This study aims to determine the concentration of sterols used as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. Samples were collected during different seasons through the use of a rotation drum. The analysis of sterols was performed using gas chromatography equipped with a flame ionisation detector (GC-FID). The results showed that the concentrations of total sterols in the SML ranged from 107.06 to 505.55 ng L(-1). The total sterol concentration was found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%).
The molecular composition and distribution of sterols were investigated in the East China Sea to identify the origins of suspended particulate matter (SPM) in offshore waters influenced by Changjiang River Diluted Water (CRDW). Total sterol concentrations ranged from 3200 to 31,900pgL(-1) and 663 to 5690pgL(-1) in the particulate and dissolved phases, respectively. Marine sterols dominated representing 71% and 66% in the particulate and dissolved phases, respectively. Typical sewage markers, such as coprostanol, were usually absent at ~250km offshore. However, sterols from allochthonous terrestrial plants were still detected at these sites. A negative relationship was observed between salinity and concentrations of terrestrial sterols in SPM, suggesting that significant amounts of terrestrial particulate matter traveled long distance offshore in the East China Sea, and the Changjiang River Diluted Water (CRDW) was an effective carrier of land-derived particulate organic matter to the offshore East China Sea.
Near-shore surface sediment was collected from five stations off Redang Island located on the eastern coast of Peninsular Malaysia. Freeze-dried sediments were Soxhlet extracted and then fractionated using column chromatography into aliphatic and polar fractions. Determination of these fractions was carried out using gas chromatography mass spectrometry. The concentration of total resolved aliphatic hydrocarbons in sediments ranged from 157 to 308 ng/g. The distribution of aliphatic fraction showed the presence of n-alkanes ranging from nC15 to nC33 with a minor odd-to-even predominance exhibiting carbon maximum, depending on station, at nC17, nC26, nC29 or nC31. Calculation of Carbon Preference Index (CPI) for CPI(15-33) gave values ranging from 1.09 to 1.46. n-Alkanol in all sediment exhibits even-to-odd carbon predominance ranging from nC16 to nC28 and maximising at nC22. n-Fatty acids distribution ranged from nC14 to nC24 with a dominant maximum at nC16 and exhibiting high values of short chain fatty acids (≤nC20) to long chain fatty acids (>nC20) ratios. Unsaturated fatty acids, particularly nC16:1 and nC18:1 is also ubiquitous in all samples. Cholesterol is the most abundant compound amongst the sterol group ranging from 42.8 to 62.6% of the total sterols. β-Sitosterol, brassicasterol and stigmasterol, are also present but of relatively lower amount. These observations suggest that the aliphatic lipids and sterols in the study area originate, mainly, from biogenic sources of marine microbial with minor contribution from epiticular waxes of terrestrial plants.
Southeast Asia has undergone rapid developments in terms of urbanization, economic and population growth. The progress in sewerage treatment infrastructure has not kept pace with such developments. The inadequacy and inefficiency of sewerage systems has prompted the release of untreated sewage into the aquatic environment of Southeast Asia causing many waterborne illnesses since surface water is utilized for recreational, agricultural and aquaculture purposes and, above all, as a source of water intake in Southeast Asia. This paper will review the current data on molecular markers of sewage pollution including sterols and linear alkylbenzenes (LABs) in Southeast Asian aquatic environment to clarify the state of sewage pollution and the competence of sewage treatment plants (STPs) in this area. Despite the importance of sewage pollution research in the region, the number of studies using molecular markers to trace the sources of sewage pollution is limited. So far, indicators of sewage pollution have been investigated in aquatic environments of Indonesia, Vietnam, Malaysia, the Philippines, Thailand, Cambodia and Brunei among Southeast Asian countries. The concentrations and diagnostic ratios of faecal sterols and LABs show the release of untreated and primary treated urban waste into water bodies of these countries. Further studies are required to fill the data gaps in Southeast Asia and come to a better understanding of the trends of sewage pollution in this part of the world. Graphical abstract.
The oil of Adenanthera pavonina L. seeds was analysed by chromatographic and instrumental means. The oil was found to be rich in neutral lipids (86.2%), and low in polar lipids (13.8%). The neutral lipids consisted mainly of triacylglycerols (64.2%). Unsaturated fatty acids were found as high as 71%, while the percentage of saturated fatty acids was only 29%. GC and GC/MS analyses revealed linoleic, oleic and lignocerotic acid to be predominant among all fatty acids in the A. pavonina oil, whereas stigmasterol was the major steroid identified within this study. Subsequently, the oil was used for preparation of submicron oil-in-water (o/w) lipid emulsions. Lipid emulsions were formulated by using soybean lecithin (SL) to investigate their particle size, Zeta potential and stability at the different oil and SL ratios. The results obtained indicate possible applications of the tested oil in pharmaceutical and medical fields as drug and cosmetic active ingredient carriers.
Faecal sterols detection is a promising method for identifying sources of faecal pollution. In this study, faecal contamination in water samples from point source (sewage treatment plants, chicken farms, quail farms and horse stables) was extracted using the solid phase extraction (SPE) technique. Faecal sterols (coprostanol, cholesterol, stigmasterol, beta-sitosterol and stigmastanol) were selected as parameters to differentiate the source of faecal pollution. The results indicated that coprostanol, cholesterol and beta-sitosterol were the most significant parameters that can be used as source tracers for faecal contamination. Chemometric techniques, such as cluster analysis, principal component analysis and discriminant analysis were applied to the data set on faecal contamination in water from various pollution sources in order to validate the faecal sterols' profiles. Cluster analysis generated three clusters: coprostanol was in cluster 1, cholesterol and beta-sitosterol formed cluster 2, while cluster 3 contained stigmasterol and stigmastanol. Discriminant analysis suggested that coprostanol, cholesterol and beta-sitosterol were the most significant parameters to discriminate between the faecal pollution source. The use of chemometric techniques provides useful and promising indicators in tracing the source of faecal contamination.
The steady increase of diabetes is becoming a major burden on health care systems. As diabetic complications arise from oxidative stress, an antioxidant therapy along with anti-diabetic drugs is recommended. Myrmecodia or ant plant is highly valued as a traditional medicine in West Papua. It is used as an alternative treatment for diabetes, as the substances produced by ants can reduce blood sugar levels. The aim of this study was to develop and establish high-performance thin-layer chromatographic (HPTLC)-bioautographic methods to measure the antioxidant and hypoglycemic effects in different extracts from Myrmecodia platytyrea and to compare them with sterol content. Antioxidant activity in methanol, ethanol, dichloromethane (DCM) and ethyl acetate (EA) extracts were measured with a direct HPTLC-2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) assay, while hypoglycemic effects were assessed using a newly developed α-amylase inhibitory activity assay. Stigmasterol is observed, after derivatization with anisaldehyde, as purple colored zones under visible light at hRF values of 0.66. The highest antioxidant activity was observed in the ethanol extract which is rich in polyphenols and flavonoids, while the DCM extract did not show antioxidant activity, but had significant α-amylase inhibitory activity. The highest α-amylase inhibitory activity was observed in the EA and DCM extracts and was related to their stigmasterol content.