分析および生物分析技術ジャーナル

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Determination of Effects of Sample Processing on Hibiscus sabdariffa L. Using Tri-step Infrared Spectroscopy

Yew-Keong Choong, Nor Syaidatul Akma, Mohd Yousof, Mohd Isa Wasiman, Jamia Azdina Jamal and Zhari Ismail

Hibiscus sabdariffa tea is a widely used medicinal beverage and a treatment for high blood pressure and high blood cholesterol in many parts of the world. Many studies on H. sabdariffa have been conducted including extraction and identification of main biocompounds. However, information on the effects of processing the plant is scarce. This is important as sample processing procedure influence the composition of the end product. Hence, the main objective of this present study was to examine the effect of sample processing (non-extracted, ethanol extract and water extract) on H. sabdariffa composition. Fourier Transform Infrared (FTIR) was used for the process of identification. The powdered sample of H. sabdariffa (FT34) was obtained from a local company in Peninsula Malaysia. A fresh sample obtained from the same company was processed in the Phytochemistry Laboratory, Institute for Medical Research and labelled as FT35. Sample and potassium bromide (KBr) were mixed (1:250) to form a 1-2 mm transparent disk under 9.80 psi in vacuum. The FTIR Spectra were recorded with 32 scans and 0.2 cms-1 OPD speed. Spectra of FT34 and FT35 raw samples indicated obvious differences in the range of 1500-1135 cm-1. The FT34 ethanol extract using trifluoroacetic acid (TFA) showed that the peak at 1629 cm-1 was the highest in the range of 1800-1500 cm-1, whereas for FT35, the highest peak was 1739 cm-1. The peak at 1071 cm-1 of FT35 was the only one compatible to standard dephinidin-3-O-sambubioside and cyanidin-3-Osambubioside which are used for qualification of sample content. In fact, both standards showed up as different chromatographs in thin layer chromatography. Water extract of FT35 showed a peak at 1676 cm-1 which was not detected in water extract spectrum of FT34, while the pattern of spectrum varied within the range of 1300-400 cm-1. Second derivative spectra enhanced the comparable base peaks of both sample and the target standards. There were five matched ethanol extract base peaks, indicating the macrofingerprint of H. sabdariffa. Two dimensional correlation spectrum of FT34 raw powder showed different correlation spot especially in the cluster of 1425 cm-1 to 1743 cm-1 compared with FT35. The three-stage infrared spectroscopy comprehensively analysed the holographic spectra and hierarchically characterized the integrated constituents involved.