamiide ( 3 ) and ipolamiide ( 4 ). Their structures were elucidated by spectroscopic methods (UV, 1D‐ and 2D‐NMR) and by mass spectrometry (HR‐ESI‐MS).     

Anti-Ageing Potential of S. euboea Heldr. Phenolics

In recent years, the use of Sideritis species as bioactive agents is increasing exponentially. The present study aimed to investigate the chemical constituents, as well as the anti-ageing potential of the cultivated Sideritis euboea Heldr. The chemical fingerprinting of the ethyl acetate residue of this plant was studied using 1D and 2D-NMR spectra. Isomeric compounds belonging to acylated flavone derivatives and phenylethanoid glycosides were detected in the early stage of the experimental process through 2D-NMR techniques. Overall, thirty-three known compounds were isolated and identified. Some of them are reported for the first time not only in S. euboea, but also in genus Sideritis L. The anti-ageing effect of the ethyl acetate residue and the isolated specialized products was assessed as anti-hyaluronidase activity. In silico docking simulation revealed the interactions of the isolated compounds with hyaluronidase. Furthermore, the in vitro study on the inhibition of hyaluronidase unveiled the potent inhibitory properties of ethyl acetate residue and apigenin 7-O-β-d-glucopyranoside. Though, the isomers of apigenin 7-O-p-coumaroyl-glucosides and also the 4′-methyl-hypolaetin 7-O-[6′′′-O-acetyl-β-d-allopyranosyl]-(1→2)-β-d-glucopyranoside exerted moderate hyaluronidase inhibition. This research represents the first study to report on the anti-hyaluronidase activity of Sideritis species, confirming its anti-inflammatory, cytotoxic and anti-ageing effects and its importance as an agent for cosmetic formulations as also anticancer potential.     

New highly oxidized fusicoccane diterpenoids from the liverwort subsp.

Four novel fusicoccane diterpenoids, fusicoplagins A, B, C, and D, have been isolated from the liverwort subsp. and the structures determined by spectroscopic methods, chemical transformations, and X-ray crystallographic analysis.     

Flavonoids from Sedum japonicum subsp. oryzifolium (Crassulaceae)

Twenty-two flavonoids were isolated from the leaves and stems of Sedum japonicum subsp. oryzifolium (Crassulaceae). Of these compounds, five flavonoids were reported in nature for the first time, and identified as herbacetin 3-O-xyloside-8-O-glucoside, herbacetin 3-O-glucoside-8-O-(2′′′-acetylxyloside), gossypetin 3-O-glucoside-8-O-arabinoside, gossypetin 3-O-glucoside-8-O-(2′′′-acetylxyloside) and hibiscetin 3-O-glucoside-8-O-arabinoside via UV, HR-MS, LC-MS, acid hydrolysis and NMR. Other seventeen known flavonoids were identified as herbacetin 3-O-glucoside-8-O-arabinoside, herbacetin 3-O-glucoside-8-O-xyloside, gossypetin 3-O-glucoside-8-O-xyloside, quercetin, quercetin 3-O-glucoside, quercetin 3-O-xylosyl-(1→2)-rhamnoside-7-O-rhamnoside, quercetin 3-O-rhamnoside-7-O-glucoside, kaempferol, kaempferol 3-O-glucoside, kaempferol 7-O-rhamnoside, kaempferol 3,7-di-O-rhamnoside, kaempferol 3-O-glucoside-7-O-rhamnoside, kaempferol 3-O-glucosyl-(1→2)-rhamnoside-7-O-rhamnoside, kaempferol 3-O-xylosyl-(1→2)-rhamnoside, kaempferol 3-O-xylosyl-(1→2)-rhamnoside-7-O-rhamnoside, myricetin 3-O-glucoside and cyanidin 3-O-glucoside. Some flavonol 3,8-di-O-glycosides were found in Sedum japonicum subsp. oryzifolium as major flavonoids in this survey. They were presumed to be the diagnostic flavonoids in the species. Flavonoids were reported from S. japonicum for the first time.     

Three New Alkaloids from Hippophae rhamnoides Linn. subsp. sinensis Rousi

Two novel organic amide alkaloids, 4‐[(E)‐p‐coumaroylamino]butan‐1‐ol ( 1 ) and 4‐[(Z)‐p‐coumaroylamino]butan‐1‐ol ( 2 ), together with a rare pyridoindole alkaloid, hippophamide ( 3 ), were isolated from the seed residue of Hippophae rhamnoides Linn . subsp. sinensis Rousi . Their structures were determined by spectroscopic means. The results show that compounds 1 and 2 are (E/Z)‐isomers, compound 3 , a pyridoindole alkaloid concerted with γ‐lactam ring.     

Phenolics with antiviral activity from Millettia erythrocalyx and Artocarpus lakoocha

From the leaves of Millettia erythrocalyx, a new flavone named 3',5'-dimethoxy-[2",3": 7,8]-furanoflavone and three known compounds were isolated. Assays for anti-herpes simplex virus activity (HSV-1 and HSV-2) were performed on 24 phenolic compounds obtained from M. erythrocalyx and Artocarpus lakoocha. It was found that the flavones ovalifolin, pongol methyl ether and millettocalyxin A, and the stilbene oxyresveratrol possessed moderate activity against both types of HSV. In addition, oxyresveratrol was evaluated for potential anti-HIV activity against a wild-type human immunodeficiency virus type 1 (HIV-1/LAI) isolate and was found to be a modest inhibitor of HIV (EC50 28.2 microM), showing no toxicity in PBM, CEM and Vero cells at 100 microM. The heartwood of A. lakoocha, which contains a large amount of oxyresveratrol, could be considered as a source of starting material for the development of new natural product-based anti-HSV and anti-HIV agents.     

Steroidal saponins from the roots of Smilax aspera subsp. mauritanica

Two new steroidal saponins (1, 2) were isolated from the roots of Smilax aspera subsp. mauritanica (POIR.) ARCANG. (Liliaceae), together with the known curillin G (3), asparagoside E (4), asparoside A (5), asparoside B (6) and the phenolic compound resveratrol (7). Their structures were established mainly on the basis of 600 MHz 2D-NMR spectral data. 3 exhibited antifungal activity against the human pathogenic yeasts Candida albicans, C. glabrata and C. tropicalis (minimum inhibitory concentrations of 25, 25 and 50 microg/ml, respectively) whereas the other compounds were inactive.     

A novel dimeric flavonol glycoside from Cynanchum acutum subsp. sibiricum

A novel dimeric flavonol glycoside, Cynanflavoside A (1), together with six analogues, kaempferol-3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (2), quercetin-3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (3), kaempferol-3-O-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranoside (4), quercetin-3-O-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranoside (5), kaempferol-3-O-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside (6), and quercetin-3-O-galactoside (7) were isolated from the n-butyl alcohol extract of Cynanchum acutum subsp. sibiricum. Their structures were determined spectroscopically and compared with previously reported spectral data. All compounds were evaluated for their anti-complementary activity in vitro, and only compound 5 exhibited anti-complement effects with CH₅₀ value of 0.33 mM.     

Chemical Constituents and Biological Activities of the Leaves of Knema saxatilis

Chemistry of Natural Compounds -     

Phenolics and plant allelopathy

Phenolic compounds arise from the shikimic and acetic acid (polyketide) metabolic pathways in plants. They are but one category of the many secondary metabolites implicated in plant allelopathy. Phenolic allelochemicals have been observed in both natural and managed ecosystems, where they cause a number of ecological and economic problems, such as declines in crop yield due to soil sickness, regeneration failure of natural forests, and replanting problems in orchards. Phenolic allelochemical structures and modes of action are diverse and may offer potential lead compounds for the development of future herbicides or pesticides. This article reviews allelopathic effects, analysis methods, and allelopathic mechanisms underlying the activity of plant phenolic compounds. Additionally, the currently debated topic in plant allelopathy of whether catechin and 8-hydroxyquinoline play an important role in Centaurea maculata and Centaurea diffusa invasion success is discussed. Overall, the main purpose of this review is to highlight the allelopacthic potential of phenolic compounds to provide us with methods to solve various ecology problems, especially in regard to the sustainable development of agriculture, forestry, nature resources and environment conservation.     

Mentha longifolia subsp. typhoides and subsp. schimperi: Antimicrobial and Antiquorum-Sensing Bioactivities

Chemistry of Natural Compounds -