Three Australian Lepidosperma Labill. Species as sources of prenylated and oxyprenylated derivatives of piceatannol, resveratrol and pinosylvin: Melatoninergic binding and inhibition of quinone reductase 2.

Prenylated and hydroxyprenylated piceatannol, resveratrol and pinosylvin derivatives were isolated from resin produced by three Australian Lepidosperma Labill. Species (Cyperaceae). From L. congestum R.Br. one known compound, 3',5'-bis-prenyl-E-resveratrol, and five undescribed compounds were isolated, 3'-O-prenyl-5'-prenyl-E-piceatannol, 5',6'-bis-prenyl-E-piceatannol, 5'-prenyl-E-piceatannol, 3',5'-bis(3-hydroxy-3-methylbutyl)-E-resveratrol and 3',5'-bis-E-hydroxyprenyl-E-resveratrol. From L. gunnii Boeckeler one undescribed compound was isolated, 3'-E-hydroxyprenyl-5'-Z-hydroxyprenyl-E-resveratrol. From L. laterale R.Br. six undescribed compounds were isolated, 3-O-prenyl-E-pinosylvin, 3-O-Z-hydroxyprenyl-E-pinosylvin, 3'-Z-hydroxyprenyl-E-resveratrol, 3-O-Z-hydroxyprenyl-E-resveratrol, 3-O-Z-hydroxyprenyl-4'-O-methyl-E-resveratrol, and 3-O-prenyl-3'-δ,δ'-dihydroxyprenyl-E-resveratrol. Compounds, including a reference compound 3-O-prenyl-3'-O-methyl-E-piceatannol, were screened in an assay for melatoninergic binding to MT1 and MT2 receptors and binding to QR2/MT3 enzyme, and for inhibition of QR2/MT3 in a functional assay. Strong binding was observed for 3-O-Z-hydroxyprenyl-E-resveratrol with a Ki of 0.022 nM and the strongest inhibition of QR2/MT3 observed was for the reference compound, 3-O-prenyl-3'-O-methyl-E-piceatannol, with an inhibition of 61% at 1 µM and 95% at 10 µM. The three most active binders and inhibitors of QR2/MT3 were found to have a common substructure corresponding to 3-O-prenylresveratrol.

Kangaroo Island propolis types originating from two Lepidosperma species and Dodonaea humilis.

The endemic Australian plants Lepidosperma sp. Flinders Chase (Cyperaceae), Lepidosperma viscidum (Cyperaceae) and Dodonaea humilis (Sapindaceae) were found to be the botanical origin of three propolis types found on Kangaroo Island identified by TLC and 1H NMR matching of propolis and plant resin analytical profiles. Resin samples extracted from the plant, Lepidosperma sp. Flinders Chase, were chromatographically fractionated to give: methyl 3-phenyl-2-(E-cinnamoyloxy)propanoate (1), 3-(E-8-methoxy-8-oxo-3,7-dimethyloct-2-enyl)-4-hydroxy-E-cinnamic acid (2), 3-(E-6,7-dihydroxy-3,7-dimethyloct-2-enyl)-4-hydroxy-E-cinnamic acid (3), previously undescribed; and the known stilbenes, 2-prenyl-3,5-dihydroxy-E-stilbene (6) and 2-prenyl-3-methoxy-5-hydroxy-E-stilbene (7). The resin from L. viscidum gave: 5'-(E-4-hydroxy-3-methylbut-2-enyl)-4,2',4'-trihydroxydihydrochalcone (4); 5'-(E-4-hydroxy-3-methylbut-2-enyl)-4'-methoxy-4,2'-dihydroxydihydrochalcone (5), previously undescribed; and three known flavanones, farrerol (8), 5,7,3',5'-tetrahydroxy-6,8-dimethylflavanone (9) and 5,7,3',5'-tetrahydroxy-6-methylflavanone (10). The major constituent in the propolis identified as being sourced from D. humilis was identified as 6,8-diprenyl-5,7,3',4'-tetrahydroxyflavanone (11), a known compound identified in several unrelated plant species.

A sedge plant as the source of Kangaroo Island propolis rich in prenylated p-coumarate ester and stilbenes.

Propolis samples from Kangaroo Island, South Australia, were investigated for chemical constituents using high-field nuclear magnetic resonance spectral profiling. A type of propolis was found containing a high proportion of prenylated hydroxystilbenes. Subsequently, the botanical origin of this type of propolis was identified using a beehive propolis depletion method and analysis of flora. Ligurian honey bees, Apis mellifera ligustica Spinola, were found to produce propolis from resin exuded by the Australian native sedge plant Lepidosperma sp. Montebello (Cyperaceae). The plants, commonly known as sword sedge, were found to have resin that matched with the propolis samples identified as the most abundant propolis type on the island containing C- and O-prenylated tetrahydroxystilbenes (pTHOS) in addition to a small amount of prenylated p-coumarate. The isolation of five pTHOS not previously characterized are reported: (E)-4-(3-methyl-2-buten-1-yl)-3,4',5-trihydroxy-3'-methoxystilbene, (E)-2,4-bis(3-methyl-2-buten-1-yl)-3,3',4',5-tetrahydroxystilbene, (E)-2-(3-methyl-2-buten-1-yl)-3-(3-methyl-2-butenyloxy)-3',4',5-trihydroxystilbene, (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,3',5,5'-tetrahydroxystilbene and (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,4',5-trihydroxy-3'-methoxystilbene. A National Cancer Institute 60 human cell line anticancer screen of three of these compounds showed growth inhibitory activity. The large Australasian genus Lepidosperma is identified as a valuable resource for the isolation of substances with medicinal potential.

An Investigation of the Differential Effects of Ursane Triterpenoids from Centella asiatica, and Their Semisynthetic Analogues, on GABAA Receptors.

The ursane triterpenoids, asiatic acid 1 and madecassic acid 2, are the major pharmacological constituents of Centella asiatica, commonly known as Gotu Kola, which is used traditionally for the treatment of anxiety and for the improvement of cognition and memory. Using the two-electrode voltage-clamp technique, these triterpenes, and some semisynthetic derivatives, were found to exhibit selective negative modulation of different subtypes of the GABAA receptor expressed in Xenopus laevis oocytes. Despite differing by only one hydroxyl group, asiatic acid 1 was found to be a negative modulator of the GABA-induced current at α1 ß2 γ2L, α2 ß2 γ2L and α5 ß3 γ2L GABAA receptors, while madecassic acid 2 was not. Asiatic acid 1 exhibited the greatest effect at α1 ß2 γ2L (IC50 37.05 µm), followed by α5 ß3 γ2L (IC50 64.05 µm) then α2 ß2 γ2L (IC50 427.2 µm) receptors. Conversion of the carboxylic acid group of asiatic acid 1 to a carboxamide group (2α,3ß,23-trihydroxy-urs-12-en-28-amide 5) resulted in enhanced inhibition at both the α1 ß2 γ2L (IC50 14.07 µm) and α2 ß2 γ2L receptor subtypes (IC50 28.41 µm). The results of this study, and the involvement of α5 -containing GABAA receptors in cognition and memory, suggest that asiatic acid 1 may be a lead compound for the enhancement of cognition and memory.

The Differential Effects of Resveratrol and trans-ε-Viniferin on the GABA-Induced Current in GABAA Receptor Subtypes Expressed in Xenopus Laevis Oocytes.

PURPOSE: The natural products resveratrol and trans-ε-viniferin have been reported to have many beneficial effects, which include the enhancement of cognition and memory. There have been no studies which have reported the effects of these compounds on the different GABAA receptor subtypes and this study aimed to address this. METHODS: The effects of both resveratrol, and its dimer, trans-ε-viniferin, have been investigated on different GABAA receptor subtypes expressed in Xenopus laevis oocytes, using the two-electrode voltage clamp technique. RESULTS: Resveratrol induced a current of 22 ± 3.53 nA in the α1ß2γ2L subtype of the GABAA receptor (but not in the α5ß3γ2L and α2ß2γ2L subtypes) when applied alone. It also positively modulated the GABA-induced current (IGABA) in α1ß2γ2L receptors, in adose-dependent manner (EC50 58.24 µM). The effects of resveratrol were not sensitive to the benzodiazepine antagonist flumazenil. trans-ε-Viniferin exhibited a different pattern of activity to resveratrol; it alone had no effect on any of the subtypes, but it did negatively modulate the GABA-induced current (IGABA) in all three subtypes. The greatest inhibition was found in the α1ß2γ2L subtype (IC50 5.79 µM), with the inhibition in the α2ß2γ2L (IC50 of 19.08 µM) and α5ß3γ2L (IC50 of 21.05 µM) subtypes being similar. The effects of trans-ε-viniferin in α1ß2γ2L and α2ß2γ2L receptors werealso not sensitive to the benzodiazepine antagonist flumazenil while, in the α5ß3γ2L subtype the effect was not sensitive to the inverse agonist L-655,708, indicating different binding sites for this molecule. CONCLUSIONS: The results of the present study indicate that both resveratrol and trans-ε-viniferin modulate the GABA-induced current in different ways, and that trans-ε-viniferin may be a lead compound for the discovery of agents which selectively inhibit the GABA-induced current in α1-containing subtypes.This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Tetracyclic triterpenoids in herbal medicines and their activities in diabetes and its complications.

Tetracyclic triterpenoids, including the dammarane, cucurbitane, cycloartane, lanostane and protostane groups, is a class of triterpenoids widely distributed in various medicinal plants, particularly those commonly used for the treatment of diabetes and its complications, such as Panax ginseng, Panax quinquefolium, Panax notoginseng, Gynostemma pentaphyllum, Astragalus membranaceus, Momordica charantia, and Ganoderma lucidum. This review highlights recent findings on the chemistry and bioactivities of tetracyclic triterpenoids from these plants and other popular herbal medicines.

Anti-bacterial activity and brine shrimp lethality bioassay of methanolic extracts of fourteen different edible vegetables from Bangladesh.

OBJECTIVE: To investigate the antibacterial and cytotoxic activity of fourteen different edible vegetables methanolic extract from Bangladesh. METHODS: The antibacterial activity was evaluated using disc diffusion assay method against 12 bacteria (both gram positive and gram negative). The plant extracts were also screened for cytotoxic activity using the brine shrimp lethality bioassay method and the lethal concentrations (LC50) were determined at 95% confidence intervals by analyzing the data on a computer loaded with "Finney Programme". RESULTS: All the vegetable extracts showed low to elevated levels of antibacterial activity against most of the tested strains (zone of inhibition=5-28 mm). The most active extract against all bacterial strains was from Xanthium indicum which showed remarkable antibacterial activity having the diameter of growth inhibition zone ranging from 12 to 28 mm followed by Alternanthera sessilis (zone of inhibition=6-21 mm). All extracts exhibited considerable general toxicity towards brine shrimps. The LC50 value of the tested extracts was within the range of 8.447 to 60.323 µg/mL with respect to the positive control (vincristine sulphate) which was 0.91 µg/mL. Among all studied extracts, Xanthium indicum displayed the highest cytotoxic effect with LC50 value of 8.447 µg/mL. CONCLUSIONS: The results of the present investigation suggest that most of the studied plants are potentially good source of antibacterial and anticancer agents.

Studies of lipid profile, liver function and kidney function parameters of rat plasma after chronic administration of "Sulavajrini Vatika".

The successful use of Ayurvedic medicines is for many years but there is no guideline for studying the toxicity of these preparations through preclinical or clinical investigations. The present study was conducted to evaluate the effect of conventionally prepared Sulavajrini Vatika (SBB), an Ayurvedic formulation on various biochemical parameters of experimental animals after chronic administration. The animal used was albino rats (Rattus norvegicus: Sprague-Dawley strain) and SBB was administered orally at a single dose of 100 mg kg(-1) b.wt. day(-1), up to 62 days. During the study, forty rats, equally of both sexes, were randomly grouped into four where one male and one female group were used as control and other groups were used as test. Among the lipid components, Triglyceride (TG) was decreased very high significantly in both sexes of animal. The decrease of Total Cholesterol (TC), Very Low Density Lipoprotein (VLDL) and high-density lipoprotein (HDL) were also highly significant. Low Density Lipoprotein (LDL) decreased in all SBB treated group. In the liver function parameters, the total protein and albumin content were increased very high significantly in both sexes of rat. But the bilirubin was decreased insignificantly in male and female rats. Serum Glutamic Pyruvic Transaminase (GPT), Glutamic Oxaloacetic Transaminase (GOT) and Alkaline Phosphatase (ALP) were decreased in all treated animals and it was very high significant. In case of kidney function parameters, creatinine was increased very high significantly but the urea was decreased very high significantly in both sexes of rat. The decrease in uric acid was not significant in none of the sexes of rat. The present study confirms that SBB can be contributory for the complications in diabetics with hyperlipidemia and nephropathy as it lowers most of the lipids components and improves liver function and kidney function parameters.