Terpenoids as Important Bioactive Constituents of Essential Oils

Plant and plant-derived natural products have a long and significant history in traditional medicine all over the world. Many studies in the recent past years focused on the benefic properties of essential oils (EOs) and their major components, terpenes and terpenoids (that are mostly monoterpenes and sesquiterpenes), and their biological properties. This chapter focuses on terpenoids as important bioactive constituents of EOs. It describes their uses, importance, extraction processes, and classification. The chapter provides an in-depth overview of the latest findings/research about terpenoids in EOs. It contains a well-prepared background, introduction, classification, chemical tests, bioactivities, as well as the characterization of terpenoids. It also discusses the bioactivities of EOs and that of terpenoids, with regard to their synergetic and/or their antagonistic effects

Extraction of Bioactive Compounds from Medicinal Plants and Herbs

Human beings have relied on herbs and medicinal plants as sources of food and remedy from time immemorial. Bioactive compounds from plants are currently the subject of much research interest, but their extraction as part of phytochemical and/or biological investigations present specific challenges. Herbalists or scientists have developed many protocols of extraction of bioactive ingredients to ensure the effectiveness and the efficacy of crude drugs that were used to get relief from sickness. With the advent of new leads from plants such as morphine, quinine, taxol, artemisinin, and alkaloids from Voacanga species, a lot of attention is paid to the mode of extraction of active phytochemicals to limit the cost linked to the synthesis and isolation. Thus, the extraction of active compounds from plants needs appropriate extraction methods and techniques that provide bioactive ingredients-rich extracts and fractions. The extraction procedures, therefore, play a critical role in the yield, the nature of phytochemical content, etc. This chapter aims to present, describe, and compare extraction procedures of bioactive compounds from herbs and medicinal plants

Isoderrone

Bankeu Kezetas JJ, Ndjakou Lenta B, Ngouela S, et al. Isoderrone. Acta Crystallographica. Section E, Crystallographic Communications. 2007;63(2):o523-o525.The title compound, C20H16O5, also known as 5,7-dihyroxy-3-(2',2'-dimethyl-2H'-chromen-7'-yl) chroman-4-one, was isolated from the medicinal plant Ficus mucuso. The benzopyranone (chromen-4-one) ring system is essentially planar and the dihedral angle between the benzopyranone ring system and the other benzene ring is 37.7 (10)degrees. In the crystal structure, one-dimensional chains are formed via intermolecular O-H center dot center dot center dot O hydrogen bonds

Dewerin and gilbertionol two new secondary metabolites from the stem bark of Gilbertiodendron dewevrei (De Wild) J. Leonard.

Stephanie DM, Stephane FFY, Jules BKJ, et al. Dewerin and gilbertionol two new secondary metabolites from the stem bark of Gilbertiodendron dewevrei (De Wild) J. Leonard. Natural product research. 2020.The phytochemical investigation of the methanol extract of the stem bark of Gilbertiodendron dewevrei led to the isolation of two new secondary metabolites, 5,7-dihydroxy-4'-methoxyisoflavan-2,4-dione (1) and 23-hydroxy-2-tricosanone (2) along with 19 known compounds (3-21). The structure of these compounds were established by interpretation of their spectral data, mainly HR-TOFESIMS, 1D NMR (1H, 13C and DEPT) and 2D NMR (1H-1H COSY, HSQC, HMBC, and NOESY), and by comparison with those reported in the literature. The methanol extract and some isolates were screened for their antiradical, antibacterial, and inhibitory properties against acetylcholinesterase

Bioguided isolation of antiplasmodial secondary metabolites from Mill. (Lauraceae)

Waleguele CC, Tchuente Tchuenmogne MA, Fotsing Fongang YS, et al. Bioguided isolation of antiplasmodial secondary metabolites from Mill. (Lauraceae). Zeitschrift für Naturforschung C. Accepted.**Abstract** The antiplasmodium assay-guided investigation of the roots, stem bark, and leaves ofPersea americanaMill. led to the isolation of a new fatty alcohol, perseatriol (1), along with six known compounds (2–7). Their structures were elucidated based on the analysis of their NMR and MS data. All crude extracts and fractions exhibited good antiplasmodial activity onPlasmoduim falciparum3D7 with IC50values ranging from 0.76 to 10.5 μg/mL; they also displayed cytotoxicity against HeLa cells with low selectivity indexes (SIs). A preliminaryPlasmodiumlactate dehydrogenase (pLDH) assay was also performed on the isolated compounds. 9,9′-Di-O-feruloyl-5,5′-dimethoxysecoisolariciresinol (4) turned out to be non-toxic and displayed the best activities onP. falciparumwith an IC50value of 0.05 μM, comparable to the reference drug chloroquine with an IC50value of 0.03 μM. Furthermore, besides compound4, this work reports the first isolation of lutein (2) and scopoletin (3) fromP. americana. The crude extracts of roots, stem bark, and leaves ofP. americana, their fractions and compounds completely suppressed the growth ofP. falciparum. The observed activity supports the use ofP. americanain folk medicine for the treatment of malaria

Bioactive Arylnaphthalide Lignans from Justicia depauperata

Tchegnitegni Toussie B, Nguengang Tchuinkeu R, Mawabo IK, et al. Bioactive Arylnaphthalide Lignans from Justicia depauperata . Journal of Natural Products. 2022

Antileishmanial, antibacterial and cytotoxicity activity of the extracts, fractions, and compounds from the fruits and stem bark extracts of Sabine

Garba JK, Nguengang RT, Youmbi GT, et al. Antileishmanial, antibacterial and cytotoxicity activity of the extracts, fractions, and compounds from the fruits and stem bark extracts of Sabine. Zeitschrift für Naturforschung B. 2022;77(1):9-15.**Abstract** The search for antileishmanial plants used in traditional medicine led to the choice of CH2Cl2–MeOH (1:1) crude extract of the fruits and stem bark ofPentadesma butyraceaSabine (Clusiaceae) which displayed good activityin vitroagainstLeishmania donovani1S (MHOM/SD/62/1S) promastigotes during preliminary screening with IC50values 5.96 and 26.43 μg mL−1, respectively. The fractionation of both extracts using flash chromatography yielded active fractions with IC50values ranging from 2.71 to 18.88 μg mL−1. Fourteen compounds (1–14) were isolated from the obtained fractions using successive column chromatographies and their structures were elucidated based on the analysis of their NMR and MS data. Daphnifolin (1), epicathechin (3), α-mangostin (9) and 9-hydroxycalabaxanthone (14) exhibited potent antileismanial activity againstL. donovani1S (MHOM/SD/62/1S) promastigotes with IC50values of 2.01, 9.09, 3.37, and 6.87 μg mL−1, respectively and good selectivity towards Raw 264.7 macrophage cells (SI > 2.4). Extracts, fractions and some isolates were also assessed in vitro for their antibacterial activity against six bacterial strains [Salmonella typhi(CPC),Enterobacter cloacae(CPC),Pseudomonas aeruginosaHM801,Staphylococcus aureusATCC 43300,Streptococcus pneumoniaeATCC 491619,Escherichia coliATCC 25322] using serial microdilution method. Among the tested samples, the stem bark extract ofP. butyraceaas well as compounds2and8showed good to moderate activity against the aforementioned bacterial strains with MIC ≤ 250 μg mL−1

Antibacterial constituents of Rumex nepalensis spreng and its emodin derivatives

Nguengang RT, Tchegnitegni BT, Ateba JET, et al. Antibacterial constituents of Rumex nepalensis spreng and its emodin derivatives. Natural Product Research. 2022.The CH2Cl2-MeOH (1:1) extract of roots of Rumex nepalensis (Polygonaceae) displayed significant antibacterial activity against five bacterial strains with MICs (62.5-31.2mug.mL-1). The EtOAc soluble fraction displayed a significant activity against the same strains with MICs (31.2-3.9mug.mL-1). The purification of the EtOAc fraction yielded one new phenylisobenzofuranone derivative, berquaertiide (1), along with 19 known compounds (2-20). Their structures were elucidated based on the analysis of their NMR and MS data. All the isolated compounds were assessed for their antibacterial activity. Compound 2 was the most active against all the tested strains (15.7 to 1.9mug.mL-1), while compounds 3-7 displayed good activities on at least one of the tested strains. In addition, seven analogues (21-27) of compound 2 were prepared and further assessed for their antibacterial activity. Compounds 26 and 27 were most active than 2 against Salmonella enterica and Klebsiella pneumoniae with MIC (125 and 15.6mug.mL-1, respectively)

A new diterpenoid and other chemical constituents from the stem bark of Sapium ellipticum and their chemophenetic significance

Noume VL, Tsafack VC, Zeutsop JF, et al. A new diterpenoid and other chemical constituents from the stem bark of Sapium ellipticum and their chemophenetic significance. Biochemical Systematics and Ecology. 2023;111: 104744.A chemical study of the stem bark extract of Sapium ellipticum (Hochst.) Pax led to the isolation of a total of fourteen compounds including one new diterpenoid, sapiumic acid (1) together with thirteen known derivatives (2-14). Their structures were determined by spectroscopic analysis and, by comparison of their spectral data with those of related compounds in the literature. Extracts and fractions were assessed in vitro against some resistant bacterial strains. Fraction C of the ethyl acetate was the most active one among all of the tested samples against Pseudomonas agarici DSMZ 11810 with a MIC value of 58.6 mu g mL-1. The chemotaxonomic significance of the obtained compounds was also discussed

Elemane‐Type Sesquiterpene, Acetonide Derived Polyacetylene and Other Constituents from the Whole Plant of (Schweinf. ex Oliv. & Hiern) H.Rob. and Their Chemophenetic Significance

Tafouo Tsakou A, Laure Ndontsa B, Carly Nono Nono E, et al. Elemane‐Type Sesquiterpene, Acetonide Derived Polyacetylene and Other Constituents from the Whole Plant of (Schweinf. ex Oliv. & Hiern) H.Rob. and Their Chemophenetic Significance. Chemistry & Biodiversity. 2023;20: e202200196.The chemical investigation of the methanol extract of the whole plant of Gymnanthemum theophrastifolium (Schweinf. ex Oliv. & Hiern) H.Rob. (Asteraceae) led to the isolation of a new elemane-type sesquiterpene (1), a new acetonide derived polyacetylene (2) and a naturally occurring compound (3) from the plant kingdom along with sixteen known compounds (4–19). Their structures were elucidated by extensive NMR and MS analysis. This is the first report on the chemical constituents of G. theophrastifolium. Furthermore, compounds 12, 13, and 14 are reported for the first time from the family Asteraceae, while compound 9 is reported for the first time from the genus Gymnanthemum. Thus, the present results provide valuable insights to the chemophenetic knowledge of G. theophrastifolium, which is also discussed in this work