The New TLC Method for Separation and Determination of Multicomponent Mixtures of Plant Extracts

Development of a Combined 2D-MGD TLC/HPTLC Method for the Separation of Terpinen-4-ol and α-Terpineol from Tea Tree, Melaleuca alternifolia, Essential Oil

Tea tree oil (TTO), acquired from Melaleuca alternifolia (Maiden & Betche) Cheel, Myrtaceae, is a widely utilized essential oil (EO) due to its bioactive properties. The identification and quantification of TTO ingredients is generally performed by GC-MS, which provides the most accurate results. However, in some instances, the cost and time of analysis may pose a challenge. Thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) offer a simpler, faster, cost-effective alternative capable of simultaneously analyzing and quantifying multiple samples. In addition, for more complex oils, two-dimensional (2D) or multigradient development (MGD) TLC provide better separation. Nevertheless, further development is sometimes necessary for the isolation of comigrating components. This study showcases a combined 2D-MGD TLC/HPTLC method for the successful separation of TTO components of interest. While human error, limited separation, and the partial evaporation of volatile components may still present a challenge during the process, considerable recovery of mono- and sesquiterpenes was achieved. This protocol also resulted in the successful isolation of target oxygenated monoterpenes (OMs) producing highly pure terpinen-4-ol (100%) and α-terpineol (≥94%), confirmed by GC-MS. The accurate enantiomeric distribution of these major OMs was verified by GC-FID through the use of a chiral cyclodextrin-based stationary phase. The observed positive enantiomer range (area percent) as well as (+)/(-) ratio for each terpinen-4-ol and α-terpineol were within acceptable ISO criteria.

Colonization of chickens with competitive exclusion products results in extensive differences in metabolite composition in cecal digesta

The concept of competitive exclusion is well established in poultry and different products are used to suppress the multiplication of enteric pathogens in the chicken intestinal tract. While the effect has been repeatedly confirmed, the specific principles of competitive exclusion are less clear. The aim of the study was to compare metabolites in the cecal digesta of differently colonized chickens. Metabolites in the cecal contents of chickens treated with a commercial competitive exclusion product or with an experimental product consisting of 23 gut anaerobes or in control untreated chickens were determined by mass spectrometry. Extensive differences in metabolite composition among the digesta of all 3 groups of chickens were recorded. Out of 1,706 detected compounds, 495 and 279 were differently abundant in the chicks treated with a commercial or experimental competitive exclusion product in comparison to the control group, respectively. Soyasaponins, betaine, carnitine, glutamate, tyramine, phenylacetaldehyde, or 3-methyladenine were more abundant in the digesta of control chicks while 4-oxododecanedioic acid, nucleotides, dipeptides, amino acids (except for glutamate), and vitamins were enriched in the digesta of chickens colonized by competitive exclusion products. Metabolites enriched in the digesta of control chicks can be classified as of plant feed origin released in the digesta by degradative activities of the chicken. Some of these molecules disappeared from the digesta of chicks colonized by complex microbiota due to them being metabolized. Instead, nucleotides, amino acids, and vitamins increased in the digesta of colonized chicks as a consequence of the additional digestive potential brought to the cecum by microbiota from competitive exclusion products. It is therefore possible to affect metabolite profiles in the chicken cecum by its colonization with selected bacterial species.

Molecular Docking Study of Phytosterols in Lygodium microphyllum Towards SIRT1 and AMPK, the in vitro Brine Shrimp Toxicity Test, and the Phenols and Sterols Levels in the Extract

Background

Lygodium microphyllum is a fern plant with various pharmacological activities, and phytosterols were reported contained in the n-hexane and ethyl acetate extract of this plant. Phytosterols are known to inhibit steatosis, oxidative stress, and inflammation. Sirtuin 1 (SIRT1) and adenosine monophosphate-activated protein kinase (AMPK) are the key proteins that control lipogenesis. However, information about L. microphyllum on SIRT1 and AMPK is still lacking.

Purpose

This study aims to investigate the binding mode of phytosterols in L. microphyllum extract towards AMPK and SIRT1, and the toxicity of the extract against brine shrimp (Artemia salina) larvae, and to determine the phenols and sterols levels in the extract.

Methods

The molecular docking was performed towards SIRT1 and AMPK using AutoDock v4.2.6, the toxicity of the extract was assayed against brine shrimp (Artemia salina) larvae, and the phytosterols were analyzed by employing a thin layer chromatography densitometry, and the total phenols were by spectrophotometry.

Results

The molecular docking study revealed that β-sitosterol and stigmasterol could occupy the active allosteric-binding site of SIRT1 and AMPK by binding to important residues similar to the protein's activators. The cold extraction of the plant yields 15.86% w/w. Phytochemical screening revealed the presence of phenols, steroids, flavonoids, alkaloids, and saponins. The total phenols are equivalent to 126 mg gallic acid (GAE)/g dry extract, the total sterols are 954.04 µg/g, and the β-sitosterol level is 283.55 µg/g. The LC50 value of the extract towards A. salina larvae is 203.704 ppm.

Conclusion

Lygodium microphyllum extract may have the potential to be further explored for its pharmacology activities, particularly in the discovery of plant-based anti-dyslipidemic drug candidates. However, further studies are needed to confirm their roles in alleviating lipid disorders.

Bioactivity of Deverra tortuosa essential oil, its nanoemulsion, and phenylpropanoids against the cowpea weevil, a stored grain pest with eco-toxicological evaluations

The essential oil (EO) was hydrodistilled from of Deverra tortuosa aerial parts. Fifty-six components amounting 99.3% were identified in EO through using gas chromatography-flame ionization detection (GC-FID) and (GC-MS). Phenylpropanoids, dillapiole (41.6%), elemicin (7.3%) and myristicin (5.1%), and the monoterpene, sabinene (4.2%) were identified as the major terpenes. An oil-in-water nanoemulsion (particle size 70.3 nm) was developed from EO adopting a low-energy method. The EO products showed insecticidal and biochemical effects against the cowpea weevil Callosobruchus maculatus. Based on a 48-h exposure period, the oil nanoemulsion exhibited a superior contact bioactivity (LC₅₀ = 10.3 µg/cm²), followed by EO (LC₅₀ = 23.1 µg/cm²), dillapiole (LC₅₀ = 27.8 µg/cm²), and myristicin (LC₅₀ = 37.1 µg/cm²). Upon fumigation, nanoemulsion and EO were superior as fumigants (LC₅₀ after 48 h were 6.9 and 14.3 µl/l, respectively). Test materials showed a residual bioactivity against C. maculatus, where EO, dillapiole, and myristicin showed the strongest grain protecting activity. EO products significantly inhibited acetylcholinesterase (AChE) activity of C. maculatus adults. Test products were safe toward the non-target earthworms and did not alter the viability of cowpea seeds. There are evidences for the potential of using EO of D. tortuosa and its nanoemulsion and phenylpropanoids as natural grain protectants against C. maculatus.

Chemical profile, mosquitocidal, and biochemical effects of essential oil and major components of Dysphania ambrosioides against Culex quinquefasciatus Say

To seek new mosquito control agents while avoiding the environmental impacts and toxicity hazards of conventional pesticides, the essential oil of Dysphania ambrosioides was obtained by hydrodistillation and analysed using GC-FID and GC-MS. The compounds 1-methyl-4-(1-methylethyl)-2,3-dioxabicyclo[2.2.2]oct-5-ene (cis-ascaridole), 1-methyl-4-(1-methylethyl) benzene (р-cymene), and 1-isopropyl-4-methyl-1,3-cyclohexadiene (p-mentha-1,3-diene also known as α-terpinene) were identified as the major components. The EO and the major fractions showed remarkable mosquitocidal activity against third instar larvae and adults of Culex quinquefasciatus Say. The oil and fractions were assayed at 3.125, 6.25, 12.5, 25, and 50 μl/l. Mortality was time- and dose-dependent. At 24 h post-exposure at an assayed concentration of 50 μl/l, the larval and adult mortalities ranged between 80.11-100% and 91.22-100%, respectively. Strong larvicidal and adulticidal activities were recorded in the cases of the crude oil and cis-ascaridole. The LC₅₀ values after 24 h of treatment ranged between 6.2-20.1 μl/l and 5.1-13.9 μl/l against larvae and adults, respectively. The corrected percentage mortalities increased over time with the tested plant oil and the major fractions relative to the control. The time required to achieve 50% mortality (LT₅₀) decreased remarkably with all treatments. The tested EO and major fractions effectively inhibited larval acetylcholinesterase activity with IC₅₀ values ranging from 8.44 to 64.80 mM compared with 2.08 × 10^-3 mM for the reference standard, methomy. The results indicate the potential of developing natural mosquitocides against C. quinquefasciatus based on the tested EO and its major fractions. Graphical abstract.

Chemical composition, insecticidal and biochemical effects of two plant oils and their major fractions against Aedes aegypti, the common vector of dengue fever

In an attempt to reduce the massive application of the toxic chemical pesticides, essential oils (EOs) of Achillea biebersteinii and Juniperus procera were obtained through hydrodistillation and analyzed using (GC–FID) and (GC–MS). α-terpinene and p-cymene were detected as the major components in the EO of A. biebersteinii, while eugenol and ß-caryophyllene were the major constituents in the EO of J. procera. The plant EOs and major fractions act as considerable mosquitocides against Aedes aegypti L, the common transmitter of Dengue fever. The EOs and major fractions were tested at 6.25, 12.5, 25, 50 and 100 μl/l. Insect mortality was time and dose-dependent, and the adult stage was more sensitive than larvae. At a concentration of 50 μl/l, 24 post treatment larval and adult mortality ranged between (40.3 and 89.3%) and (51.4 and 95.6%), respectively. The LC₅₀ values ranged between 12.2 and 70.1 μl/l against larvae and between 10.1 and 63.12 μl/l against adults. All of the crude EOs were more potent than their major fractions. Eugenol and ß-caryophyllene showed strong mosquitocidal activity than p-cymene and α-terpinene. The corrected percentage mortality was increased over time with all of the test materials. In terms of lethal time required to kill 50% of the population (LT₅₀), a concentration of 100 μl/l of J. procera EO showed LT₅₀ values of 2.3 and 1.7 h against larvae and adult, respectively. The EOs induced considerable inhibition of acetylcholinesterase activity, where J. procera crude oil (IC₅₀ = 13.12mM) and eugenol (IC₅₀ = 19.65mM) were the most potent. Results proved that the test plant oils and their major fractions could be developed as natural pest control agents to control A. aegypti.

Profile of Thin-Layer Chromatography and UV-Vis Spectrophotometry of Akar Kuning Stem Extract (Arcangelisia flava)

This study aims to obtain the profile of Thin-Layer Chromatography (TLC) and Ultraviolet-Visible (UV-Vis) spectrophotometry from ethanol extract of akar kuning stems (Arcangelisia flava) from Central Kalimantan. The TLC method is used with the orientation phase of the combination of polar-non-polar solvents resulting from orientation, while ethanol is used as the solvent for UV-Vis spectrophotometers. TLC results showed the formation of 3 stains on a combination of polar solvents chloroform : methanol : water while in a non-polar solvent combination n-hexane : ethyl acetate did not show any stains. Comparison of retention factor (Rf) values show the best combination of polar solvents to separate stains at a ratio of 5 : 2 : 1, respectively. Separation in 2-dimensional TLC with polar solvents showed a similar pattern with 1-dimensional separation in the form of 3 stains. UV-Vis spectrophotometer results showed 4 main peaks with wavelength 227.2; 267.4; 345.2; and 425.3 nm, respectively. The profile of the peak formed is very similar to that shown by berberine, one of the main metabolites of akar kuning. TLC and UV-Vis spectrophotometers profiles obtained are expected to support further research using akar kuning stems, especially those from Central Kalimantan.