Vijay K. Kaul

Volatile constituents of the aerial parts of Capillipedium parviflorum were studied by two different extraction procedures, hydrodistillation (HD), supercritical CO₂ extraction (Sc-CO₂) and compared with headspace analysis (HS). Sc-CO₂ extraction was carried out using nine differential optimization extractions (DOX) at different temperatures (°C) and pressures (MPa), i.e. 35/9, 60/9, 85/9, 35/17, 60/17, 85/17, 35/25, 60/25 and 85/25, to assess the influence on the yield and composition of volatile constituents. In DOX experiments, oil yields varied between 0.01–0.18% and maximum yield (0.18%) was obtained using temperatures and pressures 35/17 and 85/25. The oil is characterized by distinctive presence of very high content of non-terpenes (90.7%) identified in HD oil, 84.0% in Sc-CO₂ oil and 92.5% in HS analysis. Monoterpenes were represented in low concentrations in HD oil and were totally absent in Sc-CO₂ as well as in HS analysis. Very little variability was observed in the oxygenated monoterpenes in both Sc-CO₂ and HD oil representing a low percentage of constituents. Sesquiterpene hydrocarbons were represented between 1.5% and 3.1% in Sc-CO₂ extraction, which was higher in comparison with HD and HS techniques. Oxygenated sesquiterpenes were represented in higher percentage in Sc-CO₂ than in HD oil and HS analysis. Variability among the major constituents of 4-nonanone, 4-nonanol, 4-undecanone and 4-undecanol was observed in Sc-CO₂ extraction carried out under varied temperatures and pressures. Their percentage also varied in HD and HS analysis. 4-Nonanone (2.5%, 60/9 in Sc-CO₂; 6.4% in HD and 4.3% in HS), 4-nonanol (21.5% in Sc-CO₂, 31.7% in HD and 29.5% in HS), 4-undecanone (33.3%, 85/9 in Sc-CO₂; 35.3% in HD and 44.5% in HS) and 4-undecanol (16.5%, 84/17, 60/25 in Sc-CO₂; 14.6% in HD and 10.3% in HS) dominated the volatile constituents.

Volatile oil composition of the leaves of Rhododendron anthopogon (Ericaceae) growing wild in alpine Western Himalaya was studied using different extraction techniques including SC-CO₂ extraction and hydrodistillation (HD). Results from different extraction methodologies were compared with headspace analysis (HS) and evaluated for the effectiveness of techniques in characterisation of various terpene categories and to assess their influence on the yield and composition of volatiles. Variability in constituents and in quantitative yields was observed. The results varied with different extraction methods. A total of 27 constituents in SC-CO₂ extraction, 31 in HD and 17 in HS analysis were identified. Constituents in SC-CO₂ and HD oils were identified by gas chromatography mass spectrometry analysis. SC-CO₂ extraction was carried out at 40°C and 140 bar pressure and the oil represented by major constituents as β-caryophyllene (5.96%), α-humulene (4.06%) and p-menthadiene-2,9-diol (7.28%); in HD, oil limonene (11.26%), β-caryophyllene (11.62%), α-humulene (7.22%), and E-nerolidol (5.83%) dominated the oil and in HS analysis, limonene (24.14%), γ-terpinene (40.73%), α-terpinene (4.92%), β-phellandrene (3.44%) and β-ocimene (7.15%) were present as major constituents.

Volatile oil composition of hydro-distilled (HD) and supercritical carbon dioxide (SC-CO₂) essential oil of freshly collected aerial parts of Heracleum thomsonii (Umbeliferae) from the western Himalayas was studied by GC-FID and GC-MS. Results revealed qualitative and quantitative dissimilarity in the composition of hydro-distilled and SC-CO₂ extracted oils. Nineteen constituents, which accounted for 89.32% of total constituents in HD oil, represented by limonene (4.31%), (Z)-β-ocimene (3.69%), terpinolene (22.24%), neryl acetate (36.19%), nerol (9.51%) and p-cymene-8-ol (2.61%) were identified. In SC-CO₂ extracted oil, 24 constituents representing 89.95% of total constituents were identified. Terpinolene (5.08%), germacrene D (2.17%), neryl acetate (51.62%), nerol (9.78%), geranyl acetate (2.06%), α-bisabolol (2.48%) and 1-nonadecanol (4.96%) were the dominating constituents. In vitro antimicrobial activity of hydro-distilled oil was conducted against microrobial strains including two Gram-positive (Staphylococcus aureus and Bacillus subtilis) and five Gram-negative (Burkholderia cepacia, Escherichia coli, Enterobacter cloacae, Klebseilla pneumoniae and Pseudomonas aeruginosa) bacteria as well as seven fungi (Candida albicans, Issatchenkia orientalis, Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus, Aspergillus sydowii and Trichophyton rubrum) using broth microdilution method. The results of bioassay showed that the oil exhibited moderate to high antimicrobial activity against fungi C. albicans (MIC 625 µg ml⁻¹), A. parasiticus (MIC 312.5 µg ml⁻¹), A. sydowii (MIC 312.5 µg ml⁻¹), T. rubrum (MIC 625 µg ml⁻¹), Gram-positive bacteria B. subtilis (MIC 625 µg ml⁻¹) and Gram-negative bacteria P. aeruginosa (MIC 312.5 µg ml⁻¹).

A regioselective base-promoted Michael and Thorpe–Ziegler reaction between aryl methyl ketones and α,β-unsaturated nitrile was carried out in a single step. Different functional groups in addition to active positions were tolerated under this condition. Results indicated that the reaction proceeds in a consecutive manner as double Michael, triple Michael, and Thorpe–Ziegler condensation. By applying click chemistry, double Michael adducts were converted to bis-tetrazoles, which have broad applications in coordination and medicinal chemistry. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

Acylation of β-caryophyllene, a sesquiterpene hydrocarbon with acetic anhydride, was carried out under mild catalytic conditions using Lewis acids such as BF₃ · Et₂O, ZnCl₂, FeCl₃, I₂ and AlCl₃ as catalysts. Among these, BF₃ · Et₂O was found to catalyse the reaction most efficiently, yielding three acylated products in 75% yield under solvent-free conditions. The structures were confirmed by NMR and MS techniques.

Stevioside was subjected to 1,4-intermolecular transglycosylation using β-cyclodextrin glucanotransferase (β-CGtase) produced from an alkalophilic strain of Bacillus firmus. The reaction was carried out by traditional, ultrasound-assisted and microwave-assisted techniques. Reaction under microwave conditions was faster and was completed in 1 min yielding two 1,4 transglycosylated products, 4′-O-alpha-d-glycosyl stevioside (I) and 4′′-O-alpha-d-maltosyl stevioside (II) in 66% and 24%, respectively. The optimum transglycosylation occurred by using stevioside (1.24 mmol), β-CD (1.76 mmol) and β-CGtase (2 U/g) under microwave assisted reaction (MAR) in 5 ml sodium phosphate buffer (pH 7) at 50°C and 80 W power. MAR is therefore potentially a useful and economical method for faster transglycosylation of stevioside.

Introduction: Stevioside and rebaudioside‐A are major low‐calorie diterpene steviol glycosides in the leaves of Stevia rebaudiana . They are widely used as natural sweeteners for diabetic patients, but the long extraction procedures required and the optimisation of product yield present challenging problems. Objective: To develop a rapid and effective methodology for the extraction of stevioside and rebaudioside‐A from S. rebaudiana leaves and to compare yields using different extraction techniques. Methodology: Dried and powdered leaves of S. rebaudiana were extracted by conventional, ultrasound and microwave‐assisted extraction techniques using methanol, ethanol and water as single solvents as well as in binary mixtures. Conventional cold extraction was performed at 25°C for 12 h while ultrasound extraction was carried out at temperature of 35 ± 5°C for 30 min. Microwave‐assisted extraction (MAE) was carried out at a power level of 80 W for 1 min at 50°C. Results: MAE yielded 8.64 and 2.34% of stevioside and rebaudioside‐A, respectively, while conventional and ultrasound techniques yielded 6.54 and 1.20%, and 4.20 and 1.98% of stevioside and rebaudioside‐A, respectively. Conclusion: A rapid and efficient method has been developed for the extraction of stevioside and rebaudioside‐A in optimum yields using MAE procedure. This method has the advantage of rapid extraction and fast screening of a large number of S. rebaudiana samples for assessment of planting material. MAE saves considerable time, energy and has implications in the quality assessment of stevioside and rebaudioside‐A prior to their industrial production from the leaves of S. rebaudiana . Copyright © 2009 John Wiley & Sons, Ltd.

Seeds of three accessions of Dracocephalum heterophyllum growing wild in high altitude locations in the cold desert regions of trans-Himalaya were collected and propagated under polyhouse conditions at IHBT Palampur to evaluate, compare their growth performance and essential oil composition. Three different chemotypes viz., citronellol-rose oxides type, citronellol type and citronellal-trans rose oxide type were identified. Samples of essential oils were distilled separately from leaves and inflorescence of all the three cultivated accessions and characterised by capillary GC and GC–MS techniques, which showed variation in the volatile constituents. In all the three accessions, citronellol was higher in the inflorescence oils as compared to leaf oils. Rose oxides, which are important high odour value cyclic monoterpene ethers were found in the essential oil samples of leaves as well as in the inflorescence of accession II, whereas these constituents were absent in the leaves of other two accessions. The essential oil from the inflorescence part of accession I was devoid of both cis and trans isomers of rose oxide, while accession III contained only one isomer of trans rose oxide. Under polyhouse conditions, seed germination was higher in accession III, whereas aerial biomass was higher in accession I. In comparison to other accessions, yield of volatile oil was higher in both leaf and inflorescence of accessions I, whereas accession II had higher oil yield from inflorescence. This is the first report of volatile oil composition of three accessions of D. heterophyllum cultivated at Palampur having potential as a new source of high valued essential oil for introduction in the perfumery industry.

Chemical composition of the essential oil of Artemisia maritima, collected from three different high altitude locations in western Himalaya was studied by gas-chromatography mass spectrometry. Twenty-five constituents were identified in the oil distilled from the sample from Pooh, of which 1,8-cineole (23.8%) and chrysanthenone (17.54%) were the major constituents. Twenty volatile constituents were identified from the sample collected from Rhongtong pass, of which chrysanthenone (38.1%) and 1,8-cineole (37.3%) were the major constituents. In the oil distilled from the sample collected from Lahaul-Spiti 28 constituents were identified, of which 1,8-cineole (44.22%), camphor (9.16%) and borneol (10.94%) were the major constituents. In this sample chrysanthenone was present in very low percentage.