Monoterpene indole alkaloids from Vinca minor L. (Apocynaceae): Identification of new structural scaffold for treatment of Alzheimer's disease.

One undescribed indole alkaloid together with twenty-two known compounds have been isolated from aerial parts of Vinca minor L. (Apocynaceae). The chemical structures of the isolated alkaloids were determined by a combination of MS, HRMS, 1D, and 2D NMR techniques, and by comparison with literature data. The NMR data of several alkaloids have been revised, corrected, and missing data have been supplemented. Alkaloids isolated in sufficient quantity were screened for their in vitro acetylcholinesterase (AChE; E.C. 3.1.1.7) and butyrylcholinesterase (BuChE; E.C. 3.1.1.8) inhibitory activity. Selected compounds were also evaluated for prolyl oligopeptidase (POP; E.C. 3.4.21.26), and glycogen synthase 3ß-kinase (GSK-3ß; E.C. 2.7.11.26) inhibition potential. Significant hBuChE inhibition activity has been shown by (-)-2-ethyl-3[2-(3-ethylpiperidinyl)-ethyl]-1H-indole with an IC50 value of 0.65 ± 0.16 µM. This compound was further studied by enzyme kinetics, along with in silico techniques, to reveal the mode of inhibition. This compound is also predicted to cross the blood-brain barrier (BBB) through passive diffusion.

Effect of aqueous extract and anthocyanins of calyces of Hibiscus sabdariffa (Malvaceae) in rats with adenine-induced chronic kidney disease.

OBJECTIVES: The aim of this work was to assess the possible beneficial effects of aqueous extracts of Hibiscus sabdariffa L. calyces and anthocyanins isolated therefrom in an adenine-induced chronic kidney disease (CKD) model. METHODS: Rats were orally given, for 28 consecutive days, either adenine alone or together with either aqueous extract of H. sabdariffa calyces (5 and 10%) or anthocyanins (50, 100 and 200 mg/kg of anthocyanin concentrate). For comparative purposes, two groups of rats were given lisinopril (10 mg/kg). KEY FINDINGS: When either H. sabdariffa aqueous extract or the anthocyanins isolated from it was administered along with adenine, the adverse effects of adenine-induced CKD were significantly lessened, mostly in a dose-dependent manner. The positive effects were similar to those obtained by administration of lisinopril. CONCLUSIONS: The results obtained show that both H. sabdariffa and its anthocyanins could be considered as possible promising safe dietary agents that could be used to attenuate the progression of human CKD. This could have added significance as H. sabdariffa tea is widely consumed in many parts of Africa and Asia and is thus readily available.

Preparation and Validated Analysis of Anthocyanin Concentrate from the Calyces of Hibiscus sabdariffa.

Extracts of Hibiscus sabdarnffa calyces have been shown to have various medicinal properties, some of which have been reported to be due to anthocyanins present in the calyces. To study whether these claims are valid, it is necessary to produce an extract with a high anthocyanin content and to have available a method to identify and quantify the individual compounds in the product. A method of extraction and purification has been developed based on a polyamide column chromatographic purification step. Using this method, anthocyanin concentrates were produced containing from 57 to 64% of delphinidin-3- sambubioside plus cyanidin-3-sambubioside. A rapid, efficient and validated HPLC analytical method was developed and used for the analysis of the anthocyanin concentrate.

Antifungal and Antibacterial Activity of Extracts and Alkaloids of Selected Amaryllidaceae Species.

Alkaloidal extracts of six selected species of Amaryllidaceae were studied with respect to their antibacterial and anti-yeast activity and their alkaloidal fingerprint. Twenty-five alkaloids were determined by GC/MS, and sixteen of them identified from their mass spectra, retention times and retention indexes. In the antimicrobial assay, Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were used, along with isolates of the human pathogenic yeasts Candida albicans, C. glabrata, C. dubliniensis and Lodderomyces elongiosporus. The six extracts, together with 19 Amaryllidaceae alkaloids isolated in our laboratory, showed almost no inhibitory activity against the bacteria tested. However, promising anti-yeast properties were detected; the most potent activity was shown by lycorine, which inhibited C. dubliniensis with a MIC of 32 µg/mL, C. albicans and L. elongiosporus, both with MICs of 64 µg/mL, followed by caranine inhibiting C. dubliniensis with a MIC of 128 µg/mL. Among the alkaloidal extracts, Narcissus jonquilla cv. Baby Moon showed the most potent anti-yeast activity, with minimal and average MIC values of 128 and 192 µg/mL, respectively, followed by Leucojum aestivum, Narcissus poeticus var. recurvus and N. canaliculatus (average MICs 256, 267 and 299 µg/mL, respectively). The lowest MIC value among extracts was obtained for N. canaliculatus against L. elongiosporus (MIC 64 µg/mL).

Isoquinoline alkaloids as prolyl oligopeptidase inhibitors.

Prolyl oligopeptidase is a cytosolic serine peptidase that hydrolyses proline-containing peptides at the carboxy terminus of proline residues. It has been associated with schizophrenia, bipolar affective disorder, and related neuropsychiatric disorders and therefore may have important clinical implications. Thirty-one isoquinoline alkaloids of various structural types, previously isolated in our laboratory, were screened for their ability to inhibit prolyl oligopeptidase. Promising results have been showed by alkaloids californidine (IC50=55.6±3.5 µM), dihydrosanquinarine (IC50=99.1±7.6 µM), corypalmine (IC50=128.0±10.5 µM) and N-methyllaurotetanine (IC50=135.0±11.7 µM).

Chemical composition of bioactive alkaloid extracts from some Narcissus species and varieties and their biological activity.

Alkaloid extracts of eight Narcissus (Amaryllidaceae) species and varieties were studied with respect to their acetylcholinesterase (HuAChE) and butyrylcholinesterase (HuBuChE) inhibitory activity and alkaloid patterns. Thirty alkaloids were determined by GC/MS, and twenty-five of them identified from their mass spectra, retention times and retention indexes. Promising HuAChE inhibition activity was demonstrated by six Narcissus taxa and HuBuChE inhibition by N. jonquila cv. Double Campernelle and N. nanus cv. Elka with IC50 values of 24.1 +/- 1.9 microg/mL and 25.1 +/- 1.8 microg/mL, respectively. Two alkaloids were isolated in pure form using preparative TLC and identified as the galanthamine type alkaloid narwedine and the lycorine type alkaloid incartine. Both compounds were tested for their biological activity. They were considered inactive in HuAChE/HuBuChE assays, but showed promising prolyl oligopeptidase inhibition activities with IC50 values of 0.95 +/- 0.12 mM and 0.91 g 0.09 mM, respectively.

Antimicrobial activity of extracts and isoquinoline alkaloids of selected papaveraceae plants.

Alkaloidal extracts of seven selected plants of the family Papaveraceae were studied with respect to their activity against six strains of pathogenic bacteria and their alkaloidal fingerprint. Twenty-four alkaloids were determined by GC/MS, and twenty of them identified from their mass spectra, retention times and retention indexes. In the antibacterial assay, three Gram-positive (Enterorococcus faecalis, Staphylococcus aureus and S. hyicus), and three Gram-negative (Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa) strains were used. The most promising antimicrobial activity was shown by the alkaloidal extract of Macleaya cordata with MIC values of 16 µg/mL for Staphylococcus aureus, 32 µg/mL for Enterococcus faecalis and 64 µg/mL for Staphylococcus hyicus and Escherichia coli. All the tested pure isoquinoline alkaloids were considered inactive within the tested concentrations.