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

Monoterpenoid synergy: a new frontier in biological applications

Monoterpenoids, compounds found in various organisms, have diverse applications in various industries. Their effectiveness is influenced by the oil's chemical composition, which in turn is influenced by plant genotype, environmental conditions, cultivation practices, and plant development stage. They are used in various industries due to their distinctive odor and taste, serving as ingredients, additives, insecticides, and repellents. These compounds have synergistic properties, resulting in superior combined effects over discrete ones, potentially beneficial for various health purposes. Many experimental studies have investigated their interactions with other ingredients and their antibacterial, insecticidal, antifungal, anticancer, anti-inflammatory, and antioxidant properties. This review discusses potential synergistic interactions between monoterpenoids and other compounds, their sources, and biological functions. It also emphasizes the urgent need for more research on their bioavailability and toxicity, underlining the importance and relevance of this comprehensive study in the current scientific landscape.

Electrode Based on the MWCNTs and Electropolymerized Thymolphthalein for the Voltammetric Determination of Total Isopropylmethylphenols in Spices

Isopropylmethylphenols, namely thymol and carvacrol, are natural phenolic monoterpenoids with a wide spectrum of bioactivity making them applicable in the cosmetic, pharmaceutical, and food industry. The dose-dependent antioxidant properties of isopropylmethylphenols require their quantification in real samples. Glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and electropolymerized thymolphthalein has been developed for the sensitive quantification of isopropylmethylphenols. Conditions of thymolphthalein electropolymerization (monomer concentration, number of cycles, and electrolysis parameters) providing the best response to thymol have been found. Scanning electron microscopy and electrochemical methods confirm the effectivity of the electrode developed. The linear dynamic ranges of 0.050-25 and 25-100 µM for thymol and 0.10-10 and 10-100 µM for carvacrol with detection limits of 0.037 and 0.063 µM, respectively, have been achieved in differential pulse mode in Britton-Robinson buffer pH 2.0. The selectivity of the isopropylmethylphenols response in the presence of typical interferences (inorganic ions, saccharides, ascorbic acid) and other phenolics (caffeic, chlorogenic, gallic and rosmarinic acids, and quercetin) is a significant advantage over other electrochemical methods. The electrode has been used in the analysis of oregano and thyme spices. Total isopropylmethylphenols contents have been evaluated after a single sonication-assisted extraction with methanol.

In-Depth Study of Thymus vulgaris Essential Oil: Towards Understanding the Antibacterial Target Mechanism and Toxicological and Pharmacological Aspects

Questions have been raised apropos the emerging problem of microbial resistance, which may pose a great hazard to the human health. Among biosafe compounds are essential oils which captured consumer draw due to their multifunctional properties compared to chemical medication drugs. Here, we examined the chemical profile and the mechanism(s) of action of the Thymus vulgaris essential oil (TVEO) against a Gram-negative bacterium Salmonella enterica Typhimurium ATTCC 10028 (S. enterica Typhimurium ATTCC 10028) and two Gram-positive bacteria Staphyloccocus aureus ATCC 6538 (S. aureus ATCC 6538) and Listeria monocytogenes ATCC 19117 (L. monocytogenes ATCC 19117). Findings showed that TVEO was principally composed of thymol, o-cymene, and γ-terpinene with 47.44, 16.55, and 7.80%, respectively. Molecular docking simulations stipulated that thymol and β-sesquiphellandrene (a minor compound at 1.37%) could target multiple bacterial pathways including topoisomerase II and DNA and RNA polymerases of the three tested bacteria. This result pointed plausible impairments of the pathogenic bacteria cell replication and transcription processes. Through computational approach, the VEGA quantitative structure–activity relationship (QSAR) model, we revealed that among twenty-six TVEO compounds, sixteen had no toxic effects and could be safe for human consumption as compared to the Food and Drug Administration (FDA) approved drugs (ciprofloxacin and rifamycin SV). Assessed by the SwissADME server, the pharmacokinetic profile of all identified TVEO compounds define their absorption, distribution, metabolism, and excretion (ADME) properties and were assessed. In order to predict their biological activity spectrum based on their chemical structure, all TVEO compounds were subjected to PASS (Prediction of Activity Spectra for Substances) online tool. Results indicated that the tested compounds could have multiple biological activities and various enzymatic targets. Findings of our study support that identified compounds of TVEO can be a safe and effective alternative to synthetic drugs and can easily combats hazardous multidrug-resistant bacteria.

Determination of Colchicine in Pharmaceutical Formulations, Traditional Extracts, and Ultrasonication-Based Extracts of Colchicum autumnale Pleniflorum (L.) Using Regular and Greener HPTLC Approaches: A Comparative Evaluation of Validation Parameters

In the literature, there is a scarcity of greener analytical approaches for colchicine (CLH) analysis. As a result, efforts were made in this study to develop and validate a greener reversed-phase high-performance thin-layer chromatography (HPTLC) technique for CLH analysis in traditional extracts (TE) and ultrasonication-based extracts (UBE) of commercial Unani formulations, commercial allopathic formulations, and Colchicum autumnale Pleniflorum (L.) obtained from Egypt and India. This new technique was compared to the regular normal-phase HPTLC method. The greenness profile of both methods was estimated using the Analytical GREENness (AGREE) approach. In the 100–600 and 25–1200 ng/band ranges, regular and greener HPTLC procedures were linear for CLH analysis, respectively. For CLH analysis, the greener HPTLC method was more sensitive, accurate, precise, and robust than the regular HPTLC method. For CLH analysis in TE and UBE of commercial Unani formulations, commercial allopathic formulations, and C. autumnale obtained from Egypt and India, the greener HPTLC method was superior in terms of CLH content compared to the regular HPTLC method. In addition, the UBE procedure was superior to the TE procedure for both methods. The AGREE scores for regular and greener reversed-phase HPTLC methods were found to be 0.46 and 0.75, respectively. The AGREE results showed excellent greener profile of the greener HPTLC method over the regular HPTLC technique. Based on several validation criteria and pharmaceutical assay findings, the greener HPTLC method is regarded as superior to the regular HPTLC approach.

Phytochemical Profiling and Antibacterial Activity of Methanol Leaf Extract of Skimmia anquetilia

Skimmia anquetilia is a plant species native to the Western Himalaya region that has tremendous potential for phytochemical activities. This study aimed to identify bioactive compounds and assess the antibacterial activity of S. anquetilia. To determine the major bioactive chemicals in the methanol leaf extract of S. anquetilia, we used a gas chromatography-mass spectrometer (GC-MS). The presence of 35 distinct phytoconstituents was discovered using GC-MS, which could contribute to the therapeutic capabilities of this plant species. The most predominant compound was 2R-acetoxymethyl-1,3,3-trimethyl-4t-(3-methyl-2-buten-1-yl)-1t-cyclohexanol (23.9%). Further, the leaf extract was evaluated for antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, and Staphylococcus aureus. The extract showed the highest zone of inhibition against E. coli (19 mm) followed by P. aeruginosa (18 mm) and K. Pneumoniae (17 mm) at 160 mg mL^-1. The minimum inhibitory concentration (MIC) of methanol extract against the strain of P. aeruginosa (2 mg mL^-1) demonstrated significant antibacterial activity. The findings of the present study highlight the potential of S. anquetilia for the development of herbal medicines for the treatment of various pathogenic infections.

A Simple, Cost-Effective, and Green HPTLC Method for the Estimation of Ascorbic Acid in Solvent and Ultrasound-Assisted Extracts of Phyllanthus emblica, Capsicum annuum, and Psidium guajava

Greener analytical methodologies for the estimation of ascorbic acid (AA) are poorly reported in the literature. Furthermore, the green indexes of the literature’s analytical assays of AA estimation have not been assessed. As a consequence, the aim of this research is to invent and validate a simple, cost-effective, and green reverse-phase “high-performance thin-layer chromatography (HPTLC)” method for the estimating AA in the solvent extracts (SE) and ultrasound-assisted extracts (UAE) of Phyllanthus emblica, Psidium guajava, and Capsicum annuum. The greener mobile phase for AA estimation was a binary mixture of water and ethanol (70:30, v/v). At a wavelength of 265 nm, the detection of AA was carried out. The greener HPTLC technique was linear in the 25–1200 ng/band range. In addition, the method was simple, cost-effective, accurate, precise, robust, sensitive, and green. The amount of AA was highest in the SE and UAE of P. emblica compared to the SE and UAE of P. guajava and C. annuum. The amount of AA in the SE of P. emblica, P. guajava, and C. annuum was found to be 491.16, 168.91, and 144.30 mg/100 g, respectively. However, the amount of AA in the UAE of P. emblica, P. guajava, and C. annuum was found to be 673.02, 218.71, and 199.30 mg/100 g, respectively. Using the “analytical GREEnness (AGREE)” methodology, the greenness index for the developed method was calculated to be 0.88, showing that the developed method has an excellent green profile. When it came to extracting AA, the UAE method outperformed the SE method. These findings suggested that the developed method might be used to estimate the AA in a variety of vegetable crops, plant-based extracts, and commercial formulations. Furthermore, because of the use of greener solvent systems against the commonly utilized hazardous solvent systems for AA determination, this technique is also safe and sustainable.

A Green High-Performance Thin-Layer Chromatography Method for the Determination of Caffeine in Commercial Energy Drinks and Formulations

The literature on green analytical approaches for caffeine estimation is limited. As a consequence, this study aimed to establish a reverse-phase high-performance thin-layer chromatography (HPTLC) technique for caffeine estimation in a variety of commercial energy drinks (ED) and pharmaceutical formulations that is rapid, sensitive, and green. The combination of ethanol-water (55:45 v v−1) was used as a mobile phase. The detection of caffeine was carried out at 275 nm. The green reverse-phase HPTLC method was linear in the concentration range of 50−800 ng band−1. Furthermore, the developed method for caffeine estimation was simple, quick, economical, accurate, precise, robust, sensitive, and green. The amount of caffeine in different marketed ED (ED1−ED10) was recorded in the range of 21.02−37.52 mg 100 mL−1 using the developed HPTLC method. However, the amount of caffeine in different commercial formulations (F1−F3) was estimated as 10.63−20.30 mg 100 mL−1 using the same method. The “analytical GREEnness (AGREE)” scale for the developed analytical method was predicted to be 0.80, utilizing 12 distinct components of green analytical chemistry, indicating the HPTLC approach’s excellent greener profile. Overall, the developed method for estimating caffeine in marketed ED and dosage forms was found to be reliable.

A Greener Stability-Indicating High-Performance Thin-Layer Chromatography Approach for the Estimation of Topiramate

Despite various reported analytical methods for topiramate (TPM) analysis, greener analytical approaches are scarce in literature. As a consequence, the objective of the current research is to design a normal-phase stability-indicating high-performance thin-layer chromatography (SI-HPTLC) methodology for TPM analysis in marketed tablet dosage forms that is rapid, sensitive, and greener. TPM was derivatized densitometrically and analyzed at 423 nm in visible mode with anisaldehyde-sulfuric acid as the derivatizing agent. The greener SI-HPTLC technique was linear in the 30-1200 ng band-1 range. In addition, the suggested SI-HPTLC methodology for TPM analysis was simple, rapid, cheaper, precise, robust, sensitive, and environmentally friendly. The greener SI-HPTLC method was able to detect TPM along with its degradation products under acid, base, and oxidative degradation conditions. However, no TPM degradation was recorded under thermal and photolytic stress conditions. TPM contents in commercial tablet dosage forms were recorded as 99.14%. Using 12 different principles of green analytical chemistry, the overall analytical GREEnness (AGREE) score for the greener SI-HPTLC method was calculated to be 0.76, confirming the proposed normal-phase SI-HPTLC method's good greener nature. Overall, these results demonstrated that the suggested SI-HPTLC technique for TPM measurement in pharmaceutical products was reliable and selective.