HPLC-Guided Isolation, Purification and Characterization of Phenylpropanoid and Phenolic Constituents of Nutmeg Kernel (Myristica fragrans)

Abstract

Many studies on the biological activities of nutmeg continue to appear in the literature. The most common targets include GIT, CNS, oxidative stress and inflammation. However, results obtained from most studies are often inconsistent due to the variability of utilized samples, lack of standardized nutmeg products or insufficient amounts of pure compounds for comprehensive follow-up investigation. To address the consistency and supply issue we utilized available technology to develop a reproducible procedure for preparation of specific extracts and isolation of the major phenolic constituents present in nutmeg kernel. A well-defined and reproducible sequence of extraction, fractionation and chromatographic purification was adopted and was guided by HPLC fingerprinting. Spectroscopic methods, mainly NMR, and mass spectrometry were utilized to identify each compound. Thirteen compounds were isolated in a pure form and identified as: elemicin (1), isoelemicin (2), myristicin (4), surinamensin (5), malabaricone C (6), 2-(3′-allyl-2′,6′-dimethoxy-phenyloxy)-1-acetoxy-(3,4-dimethoxyphenyl)-propyl ester (7), methoxylicarin A (8), licarin A (9), malabaricone B (10), licarin C (11), 5′-methoxylicarin B (12), licarin B (13), and 2-(3′-allyl-2′,6′-dimethoxy-phenyloxy)-1-methyl-5-methoxy-1,2-dihydrobenzofuran (3, a new compound). With repeated isolation runs, these pure compounds can be prepared in quantities sufficient for biological evaluation as needed. The availability of purified compounds will also allow the development of specific, accurate, and sensitive analytical procedures for pharmacokinetic studies and for quality control of nutmeg products. Both aspects are essential for nutmeg-focused drug discovery. The same approach can also be adapted to other medicinal plants of potential interest.