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Background Limonoids are highly oxygenated compounds with a prototypical structure. Their occurrence in the plant kingdom is mainly confined to plant families of Meliaceae and Rutaceae. Owing to their wide range of pharmacological and therapeutic properties, this study was aimed at investigating the potential nitric oxide (NO) and acetylcholinesterase (AChE) inhibitory activity and the cytotoxicity of three limonoids: trichilia lactone D5 (1), rohituka 3 (2) and dregeanin DM4 (3), isolated from Trichilia welwitschii C.DC.ResultsResults indicated that the three limonoids had low cytotoxicity towards Vero cells with LC50 values ranging from 89.17 to 75.82 μg/mL. Compounds (2) and (3) had lower cytotoxicity compared to puromycin and doxorubicin used as reference cytotoxic compounds. Compound (1) (LC50 of 23.55 μg/mL) had good antiproliferative activity against RAW 264.7 cancer cells. At the lowest concentration tested (0.5 µg/mL), compound (2) and (3) released the lowest amount of nitric oxide (2.97 and 2.93 µM, respectively). The three limonoids had anti-AChE activity with IC50 values ranged of 19.13 μg/mL for (1), 34.15 μg/mL for (2) and 45.66 μg/mL for (3), compared to galantamine (IC50 of 8.22 μg/mL) used as positive control.ConclusionThe limonoid compounds studied in this work inhibited nitric oxide production in LPS-stimulated macrophages and had anti-AChE activity. Trichilia lactone D5 had potential antiproliferative activity against RAW 264.7 cancer cells. The limonoids had low cytotoxicity towards Vero cells lines. This study provided further examples of the importance of limonoids compounds as potential AChE inhibitors and anti-inflammatory agents targeting the inhibition of NO production.

Background Entada abyssinica is a plant traditionally used against gastrointestinal bacterial infections. Eight compounds including three flavonoids, three terpenoids, a monoglyceride and a phenolic compound isolated from E. abyssinica were investigated for their cytotoxicity, antibacterial and antioxidant activity.ResultsCompounds 7 and 2 had remarkable activity against Salmonella typhimurium with the lowest respective minimum inhibitory concentration (MIC) values of 1.56 and 3.12 µg/mL. The antioxidant assay gave IC50 values varied from 0.48 to 2.87 μg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, from 2.53 to 17.04 μg/mL in the 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) assay and from 1.43 to 103.98 µg/mL in the FRAP assay. Compounds had relatively low cytotoxicity (LC50 values ranging from 22.42 to 80.55 µg/mL) towards Vero cells. Ursolic acid had the most potent cytotoxicity against THP-1 and RAW 264.7 cells with LC50 values of 9.62 and 4.56 μg/mL respectively, and selectivity index values of 7.32 and 15.44 respectively.ConclusionOur findings suggest that among the terpenoid and flavonoid compounds studied, entadanin (compound 7) possess tremendous antibacterial activity against S. typhimurium and could be developed for the treatment of bacterial diseases.

Three new limonoids, designated as rubescins F (1), G (2), and H (3), together with two known compounds of this type, TS1 (4) and trichirubine A (5), were isolated from methylene chloride/methanol extracts of Trichilia rubescens leaves. The structures of these compounds were elucidated based on 1D and 2D nuclear magnetic resonance (NMR) analysis and complemented by electrospray ionization high-resolution mass spectrometry results and by comparison to data of related compounds described in the literature and ab initio calculations. Rubescin F (1) is the first limonoid from Trichilia spp. with an oxetane ring between C-7 and C-14, which seems to be formed by the isomerization of TS1 (4). The γ-hydroxybutenolide rubescin G (2) is a potential precursor of trichirubine A (5), whereas rubescin H (3) is the first example of a triterpenoid with a single bond between C-7/C-14, forming a cyclopropane ring. The absolute configuration of these limonoids was derived from biosynthetic considerations and ab initio calculations of NMR and optical rotation dispersion data.

Two new limonoids, named rubescins D-E (1-2) along with eight known compounds, including five havanensin type limonoids, TS1 (3), TS3 (4), rubescins A-C (5-7) and three known phytosterols, β-sitosterol, stigmasterol and its 3β-O-glucopyranoside derivative were isolated from the roots and stem bark of Trichilia rubescens, collected from Cameroon. The structures of the new compounds were determined by detailed analyses of 1D and 2D NMR spectra, in combination with high-resolution mass spectrometry data and by comparison with related data from literature. Anti-plasmodial activities of some of the isolated limonoids 1, 2, 4, 6 and 7 were evaluated against erythrocytic stages of strain 3D7 Plasmodium falciparum. Compounds 2 and 4 exhibited significant anti-plasmodial in vitro activity with IC50 values of 1.13 and 0.79 μM, respectively.

The study attempts to elucidate the metabolite profiles of seed-coats from cowpea (Vigna unguiculata L) accessions of varying phenotypes. The chemical profiles were assessed using a non-targeted approach based on reversed-phase UPLC-QTOF-MS coupled to chemometrics. A total of 34 secondary metabolites were characterized, which comprised phenolic acids, flavonoids, anthocyanins, sphingolipids and fatty acids. Selected phenolic compounds were then quantified. The chemical profiles of the test accessions were distinguished by multivariate analysis, and the results showed that seed-coat pigmentation accounted for the observed differences in metabolite profiles. Delphinidin (traces to 2257.6 µg/ g), catechin glucoside (traces to 2840.6 µg/ g), catechin (traces to 2089.2 µg/ g) and epicatechin (26.3 to 3222.7 µg/ g) contributed to the segregation amongst the studied samples. The discriminant metabolites were accumulated in larger amounts in the dark seeded cowpeas compared to the light seeded ones. The findings suggest that cowpea hulls are a natural source of bioactive compounds which could be utilized in the development of food and pharmaceutical products due to their associated health benefits.

Two new tetranorterpenoid derivatives named rubescins I (1) and J (2), were isolated along with six known compounds including rubescin D (3), lichexanthone (4), scopoletin (5), scopoletin O-glycoside (6), β-sitosterol (7) and stigmasterol (8) from the stem bark of Trichilia rubescens (Meliaceae). The structures of the compounds were determined by means of MS, different NMR and by comparison with related data reported in the literature.