Medicinal uses, thin-layer chromatography and high-performance liquid chromatography profiles of plant species from Abomey-Calavi and Dantokpa Market in the Republic of Benin

Research on Moringa (Moringa oleifera Lam.) in Africa

While Moringa oleifera Lam. is gaining importance in Africa, especially sub-Saharan Africa, it is unclear whether research is following the quick pace of its development on the continent. Therefore, this article analyzes the landscape of research dealing with moringa in Africa. This systematic review draws upon 299 eligible articles identified through a search carried out on the Web of Science in April 2023. Research on M. oleifera is rather recent in Africa but interest is increasing among scholars. While the research field is multidisciplinary and cross-sectoral, the literature seems to focus on biological and environmental sciences. Moreover, research is performed mainly in South Africa, Nigeria, Egypt, and Ghana. The analysis suggests a significant potential contribution of moringa to food security and nutrition, climate change mitigation/adaptation, farming systems resilience, and livelihoods. Its versatility and diverse applications and uses make moringa particularly interesting for developing countries, such as African ones. However, this review also underscores some factors hindering its development. Therefore, there is a need to strengthen research on moringa to unlock its potential in Africa. Investments in research, innovation, and development can help address the many challenges that Africa faces and contribute to the transition towards sustainable and resilient food systems.

Local knowledge, practices, challenges of ethnopharmacologically used medicinal plants in Benin and implications for brain illnesses

Traditional medicine (TM) is a significant resource for primary healthcare management all over the world, and principally in Africa. Quality improvement activities that promote evidence-based practices and the integration of traditional medicine into primary healthcare systems can help improve the quality of patient care. In the Republic of Benin (West Africa), traditional medicine practitioners (TMPs) provide different treatments and ways of use, depending on the ailments and the medicinal plants used. The present study aimed at documenting the knowledge, attitudes and practices of Beninese TMPs regarding the use of medicinal plants and the challenges associated with their activities. A focus group survey was conducted using semi-structured interviews with a sample of 91 TMPs in 8 departments of the Republic of Benin. The respondents had an average age of 50 years old and belonged to various categories of TMPs. Medicinal plants are harvested depending on the season and time of the day, and are dried in the shade before being used as decoctions or infusions. Nevertheless, the majority of TMPs do not conduct the necessary tests for quality control, efficacy or toxicity of the proposed remedies, which raises several scientific interrogations, particularly for the treatment of mental and brain-related disorders. Among ~ 110 plants used in the treatment of several pathologies, 66 were revealed as threatened species. The challenges faced by TMPs are mainly material, financial and technical difficulties. The present study reports the importance of intervention to modernize TM practices in Benin. Quality improvement could enhance healthcare delivery and provide support for evidence-based interventions aimed at addressing behavioral, social, and environmental determinants of health.

Isolation, development and validation of HPTLC method for the estimation of β-carotene from Gymnosporia senegalensis (Lam.) Loes

The present study is aimed to isolate terpenoids from Gymnosporia senegalensis through analytical and preparative thin-layer chromatography (TLC) and to determine their antioxidant activity using the 2, 2-diphenyl-1- picrylhydrazyl (DPPH) assay and to find out the presence of β-carotene through high-performance thin-layer chromatography (HPTLC). The validation included linearity, limit of detection (LOD), limit of quantification (LOQ), specificity, precision, recovery, and robustness. All the isolated compounds from TLC exhibited significant antioxidant activity. Among all, isolated compounds from leaf showed highest IC50 values. The highest total terpenoid content (TTC) was found 51.6 ± 0.06 in stem, then 49.02 ± 0.01 in bark, and 46.27 ± 0.01 in leaf. DPPH results indicated that leaf-isolated compound 1 (LIC1) showed the highest IC50 at 7.55 ± 0.02 and stem-isolated compound 2 (SIC2) showed the lowest IC50 at 0.616 ± 0.01 among all the isolated compounds of G. senegalensis. HPTLC separation was carried out on aluminium plates pre-coated with silica gel 60 F254 as the stationary phase and n-hexane: ethyl acetate (6:4, v/v) as the mobile phase. Quantification was achieved based on a densitometric analysis of β-carotene in the concentration range of 100-500 ng/band at 254 nm. For the calibration plots, linear regression produced r2 = 0.96450 and Rf = 0.27. The LOD and LOQ were 10.15 and 30.76 ng/mL for HPTLC and relative standard deviation were 137.26 ± 2.03 and 160.43 ± 2.95 (intra-day) and 127.88 ± 2.14 and 157.27 ± 1.90 (inter-day) for 200 and 400 ng/band, respectively. The present study shows the presence of various types of terpenoids through TLC whereas the HPTLC results indicated that the developed methods were accurate and precise. It also shows that the approach is appropriate for its intended use in routine quality control testing of commercially available tablet formulations and drug assay to assist both industries and researchers in making important decisions at a reasonable cost. Moreover, due to the use of a safer and more environmentally friendly mobile phase in comparison to the toxic mobile phases used in recent analytical techniques to estimate β-carotene, this methodology is also secure and sustainable.

Essential oils from Melia azedarach L. (Meliaceae) leaves: chemical variability upon environmental factors

The chemical composition of the essential oils extracted from the leaves of Melia azedarach L. collected monthly from July 2019 to June 2020 was examined via gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques. Analysis of the essential oils identified about 17 compounds representing more than 85% of the oil. Oil yields were higher in the months of June and August, and the primary compounds identified were β-caryophyllene (3.50-63.41%), benzaldehyde (3.50-55.98%), and azulene (1.27-19.05%). A correlation analysis was performed to determine the relationship between yields and climatic conditions, and between constituent concentration and temperature and precipitation values during the study period. As per our findings, although not significant, a positive correlation was determined between yield and climatic parameters. However, the oil components were categorized into four groups based on their correlation with temperature and precipitation indices. Among the major components of the essential oils, only azulene and β-caryophyllene exhibited a negative correlation with both precipitation and temperature. The results show substantial differences in the chemical composition of M. azedarach essential oils and provide further insight into the phytochemical constituents that are sensitive to climate fluctuations. Furthermore, it provides an indication of the optimal time that the plant produces the important mono- and sesquiterpene components and the biological significance of their regulation.

Essential Oil from the Leaves of Chromolaena odorata, and Sesquiterpene Caryophyllene Oxide Induce Sedative Activity in Mice

Chromolaena odorata (L.) R.M.King & H.Rob. essential oil (COEO) was investigated for its sedative activity in mice. The results showed that COEO significantly reduced mice locomotor activity and the most efficient concentrations were 0.04 and 0.00004 mg/cage (volume of the cage 61.2L). Analysis of chemical composition of the oil indicated that caryophyllene oxide (43.75%) was the major compound and bioactivity-guided fractionation of the oil was performed to isolate the compound responsible for activity. The data clearly identified sesquiterpene caryophyllene oxide as the compound inducing COEO sedative activity and it was effective in decreasing mice locomotor activity by 56% and 57% at 0.0004 and 0.04 mg/cage, respectively. In order to understand the action mechanisms, caryophyllene oxide was tested for its effects on the central nervous system (CNS) by using a caffeine pre-excited mice test and a pentobarbital sleeping-induced test in mice. The results showed that caryophyllene oxide is a potent CNS depressant. Nevertheless, it fails to potentiate the effects of pentobarbital on the GABAergic system, nor did flumazenil, a GABA_A receptor antagonist, reversed its effects. It was especially interesting to note that β-caryophyllene, the precursor of caryophyllene oxide, demonstrated a similar pattern of sedative activity, and the present work further extends actual knowledge on these naturally occurring sesquiterpenes. The findings in this study reveal the new activity of caryophyllene oxide as an innovative way to manage sleep and CNS-related disorders, and demonstrates a satisfactory effect of two interesting sesquiterpene compounds on the CNS.

Role of Ascaridole and p-Cymene in the Sleep-Promoting Effects of Dysphania ambrosioides Essential Oil via the GABAergic System in a ddY Mouse Inhalation Model

The essential oil obtained from Dysphania ambrosioides leaves (DAEO) has antifungal, antioxidant, and antimicrobial properties. This study investigated DAEO's chemical composition and its sleep-promoting effects via administration by inhalation in ddY mice. Ascaridole (35.5%) and p-cymene (47.2%) were the major components. To obtain insight into DAEO's effects on the central nervous system (CNS), ascaridole and p-cymene were evaluated for sedative activity by using the caffeine-treated excitatory mouse model. DAEO administration significantly decreased locomotor activity at all doses except 0.000 04 mg per 400 μL of triethyl citrate. Both ascaridole and p-cymene were highly effective in decreasing locomotor activity of excited mice by more than 50%. In addition, ascaridole and p-cymene prolonged the pentobarbital-induced sleeping duration by 42% and 77%, respectively. These effects were antagonized by coadministration of gamma-aminobutyric acid (GABA_A)-benzodiazepine receptor antagonist, flumazenil (3 mg/kg), indicating that the GABAergic system mediates the sedative effect. Finally, inhaled ascaridole and p-cymene had no negative effect on motor coordination, as observed during the Rota-rod test. Therefore, via activation of the GABAergic system, ascaridole and p-cymene mediate the sleep-promoting effect of DAEO. The results further extend the knowledge on their use as potential promising natural products for the management of sleep disorders and CNS-related ailments.