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. 2022 Feb 9;27(4):1164.
doi: 10.3390/molecules27041164.

Determination of Thymol in Commercial Formulation, Essential Oils, Traditional, and Ultrasound-Based Extracts of Thymus vulgaris and Origanum vulgare Using a Greener HPTLC Approach

Ahmed I Foudah  1 , Faiyaz Shakeel  2 , Mohammed H Alqarni  1 , Abuzer Ali  3 , Sultan Alshehri  2 , Mohammed M Ghoneim  4 , Prawez Alam  1
Affiliations

Determination of Thymol in Commercial Formulation, Essential Oils, Traditional, and Ultrasound-Based Extracts of Thymus vulgaris and Origanum vulgare Using a Greener HPTLC Approach

Ahmed I Foudah et al. Molecules. .

Abstract

In the literature, greener analytical approaches for determining thymol in its commercial formulations, plant-based phytopharmaceuticals, and biological fluids are scarce. As a result, the goal of this study is to develop and validate a normal-phase "high-performance thin-layer chromatography (HPTLC)" method for determining thymol in commercial formulations, essential oils, traditional extracts (TE), and ultrasound-based extracts (UBE) of Thymus vulgaris and Origanum vulgare obtained from various geographical regions. The greener mobile phase for thymol analysis was a binary combination of cyclohexane and ethyl acetate (85:15, v/v). The derivatized densitometric analysis of thymol was carried out under visible mode at 530 nm utilizing anisaldehyde-sulfuric acid as a derivatizing/visualizing agent. In the 10-2000 ng/band range, the greener normal-phase HPTLC method was linear. Furthermore, for thymol analysis, the proposed analytical approach was simple, quick, inexpensive, accurate, precise, robust, sensitive, and greener. The thymol contents in commercial formulation were computed as 7.61% w/w. In general, the thymol contents were maximum in essential oils of T. vulgaris and O. vulgare compared to the other sample matrices studied. The thymol contents of TE of T. vulgaris and O. vulgare of different geographical regions were significantly low compared to their UBE extract. Using 12 distinct components of green analytical chemistry, the overall "analytical GREEnness (AGREE)" scale for the proposed analytical approach was computed 0.79, showing the good greener nature of the proposed analytical approach. Overall, the greener normal-phase HPTLC technique was found to be reliable for determining thymol in commercial formulations and plant-based phytopharmaceuticals.

Keywords: AGREE scale; essential oils; greener HPTLC; thymol; ultarsonication; validation.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Thin-layer chromatography (TLC)-plate for standard thymol, essential oils, extracts, and commercial formulation developed using CY-EtOAc (85:15, v/v) as the greener mobile phase after derivatization using anisaldehyde-sulfuric acid under chamber saturation conditions for the greener normal-phase HPTLC assay.
Figure 2
Figure 2
Normal-phase HPTLC densitogram of 500 ng/band concentration of standard thymol for the greener normal-phase HPTLC approach.
Figure 3
Figure 3
UV absorption spectra of (A) standard thymol, (B) essentail oil of Origanum vulgare (SA), (C) essentail oil of Thymus vulgaris (SA), (D) UBE of Origanum vulgare (SA), (E) UBE of Thymus vulgaris (SA), (F) TE of Origanum vulgare (SA), (G) TE of Thymus vulgaris (SA), and (H) commercial formulation, superimposed.
Figure 4
Figure 4
Representative HPTLC chromatograms of thymol in TE of (A) T. vulgaris (SA), (B) T. vulgaris (IND), and (C) T. vulgaris (UK).
Figure 5
Figure 5
Representative HPTLC chromatograms of thymol in TE of (A) O. vulgare (SA), (B) O. vulgare (IND), and (C) O. vulgare (UK).
Figure 6
Figure 6
Representative HPTLC chromatograms of thymol in its commercial formulation.
Figure 7
Figure 7
Analytical GREEnness (AGREE) scale for the greener normal-phase HPTLC approach.
Figure 8
Figure 8
AGREE scale sheet for the greener normal-phase HPTLC approach of thymol, demonstrating the AGREE scale for 12 different components/principles of GAC.
See this image and copyright information in PMC

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