Plant-Derived Compounds against Microbial Infections and Cancers

Plants synthesize and preserve a variety of metabolites known as natural products. Many of them are easily extractable and can be used as starting material or chemical scaffolds for various purposes, especially in drug discovery. Numbers of reports have listed valuable candidates with privilege scaffolds currently in active development as drugs. New compounds with anticancer and antiinfective activities have been discovered recently, some presented these backbones. The present book chapter aims to highlight these findings from plants which can be considered valuable for the development of new drugs against malignant cells and infective diseases. Interest in anti-infective agents is increasing due to the resistance of microorganisms to existing drugs and newly emerging infectious diseases. This resistance is also, nowadays, associated to some forms of cancers. In addition, the value of plants as essential part in the health care pipeline in low- and middle-income countries is under consideration even though these countries are almost all surrounded by a rich and untapped biodiversity. People are always relying on “modern drugs and treatment” which is unfortunately not affordable to all. Therefore, the present compilation of data on plant-derived compounds can inspire the formulation of ameliorated traditional medicines (ATM) against the targeted diseases and the conservation of species

Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance

Tseme Wandji N, Bitchagno GTM, Mawabo Kamga I, et al. Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance. Molecules. 2023;28(13): 5278.Four polyoxygenated stigmastanes (1–4) alongside known analogues (7–8) and flavonoids (5–6) were isolated from a dichloromethane/methanol (1:1, v/v) extract of the whole plant of Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae). Their structures were determined by means of spectroscopic and spectrometric analysis. The relative stereochemistry of the new compounds was established and confirmed via biosynthesis evidence and cyclization of 1 under acidic conditions. A plausible biosynthetic pathway to the new compounds and the chemophenetic significance of the isolated constituents were also discussed. The crude extract, fractions, and compounds (1–3) were assessed for their antibacterial activity against five highly prevalent bacterial strains. The fractions and compounds showed low to moderate activity with minimal inhibitory concentrations (MICs) > 125 µg/mL

Chemical constituents from Diospyros fragrans Gurke (Ebenaceae)

Tameye NSJ, Akak CM, Tabekoueng GB, et al. Chemical constituents from Diospyros fragrans Gurke (Ebenaceae). Biochemical Systematics and Ecology . 2022;100: 104373.A new naphtalenone derivative named fragranone, alongside seventeen known compounds: ten triterpenoids, one monoglycerol, one polyterpenoid, one carotenoid, two steroids and two polyols were isolated from the leaves and roots of Diospyros fragrans. Four semi-synthetic derivatives obtained from the acetylation and allylation of betulinic acid, allylation of ursolic acid and acetylation of vismiaefolic acid are also reported. The structures of the compounds were established using their MS and NMR spectral data. The chemotaxonomic relevance of the compounds is also discussed in this paper. The extracts, as well as the isolates and the semi-synthetic compounds were evaluated for their antibacterial and cytotoxic activities. The obtained results showed a moderate anti-bacterial activity for myrtifolic acid and the semi-synthetic compound betulinic acid acetate against Bacillus subtilis DSMZ 704 with a diameter zone of inhibition of 9 and 10 mm, respectively. Ursolic acid and corosolic acid exhibited a moderate cytotoxicity against human colorectal adenocarcinoma cells HT-29 and the cervix carci-noma cells KB-3-1 with inhibitory concentration 50 values of 34.4 and 50.9 mu M for ursolic acid, and 16.5 and 14.6 mu M for corosolic acid, respectively

C-28/C-30 oxidized cycloartanes from the leaves and twigs of Caloncoba dusenii Gilg

Nguetsa LZ, Mpetga JDS, Bitchagno GTM, et al. C-28/C-30 oxidized cycloartanes from the leaves and twigs of Caloncoba dusenii Gilg. Phytochemistry Letters. 2021;43:145-149.Four hitherto unreported cycloartane-type triterpenes (1-4) with C-28/C-30 oxidized methyl groups together with two known compounds (5-6) have been obtained from the leaves and twigs of Caloncoba dusenii Gilg. The compounds were isolated through extraction and silica gel column chromatography. Their structures and relative stereochemistry were determined by extensive use of spectroscopic techniques including IR, 1D and 2D-NMR as well as mass spectrometry. This is the first report of C-28/C-30 oxidized positions in cycloartanes from nature

Chemical constituents from Ficus natalensis hochst (Moraceae) and their chemophenetic significance

Mbougnia JFT, Happi GM, Bitchagno Mbahbou GT, et al. Chemical constituents from Ficus natalensis hochst (Moraceae) and their chemophenetic significance. Biochemical Systematics and Ecology. 2021;95: 104227.Phytochemical investigation of the stem bark of Ficus natalensis afforded eleven compounds including one ceramide (1), two anthraquinones (2, 3), four triterpenes (4–7), two polyols (8, 9) and two steroids (10, 11). The structures of the compounds were determined by spectroscopic analyses including IR, UV, MS, 1D- and 2D- NMR (1H, 13C, 1H–1H COSY, HMQC, HMBC and NOESY), as well as by comparison with literature data. The antibacterial activity and the cytotoxicity of the extract, fractions and some isolated compounds (3, 5, 8 and 9) were evaluated. Some fractions and sub-fractions from various column chromatography displayed moderate antibacterial activity with diameter zone of inhibition (DZI) ranging from 7 to 10 mm. None of the compounds tested had activity. In the present study, all the compounds are isolated for the first time from the species F. natalensis. Compounds 2, 4–7, 10 and 11 were previously reported from the genus Ficus. The chemophenetic significance of the isolated compounds is discussed

Alkenylbenzoquinones and other compounds from the fruit of Maesa lanceolata exhibited potent cytotoxic, antibacterial, and antiradical scavenging activities

Seumo AS, Nanfack ARD, Ndontsa BL, et al. Alkenylbenzoquinones and other compounds from the fruit of Maesa lanceolata exhibited potent cytotoxic, antibacterial, and antiradical scavenging activities. Natural Product Research . 2021.A phytochemical study of the methanol extract of the fruit of Maesa lanceolata resulted in the isolation of a new alkenylbenzoquinone (1), alongside the known compounds (Z)-2,5-dihydroxy-6-methyl-3-(pentadec-10'-enyl)-1,4-benzoquinone (2), 2,5-dihydroxy-6-methyl-3-(nonadec-14'-enyl)-1,4-benzoquinone (3), 2,5-dihydroxy-6-methyl-3-(tridecyl)-1,4-benzoquinone (4), (2S,3S,4R,2'R,9E)-[2'-hydroxytetraeicosanoyl]-2-aminooctadec-9-ene-1,3,4-triol (5), monopalmitin (glyceryl palmitate) (6), lupeol (7), and 3-O-(beta-D-glucopyranoside)-beta-sitosterol (8). The structures of the compounds were established by the means of spectroscopic (1D- and 2D-NMR) and spectrometric techniques (MS). The isolated compounds were assessed for their antibacterial, cytotoxic, and antiradical activities. Compound 2 showed moderate activity against Staphylococcus warneri (DSMZ 20036), while the other compounds were inactive. The two quinones 1 and 2 were significantly cytotoxic, with IC50 values of 0.005M and 12.5M respectively, and were weakly active towards DPPH radical (IC50 >250g/mL)

Two new flavone glycosides from the leaves of Ochna afzelii Oliv. (Ochnaceae)

Kakabi MHD, Simo Mpetga JD, Tamokou J-D-D, et al. Two new flavone glycosides from the leaves of Ochna afzelii Oliv. (Ochnaceae). Natural Product Research . 2022.Two new glycosylflavones, 6''-O-acetyl-8-C-beta-D-galactopyranosylchrysoeriol (1) and 8-C-beta-D-galactopyranosylchrysoeriol (2) were isolated from the methanol extract of the leaves of Ochna afzelii Oliv., along with four known compounds namely 8-C-beta-D-galactopyranosylapigenin (3), ochnaflavone (4), sitosterol-3-O-beta-D-glucopyranoside (5) and D-mannitol (6). Isolation was performed chromatographically and the structures of the purified compounds were elucidated by analyzing their spectroscopic and mass spectrometric data. The antibacterial activity of extract, fractions, and compounds 1-4 was evaluated using broth microdilution method against Gram-positive and Gram-negative bacteria while the antioxidant capacity was performed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the ferric reducing antioxidant power (FRAP) methods. The new flavones (1 and 2) displayed moderate antibacterial activities (MIC = 32-64g/mL) and weak antioxidant properties

Ericoside, a new antibacterial biflavonoid from Erica mannii (Ericaceae)

A new dihydroflavonol-flavonol biflavonoid derivative, named ericoside was isolated from the ethanol extract of the whole plant of Erica mannii along with the known flavonoid, taxifolin 3-O-α-l-rhamnopyranoside; and two readily available sterols (sitosterol, sitosterol 3-O-β-d-glucopyranoside). The isolation was performed using chromatographic methods and the structure of purified molecules were elucidated using spectroscopic techniques (e.g. MS, NMR) and by comparison with literature data. The crude ethanol extract, ericoside, and taxifolin 3-O-α-l-rhamnopyranoside were tested against ten Gram-negative bacteria including multidrug resistant clinical isolates using a broth microdilution method. The crude ethanol extract showed no noteworthy activity. Of the purified compounds, ericoside displayed moderate activity against the resistant Escherichia coli AG100 with a MIC of 64 μg/mL