A. Choudhury

Pentacyclic triterpenoids and sterols from seven species of mangrove

Abstract The isolation of pentacyclic triterpenoids from seven species of fresh mangrove leaves using a simple and rapid method is described. The leaves were homogenized using chloroform—methanol and the extract was diluted with water to precipitate out triterpenoids which were separated into neutral and acidic fractions. These were analysed by gas-liquid chromatography as acetyl and trimethylsilyl ether derivatives on a 3% OV-17 column. Sterols were isolated from the chloroform layer by preparative thin layer chromatography and were analysed by gas-liquid chromatography as their trimethylsilyl ether derivatives on a 3% OV-17 column. The triterpenoids found were α-amyrin, β-amyrin, lupeol, oleanolic acid and ursolic acid in most of the samples. Sterols found in all the samples were cholesterol, campesterol, stigmasterol, sitosterol and stigmast-7-en-3β-ol. Retention indices of the triterpenoids and sterols have been determined.

Sterols and fatty acids from three species of mangrove

Abstract The hydrolysis of steryl esters on thin-layer chromatographic plates by porcine pancreatic lipase is described. The sterols and fatty acids produced were separated on the same plate, recovered, and analysed by gas-liquid chromatography for their compositions. Synthetic cholesteryl esters containing various saturated and unsaturated fatty acids and synthetic steryl oleates with various sterols were lipolysed along with steryl esters of Acanthus ilicifolius , Bruguiera gymnorhiza and Rhizophora mucronata mangrove leaves. The major sterol was sitosterol which was accompanied by cholesterol, campesterol, stigmasterol and 28-isofucosterol. In addition, stigmast-7-en-3β-ol was present in R. mucronata leaves. The component fatty acids found in all three species were 16:0, 18:0, 18:1, 18:2 and 18:3. The relative proportions of the sterols and fatty acids were significantly different from the chemotaxonomic standpoint. The results obtained by carrying out plate lipolysis for 45 min at 40° compared well with those produced by conventional chemical hydrolysis.

Effect on the leaf lipids of three species of mangrove of periodic submergence in tidal water

Abstract Mangrove plant leaves of Avicennia officinalis , Acanthus illicifolius and Bruguiera gymnorhiza , grown under tidal water stress, were found to biosynthesize higher proportions of hydrocarbons, wax esters, sterol esters, triglycerides, sterols and low- M , terpenes, compared to the plants grown normally. Hydrocarbons and n -alcohols of wax esters, with longer chain lengths were found in higher proportions in the plants grown normally. Higher proportions of unsaturated n -alcohols of wax esters were present in the leaves of periodically submerged plants. Proportions of unsaturated fatty acids of wax esters, sterol esters and triglycerides were also higher in the submerged plants. Sitosterol, stigmasterol and campesterol of the sterol esters, were higher in submerged plants, whereas 28-isofucosterol was higher in normal plants. Of the free sterols, sitosterol was higher in submerged plants, whereas stigmast-7-en-3β-ol and campesterol were higher in normal plants and 28-isofucosterol was found only in submerged plants. Pentacyclic triterpenoids were found only in normal plants, whereas, the submerged plants contained low- M , terpenes in higher proportions.

Lipids and fatty acids of the horseshoe crabsTachypleus gigas andCarcinoscorpius rotundicauda

Total lipids from hepatopancreas of the horseshoe crabs,Tachypleus gigas andCarcinoscorpius rotundicauda, obtained in 7.6 and 3.3% wet weight respective yields, were fractionated by various chromatographic techniques and identified by gas-liquid chromatography and spectroscopic methods. Fatty acid-containing lipids were rich in 16∶0 (8.0–25%), 18∶1ω9 (6.9–22%) and 18∶2ω6 (6.8–18.5%); appreciable amounts of 16∶1ω7, 18∶3ω3, 20∶5ω3 and 22∶6ω3 were also present. The level of 26∶0 in the hydrocarbon fractions was unusually high (64 and 68%). Carbon chain lengths of major wax esters were 44, 46 and 48 forT. gigas and 38, 40 and 42 forC. rotundicauda. 1-O-Alkyl diglycerides were 7.2 and 9.1% of the total lipids in the two species and contained 14∶0(20%), 16∶0(60%) and 18∶0(20%) alkyl chains along with a relatively higher percentage (32–35%) of saturated fatty acids. High levels of cholesterol (>50% of total sterol) in the free and combined state were encountered in both samples, phospholipid contents being 40 and 35%, respectively, and contained highest levels of unsaturated fatty acids.

Lipid composition of Porteresia coarctata from two different mangrove habitats in India

Abstract Porteresia coarctata collected, at Prentice and Chuksar Islands of the Sunderban mangrove ecosystem, was studied for its lipid composition. Hydrocarbon, wax ester, sterol esters, triacylglycerols, sterols and terpenoids, were all found in higher proportions in the Prentice Island sample. Palmitic acid was the major fatty acid in all fractions except for the steryl esters of P. coarctata collected from Prentice Island, where oleic and linoleic acids were the major components. Sterols found were, sitosterol, stigmasterol, campesterol and cholesterol, of which, sitosterol and stigmasterol were the major components. Terpenoids present were, β-amyrin, α-amyrin, lupeol, betulin, oleanolic acid and ursolic acid, of which, lupeol and oleanolic acid were the major components. Quantitative variations of the lipid constituents were found between the two samples studied.

The role of hydrophobic substances in leaves in adaptation of plants to periodic submersion by tidal water in a mangrove ecosystem

SUMMARY (1) Three species of plants, Acanthus ilicifolius, Avicennia officinalis and Bruguiera gymnorhiza, grow abundantly in the tidal mangrove area of the Sunderbans, India. (2) The leaves from plants not normally submerged and from those periodically submerged have been analysed for their hydrophobic components (lipid, wax ester and hydrocarbons). The weights of hydrocarbons and wax esters per unit leaf area of the submerged plants were about three times greater than those of emergent plants; this apparently makes them tolerant to flooding. (3) In addition, the area, thickness, fresh weight to dry weight quotient, loss in weight on drying, and chlorophyll content of leaves were all higher in the periodically submerged plants. The great increases in leaf area and chlorophyll content may help in overcoming the limitations imposed on photosynthesis due to periodic submergence.

Lipid contaminants in commercial lipases.

During lipolysis of wax esters on thin layer chromatography (TLC) plates (1), abnormally high errors for stearic (18:0), palmitic (16:0) and oleic (18: t ) acids were found in the hydrolysates. These anomalous results prompted us to examine the source of the contaminations, which was found to be the lipase used. We have analyzed 2 commercial lipase samples that were used for the lipolysis of wax esters and developed a procedure for the preparation of commercial lipase free of fatty acid (FA) contaminants. Pancreatic lipase from 300 mg each from Sigma Chemical Co. (St. Louis, MO, Type II, crude from porcine pancreas) and from Calbiochem (Los Angeles, CA, B grade from porcine pancreas) were mixed vigorously with 15 ml of redistilled diethyl ether and centrifuged. The supernatnats were carefully removed with a syringe and saved. The extract ion procedure with diethyl ether was repeated 6 times for each lipase sample. The pooled etherial extracts were dried over anhydrous sodium sulphate and the solvent was evaporated and weighed. The lipases were then washed 6 times with 15 ml protions of acetone. The acetone extracts were also pooled and the solvent was evaporated and weighed. The etherial extracts were spotted on preparative TLC plates that were developed using a solvent system of light petroleum ether (40 C60 C) diethyl ether/acetic acid (80:20:1.5, v/v). The bands were visualized by putting the plates in an iodine chamber. The bands were identified by comparing the Rf values with those of known standards. Finally, the various bands were scraped off the plates and the compounds were extracted using diethyl ether, the solvent was evaporated and then weighed. The free fatty acid (FFA) bands from the 2 lipase samples were methylated using diazomethane (2). To each of the methyl ester samples, 50 /~g of methyl pentadecanoate (15:0) were added and analyzed by gas liquid chromatography (GLC) using a 10% DEGS column. From the chromatograms, peak areas were determined and each of the components was identified and quantified. Beeswax and Avicennia officinalis leafwax were hydrolyzed with extracted and unextracted lipases on TLC plates, using 1 mg lipase and 1 mg wax esters, according to the method des-

Lipids and fatty acids of the gastropod molluscCerethidea cingulata

Fatty acids of total lipid, neutral lipid, triglyceride, sterol ester and phosphatidylcholine ofCerethidea cingulata (Gmelin) have been determined. Levels of 16:1 (14%), 20:5ω3 (15%) and nonsaponifiables (40%) were found.

Lipids and fatty acids of the gastropod mollusc Cerethidea obtusa

Abstract The gastropod mollusc Cerithidea obtusa was examined for its lipids and fatty acids. The non-polar lipids identified were hydrocarbons, steryl esters, triglycerides, free fatty acids and sterols. The major phospholipid was phosphatidyl choline. The predominant fatty acids were myristic, palmitic, stearic, oleic, linolenic, arachidonic and eicosapentaenoic acids. Combinations of chromatographic techniques have been employed for the qualitative and quantitative determination of the lipids and fatty acids of C. obtusa .

Oxidation of oleanolic acid ofAvicennia officinalis leaves to oleanonic acid in the natural environment of Sunderban mangrove ecosystem

Oleanolic acid, a major component pentacyclic triterpene in the leaves ofAvicennia officinalis was found to be oxidized to oleanonic acid in the natural environment of Sunderban mangrove forest.