Bioactivity-guided isolation of the active compounds from Rosa nutkana and quantitative analysis of ascorbic acid by HPLC.

Rosa nutkana Presl. (Rosaceae) is distributed abundantly throughout central and southern areas of British Columbia, Canada. Aboriginal people in the Pacific Northwest have traditionally used R. nutkana as a food, medicine, and source of cultural material. The methanolic extract of the fruits of R. nutkana was previously found to have inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA). In our study, bioactivity-guided fractionation of the methanol extract from R. nutkana led to the isolation of the following 10 compounds: (i) tormentic acid, (ii) euscaphic acid, (iii) ursolic acid, (iv) maslinic acid, (v) quercetin, (vi) catechin gallate, (vii) quercetin-3-O-glucoside, (viii) 1,2,3,4,6-penta-O-galloyl-beta-D-glucoside, (ix) L-ascorbic acid (vitamin C), and (x) 1,6-digalloyl-beta-D-glucoside. Structures were elucidated by ultraviolet, infrared, mass spectrometry, and nuclear magnetic resonance data, as well as by comparison with those of the literature. The compounds quercetin, catechin gallate, quercetin-3-O-glucoside, 1,2,3,4,6-penta-O-galloyl-beta-D-glucoside, and 1,6-digalloyl-beta-D-glucoside exhibited weak antibacterial activity against MRSA. Our research demonstrates the value of traditional knowledge held by Aboriginal people in the Pacific Northwest with respect to uses of R. nutkana. Some described uses in the ethnobotanical literature correspond to activities observed under laboratory conditions. Further work on British Columbia Rosa spp. may contribute to identifying other potential therapeutic uses.

Antioxidant and antimicrobial activities of native Rosa sp. from British Columbia, Canada.

Indigenous traditional knowledge and western science have revealed the potential for significant nutritional and therapeutic benefits among natural antioxidants. We investigated antioxidant and antimicrobial activity of rose hip extracts (Rosa nutkana, Rosa pisocarpa and Rosa woodsii) from wild British Columbia populations using liposome oxidation and disc diffusion assays. All extracts exhibited strong antioxidant activity. R. nutkana pericarp extracts contained high phenolic concentrations and showed greater antioxidant and antimicrobial activity than seed extracts. R. woodsii seed extracts had a higher phenolic concentration and greater antioxidant activity than pericarp extracts. Antioxidant activity was correlated with antimicrobial activity, and both extracts showed antimicrobial activity against yeast and Gram-positive bacteria. Our study is the first to demonstrate the antioxidant and antimicrobial properties of wild British Columbia roses. The effectiveness of selected species compared with standards demonstrates the significance of this natural resource to the continued health of human populations, and the need for conservation practices.

Bioactive compounds from Rhodiola rosea (Crassulaceae).

The methanol extract of the underground part of Rhodiola rosea was found to show inhibitory activity against Staphylococcus aureus. Bioactivity-guided fractionation of a 95% ethanol extract from the stems of R. rosea led to the isolation of five compounds: gossypetin-7-O-L-rhamnopyranoside (1), rhodioflavonoside (2), gallic acid (3), trans-p-hydroxycinnamic acid (4) and p-tyrosol (5). Their structures were elucidated by UV, IR, MS and NMR data, as well as by comparison with those of the literature. Compounds 1 and 2 were evaluated for their antibacterial and antiprostate cancer cell activities. Compounds 1 and 2 exhibited activity against Staphylococcus aureus with minimum inhibitory concentrations of 50 microg/mL and 100 microg/mL, respectively. Cytotoxicity studies of 1 and 2 also displayed activity against the prostate cancer cell line with IC(50) values of 50 microg/mL and 80 microg/mL, respectively.

Inhibition of restriction enzyme's DNA sequence recognition by PUVA treatment.

Applying various restriction enzymes on a specially designed 1.5 kb DNA fragment revealed that the inhibitory effects of PUVA treatment on restriction endonuclease activities are caused by recognition inhibition. In this study, Restriction enzymes which have a 5'-TpA sequence at the cleaving site (Kpn I, Xba I, Pme I, and Dra I), and non-cleaving site (Pac I) in recognition sites, or have two 5'-TpA sequences at the recognition site and a non-specific sequence between recognition and cleaving site (BciV I) were inhibited by PUVA treatment. Most of the other restriction enzymes used in this study which do not have a 5'-TpA sequence at their restriction site were not inhibited by PUVA treatment, although a 5'-TpA sequence is located adjacent (Sma I) or very close (BamH I, Sac I and Pst I) to the recognition and cleaving site for them.

Bioactive constituents from Iryanthera megistophylla.

Activity-guided fractionation of the 95% ethanol extract from the stem bark of Iryanthera megistophylla led to the isolation of two new compounds, named megislignan [2,3-dimethyl-4-(4-methoxyphenyl)-6-hydroxynaphthalene] (1) and megislactone [(2R,3R,4R)-3-hydroxy-4-methyl-2-(hexacos-17-enyl)butanolide] (2), along with seven known compounds, grandinolide (3), iryantherin K (4), iryantherin L (5), cinchonain I b (6), cinchonain I a (7), procyanidin B-2 (8), and cinchonain IIa (9). The structures of the new compounds were elucidated by spectral data interpretation. Isolates were evaluated for their antibacterial, antifungal, antiviral, and antiacetylcholinesterase activities.

Anthocyanins protect light-sensitive thiarubrine phototoxins.

Thiarubrines are phototoxic plant pigments that decompose to thiophenes when exposed to sunlight. We investigated the mechanism of thiarubrine photoprotection in Ambrosia chamissonis (Less.) Greene (Asteraceae), which contains high amounts of these chemicals in its stems and leaf petioles. Thiarubrines are compartmentalized in laticifers that are surrounded by anthocyanin-containing cells. When this light-screening sheath was removed and laticifers exposed to light, rapid bleaching of the thiarubrine contents occurred. The leaves and stems of A. chamissonis seedlings were found to contain 10.5+/-6.8 microg/g total anthocyanins, predominantly cyanidin 3-O-(6'-O-malonylglucoside) and cyanidin 3-O-glucoside, while none was detected in roots. To correlate anthocyanin distribution with thiarubrine photoprotection, changes in thiarubrine A and thiophene A levels were measured in seedlings exposed to light. In roots, thiarubrine A levels decreased by 94% after 30 min of irradiation, and thiarubrines were completely absent after 4 h. A concomitant 3-fold increase in thiophene A levels in roots occurred during light exposure. In leaves and stems, thiarubrine A levels did not change appreciably during light exposure, with a nominal increase from 102.8+/-33.1 microg/g FW to 108.4+/-20.7 microg/g FW after 4 h. To confirm their photoprotective function, solutions of cyanidin 3-O-glucoside were used to filter visible light incident on a solution of thiarubrine A. Anthocyanin solutions of greater than 0.1 mM completely prevented thiarubrine photoconversion. This is the first report that anthocyanins function to photoprotect light-sensitive defensive chemicals in plants.

A new compound from Geum rivale L.

A new compound, 1-O-methyl-6-O-caffeoyl-beta-D-glucopyranose (1), has been isolated from the aerial part of G. rivale, together with five known compounds, cecropiacic acid (2), niga-ichgoside (3), gallic acid (4), 1-o-protocatechuoylglucose (5), and sucrose (6). Their structures were elucidated by spectral methods and chemical reactions.

Antimicrobial DNA-binding photosensitizers from the common rush, Juncus effusus.

Our continuing survey of phototoxins from higher plants has led to the isolation and identification from the common rush, Juncus effusus L., of the phenanthrene, dehydroeffusol (1), and the dihydrophenanthrene, juncusol (2), compounds that display enhanced antimicrobial activities in light. The antimicrobial activities (minimum inhibitory concentrations) for these compounds against methicillin-resistant and -sensitive Staphylococcus aureus and Candida albicans were increased 16- and two-fold, respectively, by irradiation with ultraviolet A (UVA). Photosensitized DNA-binding activities (as possible covalent bond formation) of these compounds were determined by using restriction enzymes and a specially prepared 1.5 kb DNA fragment. Under UVA irradiation, dehydroeffusol strongly inhibited all the restriction enzymes (KpnI, XbaI, PmeI, DraI, PacI and BciVI) that have at least one 5'-TpA sequence in their recognition sites. Weak inhibitions were found for the restriction enzymes EcoRI, SacI, BamHI, SalI, PstI and HindIII, which do not possess a 5'-TpA sequence at their restriction sites and the restriction site sequences of which consist of all bases, A, T, G and C. Trace or no inhibition was found for AscI and SmaI, the restriction site sequences of which are composed of only C and G. The results indicate the necessity of thymine (adenine) for the photosensitized DNA-binding activity of dehydroeffusol. A strong inhibition against SphI, which does not have a 5'-TpA sequence in the restriction sequence, indicates that there are possibly other binding sequence(s) for dehydroeffusol. With juncusol and UVA, strong inhibitions for KpnI and BciVI and trace inhibitions for PacI, XbaI, PmeI and DraI were found. This result also showed a preference of juncusol for 5'-TpA, but the preference could be more selective than that of dehydroeffusol depending on the surrounding sequences of 5'-TpA in the respective restriction sites. A strong inhibition of SphI by juncusol with UVA also indicated the existence of an unknown binding sequence for this compound. Generally, the DNA-binding activity of this compound was weaker than that of dehydroeffusol.

Chemical constituents of Ganoderma applanatum of British Columbia forests.

A new compound, ganoderma aldehyde (1),was isolated from the fruiting body of Ganoderma applanatum. Its structure was elucidated on the basis of one-dimensional and two-dimensional NMR as well as MS spectroscopic analysis.

Antifungal activity of benzoic acid derivatives from Piper lanceaefolium.

Bioactivity-guided fractionation of a methanol extract from the leaves of Piper lanceaefolium resulted in the isolation of four new benzoic acid derivatives (1-4), together with taboganic acid, pinocembrin, and pinocembrin chalcone. Lanceaefolic acid methyl ester (3) and pinocembrin chalcone displayed activity against Candida albicans with a minimal inhibitory concentration value of 100 microg/mL in both cases.