Development and validation of a rapid ultra-high performance liquid chromatography diode array detector method for Vitex agnus-castus

Metabolic profiling of Vitex Pubescens Vahl bark via UPLC-ESI-QTOF/MS/MS analysis and evaluation of its antioxidant and acetylcholinesterase inhibitory activities

BACKGROUND

Alzheimer's disease is a neurodegenerative age-related disease that primarily affects the elderly population leading to progressive memory impairments and neural deficits. It is counted as a major cause of geriatric dependency and disability. The pathogenesis of Alzheimer's disease incidence is complex and involves various hypotheses, including the cholinergic hypothesis, deposition of β-amyloid plaques, neuroinflammation, oxidative stress, and apoptosis. Conventional treatments such as donepezil aim to delay the symptoms but do not affect the progression of the disease and may cause serious side effects like hepatoxicity. The use of natural candidates for Alzheimer's disease treatment has drawn the attention of many researchers as it offers a multitargeted approach.

METHODS

This current study investigates the metabolic profiles of total defatted methanolic extract of Vitex pubescens bark and its polar fractions, viz. ethyl acetate and n-butanol, using ultra-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight tandem mass spectrometry(UPLC-ESI-QTOF/MS/MS) technique as well as evaluate the antioxidant using free radical scavenging assays, viz. DPPH and ABTS assays and in-vitro acetylcholinesterase inhibitory activities using Ellman's microplate assay.

RESULTS

Metabolic profiling revealed a total of 71, 43, and 55 metabolites tentatively identified in the defatted methanolic extract, ethyl acetate, and n-butanol fractions, respectively. Phenolic acids were the most abundant class, viz. benzoic acids, and acyl quinic acid derivatives followed by flavonoids exemplified mainly by luteolin-C-glycosides and apigenin-C-glycosides. Quantification of the total phenolic and flavonoid contents in the total defatted methanolic extract confirmed its enrichment with phenolics and flavonoids equivalent to 138.61 ± 9.39 µg gallic acid/mg extract and 119.63 ± 4.62 µg rutin/mg extract, respectively. Moreover, the total defatted methanolic extract exhibited promising antioxidant activity confirmed through DPPH and ABTS assays with a 50% inhibitory concentration (IC50) value equivalent to 52.79 ± 2.16 µg/mL and 10.02 ± µg/mL, respectively. The inhibitory activity of acetylcholine esterase (AchE) was assessed using in-vitro Ellman's colorimetric assay, the total defatted methanolic extract, ethyl acetate, and n-butanol fractions exhibited IC50 values of 52.9, 15.1 and 108.8 µg/mL that they proved the significant inhibition of AchE activity.

CONCLUSION

The results obtained herein unraveled the potential use of the total methanolic extract of Vitex pubescens bark and its polar fractions as natural candidates for controlling Alzheimer's disease progression.

Assessment of metabolic, mineral, and cytotoxic profile in pineapple leaves of different commercial varieties: A new eco-friendly and inexpensive source of bioactive compounds

Pineapple is among the most produced and consumed fruits worldwide, and consequently, its agroindustrial production/processing generates high amounts of agricultural waste, which are routinely discarded. Thus, it is crucial to seek alternatives to reuse this agricultural waste that are in high availability. Therefore, this work aims to evaluate the chemical composition of a specific residue (leaves) of seven commercial varieties of pineapples, to attribute high added value uses, and to evaluate its potential as a source of secondary metabolites and minerals. Thereby, twenty-eight metabolites were annotated by UPLC-QTOF-MS^E, including amino acids, organic acids, and phenolic compounds. The following minerals were quantitatively assessed by ICP-OES: Zn (5.30-19.77 mg kg^-1), Cr, Cd, Mn (50.80-113.98 mg kg^-1), Cu (1.05-4.01 mg kg^-1), P (1030.77-6163.63 mg kg^-1) and Fe (9.06-70.17 mg kg^-1). In addition, Cr and Cd (toxic materials) present concentration levels below the limit of quantification of the analytical method (LOQ_Cr and LOQ_Cd = 0.02 mg kg^-1) for all samples. The multivariate analysis was conceived from the chemical profile, through the tools of PCA (principal component analysis) and HCA (hierarchical cluster analysis). The results show that pineapple leaves have similarities and differences concerning their chemical composition. In addition, the cytotoxicity assays of the extracts against tumor and non-tumor strains shows that the extracts were non-toxic. This fact can corroborate and enhance the prospection of new uses and applications of agroindustrial co-products from pineapple, enabling the evaluation and use in different types of industries, such as pharmacological, cosmetic, and food, in addition to the possibility of being a potential source of bioactive compounds.

Combining HPLC-DAD-QTOF-MS and HPLC-SPE-NMR to Monitor In Vitro Vitetrifolin D Phase I and II Metabolism

By combining HPLC-DAD-QTOF-MS and HPLC-SPE-NMR, the in vitro metabolism of vitetrifolin D, a pharmacologically active key molecule from Vitex agnus-castus in liver cell fractions, was investigated. Twenty-seven phase I and phase II metabolites were tentatively identified from the culture broth by HPLC-DAD-QTOF-MS. The subsequent HPLC-SPE-NMR analysis allowed for the unequivocal structural characterization of nine phase I metabolites. Since the preparative isolation of the metabolites was avoided, the substance input was much lower than in conventional strategies. The study did prove that the use of hyphenated instrumental analysis methodologies allows for the successful performance of in vitro metabolism studies, even if the availability of substances is very limited.

Anti-Atherosclerotic Effects of Fruits of Vitex rotundifolia and Their Isolated Compounds via Inhibition of Human LDL and HDL Oxidation

Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) oxidation are well known to increase the risk for atherosclerosis. In our ongoing research on natural products with inhibitory activities against oxidation of lipoproteins, fruits of Vitex rotundifolia were found to be highly active. There is no report on the effects on LDL and HDL oxidation. Herein, we investigated the inhibitory effects of V. rotundifolia fruit extract and its six compounds, which are: (1) artemetin, (2) casticin, (3) hesperidin, (4) luteolin, (5) vitexin, and (6) vanillic acid, against LDL and HDL oxidation. The LDL and HDL oxidations were determined by measuring production of conjugated dienes and thiobarbituric acid reactive substances, amount of hyperchromicity and carbonyl content, change in electrical charge, and apoA-I aggregation. In addition, the contents of the compounds in the extracts were analyzed using HPLC-DAD. Consequently, extracts of Vitex rotundifolia fruits and compounds 2 and 4 suppressed oxidation of LDL and HDL, showing inhibition of lipid peroxidation, decrease of negative charges in lipoproteins, reduction of hyperchromicity, decrease in carbonyl contents, and prevention of apoA-I aggregation. In particular, compounds 2 and 4 exhibited more potent inhibitory effect on oxidation of LDL and HDL than the extracts, suggesting their protective role against atherosclerosis via inhibition of LDL and HDL oxidation. The contents of artemetin, casticin, and vanillic acid in the extracts were 1.838 ± 0.007, 8.629 ± 0.078, and 1.717 ± 0.006 mg/g, respectively.

Recent Trends in Fast Liquid Chromatography for Pharmaceutical Analysis

Background:

Liquid chromatography is the workhorse of analytical laboratories of pharmaceutical companies for analysis of bulk drug materials, intermediates, drug products, impurities and degradation products. This efficient technique is impeded by its long and tedious analysis procedures. Continuous efforts of scientists to reduce the analysis time resulted in the development of three different approaches namely, HTLC, chromatography using monolithic columns and UHPLC.

Methods:

Modern column technology and advances in chromatographic stationary phase including silica-based monolithic columns and reduction in particle and column size (UHPLC) have not only revolutionized the separation power of chromatographic analysis but also have remarkably reduced the analysis time. Automated ultra high-performance chromatographic systems equipped with state-ofthe- art software and detection systems have now spawned a new field of analysis, termed as Fast Liquid Chromatography (FLC). The chromatographic approaches that can be included in FLC are hightemperature liquid chromatography, chromatography using monolithic column, and ultrahigh performance liquid chromatography.

Results:

This review summarizes the progress of FLC in pharmaceutical analysis during the period from year 2008 to 2017 focusing on detecting pharmaceutical drugs in various matrices, characterizing active compounds of natural products, and drug metabolites. High temperature, change in the mobile phase, use of monolithic columns, new non-porous, semi-porous and fully porous reduced particle size of/less than 3μm packed columns technology with high-pressure pumps have been extensively studied and successively applied to real samples. These factors revolutionized the fast high-performance separations.

Conclusion:

Taking into account the recent development in fast liquid chromatography approaches, future trends can be clearly predicated. UHPLC must be the most popular approach followed by the use of monolithic columns. Use of high temperatures during analysis is not a feasible approach especially for pharmaceutical analysis due to thermosensitive nature of analytes.

Nanoemulsion for improving solubility and permeability of Vitex agnus-castus extract: formulation and in vitro evaluation using PAMPA and Caco-2 approaches

The purpose of this study was to develop new formulation for an improved oral delivery of Vitex agnus-castus (VAC) extract. After the optimization and validation of analytical method for quali-quantitative characterization of extract, nanoemulsion (NE) was selected as lipid-based nanocarrier. The composition of extract-loaded NE resulted in triacetin as oil phase, labrasol as surfactant, cremophor EL as co-surfactant and water. NE contains until 60 mg/mL of extract. It was characterized by DLS and TEM analyses and its droplets appear dark with an average diameter of 11.82 ± 0.125 nm and a polydispersity index (PdI) of 0.117 ± 0.019. The aqueous solubility of the extract was improved about 10 times: the extract is completely soluble in the NE at the concentration of 60 mg/mL, while its solubility in water results less than 6 mg. The passive intestinal permeation was tested by using parallel artificial membrane permeation assay (PAMPA) and the permeation across Caco-2 cells after preliminary cytotoxicity studies were also evaluated. NE shows a good solubilizing effect of the constituents of the extract, compared with aqueous solution. The total amount of constituents permeated from NE to acceptor compartment is greater than that permeated from saturated aqueous solution. Caco-2 test confirmed PAMPA results and they revealed that NE was successful in increasing the permeation of VAC extract. This formulation could improve oral bioavailability of extract due to enhanced solubility and permeability of phytocomplex.

A Review on the Terpenes from Genus Vitex

The genus Vitex, which belongs to the Verbenaceae family, includes approximately 250 species. Some species of the genus Vitex have traditionally been used for the treatment of headaches, ophthalmodynia, coughs, asthma, premenopausal syndrome, etc. Chemical investigations indicate that the characteristic constituents of the genus Vitex are terpenes, and 210 of these compounds, including monoterpenoids, sesquiterpenoids, diterpenoids and triterpenoids, have been obtained from 12 species. Pharmacological studies had shown that these terpenes possess anti-inflammatory, antitumor, antibacterial, antioxidant activities, and so on. In this paper, the identity of these terpenes and their pharmacological effects are reviewed, which can provide references for further research regarding the chemistry and utilization of the Vitex species.

Qualitative and Quantitative Analysis of Phenolic Acids, Flavonoids and Iridoid Glycosides in Yinhua Kanggan Tablet by UPLC-QqQ-MS/MS

A simple, rapid and specific ultra-performance liquid chromatography-triple quadrupole mass spectrometry method was developed for the analysis of 29 bioactive components (10 phenolic acids, 16 flavonoids, and three iridoid glycosides) in Yinhua Kanggan tablet (YHKGT), a herbal prescription used for treating upper respiratory infections, fevers, coughs and pharyngalgia. The separation was successfully achieved using a Waters Cortecs UPLC C18 column (50 × 2.1 mm, 1.6 μm) and gradient elution with water-0.1% formic acid and acetonitrile. Polarity switching mode was used in the optimization of multiple reaction monitoring conditions. The analytical method was validated for linearity, precision and accuracy. Calibration curves for the 29 marker compounds showed good linear regression (r > 0.9982). The limits of detection (LOD) and limits of quantification (LOQ) for the 29 analytes were in the range of 0.03–4.99 ng/mL and 0.16–14.87 ng/mL, respectively. The relative standard deviation (RSD) values of intra-day precision, inter-day precision, repeatability, and stability were less than 2.79%, 4.87%, 4.18% and 4.71%, respectively. The recoveries of the 29 marker compounds were in the range of 94.67%–104.78% (RSD ≤ 4.72%). These results have shown that this developed method was efficient for the quality evaluation of YHKGT.