Xiaoli Liu

Bio: Xiaoli Liu is an academic researcher from South China University of Technology. The author has contributed to research in topics: Phyllanthus emblica & Kaempferol. The author has an hindex of 6, co-authored 7 publications receiving 411 citations. Previous affiliations of Xiaoli Liu include Guangdong University of Technology.

Identification of volatile components in Phyllanthus emblica L. and their antimicrobial activity.

Abstract: The volatile components and in vitro antimicrobial activities of Emblica (Phyllanthus emblica L.) essential oils (EOs) obtained by hydrodistillation (HD-EO) and supercritical fluid extraction (SFE-EO) were investigated. The compositions of volatile compounds in these oils were tentatively determined by gas chromatography-mass spectrometry. The antimicrobial activites of these two extracts were investigated with microbiological tests against Gram-positive and Gram-negative bacteria and three pathogenic fungi. The main components of both oils were beta-caryophyllene, beta-bourbonene, 1-octen-3-ol, thymol, and methyleugenol. Both essential oils showed a broad spectrum of antimicrobial activity against all the tested microorganisms. Gram-positive bacteria were more sensitive to the investigated oils than Gram-negative bacteria. SFE-EO exhibited a higher antifungal activity compared to HD-EO.

Antimicrobial and antioxidant activity of emblica extracts obtained by supercritical carbon dioxide extraction and methanol extraction

Abstract: This study is aimed to evaluate the antimicrobial and antioxidant activities of two extracts of emblica (Phyllanthus emblica L.) obtained by supercritical fluid extraction (SFE) and methanol extraction. The SFE extract showed strong antimicrobial activity against all microorganisms tested, whereas the methanolic extract showed low activity against Staphylococcus aureus and fungi. In contrast, the methanolic extract exhibited significantly higher antioxidant activity than the SFE extract. The SFE extract was analyzed by gas chromatography with mass spectrometric detector. Thirty compounds were tentatively identified, representing 99.67% of the volatile components. β-Bourbonene, teracosane, palmitic acid, thymol, β-caryophyllene and undecane were the major compounds. The methanolic extract was subjected to separation and purification using reverse-phase high-performance liquid chromatography. Kaempferol 3-β-D-glucopyranoside (1), kaempferol (2), quercetin (3), isocorilagin (4) and geraniin (5) respectively, were identified by spectral methods, 1H and 13C nuclear magnetic resonance spectroscopy, ultraviolet-visible spectrophotometry and mass spectroscopy, and comparison with literatures. PRACTICAL APPLICATIONS The study can be considered as the first report on the in vitro antimicrobial and antioxidant properties of supercritical fluid extraction (SFE) and methanolic extracts prepared from Phyllanthus emblica. The results introduce a unique natural source that possesses strong antimicrobial and antioxidant substances. The SFE extract had a strong and broad spectrum of antimicrobial activity, and in some cases, even found to have similar activity to the antibiotics ampicillin and nystatin. On the other hand, the methanolic extract exhibited quite strong antioxidant activities, which were found to be similar, and in some cases even higher than the reference compound butylated hydroxytoluene (BHT). Hence, the extracts of P. emblica could be used as a natural preservative ingredient in food and/or pharmaceutical industry.

Phyllanthus emblica extract and its preparation and application

Abstract: The present invention relates to emblic extract and the preparation process and application for the same. The preparation process comprises the following steps: Dried emblic powder is first microwave assisted solvent extracted, and the emblic extract is then extracted with diethyl ether and ethyl acetate and macroporous resin purified to obtain purified emblic extract. The purified emblic extract is one kind of natural antioxidant with emblic polyphenol in the content over 93 % as the main effective component. The emblic extract is respectively extracted through ether and ethyl acetate so as to obtain a natural antioxidant having emblic polyphenol as main active constituent. The natural antioxidant is superior to available synthetic antioxidants (VC, VE and TBHQ) due to high DPPH free radical eliminating activity which is 2 times higher than VC and 1 to 2 times higher than TBHQ, high lipid peroxide inhibiting activity which is 2 to 8 times higher than VE and 1 to 6 times higher than TBHQ, and high peroxidation resisting capacity which, in peanut oil, is 2 to 4 times higher than VE and 1 to 2 times higher than TBHQ, and, in lard oil, is 2 to 4 times higher than VE and 1 to 2 times higher than TBHQ.

Green and Sustainable Solvents in Chemical Processes

Abstract: Sustainable solvents are a topic of growing interest in both the research community and the chemical industry due to a growing awareness of the impact of solvents on pollution, energy usage, and contributions to air quality and climate change. Solvent losses represent a major portion of organic pollution, and solvent removal represents a large proportion of process energy consumption. To counter these issues, a range of greener or more sustainable solvents have been proposed and developed over the past three decades. Much of the focus has been on the environmental credentials of the solvent itself, although how a substance is deployed is as important to sustainability as what it is made from. In this Review, we consider several aspects of the most prominent sustainable organic solvents in use today, ionic liquids, deep eutectic solvents, supercritical fluids, switchable solvents, liquid polymers, and renewable solvents. We examine not only the performance of each class of solvent within the context of the...

In vitro models for antioxidant activity evaluation and some medicinal plants possessing antioxidant properties: An overview

Abstract: Reactive oxygen species (ROS) are a class of highly reactive molecules derived from the metabolism of oxygen. ROS, including superoxide radicals, hydroxyl radical and hydrogen peroxide molecules are often generated as by products of biological reactions or from exogenous factors. There is extensive evidence to involve ROS in the development of degenerative diseases. Evidence suggests that compounds especially from natural sources are capable of providing protection against free radicals. This has attracted a great deal of research interest in natural antioxidants. It is necessary to Screen out medicinal plants for their antioxidant potential. Therefore an attempt has been made to review different in vitro models for estimating antioxidant properties of natural products from medicinal plants. All the models are described along with the different standards that can be used for estimation. In the end, a large number of plants showing in vitro antioxidant activity are listed but in vivostudies are lacking. Key words: Antioxidant assay, in vitro models, antioxidant medicinal plants.

Supercritical fluid extraction of vegetable matrices: Applications, trends and future perspectives of a convincing green technology

Abstract: Along more than a decade, R&D on supercritical fluid extraction (SFE) of vegetable matrices has been increasingly reported in the literature. Aiming at portraying the current state of this field and its evolution in terms of raw materials, products, modes of operation, optimization, modeling techniques, and closeness to industrial application, a large compilation of almost 600 essays from 2000 to 2013 has been deeply analyzed in order to unveil those indicators and their trends. Furthermore, strengths and weaknesses are identified, and some remarks that may drive upcoming research are provided. Globally, more than 300 species are reported in the literature, with prevalence of the extraction of seeds (28% of works) and leaves (17%). The main families of extracted compounds, cosolvents and operating conditions adopted are critically examined, being possible to conclude that researchers investigate many times working regions far from the optimum due to practical limitations or absence of experimental optimization. Current phenomenological, statistical and semi-empirical approaches are reviewed, along with scale-up studies, and economic analysis. In the whole, the most comprehensive picture over SFE of vegetable matrices is provided in this review, highlighting pertinent aspects and opportunities that may further consolidate the convincing route of this technology for the next years.