Aqueous Methanol Fractions Research Articles

Anti-Hyperglycemic Activity of Kiwifruit Leaf (Actinidia deliciosa) in Mice

The methanol extract of kiwifruit leaf suppressed the postprandial blood glucose level after an oral administration of soluble starch or sucrose in mice. The mechanism of action is proposed to be due to the alpha-amylase-inhibiting activity in the 90% aqueous methanol fraction and alpha-glucosidase-inhibiting activity in the n-buthanol fraction, based on the results of in vitro experiments.

Extracts of Momordica charantia Suppress Postprandial Hyperglycemia in Rats

Momordica charantia (bitter melon) is commonly known as vegetable insulin, but the mechanisms underlying its hypoglycemic effect remain unclear. To address this issue, the effects of bitter melon extracts on postprandial glycemic responses have been investigated in rats. An aqueous extract (AE), methanol fraction (MF) and methanol insoluble fraction (MIF) were prepared from bitter melon. An oral sucrose tolerance test revealed that administration of AE, MF or MIF each significantly suppressed plasma glucose levels at 30 min as compared with the control. In addition, the plasma insulin level at 30 min was also significantly lower after MF administration than in the control in the oral sucrose tolerance test. By contrast, these effects of bitter melon extracts were not observed in the oral glucose tolerance test. In terms of mechanism, bitter melon extracts dose-dependently inhibited the sucrase activity of intestinal mucosa with IC(50) values of 8.3, 3.7 and 12.0 mg/mL for AE, MF and MIF, respectively. The fraction with a molecular weight of less than 1,300 (LT 1,300) obtained from MF inhibited the sucrase activity most strongly in an uncompetitive manner with an IC(50) value of 2.6 mg/mL. Taken together, these results demonstrated that bitter melon suppressed postprandial hyperglycemia by inhibition of alpha-glucosidase activity and that the most beneficial component is present in the LT 1,300 fraction obtained from MF.

Brine shrimp lethality and antimicrobial studies on the seeds of <i>Garcinia kola</i> (Heckel)

Garcinia kola (Family, Guttiferae) is employed in a variety of therapies ranging from skin, gastrointestinal, chest to tumour problems. Preparations of the stem and roots are used as antitumour in traditional medicine but the potential of the seeds as antitumour had not yet been investigated hence the brine-shrimp lethality and as well as the antimicrobial studies on the seed were carried out. The crude ethanolic extract and methanol fraction elicited good antibacterial activity against S. aureus, B. subtilis and, to some extent, E. coli but gave minimal activity against Ps. Aeruginosa and none against fungal isolates (Aspergillus spp and C. albicans). The brine shrimp lethality assay, analysed using the Finney probit method, showed that the aqueous and crude ethanolic extracts and methanol fraction displayed ‘marginal' LD50 values at 565ppm, 349ppm and 316ppm respectively compared with literature values below 200ppm which are generally considered “significant”. These findings indicate the potential of the seeds as panacea for infectious ailments and therefore scientific justification to some of the folkloric uses of the plant. Key words: Brine-shrimp lethality; Antimicrobial; Seeds; Garcinia kola Journal of Pharmacy and Bioresources Vo. 2 (1) 2004: 29-35

Effects of Rikkunshi-to, a Traditional Japanese Medicine, on the Delay of Gastric Emptying Induced by NG-Nitro-L-arginine

We evaluated the effects of Rikkunshi-to and several of its ingredients on the delay of gastric emptying induced by a nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine (L-NNA). After oral administration of L-NNA to rats, the gastric emptying rate at 24 h was decreased from 82.8 ± 2.4% to 53.3 ± 5.7%. The decrease of the gastric emptying rate induced by L-NNA treatment was markedly ameliorated by administration of Rikkunshi-to (250 and 500 mg/kg, p.o.) in a dose-dependent manner. To identify the active ingredient of Rikkunshi-to, the components were separated according to polarity, and the effects of the respective fractions on gastric emptying were evaluated. Significant efficacy was found in the water and methanol fractions, but not in the 50% aqueous–methanol fraction. Furthermore, hesperidin (1 – 4.29 mg/kg, p.o.) contained in the methanol fraction and L-arginine (4.5 mg/kg, p.o.) contained in the water fraction ameliorated the decrease in the gastric emptying rate induced by L-NNA treatment. These results suggest that Rikkunshi-to ameliorated abnormalities of NO-mediated gastric functions such as delayed gastric emptying, and hesperidin and L-arginine were identified as two of the active ingredients contributing to the ability of Rikkunshi-to to facilitate gastric emptying.

Effects of the extract of the bark of Magnolia obovata and its biphenolic constituents magnolol and honokiol on histamine release from peritoneal mast cells in rats.

We have previously reported that saiboku-to, an Oriental herbal remedy composed of a mixture of 10 different herbal extracts, possesses anti-histamine release effect on mast cells in rats. This effect may be due mainly to the extract of the bark of Magnolia obovata (M. obovata), a constituent herb of saiboku-to. In the present study, it was demonstrated that the bark extract inhibited compound 48/80 (C48/80)-induced histamine release from mast cells in a concentration-dependent manner (50 % inhibitory concentration, IC(50) = 56.98 microg/ml). Furthermore, the inhibitory activity was found in the methanol fraction, but not in water and 50 % aqueous methanol fractions derived from the bark extract. Magnolol and honokiol isolated from the methanol fraction inhibited C48/80-induced histamine release from mast cells. The potency of magnolol (IC(50) = 1.04 microg/ml) was greater than that of honokiol (IC(50) = 2.77 microg/ml). Furthermore, the actual amount of magnolol (49.76 +/- 1.14 mg) contained in the bark of M. obovata (5 g) was greater than that (8.58 +/- 0.19 mg) of honokiol. Taken together, the present results suggest that magnolol may be responsible for the biological efficacy of the bark extract of M. obovata.

Isolation of new bioactive annonaceous acetogenins from Rollinia mucosa guided by liquid chromatography/mass spectrometry

Reversed-phase high-performance liquid chromatography (RP-HPLC) fractionation, monitored by liquid chromatography/electrospray mass spectrometry (LC/ESI-MS), led to the isolation of two new bioactive annonaceous acetogenins, rollidecin C (1) and rollidecin D (2), from the bioactive aqueous methanol fraction of the leaves of Rollinia mucosa (Annonaceae). The structures were confirmed by analyses of the 1H and 13C NMR data. In addition, a known adjacent bis-tetrahydrofuran (THF) acetogenin, desacetyluvaricin (3), was isolated from this plant for the first time utilizing the LC/ESI-MS monitoring approach. Compound 1 exhibited selective cytotoxicity toward the colon tumor cell line (HT-29), while 2 showed only borderline cytotoxicity in a panel of six human tumor cell lines.

Nutrition of the temperate Australian soft coral Capnella gaboensis

Capnella gaboensis Verseveldt, 1977 (Coelenterata: Octocorallia: Alcyonacea: Nephtheidae) is an abundant soft coral in the temperate waters of south-eastern Australia. From 1981 to 1984, using material collected from Sydney Harbour (33°50′S; 151°15′E), we investigated certain aspects of its apparently obligate association with its symbiotic zooxanthellae, Symbiodinium sp. Numbers of zooxanthellae and chlorophyll content were recorded throughout the first year, then net photosynthesis and respiratory rates of the coral as a function of photo-flux densities, temperature and season were measured in later years. The fractions into which photosynthetically fixed carbon was incorporated were also determined. The zooxanthellae contained a mean of 4.1 μg chlorophyll a 10-6 zooxanthellae. Neither the numbers of zooxanthellae in C. gaboensis nor the chlorophyll a content varied on a seasonal basis. Photon-flux densities in the field ranged from 5 to 120 μE m-2 s-1 over the year. The maximum net oxygen-exchange rate recorded for C. gaboensis was 9.4 μmol O2 mg-1 chlorophyll a h-1 at 871 μE m-2 s-1. The maximum carbon fixation rate obtained was 65.6 μmol C mg-1 chlorophyll a h-1 at 100 μE m-2 s-1. Photosynthesis of C. gaboensis was not light-saturated at 871 μE m-2 s-1; the light compensation point was in the range 50 to 90 μE m-2 s-1 and the optimum temperature was 25°C. Photosynthetic rates were highest in populations sampled in summer. Labelling with 14C showed that photosynthetically fixed carbon was initially incorporated into the aqueous-methanol (low molecular weight) fraction of the coral tissues. From 20 to 100 min after the introduction of the 14C label the rate of incorporation was fairly evenly divided between the aqueous methanol-soluble, the chloroform-soluble (lipid) and the insoluble fractions. In the light, little 14C was released as particulate and/or dissolved organic carbon. Translocation of products of photosynthesis represented up to approximately 10% of the total fixation.

Feeding behaviour in adult rainbow trout and Atlantic salmon parr, elicited by chemical fractions and mixtures of compounds identified in shrimp extract

A bio-assay method was used to assess the feeding response of adult rainbow trout, Salmo gairdneri R., and Atlantic salmon parr, Salmo salar, to chemical fractions and mixtures of compounds identified and quantified in an aqueous extract of shrimp. Purified agar was flavoured with (A) aqueous extract, (B) methanol fraction, (C) basic/amphoteric faction, (D) acidic fraction, (E) neutral fraction, (F) no flavouring, (G) amino acids, (H) nucleotides, (I) adenosine, inosine, hypoxanthine, creatine and glucose, (J) trimethylamine, trimethylamineoxide, glycine betaine, and homarine. Each gel was presented over a short-term feeding period and observations were made of the number of gel pieces swallowed, the number of gel pieces ejected and other behaviour patterns associated with feeding, e.g, increased activity and “tasting”. The results indicate that both species found A and B to be the most palatable whereas E and F were the least palatable (as measured by number of swallows and number of pieces ejected). The rainbow trout ate almost all the gels presented whereas the salmon parr ate only A and B. The various fractions and chemical mixtures were rated as feeding stimulants, incitants and deterrents on the basis of the behavioural data recorded for each species and the classification of Lindstedt (1971).