Polyphenols from fresh frozen tea leaves (Camellia assamica L.,) by supercritical carbon dioxide extraction with ethanol entrainer - application of response surface methodology.

Fresh frozen tea leaves (Camellia assamica L.) were extracted with SC-CO2 to obtain polyphenols rich in EGCG and compared with conventional solvent extraction. Extraction parameters such as temperature, pressure and solvent to material ratio were critical factors in extraction and optimized by response surface methodology (RSM). The maximum yield of extractable solids using SC-CO2 with ethanol entrainer was carried out at pressures 150 to 350 bar, temperatures from 40 °C to 60 °C and solvent to material ratio 100 to 200. The theoretical yield was 3.91 % (w/w), while experimental yield was 4.20 ± 0.27 % (w/w) at temperature of 50 °C, pressure 250 bar and solvent to material ratio of 200. The chemical compositions of extracted solids were investigated by HPLC which showed 722.68-848.09 ± 1.12 mg of EGCG/g of extractable solids were separated in SC-CO2. Also, 54.62 ± 1.19 mg of EGCG/g of extractable solids was separated using conventional extraction which is quantitatively lesser than SC-CO2 extraction yield. Thus, SC-CO2 extraction was proved to be effective technique in obtaining extracts rich in EGCG (>95 %).

Catechin concentrates of garden tea leaves (Camellia sinensis L.): extraction/isolation and evaluation of chemical composition.

BACKGROUND: Solid-liquid (SLE) and liquid-liquid (LLE) extraction techniques were applied to extract catechins and caffeine from quick mechanically expelled tea leaf juice (QMETLJ) and freeze-dried (FD)-QMETLJ of Camellia sinensis L. The concentrates obtained were analyzed for total polyphenol content and antioxidant activity (DPPH(•) inhibition, FRAP and phosphomolybdenum assay). Catechins were identified and quantified using HPLC. RESULTS: Overall, 95% (v/v) ethanol was the best solvent system for extracting total polyphenols (355.26 ± 23.68 to 457.89 ± 28.94 g GAE kg(-1) extractable solid yield (ESY)) and antioxidants (DPPH(•) inhibition, 16.97 ± 0.52 to 20.83 ± 3.11%; FRAP, 4.15 ± 0.32 to 6.38 ± 0.57 mmol TE g(-1) ESY; Mo(V) reduction, 2.47 ± 0.19 to 3.84 ± 0.39 mmol AAE g(-1) ESY) from FD-QMETLJ. Similarly, in LLE, ethyl acetate showed the best results for recovering polyphenols (960.52 ± 7.89 g GAE kg(-1) ESY) and antioxidants (DPPH(•) inhibition, 42.39 ± 0.91%; FRAP, 11.39 ± 0.83 mmol TE g(-1) ESY; Mo(V) reduction, 6.71 ± 1.14 mmol AAE g(-1) ESY) from QMETLJ. CONCLUSION: It was found that 95% ethanol can be used to increase the total polyphenols and antioxidants in extracts from FD-QMETLJ, while ethyl acetate can be effectively employed for concentrating catechins from QMETLJ.

Characterization of gingerol analogues in supercritical carbon dioxide (SC CO2) extract of ginger (Zingiber officinale, R.,).

Organically grown ginger rhizome (Zingiber officinale Roscoe) SC CO2 extract obtained at 280 bar and 40 °C and its column chromatographic fractions are characterised for its composition. The components in the extract and fractions are identified by HPLC and LC based MS and are used as standard for the estimation of gingerol analogues in the extract. HPLC and mass analysis of the extracts confirmed the various forms of gingerol constituents [4]-, [6]-, [10]-gingerols and [6]-, [8]-, [10]-shogaols in ginger extracts. SC CO2 extract of organic ginger was found to show 6-gingerol around 25.97 % of total extract. The estimation of [6]-gingerol, [6]-shogaols, [4]gingerol, [10]-gingerol and 6-gingediol content of the SC CO2 purified ginger extract was found to be 75.92 ± 1.14, 1.25 ± 0.04, 4.54 ± 0.04, 13.15 ± 0.30 and 0.37 ± 0.00 % respectively. Antioxidant activity was measured by 2, 2-diphenyl-1-pycryl-hydrazyl (DPPH) free radical scavenging and ferric reducing antioxidant power (FRAP) and the assay have shown 652 ± 0.37 mg TE/g and 3.68 ± 0.18 mg TE/100 g respectively, are significantly higher results with SC CO2 organic ginger extract. Paradol analogues are not detected in this study. Small quantities of [4]-, [10]gingediol and [6]-gingediacetate are also found in ginger extract.

Engineering liposomes of leaf extract of seabuckthorn (SBT) by supercritical carbon dioxide (SCCO2)-mediated process.

Seabuckthorn (SBT; Hipphophae rhamnoides) leaf extract obtained by supercritical carbon dioxide (SCCO(2)) using ethanol as an entrainer, containing mainly flavanoids as bioactive principles with antioxidant and antibacterial properties, was used for the preparation of liposomes. Liposomes are promising drug carriers with sustained release because they can enhance the membrane penetration of drugs, deliver the entrapped drugs across cell membranes, and improve extract stability and bioavailability. The aim of the present study was to compare the two different methods of liposome production: the Bangham thin-film method and SCCO(2) gas antisolvent method (SCCO(2) GAS) for the incorporation of SBT leaf extract in terms of particle size, morphology, encapsulation efficiency, antioxidant activity, and thermal stability. Liposomes obtained with the thin-film method were multilamellar vesicles with average particle size (3,740 nm), encapsulation efficiency (14.60%), and particle-size range (1.57-6.0 µm), respectively. On the other hand, liposomes by the SCCO(2) GAS method were nanosized (930 nm) with an improved encapsulation efficiency (28.42%) and narrow range of size distribution (0.48-1.07 µm), respectively. Further, the antioxidant activity of leaf extract of SBT was determined by the 2 diphenyl-1-picrylhydrazyl method and expressed as Trolox equivalents as well as of the intercalated extract in liposomes. The oxidative stability of SBT encapsulated in liposomes was again estimated using differential scanning calorimetry (DSC). Thermal-oxidative decomposition of the samples (i.e., pure liposomes and encapsulated extracts) and the modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were also studied by DSC. After encapsulation in liposomes, antioxidant activity proved to be higher than those of the same extracts in pure form.

Chemical composition of Nigella sativa L. seed extracts obtained by supercritical carbon dioxide.

Chemical composition of black cumin (Nigella sativa L.) seed extracts obtained by supercritical carbon dioxide at two different conditions that result in total extract (28 MPa/50°C, SFE 1) and major volatile part (12 MPa/40°C, SFE 2) and essential oil obtained by hydrodistillation of SFE-1 (HD SFE). SFE have been carried out to characterize the compounds and the variation of quinones and phenolics. The extracts were analysed by GC and GC-MS and the presence of phenolic compounds was further confirmed by 2D HSQCT (1)H and (13)C NMR spectroscopy. Forty-seven volatile compounds were detected where sixteen compounds were reported for the first time in the oil of this seed. Moreover, thymoquinone (TQ), dithymoquinone (DTQ), thymohydroquinone (THQ) and thymol (THY) were the major phenolic compounds. It can be concluded that the chemical composition of extracts obtained by SC CO2 extraction of the seeds showed better recovery of phenolic compounds than HD SFE and proved the occurrence of thermally labile or photosensitive bioactive volatiles of four major quinonic phenol compounds.

In vitro studies on liposomal amphotericin B obtained by supercritical carbon dioxide-mediated process.

Nanotechnology in drug delivery is a rapidly expanding field. Nanosized liposomal preparations are already in use for efficient drug delivery with better therapeutic indices. Existing methods of liposome preparation are limited by problems of scale-up, difficulty in controlling size, and intercalation efficiency. Here we prepare amphotericin B-intercalated liposomes by a novel process where amphotericin B and purified phosphatidyl choline are solubilized in suitable solvent and precipitated in supercritical fluid carbon dioxide (known as a gas antisolvent technique), to obtain microsized particles that are subsequently introduced into a buffer solution. The morphology of liposomes was characterized through a phase-contrast microscope, and the particle size distribution studied by laser technique showed nanosize with a narrow range of size distribution (between 0.5 and 15 microm) and a higher intercalation efficiency. In vitro studies conducted using Aspergillus fumigatus (MTCC 870) strain proved to be efficient in the retardation of the growth of the organism.