The development of an efficient mass balance approach for the purity assignment of organic calibration standards.

The purity determination of organic calibration standards using the traditional mass balance approach is described. Demonstrated examples highlight the potential for bias in each measurement and the need to implement an approach that provides a cross-check for each result, affording fit for purpose purity values in a timely and cost-effective manner. Chromatographic techniques such as gas chromatography with flame ionisation detection (GC-FID) and high-performance liquid chromatography with UV detection (HPLC-UV), combined with mass and NMR spectroscopy, provide a detailed impurity profile allowing an efficient conversion of chromatographic peak areas into relative mass fractions, generally avoiding the need to calibrate each impurity present. For samples analysed by GC-FID, a conservative measurement uncertainty budget is described, including a component to cover potential variations in the response of each unidentified impurity. An alternative approach is also detailed in which extensive purification eliminates the detector response factor issue, facilitating the certification of a super-pure calibration standard which can be used to quantify the main component in less-pure candidate materials. This latter approach is particularly useful when applying HPLC analysis with UV detection. Key to the success of this approach is the application of both qualitative and quantitative (1)H NMR spectroscopy.

Assessment of antidiarrhoeal activity of the methanol extract of Xylocarpus granatum bark in mice model.

The methanol extract of Xylocarpus granatum bark was studied for its antidiarrhoeal properties in experimental diarrhoea, induced by castor oil and magnesium sulphate in mice. At the doses of 250 and 500 mg/kg per oral, the methanol extract showed significant and dose-dependent antidiarrhoeal activity in both models. The extracts also significantly reduced the intestinal transit in charcoal meal test when compared to atropine sulphate (5 mg/kg; i.m.). The results showed that the extracts of Xylocarpus granatum bark have a significant antidiarrhoeal activity and supports its traditional uses in herbal medicine.

Triglycerides from Urena lobata.

Two triglycerides, both bearing polyunsaturated fatty acid residues, were isolated from the hexane extract of Urena lobata. One of them is characterized by the presence of three different polyunsaturated fatty acids. Their structures were studied with spectral methods.

Antioxidant and 15-lipoxygenase inhibitory activity of rotenoids, isoflavones and phenolic glycosides from Sarcolobus globosus.

From Sarcolobus globosus, two rotenoids (villosinol and 6-oxo-6a,12a-dehydrodeguelin), one isoflavone (genistin) and four phenolic glycosides (vanillic acid 4-O-beta-d-glucoside, glucosyringic acid, tachioside and isotachioside) were identified for the first time from this species. Extracts and compounds from S. globosus were evaluated for their DPPH radical scavenging and 15-lipoxygenase (15-LO) inhibitory activities. All tested rotenoids were found to inhibit 15-LO, while they lacked DPPH radical scavenging effect.

Can scientific evidence support using Bangladeshi traditional medicinal plants in the treatment of diarrhoea? A review on seven plants.

Diarrhoea is a common disease which causes pain and may be deadly, especially in developing countries. In Bangladesh, diarrhoeal diseases affect thousands of people every year, and children are especially vulnerable. Bacterial toxins or viral infections are the most common cause of the disease. The diarrhoea outbreaks are often associated with flood affected areas with contaminated drinking water and an increased risk of spreading the water-borne disease. Not surprisingly, plants found in the near surroundings have been taken into use by the local community as medicine to treat diarrhoeal symptoms. These plants are cheaper and more easily available than conventional medicine. Our question is: What is the level of documentation supporting the use of these plants against diarrhoea and is their consumption safe? Do any of these plants have potential for further exploration? In this review, we have choosen seven plant species that are used in the treatment of diarrhoea; Diospyros peregrina, Heritiera littoralis, Ixora coccinea, Pongamia pinnata, Rhizophora mucronata, Xylocarpus granatum, and Xylocarpus moluccensis. Appearance and geographical distribution, traditional uses, chemical composition, and biological studies related to antidiarrhoeal activity will be presented. This review reveals that there is limited scientific evidence supporting the traditional use of these plants. Most promising are the barks from D. peregrina, X. granatum and X. moluccensis which contain tannins and have shown promising results in antidiarrhoeal mice models. The leaves of P. pinnata also show potential. We suggest these plants should be exploited further as possible traditional herbal remedies against diarrhoea including studies on efficacy, optimal dosage and safety.

Antioxidant and antimicrobial effects of the mangrove tree Heritiera fomes.

Heritiera fomes is a mangrove tree which is widely distributed in the Sundarbans mangrove forest, Bangladesh. In this study, the EtOH extract of stem bark from H. fomes was shown to be rich in procyanidins. Trimeric, pentameric and hexameric procyanidins were identified in addition to highly polymeric material (average degree of polymerization 18-24). Bioactivity studies showed high DPPH radical scavenging and 15-lipoxygenase (15-LO) inhibiting activities of the bark extracts (EC50 = 19.4 +/- 1.7 and IC50 = 22 +/- 1 microg/mL, respectively) which could be ascribed to its high content of procyanidins. The procyanidins were also assayed as DPPH scavengers and 15-LO inhibitors, with EC50 and IC50 values in the range of 8-15 and 10-15 microg/mL, respectively. The bark extracts showed antibacterial activities against K. rhizophilia, S. aureus, B. subtilis and P. aeruginosa, as well. No toxicity was observed in the brine shrimp assay.

Rotenoids and isoflavones from Sarcolobus globosus.

Sarcolobus globosus is a medicinal plant growing in mangrove forests in Asia. No constituents from this plant have been reported previously. From the diethyl ether extract of S. globosus a new rotenoid sarcolobin and a new isoflavone sarcolobone, as well as the previously known rotenoids tephrosin, 12aalpha-hydroxydeguelin, 11-hydroxytephrosin, 12a-hydroxyrotenone, 12aalpha-hydroxyrotenone, 6aalpha,12aalpha-12a-hydroxyelliptone, 6a,12a-dehydrodeguelin, 13- homo-13-oxa-6a,12a-dehydrodeguelin, the isoflavone barbigerone and a chromone 6,7-dimethoxy-2,3-dihydrochromone were identified. 6,7-Dimethoxy-2,3-dihydrochromone has not previously been reported as a natural product.