Specific diversity, structure and carbon stock of urban plant formations in southern Benin

The sustainable management of urban green spaces requires the monitoring of the structural parameters of theirs trees. This study, which was carried out in the cities of Abomey-Calavi, Allada and Cotonou in southern Benin, aimed to describe the dendrometric parameters and the rate of carbon stored by urban trees. The inventory of trees planted in two types of urban forests (greened public spaces and shade rows) was performed using the roving survey method at the level of each city. Then, presence and absence data of all trees, as well as diameter at breast height (DBH) >= 10 cm and height >= 2 m were measured. These data were analyzed using R 4.0.5 software. The calculated dendrometric parameters were subjected to variance tests to assess their significance. The different counts allowed us to identify 5128 individual trees. The density per hectare varied from 36.7 to 83.1 between cities and from 40.5 to 80.4 between types of green spaces. Basal area varied from 2.25 to 11.4 m²/ha within cities. In all three cities in the study, trees had an aggregative spatial distribution, but with low numbers of individuals per site. All of the trees studied have a carbon sequestration rate of 689 t/ha. It is therefore necessary to take precautions for the strengthening and preservation of urban trees and their diversity for a more sustainable urban ecological balance. Keywords: Benin, Biomass, Carbon storage, Tree structure, Urban forest

Metrology in Africa: role of the CAFMET

This article presents the CAFMET (African Committee of Metrology), a non-profit organization that aims to meet the needs of African countries in the field of metrology. Its objectives are to spread a metrology culture in Africa via various domains in metrology such as, analysis, tests, and calibration. The difficulties of the development of metrology in Africa and the different activities, events and projects of the CAFMET are all presented

Interactions of melatonin with mammalian mitochondria. Reducer of energy capacity and amplifier of permeability transition.

Melatonin, a metabolic product of the amino acid tryptophan, induces a dose-dependent energy drop correlated with a decrease in the oxidative phosphorylation process in isolated rat liver mitochondria. This effect involves a gradual decrease in the respiratory control index and significant alterations in the state 4/state 3 transition of membrane potential (ΔΨ). Melatonin, alone, does not affect the insulating properties of the inner membrane but, in the presence of supraphysiological Ca2+, induces a ΔΨ drop and colloid-osmotic mitochondrial swelling. These events are sensitive to cyclosporin A and the inhibitors of Ca2+ transport, indicative of the induction or amplification of the mitochondrial permeability transition. This phenomenon is triggered by oxidative stress induced by melatonin and Ca2+, with the generation of hydrogen peroxide and the consequent oxidation of sulfydryl groups, glutathione and pyridine nucleotides. In addition, melatonin, again in the presence of Ca2+, can also induce substantial release of cytochrome C and AIF (apoptosis-inducing factor), thus revealing its potential as a pro-apoptotic agent

CHEMICAL CHARACTERIZATION AND BIOLOGICAL ACTIVITIES OF EXTRACTS OFTHREE PLANTS USED IN TRADITIONAL MEDICINE IN BENIN: TECTONA GRANDIS, UVARIA CHAMEAE AND JUSTICIA SECUNDA

Objective: The present study was devoted to the chemical analysis of three plants (Tectona grandis, Uvaria chameae and Justicia secunda) usually used by traditional healers in Benin, for their curative properties in the treatment of certain diseases. Methods: After characterization of large chemical groups present in ethanolic extract of these plants, the total polyphenols were measured by the Folin method, the content of condensed tannins, total flavonoids, anthocyanins and anthocyanidins was evaluated by spectrophotometry. Results: The results show the presence of several secondary metabolites such as saponins, alkaloids, tannin, mucilages, anthraquinones, leucoanthocyanins, anthocyanins and triterpene in varying proportions in the three plants. The contents of condensed tannins, of anthocyanidins, total polyphenols and total flavonoids are respectively higher in the leaves (13.409 mg/g, 1.529 mg/g, 3.479 mg/g and 24.640 mg/g) than the bark of T.g (8.612 mg/g, 0 mg/g, 2.694 mg/g and 12.410 mg/g). As against, leaves of U.care richer in condensed tannins, flavonoids and total polyphenols (44.290 mg/g, 9.135 mg/g, 4.779 mg/g) than J.s (0 mg/g, 2.011 mg/g and 1.478 mg/g) unlike anthocyanidins. Of three plants studied, U.c was revealed the richest in polyphenolic compounds (condensed tannins, total polyphenols) and J.s was least rich. This content of polyphenolic compounds explain the antiradical activities observed; an CI50 of 0.700 mg/mL for U.c, 14.340 mg/mL for leaves of T.g, 24.790 mg/mL for bark of T.g and 46.500 mg/mL for leaves of J.s. Conclusion: This study contributes to increase those plants's phytochemical knowledge and allows having a better understanding of their pharmacological properties Keywords: Polyphenols, Antiradical activities, Solid phase micro extraction, Tectona grandis, Uvaria chameae, Justicia secunda

Nontoxic and neuroprotective β-naphthotacrines for alzheimer's disease

The synthesis, toxicity, neuroprotection, and human acetylcholinesterase (hAChE)/ human butyrylcholinesterase (hBuChE) inhibition properties of β-naphthotacrines1-14 as new drugs for Alzheimer's disease (AD) potential treatment, are reported. β-Naphthotacrines1-14 showed lower toxicity than tacrine; moreover, at the highest concentration assayed (300 μM) compounds 7, 10 and 11 displayed 2.25-2.01-fold higher cell viability than tacrine in HepG2 cells. A neuroprotective effect was observed for compounds 10 and 11 in a neuronal cortical culture exposed to a combination of oligomycin A/rotenone. An efficient and selective inhibition of hAChE, was only observed for the β-naphthotacrines bearing electron-donating substituents at the aromatic ring, β-naphthotacrine10 being the most potent (hAChE: IC50 = 0.083 ± 0.024 μM). Kinetic inhibition analysis clearly demonstrated that β-naphthotacrine10 behaves as a mixed-type inhibitor (K i2= 0.72 ± 0.06 μM) at high substrate concentrations (0.5-10 μM), while at low concentrations (0.01-0.1 μM) it behaves as a hAChE competitive inhibitor (Ki1= 0.007 ± 0.001 μM). These findings identified β-naphthotacrine10 as a potent and selective hAChE inhibitor in a nanomolar range, with toxicity lower than that of tacrine both in human hepatocytes and rat cortical neurons, with a potent neuroprotective activity and, consequently, an attractive multipotent active molecule of potential application in AD treatment.Peer Reviewe