Quantification of Kavalactones and Determination of Kava (Piper methysticum) Chemotypes Using Near-Infrared Reflectance Spectroscopy for Quality Control in Vanuatu

Abstract

Kava ( Piper methysticum Forst f., Piperaceae) has anxiolytic properties and the ability to promote a state of relaxation without the loss of mental alertness. The rapid growth of the nutraceutical market between 1998 and 2000 has been stopped by a ban in Europe and Australia because of some suspicion of liver toxicity. It is now important to develop a fast, cheap, and reliable quality test to control kava exports. The aim of this study is to develop a calibration of the near-infrared reflectance spectroscopy (NIRS) using partial least-squares (PLS) regression. Two hundred thirty-six samples of kava roots, stumps, and basal stems were collected from the Vanuatu Agricultural Research and Technical Centre germplasm collection and from four villages. These samples, representing 45 different varieties, were analyzed using NIRS to record their absorption spectra between 400 and 2500 nm. A set of 101 selected samples was analyzed for their kavalactone content using HPLC. The results were used for PLS calibration of the NIRS. The NIRS prediction of the kavalactone content and the dry matter were in agreement with the HPLC results. There were good correlations between these two series of results, and coefficients ( R (2)) were all close to 1. The measurements were reproducible and had repeatability on par with the HPLC method. The NIRS system has been calibrated for the six major kavalactone content measurements, and it is suggested that this method could be used for quality control in Vanuatu.

Comparative analysis of genetic variation in kava (Piper methysticum) assessed by SSR and DArT reveals zygotic foundation and clonal diversification

“…Field experiments and analysis of kavalactones have demonstrated the stability of chemotypes across locations for a given cultivar and confirmed that chemotype is genetically controlled (Siméoni and Lebot 2002;Lasme et al 2008). Nevertheless, this is the first study enabling genetic discrimination of cultivars differing in their chemical properties and quality.…”

“…The chemotype is responsible for the quality of the physiological effects and the total kavalactone content, which also varies according to the cultivar used, determines its intensity (Siméoni and Lebot 2002;Wang et al 2015). While noble and medicinal cultivars belong to a single clonal lineage, important variations in total kavalactones exist between and within these categories of cultivars (Lasme et al 2008). So, although some environmental factors may play a role, it is likely that clonal selection is also exerted on the total kavalactone content as farmers judge the physiological effects of the beverage obtained by a single plant.…”

“…Overall, 98 cultivars and five wild kavas were studied (Table 1). Among these, 27 cultivars had already been analyzed by HPLC and their chemotypes determined (Lasme et al 2008). Morphotypes of VARTC cultivars were described with the following eight morphological descriptors (A, C, I, L, E, P, S, N), previously tested to differentiate accessions efficiently (Lebot et al 1999):…”

“…Medicinal and noble cultivars do not differ significantly in chemotyping and their classification refers to their uses as a medicinal plant or for daily consumption as a beverage, respectively. However, two-days cultivars, low in K and rich in dihydrokavain (DHK) and dihydromethysticin (DHM), are not suitable for consumption and are known for their side effects and nausea (Lebot and Lévesque 1989;Lasme et al 2008).…”

“…wichmannii. § Chemotype quality(Lasme et al 2008): HQ, high quality corresponding to a high kavain (K) content; LQ, low quality corresponding to a low K content.…”