Inhibitory effect of Ipomoea aquatica extracts on glucose absorption using a perfused rat intestinal preparation.

Investigations were carried out to evaluate the effect of Ipomoea aquatica aqueous and dichloromethane/methanol extracts on the glucose absorption using a rat intestinal preparation in situ. Extracts orally tested at the dose of 160 mg/kg exerted a significant inhibitory effect on glucose absorption when compared with control animals. The most pronounced effect was observed with the aqueous extract. Ouabain used as reference inhibitor strongly inhibited glucose absorption. On the other hand both plant extracts inhibited the gastrointestinal motility suggesting that the inhibition of glucose absorption is not due to the acceleration of intestinal transit.

Antimicrobial activity of the methanolic extract from the stem bark of Tridesmostemon omphalocarpoides (Sapotaceae).

The methanolic extract and fractions from the stem bark of Tridesmostemon omphalocarpoides were investigated for their in vitro antimicrobial properties as well as their phytochemical constituents. The stem bark was collected from Yaoundé, in the Centre Province of Cameroon. The antimicrobial activity of the extract and fractions against two Candida species and seven aerobic bacteria was evaluated on the basis of the inhibition zones (IZ) using agar hole diffusion method, the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC) by the macrodilution method. The results indicated significant anticandidal and antibacterial effect of the methanolic extract and fractions against all the nine microorganisms tested. Preliminary phytochemical analysis of methanolic extract showed the presence of biologically active components namely alkaloids, steroids, tannins, saponins, phenols, polyphenols and flavonoids. The acute toxicity of the methanolic extract was also studied. This was found to be non-toxic to the inbred Wistar rats treated per os. The results of this study suggested that the stem bark of this plant could be safely used in the treatment of some infectious diseases.

Securidacaxanthone A, a heptaoxygenated xanthone from Securidaca longepedunculata.

From the root bark of Securidaca longepedunculata, a heptaoxygenated xanthone (1) has been isolated as well as two known xanthones (2) and (3) and two salicylic acid derivatives (4) and (5). The structure of 1 has been elucidated from 1H and 13C-NMR spectral data.

Bangangxanthone A and B, two xanthones from the stem bark of Garcinia polyantha Oliv.

Two xanthones, bangangxanthone A (1) [1,5,8-trihydroxy-6'-methyl-6'-(4-methylpent-3-enyl)- pyrano[2',3':3,4]xanthone] and B (2) [1,4,8-trihydroxy-2-prenylxanthone], along with two known xanthones, 1,5-dihydroxyxanthone, 2-hydroxy-1,7-dimethoxyxanthone and the pentacyclic triterpenoids, friedelin, oleanolic acid and lupeol were isolated from the chloroform extract of the stem bark of Garcinia polyantha. The structures of these compounds were assigned by spectroscopic analysis. Compounds 1-4 showed antioxidant DPPH radical scavenging activities.

Antibacterial triterpenes from Syzygium guineense (Myrtaceae).

Antibacterial bioassay-guided fractionation of Syzygium guineense leaf extracts afforded 10 triterpenes, namely betulinic acid 1, oleanolic acid 2, a mixture of 2-hydroxyoleanolic acid 3a, 2-hydroxyursolic acid 3b, arjunolic acid 4a, asiatic acid 4b, a mixture of terminolic acid 5a, 6-hydroxyasiatic acid 5b, and a mixture of arjunolic acid 28-beta-glucopyranosyl ester 6a and the asiatic acid 28-beta-glucopyranosyl ester 6b. Isolated compounds were submitted to an antibacterial assay system against gram-positive and -negative bacteria and human pathogen bacteria. Compounds 4a and 4b showed the most significant antibacterial activity against Escherichia coli, Bacillus subtilis and Shigella sonnei. The fraction 5a-5b was the least active, whereas compounds 1, 2 and the mixtures of 3a-3b and 6a-6b were inactive in the assays.

New isoflavones from Ceiba pentandra.

Two new isoflavones, pentandrin (1) and pentandrin glucoside (2), were isolated from the stem barks of Ceiba pentandra along with beta-sitosterol and its 3-O-beta-D-glucopyranoside, which was isolated for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic techniques, while the structure of 1 was unambiguously confirmed by single-crystal X-ray diffraction studies.

Fontaineine, a new alkaloid from fontainea pancheri

A new guanidine-type alkaloid, fontaineine (1), was isolated from the leaves of Fontainea pancheri and its structure elucidated by 2D NMR.

Protective role of Anacardium occidentale extract against streptozotocin-induced diabetes in rats.

The protective effect of Anacardium occidentale aqueous extract against streptozotocin-induced diabetes was evaluated in rats. The rats were treated with 175 mg/kg of the extract per os, twice daily; beginning 2 days before streptozotocin (STZ) injection. A total of 3 days after STZ administration, there was a 48% increase in blood glucose level in pretreated rats, compared with a 208% increase in diabetic control rats treated with STZ alone. Furthermore, these pretreated animals presented no glycosuria, a normal weight gain and a non significant increase in food and fluid intake at the end of the treatment compared with the normal control. Diabetic control animals showed a positive glycosuria, body weight loss, a real polyphagia and polydypsia. These results indicate the protective role of Anacardium occidentale extract against the diabetogenic action of STZ.

In vitro antifungal activity of extract and plumbagin from the stem bark of Diospyros crassiflora Hiern (Ebenaceae).

In this study the methanol/dichloromethane (1:1) extract and plumbagin isolated from extract of stem barks of Diospyros crassiflora were tested for their antifungal activity against 12 strains of yeast pathogens and filamentous fungi: Candida albicans, Candida glabrata, Candida krusei, Candida tropicalis, Cryptococcus neoformans, Aspergillus niger, Aspergillus flavus, Alternaria sp., Cladosporium sp., Geotrichum candidum, Fusarium sp. and Penicillium sp. The growth of all fungi strains tested was inhibited by the extract and plumbagin. The diameter of inhibition zones varied from 12 to 18 mm and from 21 to 35 mm for the extract and plumbagin, respectively. The MIC values ranged from 12.5 to 25 mg/mL for the extract and 0.78-3.12 microg/mL for plumbagin. It is therefore suggested that extracts from the stem bark of Diospyros crassiflora could be used traditionally in the treatment of fungal infections. Compared with ketoconazole used as a standard antifungal, plumbagin could be considered as a promising antifungal agent.

Hypotensive effects of some extracts of the leaves of Musanga cecropioides (Cecropiaceae). Studies in the cat and the rat.

Intravenous administration of 0.1-0.4 ml of a 35mg/ml stock solution of an aqueous leaf extract of Musanga cecropioides (MC) lowered the blood pressure of both normotensive and spontaneously hypertensive rats and that of the cat. (P<0.01; n=5). In indirect (tail-cuff) blood pressure trials, oral administration of 2 ml of 35 mg/ml stock solution of MC also produced a hypotensive response. The hypotensive effect was species dependent, being more pronounced in the rat and non-specific in the cat. The n-butanol extract of the original aqueous extract, consisting of mostly saponins as revealed by phytochemical studies also exhibited hypotensive effects in the rat and cat. These effects of MC were comparable with those of acetylcholine(Ach) and were antagonised by atropine (1 mg/ml).

Myrianthiphyllin, The First Lignan Cinnamate from Myrianthus arboreus.

Studies of the methylated ethyl acetate extract of the trunk wood of MYRIANTHUS ARBOREUS (Cec-ropiaceae) have resulted in the isolation of five known pentacyclic triterpenes and a new lignan cinnamate. The structural elucidation of the new compound has been effected on grounds of the interpretation of spectroscopic data and alkaline hydrolysis.

Further Triterpenoids of Musanga cecropioides: The Structure of Cecropic Acid.

Six pentacyclic triterpenic acid methyl esters have been isolated from the methylated ethyl acetate extract of the trunk wood of MUSANGA CECROPIOIDES, as well as a triterpene saponin of the same group. One of them, cecropic acid methyl ester, is new. The structures of these compounds have been established from interpretation of spectral data or chemical transformations. The known triterpenes include euscaphic and tormentic acid methyl esters, already isolated from the root wood of the plant, methyl cecropiaceate, and methyl pomolate, already obtained from the stem bark, and methyl arjunolate and beta- D-glucosyl tormentate, encounted in this plant for the first time.

Kalaic acid, a new ursane-type saponin from Musanga cecropioides.

Six pentacyclic triterpenes were isolated from the methylated stembark polar extracts of Musanga cecropioides. One of them, methyl kalaate, is a new saponin. The known compounds were methyl ursolate, methyl oleanolate, methyl 2alpha-hydroxyursolate, methyl 2alpha-hydroxyoleanolate, and methyl pomolate. Their structures have been elucidated from 2D-NMR spectroscopic data. A complete (1)H- and (13)C-NMR spectral assignment of methyl pomolate as well as those of the new saponin have been achieved from 2D-COSY.

New antioxidant and antimicrobial ellagic acid derivatives from Pteleopsis hylodendron.

Bioassay-guided isolation of two new compounds, 3,4-methylenedioxy-3'-O-methyl-4'-O-glucoside ellagic acid (1) and the pteleoellagic acid derivative (2), from the stem bark of Pteleopsis hylodendron is reported along with 3,4-methylenedioxy-3'-O-methyl ellagic acid (3), 3,3'-di-O-methyl ellagic acid (4) and 3,3',4'-tri-O-methyl ellagic acid (5), which were obtained for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic studies. Compounds 1 and 4 were found to have significant antioxidant activity, while compounds 1-4 showed antibacterial activity against different pathogenic bacteria.