The Influence of Different Extraction Techniques on the Chemical Profile and Biological Properties of Oroxylum indicum: Multifunctional Aspects for Potential Pharmaceutical Applications.

Oroxylum indicum (L.) Kurz (Bignoniaceae), a traditional Chinese herbal medicine, possesses various biological activities including antioxidant, anti-inflammatory, antibacterial, and anticancer. In order to guide the practical application of O. indicum in the pharmaceutical, food, and cosmetic industries, we evaluated the effects of five different extraction techniques (maceration extraction (ME), oxhlet extraction (SOXE), ultrasound-assisted extraction (UAE), tissue-smashing extraction (TSE), and accelerated-solvent extraction (ASE)) with 70% ethanol as the solvent on the phytochemical properties and biological potential. The UHPLC-DAD Orbitrap Elite MS technique was applied to characterize the main flavonoids in the extracts. Simultaneously, the antioxidant and enzyme inhibitory activities of the tested extracts were analyzed. SOXE extract showed the highest total phenolic content (TPC, 50.99 ± 1.78 mg GAE/g extract), while ASE extract displayed the highest total flavonoid content (TFC, 34.92 ± 0.38 mg RE/g extract), which displayed significant correlation with antioxidant activity. The extract obtained using UAE was the most potent inhibitor of tyrosinase (IC50: 16.57 ± 0.53 mg·mL-1), while SOXE extract showed the highest activity against α-glucosidase (IC50: 1.23 ± 0.09 mg·mL-1), succeeded by UAE, ME, ASE, and TSE extract. In addition, multivariate analysis suggested that different extraction techniques could significantly affect the phytochemical properties and biological activities of O. indicum. To sum up, O. indicum displayed expected biological potential and the data collected in this study could provide an experimental basis for further investigation in practical applications.

Characterization of constituents by UPLC-MS and the influence of extraction methods of the seeds of Vernonia anthelmintica willd.: extraction, characterization, antioxidant and enzyme modulatory activities.

Vernonia anthelmintica Willd (VA) is a popular medicinal plant used in local and traditional medicine to manage various disorders. In order to explore the phytochemical profile, antioxidant and enzyme modulatory activities of extracts prepared from the seeds of VA, different extraction methodologies, including modern (accelerated-ASE, ultrasound-UAE, and tissue smashing-TSE extractions) and traditional (maceration and Soxhlet) extractions, were employed and their effects on the activities of the extracts were investigated. The chemical compounds of the extracts were qualitatively analyzed by ultra-high-pressure liquid chromatography-tandem mass spectrometry (UPLC-Orbitrap-MS) technique. Among them, 11 compounds were undoubtedly identified by comparison with reference substance, while 13 compounds were tentatively identified by comparison with literature data, including 8 phenolic acids, 14 flavonoids and 2 esters were identified in the extracts. Additionally, the quantitative analysis found that ASE showed the highest extraction efficiency. The antioxidant activity was determined in vitro via six standard assays. Two key enzymes related to the diseases of vitiligo (tyrosinase) and type II diabetes (α-glucosidase) were adopted to assess the activity of VA extracts against them. All extracts showed potent antioxidant ability with a predominance for that obtained by ASE, which corroborated with the high phenolic (22.62 ± 0.23 mg gallic acid equivalent (GAE)/g extract) and flavonoid contents (68.85 ± 0.25 mg rutin equivalent (RE)/g extract). The extracts obtained by ASE, UAE and SE could increase the tyrosinase activity and all the extracts displayed remarkable inhibitory activity against α-glucosidase. This study demonstrated that the VA extracts obtained by novel extraction techniques such as ASE, could be considered as a positive candidate to be utilized by the food and medical industries, not only for obtaining bioactive compounds to be used as natural antioxidants, but possibly also for its health benefits for therapeutic bio-product development.

Rapid screening of natural-origin tyrosinase regulators from Vernonia anthelmintica (L.) Willd. by offline two-dimensional liquid chromatography coupled with mass spectrometry.

Finding and developing safe and effective tyrosinase (TYR) regulators is of great significance for the prevention and treatment of melanin-related skin diseases in the medical and cosmetic industries. In the current research, an approach based on offline two-dimensional liquid chromatography coupled with mass spectrometry (offline 2D LC-MS) was established to screen TYR modulators from Vernonia anthelmintica (L.) Willd. (VA) extract. Firstly, the reliability of the proposed method was evaluated by using kojic acid (inhibitor), psoralen (activator) and ranitidine as positive and negative control, respectively. Some significant parameters including incubation time, TYR concentrations, and reaction temperature were investigated. Then, the developed new method was successfully applied to rapidly discover the active compounds from VA extract. Seven TYR ligands were successfully screened by comparing the chromatographic profiles of VA extract incubated with active and denatured TYR, respectively. To verify the activity of the screened compounds, in vitro bioassay was carried out and the result showed two of them, isorhamnetin and luteolin, had good TYR inhibitory activity with IC50 value of 0.86 and 1.00 mg/mL, respectively, while the other five compounds including eriodictyol, butochalcone, chlorogenic acid, isochlorogenic acid B, and isochlorogenic acid C showed strong activation against TYR. Furthermore, molecular docking displayed that these compounds could bind to the amino acid residues in TYR catalytic pocket. The results demonstrate that the established technique can be efficiently used for rapid screening of TYR-active compounds from plant extracts.

Recent advance in the discovery of tyrosinase inhibitors from natural sources via separation methods.

Tyrosinase (TYR) inhibitors are in great demand in the food, cosmetic and medical industrials due to their important roles. Therefore, the discovery of high-quality TYR inhibitors is always pursued. Natural products as one of the most important sources of bioactive compounds discovery have been increasingly used for TYR inhibitors screening. However, due to their complex compositions, it is still a great challenge to rapid screening and identification of biologically active components from them. In recent years, with the help of separation technologies and the affinity and intrinsic activity of target enzymes, two advanced approaches including affinity screening and inhibition profiling showed great promises for a successful screening of bioactive compounds from natural sources. This review summarises the recent progress of separation-based methods for TYR inhibitors screening, with an emphasis on the principle, application, advantage, and drawback of each method along with perspectives in the future development of these screening techniques and screened hit compounds.

Ultra-rapid, enhanced and eco-friendly extraction of four main flavonoids from the seeds of Oroxylum indicum by deep eutectic solvents combined with tissue-smashing extraction.

Rapid, green and efficient extraction of active compounds followed by fast analysis is always pursued in the field of food analysis and/or industry. Herein, a green and highly efficient extraction of four active flavonoids from the seeds of Oroxylum indicum using a combination of natural deep eutectic solvents (DESs) and tissue-smashing extraction (TSE) technique was applied and a UPLC method was developed for their sensitive and selective quantification. RSM coupled with BBD procedure was used to optimize the extraction conditions based on single factors, such as liquid-solid ratios, extraction speed and extraction time. Compared with other conventional methods, the TSE greatly shortens extraction time, obviously raises the extraction production, and decreases energy consumption. By combination of the DES-based TSE and UPLC, the analysis of flavonoids was accomplished within only 6 min, providing an ultra-rapid, environmentally friendly and promising choice for extraction and analysis of active compounds in natural products.