Purification and characterization of hydrosoluble components from the sap of Chinese lacquer tree Rhus vernicifera

Traditional uses, phytochemistry, and pharmacology of Toxicodendron vernicifluum (Stokes) F.A. Barkley - A review

ETHNOPHARMACOLOGICAL RELEVANCE

Toxicodendron vernicifluum (Stokes) F.A. Barkley (syn. Rhus verniciflua or vernicifera Stokes, Anacardiaceae) (RVS), the lacquer tree, also known as sumac, has been used in China, Japan and South Korea for thousands of years as a highly durable coating material and a traditional herbal medicine, which contains medicinal ingredients with anti-tumor, anti-inflammatory, antiviral, and anti-rheumatic activities.

AIM OF THIS REVIEW

This review intends to provide a comprehensive and critical appraisal of RVS, including its phytochemical data, botanical and pharmacological literature that support its therapeutic potential in treatment on human diseases, with emphasis on the isolation of natural occurring compounds and detailed pharmacological investigations.

MATERIALS AND METHODS

Specific information of RVS was collected by using the key words "Toxicodendron vernicifluum", "Rhus verniciflua Stokes", "Rhus vernicifera Stokes" and "Lacquer tree" through published scientific materials (including PubMed, ScienceDirect, Wiley, ACS, CNKI, Scifinder, Springer, Web of Science, Google Scholar, and Baidu Scholar) and other literature sources.

RESULTS

The major phytoconstituents, 175 of which are presented in this review, including flavonoids, urushiols, terpenes, phenolic acids and other types of compounds, of which flavonoids and urushiols are main components. The extracts and isolates purified from RVS showed a wide range of in vitro and in vivo pharmacological effects, such as anti-cancer, anti-oxidation, anti-inflammatory, antimicrobial, tyrosinase inhibition and so on.

CONCLUSION

The modern pharmacological research of RVS mainly focus on the pharmacological effects of crude extract or active constituents, of which the flavonoids are widely studied. However, there are few reports on the relationship between pharmacological effects and their structures. And at present, there is still a lack of researches that are of both effective and in-depth. Meanwhile, there is little research on quality control. Apart from the wood and lacquer, other botanical parts also need to be explored further. In addition to phenolic compounds, the study on other types of components in T. vernicifluum would start more sparks for the discovery of new bioactive principles.

Manufacture and Characteristics of Oil-Modified Refined Lacquer for Wood Coatings

Oriental lacquer, a natural and renewable polymeric coating, comes from the sap produced by lacquer trees. For practical applications, oriental lacquer must be refined to reduce its water content and enhance its quality. In this study, drying oils were blended with oriental lacquer during a refining process to produce oil-modified refined lacquer (OMRL). Rhus succedanea lacquer, composed of 54.1% urushiols, 34.3% water, 7.2% plant gum, and 4.4% nitrogenous compounds, and drying oils, including tung oil (TO), linseed oil (LO), and dehydrated castor oil (DCO), were used as materials in this study. The effect of type and amount (0%, 10%, and 20% by wt %) of drying oils added to lacquer on lacquer properties were evaluated. Results show that the drying oils acted as a diluent, which reduced the viscosity, and enhanced workability, shortened touch-free drying time and accelerated the hardened drying of the OMRL. The results also indicated that the hardness, mass retention, Tg, tensile strength, abrasion resistance, and lightfastness of OMRL films decreased as more drying oils were blended with lacquer. Conversely, the bending resistance, elongation at break, impact resistance increased. Gloss was greatly improved through the blending of more drying oils with lacquer. In conclusion, the LO-modified refined lacquer (RL) had the highest film gloss and the DCO-modified RL had the shortest drying time for coating. Otherwise, the film properties were similar among the three types of drying oils.

Measurement of adsorption constants of laccase on gold nanoparticles to evaluate the enhancement in enzyme activity of adsorbed laccase

Adsorption of enzymes to nanoparticles and the mechanisms responsible for enzyme activity modulation of adsorbed enzymes are not well understood. In this work, gold nanoparticles were used for electrostatic adsorption of a plant-derived laccase. Adsorption constants were determined by four independent techniques: dynamic light scattering, electrophoretic light scattering, agarose gel electrophoresis and fluorescence quenching. Stable bionanoconjugates were formed with log K in the range 6.8-8.9. An increase in enzyme activity was detected, in particular at acidic and close to neutral pH values, a feature that expands the useful pH range of the enzyme. A model for the adsorption was developed, based on geometrical considerations and volume increase data from dynamic light scattering. This indicates that enzymes adsorbed to gold nanoparticles are ca. 9 times more active than the free enzyme.

Determination of lacquer contained in samples of cultural relics by enzyme-linked immunosorbent assay

As an environmentally friendly natural polymer material, lacquer is durable, anti-bacterial, corrosion-resistant and decorative.

Allergen-Removed Rhus verniciflua Extract Induces Ovarian Cancer Cell Death via JNK Activation

Nuclear factor-[Formula: see text]B (NF-[Formula: see text]B)/Rel transcription factors are best known for their central roles in promoting cell survival in cancer. NF-[Formula: see text]B antagonizes tumor necrosis factor (TNF)-[Formula: see text]-induced apoptosis through a process involving attenuation of the c-Jun-N-terminal kinase (JNK). However, the role of JNK activation in apoptosis induced by negative regulation of NF-[Formula: see text]B is not completely understood. We found that allergen-removed Rhus verniciflua Stokes (aRVS) extract-mediated NF-[Formula: see text]B inhibition induces apoptosis in SKOV-3 ovarian cancer cells via the serial activation of caspases and SKOV-3 cells are most specifically suppressed by aRVS. Here, we show that in addition to activating caspases, aRVS extract negatively modulates the TNF-[Formula: see text]-mediated I[Formula: see text]B/NF-[Formula: see text]B pathway to promote JNK activation, which results in apoptosis. When the cytokine TNF-[Formula: see text] binds to the TNF receptor, I[Formula: see text]B dissociates from NF-[Formula: see text]B. As a result, the active NF-[Formula: see text]B translocates to the nucleus. aRVS extract (0.5[Formula: see text]mg/ml) clearly prevented NF-[Formula: see text]B from mobilizing to the nucleus, resulting in the upregulation of JNK phosphorylation. This subsequently increased Bax activation, leading to marked aRVS-induced apoptosis, whereas the JNK inhibitor SP600125 in aRVS extract treated SKOV-3 cells strongly inhibited Bax. Bax subfamily proteins induced apoptosis through caspase-3. Thus, these results indicate that aRVS extract contains components that inhibit NF-[Formula: see text]B signaling to upregulate JNK activation in ovarian cancer cells and support the potential of aRVS as a therapeutic agent for ovarian cancer.

Identification of new natural DNA G-quadruplex binders selected by a structure-based virtual screening approach

The G-quadruplex DNA structures are mainly present at the terminal portion of telomeres and can be stabilized by ligands able to recognize them in a specific manner. The recognition process is usually related to the inhibition of the enzyme telomerase indirectly involved and over-expressed in a high percentage of human tumors. There are several ligands, characterized by different chemical structures, already reported in the literature for their ability to bind and stabilize the G-quadruplex structures. Using the structural and biological information available on these structures; we performed a high throughput in silico screening of commercially natural compounds databases by means of a structure-based approach followed by docking experiments against the human telomeric sequence d[AG₃(T₂AG₃)₃]. We identified 12 best hits characterized by different chemical scaffolds and conformational and physicochemical properties. All of them were associated to an improved theoretical binding affinity with respect to that of known selective G-binders. Among these hits there is a chalcone derivative; structurally very similar to the polyphenol butein; known to remarkably inhibit the telomerase activity.

Determination of oxidoreductase activity using a high-throughput microplate respiratory measurement

High-throughput multiparallel activity profiling for oxygen consuming cell layers has been recently developed for extracellular flux analysis. This technology has great potential for determining the enzymatic activity of oxidoreductases (i.e., laccase) both in vivo and in vitro, which is usually measured using photometrical tests monitoring the colored oxidation products. Improvements in terms of sample throughput, comparability, and gain of information (i.e., stoichiometry, electron transfer rate) can be achieved by means of a multiwell plate-based fluorimetric oxygen sensor. In the present study, various laccases have been applied to develop protocols that allow the multiparallel measurement of O(2)-consumption by enzymatic reactions. The developed and validated method enables the comparative quantitation of laccase characteristics (i.e., profiles of activity at various pH values) and minimizes the time it usually takes to collect respiratory data of oxygen-consuming enzymes. Furthermore, the possibility to assess differences between single and multisubstrate kinetics of laccases has been demonstrated.

Effects of lacquer polysaccharides, glycoproteins and isoenzymes on the activity of free and immobilised laccase from Rhus vernicifera

The purified polysaccharides, glycoproteins, and isoenzymes of Rhus laccase, and crude enzymes, from Chinese lacquer (Rhus vernicifera sap) were used to determine their influence on the enzymic activity of Rhus laccase on several substrates (4-phenylenediamine, isoeugenol and coniferyl alcohol). No product identity changes were observed when these components were added singularly or in combination to the enzymic reactions (only relative product yields varied significantly), however, the polysaccharides (GP1 and GP2) and glycoprotein (stellacyanin, St) exhibited negative effects, and the two isoenzymes (L1 and L2) exhibited positive synergistic effects, on the activity of Rhus laccase. With respect to the activity of the crude enzymes, the negative effects of GP1, GP2 and St were greater than the positive effects of L1 and L2, compared with free Rhus laccase on its own (using 4-phenylenediamine as substrate), the estimated inhibitory effect (of GP1, GP2 and St) being by at least a factor of 50 (even with the positive effect of L1 and L2). This contributes to understanding of lacquer storage stability and drying rates. Immobilisation of crude enzymes using a variety of techniques (using natural and modified polysaccharides, and an inorganic support) where evaluated using isoeugenol as substrate. Agar embedding and zirconium chloride chelation methods resulted in the highest substrate conversion levels. The yields and products of isoeugenol catalysis using Vietnamese crude enzymes/purified Rhus laccase and commercial Denilite laccase were also compared and contrasted with their Chinese lacquer sap equivalents.

Does Donglan lacquer tree belong to Rhus vernicifera species?

The lacquer trees in Donglan of Guangxi Province, China, were identified totally as the species Rhus succedanea found in Vietnam and Taiwan region, based on the results of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), an easy and effective method to identify species of trees among those with similar properties. Analyses by IR and NMR, the drying properties, and conventional morphology also confirmed that the Donglan lacquer trees do not belong to Rhus vernicifera, like most trees of the China mainland. Some differences, however, such as the enzymatic activity and the components of the lacquer, were found between the Donglan lacquer and the Vietnam lacquer. The Donglan lacquer has a shorter drying time than the latter.