Selective conversion of citral from the essential oil of Cymbopogon citratus (DC) Stapf into hydrazone and UV-Visible spectrophotometric analysis

Title: Selective conversion of citral from the essential oil of Cymbopogon citratus (DC) Stapf into hydrazone and UV-Visible spectrophotometric analysis

Abstract:

The orange-yellow essential oil with a yield of 1.54 % was extracted from the dry leaves of Cymbopogon citratus (DC.) Stapf harvested south of Brazzaville. Analysis by gas chromatography (GPC) and gas chromatography coupled with mass spectrometry (GPC/MS) allowed the identification of fifteen (15) representing (96.25 %) of the total essential oil. Cymbopogon citratus oil is mainly made up of geranial (51.99 %) and neral (32.94 %), two geometric isomers constituting citral which occupy a rate of 84.93%. (citral a) 2,4-dinitrophenylhydrazone or geranial 2,4-dinitrophenylhydrazone was hemisynthesized by a simple, easy and convenient method, in a short time (two to three minutes) by reacting the essential oil of Cymbopogon citratus with 2,4-dinitophenylhydrazine with a conversion rate of 20 %. Analysis of geranial 2,4-dinitrophenylhydrazone by UV-visible spectrophotometry showed an absorption maximum wavelength of 390 nm. The UV-visible spectrophotometry method used for the determination of this hydrazone is convenient, rapid and simple. Hemisynthesized geranial 2,4-dinitrophenylhydrazone could be useful in the pharmaceutical industry, in the chemical industry, in perfumery, cosmetics, in biomedicine, in biotechnology, in photochemistry.

Audience Take Away Notes:

• The essential oil extracted from Cymbopogon citratus (D.C.) Stapf contains a diversity of bioactive molecules, among others, citral a (geranial), a carbonyl compound which is transformed into hydrazone. This hydrazone is a nitrogen compound more stable than its carbonyl precursor, with high added value, with specific biological and physicochemical properties which finds its use in perfumery, cosmetics, agrochemistry, photochemistry, the pharmaceutical industry, the plastics industry, in biotechnology, electrochemistry, organic synthesis
• This will help the public in their work to hemisynthesize high value-added nitrogen and sulfur derivatives from carbonyl compounds contained in natural, plant, animal and human substances via nitrogen and sulfur reagents
• Other faculty could use it by taking hydrazones as precursors for the synthesis of hydrazone metal complexes and other molecules of interest such as heterocycle hydrazones, phosphonate hydrazones, indole hydrazones, silane hydrazones, fluorinated hydrazones, pyrazoles, indoles with additional physicochemical and biological properties
• The transformation of citral a (geranial) into hydrazone is carried out in a reduced number of steps, that is to say in a few steps, very quickly, in a very short time of two to three minutes. This transformation is practical, simple and quick
• This hemisynthesis allows the design of citral hydrazone with additional biological and physicochemical properties giving it different or improved therapeutic and physicochemical profiles (biological, photochemical, electro-catalytic, agrochemical, etc.) compared to citral, while enhancing its economic value
• The source of citral (the Cymbopogon citratus plant) is easy to grow, abundant, non-harmful and quickly renewable. Which constitutes an inexhaustible ecological source thus conserving biodiversity and promoting the hemisynthesis of citral hydrazone
• The extraction of the essential oil of Cymbopogon citratus, source of citral, is not expensive and the proportion of citral (geranial and neral) is significant (84.93%) in this essential oil, with geranial (citral a) which occupies a high proportion of (50.99%)
• Citral hydrazone has high stability compared to the precursor citral and additional physicochemical and biological properties, leading to its potential use in perfumery, cosmetics, pharmaceutical industry, biotechnology, photochemistry, organic synthesis and chemistry analytic
• The reagent used (2,4-dinitrophenylhydrazone) thanks to its high specificity and its simple use allows the selectivity of citral in a varied range of organic compounds contained in the essential oil of Cymbopogon citratus resulting in hydrazone
• Citral hydrazone could for drugs increase existing activities or generate different activities, increase the absorption rate, bioavailability, or obtain faster or lasting effects, reduce side effects, toxicity, or compensate for the problem of resistance to existing drugs
• Citral hydrazone could complex heavy metals constituting environmental pollutants, which will constitute a positive ecological strategy making it possible to fight against environmental pollution in order to preserve it
• Citral hydrazone is produced at low cost and its accessibility is easy from the citral contained in the essential oil of Cymbopogon citratus

Biography:

NDZELI LIKIBI Belline, holder of a doctorate in Chemistry and Technology of Bioactive Plant Extracts, obtained in 2023 at the Marien NGOUABI University, is a teacher at the said University in the Chemistry department. She is the author of eight scientific articles, a scientific book, in this case, the essential oil of Mentha piperata L. in its richness and one of the co-authors of the book entitled Recent Research Advances in Biology. She contributed to the International Conference on Clinical and Medicinal Chemistry online (webinar), in 2022, in Turkey, through oral communication.