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In Cameroon, malaria is still the cause of several deaths yearly and leading to the continued search for new potent leads to fight against Plasmodium falciparum . Medicinal plants like Hypericum lanceolatum Lam. are introduced in local preparations for the treatment of affected people. The bioassay-guided fractionation of the crude extract of the twigs and stem bark of H. lanceolatum Lam. led to the identification of the dichloromethane-soluble fraction as the most active (with 32.6% of the parasite P. falciparum 3D7 survival) which was further purified by successive column chromatography to obtain four compounds identified by their spectrometric data as two xanthones 1,6-dihydroxyxanthone ( 1 ) and norathyriol ( 2 ) and two triterpenes betulinic acid ( 3 ) and ursolic acid ( 4 ). In the antiplasmodial assay against P. falciparum 3D7, the triterpenoids 3 and 4 displayed the most significant potencies with IC 50 values of 2.8 ± 0.8  μ g/mL and 11.8 ± 3.2  μ g/mL, respectively. Furthermore, both compounds were also the most cytotoxic against P388 cell lines with IC 50 values of 6.8 ± 2.2  μ g/mL and 2.5 ± 0.6  μ g/mL, respectively. Further insights on the inhibition method of the bioactive compounds and their drug-likeness were obtained from their molecular docking and ADMET studies. The results obtained help in identifying additional antiplasmodial agents from H. lanceolatum and support its use in folk medicine for the treatment of malaria. The plant might be considered as a promising source of new antiplasmodial candidates in new drug discovery., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Gervais Mouthé Happi et al.)

The triterpenes represent one of the most reported subclasses of specialized metabolites from the plant kingdom. They play a key role in the protection of plants and their metabolism in addition to displaying a high structural diversity and large scale of biological activities. The scaffold can undergo several reactions like oxidation or substitution at different positions of the skeleton leading to the formation of several types of compounds. More specifically, triterpene dimer is a small group of compounds found in nature (from plants precisely). Until 2021, the chemical and pharmacological works reported in the literature indicated the identification of 90 natural dimeric triterpenes and 11 synthetic derivatives from 19 plants species and very few of them have been biologically evaluated for their antibacterial, antioxidant, antiproliferative or molluscicide activities. This review aims to compile the literature on the occurrence, chemistry and biological activities of the triterpenoid dimers. To attend this goal, a literature survey has been done in a number of online libraries including Scifinder, PubMed, Web of Science and Google Scholar using keywords terpene, triterpene, dimer, celastroloid without language restriction. This paper provides the easiest access to the information on triterpene dimers for readers and researchers in view to enhancing the continuity of research works on this topic., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Chemical investigation of the roots of Entandrophragma congoënse (Meliaceae) led to the isolation of two new 3,4-seco-tirucallane triterpenes, namely seco-tiaminic acids B and C (1 and 2) together with nine known compounds: 3,4-secotirucalla-21-formyl-23-oxo-4(28),7,24-trien-3-oic acid (3), methyl angolensate (4), molucensin N (5), molucensin O (6), piscidinol A (7), 7α,20(S)-dihydroxy-4,24(28)-ergostadien-3-one (8), 24-methylene-cholest-5-en-3β,7α-diol (9), entilin A (10), and entilin B (11). Their structures were determined using extensive spectroscopic methods including 1D and 2D NMR, HRMS, and CD analyses; new results were compared to existing data in the literature. The two newly identified seco-tiaminic acids showed moderate antiplasmodial and cytotoxic activities against a chloroquine-sensitive strain of the malaria parasite (Plasmodium falciparum NF54) and were cytotoxic toward an L6 rat skeletal myoblast cell line, respectively., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Eight new triterpenoids, prototiamins A-G (1-6, 9) and seco-tiaminic acid A (10), were isolated along with four known compounds from the bark of Entandrophragma congoënse. Their structures were elucidated by means of HRMS and different NMR techniques and chemical transformations. Assignments of relative and absolute configurations for the new compounds were achieved using NOESY experiments and by chemical modification including the advanced Mosher's method. Additionally, the structure and relative configuration of compound 3 were confirmed by single-crystal X-ray diffraction analysis. Compounds 1, 3, and 5 displayed significant in vitro antiplasmodial activity against the erythrocytic stages of chloroquine-sensitive Plasmodium falciparum strain NF54. Prototiamin C (3) was the most potent of the compounds isolated, with an IC50 value of 0.44 μM. All compounds tested showed low cytotoxicity for the L6 rat skeletal myoblast cell line.

Two new tirucallane-type triterpenoids were isolated from the bark of Entandrophragma congoënse (Meliaceae) along with five known compounds gladoral A, bipendensin, 4-hydroxymethyl-3,5-dimethyldihydrofuran-2(3H)-one, scopoletin and 5,7-dimethoxy-6-hydroxycoumarin. Their structures were elucidated by means of spectroscopic analyses including 1D and 2D-NMR spectroscopy, high resolution mass spectrometric data as well as the comparison of data with those reported in the literature. The tested compounds (1-4) displayed moderated antiplasmodial activity against erythrocytic stages of chloroquine-resistant Plasmodium falciparum strain NF54 and low cytotoxicity on L6 cell lines. All the isolated compounds are reported for the first time from the genus Entandrophragma., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Two new 30-norfriedelane triterpenoids namely glaucalactone C (1) and glaucanoic acid (2) along with sixteen known compounds (3 – 18) have been isolated from the methanolic extracts of the stem bark and fruits of Caloncoba glauca (P.Beauv.) Gilg (Achariaceae). The structures of all the isolated compounds have been established with the aid of their extensive spectroscopic analyses (1D and 2D-NMR) as well as mass spectrometry. Six compounds (1 – 5 , 9) were screened for antiplasmodial activity against two strains P. falciparum Dd2 and P. falciparum 3D7. The results showed that glaucanoic acid (2) was the most active one with IC 50 values of (3.5 ± 0.1 μg/mL) and (4.6 ± 0.7 μg/mL) against Pf Dd2 and Pf 3D7, respectively, while glaucalactone C (1) moderately inhibited Pf Dd2 (9.4 ± 0.1 μg/mL) and weakly Pf 3D7 (15.9 ± 2.3 μg/mL). The molecular docking analyses of the isolated compounds showed that compounds 1 – 4 and 9 – 11 are potential drug targets and were further supported by their ADMET studies that revealed welwitschiilactones B and C (4 and 5) as well as β -sitosterol (10) as the most qualified compounds to be safe as drugs. The results indicate that C. glauca is an important source of good candidates in new antiplasmodial drug development. 30-norfriedelane triterpenoids isolated from the stem bark and fruits of Caloncoba glauca (P.Beauv.) Gilg (Achariaceae), their antiplasmodial potencies and molecular docking studies. [Display omitted] • Two undescribed 30-norfriedelane triterpenes glaucalactone C and glaucanoic acid were obtained from Caloncoba glauca. • The isolated triterpenes display good and moderate antiplasmodial activities against Plasmodium falciparum 3D7. • We discussed on the structure-activity relationship of the isolated 30-norfriedelane triterpenes. • We reported the molecular docking studies of the isolated compounds to three selected Plasmodium protein complexes. [ABSTRACT FROM AUTHOR]