Preparative separation of triterpene alcohol ferulates from rice bran oil using a high performance counter-current chromatography

Highly efficient synthesis of 4,4-dimethylsterol oleates using acyl chloride method through esterification

In this study, the 4,4-dimethylsterol oleates were efficiently synthesized through esterification of 4,4-dimethylsterols and oleoyl chloride. The impact of reaction parameters on the 4,4-dimethylsterol conversion were investigated. The 4,4-dimethylsterol conversion increased with pyridine dosage, molar ratio of oleoyl chloride to 4,4-dimethylsterols, and temperature. The highest conversion of 99.27% was obtained with molar ratio of 1.1:1 at 313 K for 60 min. A second-order kinetic model describing acyl chloride esterification featuring high correlation coefficients was established. Arrhenius-Van't Hoff plot suggested activation energy and pre-exponential factor were 15.54 kJ mol^-1 and 1.78 × 10³ L mol^-1 min^-1, respectively. The molecular structure of 4,4-dimethylsterol oleates were finally identified by attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR), ultra-performance liquid chromatography system coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS), and nuclear magnetic resonance (NMR).

Isolation and Structure Determination of 24-Methylenecycloartanyl Ferulate from Indian Rice Bran and Its Quantitative Analysis

BACKGROUND

γ-oryzanol is a major bioactive constituent in rice. Most of the literature reports isolation of 24-methylenecycloartanyl ferulate (24-mCAF) from rice bran oil (RBO) of other than Indian variety. Current research has successfully applied high-performance thin layer chromatography (HPTLC) method for isolation of 24-mCAF from Indian variety (Indrayani) of RBO.

MATERIALS AND METHODS

HPTLC method was developed for standard γ-oryzanol using tinidazole as an internal standard. The proposed HPTLC method was optimized and validated as per the guidelines stated by the International Conference on Harmonization Q2 R1 recommendations. The mobile phase composed of toluene:ethyl acetate:methanol (15.0:1.7:3.3, (v/v/v) was selected because well-resolved peaks were obtained. The optimum wavelength chosen for detection and quantitation was 317 nm.

RESULTS

The retention factors for tinidazole, 24-mCAF, and CAF were found to be 0.27 ± 0.02, 0.72 ± 0.02, and 0.79 ± 0.02, respectively. The percent content of 24-mCAF in ethanol fraction was found to be 1.02%. The 24-mCAF was isolated from RBO using HPTLC method.

CONCLUSION

The characterization data of 1D, 2D spectral analysis confirm that the isolated compound 1 is 24-mCAF.

SUMMARY

HPTLC method was developed for standard γ-oryzanol using tinidazole as an internal standardThe proposed HPTLC method was optimized and validated as per the guidelines stated by the ICH Q2 R1 recommendationsThe characterization data of 1D, 2D spectral analysis confirms that the isolated compound is 24-methylenecycloartanyl ferulateIn this work, high purity 24-mCAF was successfully isolated from crude RBO using HPTLC with a solvent system composed toluene: ethyl acetate: methanol (15.0:1.7:3.3, v/v/v) Abbreviations used: RBO: Rice Bran Oil, CAF: Cycloartenol ferulic acid, 24-mCAF: 24-Methylcycloartenol ferulic acid, HPLC: High-Performance Liquid Chromatography, HPTLC: High-Performance Thin Layer Chromatography, 1H: Proton nuclear magnetic resonance spectroscopy, 13C: Carbon-13 nuclear magnetic resonance spectroscopy, COSY: Correlation spectroscopy, NOESY: Nuclear overhauser effect spectroscopy, HMBC: Heteronuclear multiple bond correlation nuclear magnetic resonance spectroscopy, HSQC: heteronuclear single quantum coherence nuclear magnetic resonance spectroscopy.

Countercurrent Separation of Natural Products: An Update

This work assesses the current instrumentation, method development, and applications in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CCS). The article provides a critical review of the CCS literature from 2007 since our last review (J. Nat. Prod. 2008, 71, 1489-1508), with a special emphasis on the applications of CCS in natural products research. The current state of CCS is reviewed in regard to three continuing topics (instrumentation, solvent system development, theory) and three new topics (optimization of parameters, workflow, bioactivity applications). The goals of this review are to deliver the necessary background with references for an up-to-date perspective of CCS, to point out its potential for the natural product scientist, and thereby to induce new applications in natural product chemistry, metabolome, and drug discovery research involving organisms from terrestrial and marine sources.

Counter-current chromatography for the separation of terpenoids: a comprehensive review with respect to the solvent systems employed

Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications.

Rice brans, rice bran oils, and rice hulls: composition, food and industrial uses, and bioactivities in humans, animals, and cells

Rice plants produce bioactive rice brans and hulls that have been reported to have numerous health-promoting effects in cells, animals, and humans. The main objective of this review is to consolidate and integrate the widely scattered information on the composition and the antioxidative, anti-inflammatory, and immunostimulating effects of rice brans from different rice cultivars, rice bran oils derived from rice brans, rice hulls, liquid rice hull smoke derived from rice hulls, and some of their bioactive compounds. As part of this effort, this paper also presents brief summaries on the preparation of health-promoting foods including bread, corn flakes, frankfurters, ice cream, noodles, pasta, tortillas, and zero-trans-fat shortening as well as industrial products such bioethanol and biodiesel fuels. Also covered are antibiotic, antiallergic, anticarcinogenic, antidiabetic, cardiovascular, allelochemical, and other beneficial effects and the mechanisms of the bioactivities. The results show that food-compatible and safe formulations with desirable nutritional and biological properties can be used to develop new multifunctional foods as well as bioethanol and biodiesel fuel. The overlapping aspects are expected to contribute to a better understanding of the potential impact of the described health-promoting potential of the rice-derived brans, oils, and hulls in food and medicine. Such an understanding will enhance nutrition and health and benefit the agricultural and industrial economies.

Simultaneous HPLC quantification of five major triterpene alcohol and sterol ferulates in rice bran oil using a single reference standard

A high performance liquid chromatography (HPLC) method was developed for simultaneous quantification of five major triterpene alcohol and sterol ferulates in rice bran oils (RBO) with a single internal standard, cycloartenyl ferulate. The five compounds are cycloartenyl ferulate (1), 24-methylene cycloartanyl ferulate (2), campesteryl ferulate (3), sitosteryl ferulate (4) and stigmastanyl ferulate (5). All five compounds had good linear concentration-measurement relationships (r(2) ≥ 0.9995) and possessed similar relative response factors. The relative deviation of this method was less than 2.5% for intra- and inter-day assays, and the average recovery varied from 95.1% to 99.4%. The new method was validated by comparing the amount of 24-methylene cycloartanyl ferulate (2) in 17 RBO samples obtained with this method and that with an external standard method. This method was also successfully applied to determine five major triterpene alcohol and sterol ferulates in 17 batches of RBO samples. The results demonstrated that the present method could be utilised for quality control of RBO since some of the reference standards are not commercially available.