ABSTRACT
Cymbopogon flexuosus var. flexuosus (citral chemotype) was introduced in a local plantation in 2006 at Plateau des Cataractes, Congo-Brazzaville to remedy the difficult adaptation and low production of essential oil of C. citratus, a source of citral. After some 10â years of acclimatization, C. flexuosus had adapted perfectly with a very high biomass and essential oil production. A citronella chemotype (Cymbopogon flexuosus var. albescens) was unexpectedly identified among lemongrass in the field, grown in a local experimental citronella plot covering 0.25â ha. Its essential oil was extracted by hydrodistillation and analyzed by GC and GC/MS to determine its chemotype. The citronella chemotype indicated by the chemical profile found was confirmed by descriptive statistics (radar plot) and by principal component analysis (PCA) and ascending hierarchical clustering (AHC).
Subject(s)
Acclimatization , Cymbopogon/physiology , Acyclic Monoterpenes , Biomass , Congo , Cymbopogon/chemistry , Gas Chromatography-Mass Spectrometry , Monoterpenes , Oils, Volatile/analysisABSTRACT
The aim of this study was to optimize the extraction of p-menthadienol isomers and aristolone from the essential oil of Elyonurus hensii by hydrodistillation. The study of the seasonal variation in the chemical composition has shown that the plant material has been subject to a natural selection regarding the biosynthesis of the p-menthadienol isomers: during periods of water stress, the extracts are rich in cis and trans-p-mentha-1(7),8-dien-2-ol and poor in cis and trans-p-mentha-2,8-dien-1-ol. Regarding the modeling, eight experiments were carried out by considering three easily interpretable factors (the extraction duration, the residual water content and the state of the division of the plant material). The average yield was 1.33% for the aerial part and 0.74% for the roots. The residual water content is the most important factor, which significantly influences the average yield of the essential oil and the content of the major constituents. Regarding the aerial part, a low residual water content of the plant material varies the essential oil yield (from 0.40% to 2.11%) and the content of cis and trans-p-mentha-2.8-dien-1-ol (from 15.87% to 23.24%). At the root level, the samples that have a very low residual water content provide extracts richer in aristolone. The combined effects of the extraction duration, the state of division, and the residual water content influence greatly the extraction of aristolone (from 36.68% to 54.55%). However, these interactions are more complex and difficult to assess.
ABSTRACT
A CE technique coupled to LIF detection (488 nm) or LED-induced fluorescence detection (470 nm) has been evaluated to acquire a cheap way to analyze amino acids (AAs) whilst maintaining the best sensitivity. To quantitate AAs in milk of Cucurbitaceae of Sub-Saharan Africa, they were labeled with FITC. We used an optimized separation buffer composed of 30 mM boric acid buffer adjusted to pH 9.3 with NaOH (1 M) containing 12 mM SDS and 5% ethylene glycol v/v; prior to the injections, the derivatized samples are diluted 100 times. The LOQs in the sample are Arg: 1.1 µM, Ala: 3.5 µM, and Glu 8.9 µM. Cucumeropsis mannii (CM) Naudin and Citrullus lanatus (CL) are vegetable sources rich in proteins and AAs of high quality. Our analyses have led to the identification of 11 AAs in CL and CM milks. Phe, Trp, and Ala are predominant in the two types of lyophilized milks, while Asp and Val demonstrate very low contents. Six essential AAs (Phe, Thr, Val, Trp, Ile, and Leu) are present in both types of extracts, but lysine was not detected, indicating that this AA is missing in gourd milk. These results should be useful in efforts to complement or replace very expensive cow milk or the less-appreciated soya milk with milk from available local agroressources.
