This study investigated the chemical constituents, antioxidant potential, and in vitro and in silico antidiabetic activity of Gymnema sylvestre. Column chromatography and spectroscopic techniques identified twelve compounds from the methanol extract, including 4 sterols (1-4), 5 triterpenoids (5-9), and 3 flavonoids (10-12). The chemophenetic significance of all compounds was also investigated. The antioxidant capacity of the extract and compounds (1-4) was evaluated using FRAP and DPPH assays. The extract exhibited strong free radical scavenging activity (IC₅₀ = 48.34 µg/mL), while compounds (1-4) displayed varying degrees of efficacy (IC₅₀ = 98.30-286.13 µg/mL). The FRAP assay indicated significant reducing power for both extract and compounds (58.54, 47.61, 56.61, and 49.11 mg Eq.VitC/g for extract and compounds 1 & 2, 3, and 4, respectively). The antidiabetic potential was assessed through α-amylase and α-glucosidase enzyme inhibition assays. The crude extract demonstrated the most potent inhibition (IC₅₀ = 218.46 and 57.42 µg/mL for α-glucosidase and α-amylase respectively) suggesting its potential for managing postprandial hyperglycaemia. In silico studies employed molecular docking and dynamics simulations to elucidate the interactions between identified compounds and α-amylase/α-glucosidase enzymes. The results revealed promising binding affinities between the compounds and target enzymes, with compound 6 demonstrating the highest predicted inhibitory activity with -10 kcal/mol and -9.1 kcal/mol for α-amylase and α-glucosidase, respectively. This study highlights the presence of diverse bioactive compounds in Gymnema sylvestre. The extract exhibits antioxidant properties and inhibits carbohydrate-digesting enzymes, suggesting its potential as a complementary therapeutic approach for managing hyperglycaemia associated with type 2 diabetes.

Plasmodium falciparum and Leishmania sp. resistance to antiparasitic drugs has become a major concern in malaria and leishmaniasis control. These diseases are public health problems with significant socioeconomic impacts, and mostly affect disadvantaged populations living in remote tropical areas. This challenge emphasizes the need to search for new chemical scaffolds that preferably possess novel modes of action to contribute to antimalarial and antileishmanial research programs. This study aimed to investigate the antimalarial and antileishmanial properties of a methanol extract (KS-MeOH) of the stem bark of the Cameroonian medicinal plant Khaya senegalensis and its isolated compounds. The purification of KS-MeOH led to the isolation of a new ordered limonoid derivative, 21β-hydroxybourjotinolone A (1a), together with 15 known compounds (1bc–14) using a repeated column chromatography. Compound 1a was obtained in an epimeric mixture of 21α-melianodiol (1b) and 21β-melianodiol (1c). Structural characterization of the isolated compounds was achieved with HRMS, and 1D- and 2D-NMR analyses. The extracts and compounds were screened using pre-established in vitro methods against synchronized ring stage cultures of the multidrug-resistant Dd2 and chloroquine-sensitive/sulfadoxine-resistant 3D7 strains of Plasmodium falciparum and the promastigote form of Leishmania donovani (1S(MHOM/SD/62/1S). In addition, the samples were tested for cytotoxicity against RAW 264.7 macrophages. Positive controls consisted of artemisinin and chloroquine for P. falciparum, amphotericin B for L. donovani, and podophyllotoxin for cytotoxicity against RAW 264.7 cells. The extract and fractions exhibited moderate to potent antileishmanial activity with 50% inhibitory concentrations (IC₅₀) ranging from 5.99 ± 0.77 to 2.68 ± 0.42 μg/mL, while compounds displayed IC₅₀ values ranging from 81.73 ± 0.12 to 6.43 ± 0.06 μg/mL. They were weakly active against the chloroquine-sensitive/sulfadoxine-resistant Pf3D7 strain but highly potent toward the multidrug-resistant PfDd2 (extracts, IC₅₀ 2.50 ± 0.12 to 4.78 ± 0.36 μg/mL; compounds IC₅₀ 2.93 ± 0.02 to 50.97 ± 0.37 μg/mL) with selectivity indices greater than 10 (SI_Dd2 > 10) for the extract and fractions and most of the derived compounds. Of note, the limonoid mixture [21β-hydroxylbourjotinolone A (1a) + 21α-melianodiol (1b) + 21β-melianodiol (1c)] exhibited moderate activity against P. falciparum and L. donovani. This novel antiplasmodial and antileishmanial chemical scaffold qualifies as a promising starting point for further medicinal chemistry-driven development of a dually active agent against two major infectious diseases affecting humans in Africa.

The investigation of the methanol extract of the flowers of Jacaranda mimosifolia led to the isolation and characterisation of fourteen secondary metabolites (1-14) by the means of chromatographic and spectroscopic analysis. These compounds include eight flavonoids sorted as two flavonols (1-2), three flavones (3, 7-8), and three isoflavones (4, 9-10), two glucoiridoids (5-6), and four triterpenoids sorted as one oleanane (11), one hopane (12), and two lupane (13-14). The in vitro antioxidant potential of all the isolated compounds was evaluated using the ABTS- and FRAP- methods, which demonstrated concentration-dependent activity. Chloroflavonin A (1) and 4',5,7-trihydroxyflavone (2) demonstrated exceptional antioxidant activity, with scavenging rates of 98.63 % and 97.89 %, respectively, at a concentration of 300 μg/mL, and also showed strong ferric-reducing antioxidant power. Chloroflavonin A (1) demonstrated the most potent dual inhibitory effects on Cyclooxigenase-2 (COX-2) and NADPH-Oxidase-5 (NOX-5) enzymes, with binding affinities of -9.7 and -8.2 kcal/mol, respectively, indicating its potential as a strong anti-inflammatory compound. The molecular dynamics simulation, conducted with the Desmond v3.6, demonstrated the stability of the various complexes within the biological system. The findings indicate that compounds derived from Jacaranda mimosifolia may serve as potential therapeutic agents for the management of inflammation and oxidative stress.