Role of the methoxy group in product formation via TiCl4 promoted 4-phenyldioxolane isomerizations

The product distribution obtained from the TiCl4 initiated intramolecular isomerizations of 4- methoxyphenyl- and trimethoxyphenyldioxolanes at -78 oC, -30 oC and 0 oC provided insights into the important regiochemical role played by these groups in such Mukaiyama- type rearrangements through their resonance effects on the aryl ring of the dioxolanes.Our interest in naphthopyranquinones as potential antimicrobial and antibiotic agents has extended over two decades1-6 as a result of their well documented importance.7,8 Additionally, the synthesis of benzopyrans as model systems has received attention by ourselves6,9-13 and others.14- 16 Of particular interest to us was our earlier discovery of a TiCl4 - induced intramolecular isomerization in which phenyl- and naphthyldioxolanes were stereoselectively transformed into their corresponding benzo- and naphthopyrans.1

Isolation of Phospholipase A2 Inhibitor from Cryptolepis oblongifolia (Meins) Schltr

Chromatographic studies of Cryptolepis oblongifolia yielded a triterpene fatty acid (Oleanyl Erucoate) which was identified through spectroscopic means. The inhibitory effect of the isolated compound on PLA2 of Naja nigricollis venom was investigated. The 13CNMR of  the isolated compound showed carbonyl functional group and oleanane type of structure while EIMS analysis revealed that, the compound was Oleanyl Erucoate with molecular weight of [M+1] 735. The triterpene fatty acid inhibited the PLA2 in a dose dependent fashion with an inhibition binding constant (ki) of 1.74 mg/mL. The activity of this compound might provide a scientific basis for the local use of Cryptolepis oblongifolia in traditional medicine for the treatment of inflammation or contribute in the development of  novel drugs that could serve as potential antivenin. Keywords: Naja nigricollis venom, Oleanyl erucoate, Inhibitio

Pentacyclic triterpenoids from the stem-bark of Albizia chevalieri Hams (Mimosaceae)

OBJECTIVE : This research is focused towards isolation and identification of pure compounds from the extracts fractions of Albizia chevalieri through the means of gravity column chromatography and other chromatographic processes. METHODS : the stem bark was extracted exhaustively with hexane and subsequently with methanol. The methanolic extract was fractionated into ethyl acetate (EA) and n-butanol (NB) soluble parts, after which the hexane extracts were subjected to silica gel gravity column chromatography for the isolation of pure bioactive molecules.The major compounds isolated, were then determined and identified by the use of spectrometric analysis of HR-ESIMS, 1HNMR, [13]CNMR, IR and UV spectra. RESULTS : Investigation of the stem bark hexane extract fraction of A. chevalieri led to the isolation of three known pentacyclic triterpenoids: friedelin (HXC1), Friedelan-3-ol (HXC2) and Lupeol (HXC3), for the first time in the plant. CONCLUSION : The results obtained will be useful in the evaluation (bioassay) of the isolated compounds against the list of folklore therapeutic claims of A. chevalieri (which include its use as purgative, taenicidal, remedies of cough, dysentery, cancer, diabetes mellitus, tuberculosis and snake bite), and thereby providing scientific basis for its used for treatment of the aforementioned ailments.https://www.ijppsjournal.comam2017Chemistr

Isolation of oleanolic acid from Parinari curatellifolia (Planch Ex. Benth) stem bark and evaluation of its anticonvulsant and sedative activities in rodents

Parinari curatellifolia is used by traditional medicine practitioners for the treatment of epilepsy. So far, no study has isolated the active principle that may be responsible for its anticonvulsant activity. The study aimed to isolate compound(s) present from Parinari curatellifolia that may be responsible for its anticonvulsant activity. The ethyl acetate fraction of the stem bark of Parinari curatellifolia was chromatographed over silica gel column chromatography which led to the isolation of compound C. The structure of the compound was elucidated using IR, 1H-NMR, 13CNMR and DEPT-135 spectroscopy. Acute toxicity study of the isolated compound was evaluated in mice using OECD 425 guidelines (2000 mg/kg orally). The anticonvulsant study of the isolated compound (at 50, 75 and 100 mg/kg) was evaluated in mice using pentylenetetrazole (PTZ)- induced convulsion. The sedative properties of the compound (at 10, 50 and 100 mg/kg) were evaluated using the diazepam-induced sleep model in rats. Structure elucidation of the isolated compound confirmed the compound to be oleanolic acid. Acute toxicity study revealed no lethal effects at 2000 mg/kg. the compound (oleanolic acid) significantly (p<0.05) increased the onset of seizure at all doses and resulted in 25% protection against seizure at 100 mg/kg. It exerted sedative effect at all doses by significantly (p<0.05) reducing sleep latency and increasing total duration of sleep induced by diazepam. The results obtained from this study have revealed the presence of oleanolic acid in P. curatellifolia and have shown its anticonvulsant and sedative activities for the first time.The authors expressed their sincere appreciation to the Academic Staff Union of Universities (ASUU), Tertiary Education Trust fund (TETFund) and the management of Usmanu Danfodiyo University Sokoto for their financial support.The Academic Staff Union of Universities (ASUU), Tertiary Education Trust fund (TETFund) and the management of Usmanu Danfodiyo University Sokoto.https://www.tjnpr.orgam2020Chemistr

Design, synthesis, and in silico‑in vitro antimalarial evaluation of 1,2,3‑triazole‑linked dihydropyrimidinone quinoline hybrids

Please read abstract in the article.The National Research Foundation (South Africa) and the University of Pretoria, South Africa. Open access funding provided by University of Pretoria.https://link.springer.com/journal/11224Chemistr

Potential of South African medicinal plants targeting the reduction of Aβ42 protein as a treatment of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE : Twenty South African medicinal plant species were selected by conducting a literature review based on the relevant information of their reported traditional medicinal uses and scientific reports against Alzheimer's disease, dementia, anxiety, mental illness, depression, acetylcholinesterase inhibition, headache, epilepsy, convulsion, hysteria, and sedative effects. AIM OF STUDY : The goal of this study was to investigate the biological activity of the traditionally used medicinal plant extracts against Alzheimer's disease by in vitro screening of the extracts to determine their potential to decrease levels of Aβ42 protein. MATERIAL AND METHODS: Different plant parts (leaves, stem, bark, and stalks) of twenty selected plants were collected from the Manie van der Schijff Botanical Garden, University of Pretoria. Plant parts were dried, ground and then extracted using DCM:MeOH (1:1). We measured the levels of β-amyloid precursor protein proteolytic products in HeLa cells stably transfected with APP carrying the Swedish mutation using ELISA. RESULTS : Of 33 plant extract 10 (30.3%) were found active based on the potential to significantly reduce the production of Aβ42. Amongst them extracts of leaves of Xysmalobium undulatum (Apocynaceae), leaves of Cussonia paniculata (Araliaceae) and leaves of Schotia brachypetala (Fabaceae) potently decreased the production of Aβ42 by 77.3 ± 0.5%, 57.5 ± 1.3%, and 44.8 ± 0.1%, respectively. X. undulatum and S. brachypetala enhanced non-amyloidogenic processing of β-amyloid precursor protein, thereby decreasing Aβ42 level. We also showed that C. paniculata induced the decrease of Aβ42 level through inhibiting APP processing. In addition, we isolated two cardenolides, compound [A] and [B], from X. undulatum and found that they potently decreased the Aβ42 production. CONCLUSION : These data suggest that the extract of X. undulatum, C. paniculata, and S. brachypetala have potential to be developed for Alzheimer's disease treatment. These active extracts and compounds are considered for further studies which examine their efficacy towards the reduction of Aβ42 through inhibiting APP process.The University of Pretoria Post Graduate Research Support Bursay, South Africa and by the Bio-Synergy Research Project (NRF-2012M3A9C4048793) and the Bio & Medical Technology Development Program (NRF-2015M3A9A5030735) of the Ministry of Science, ICT, and Future Planning through the National Research Foundation, Republic of Korea.http://www.elsevier.com/locate/jethpharm2020-03-01hj2019Chemistr

Microwave assisted synthesis, characterization and investigation of antibacterial activity of 3-(5- (substituted-phenyl)-4,5-dihydro-1H-pyrazol-3- yl)-2H-chromen-2-one derivatives

A variety of 3-(5-(substituted-phenyl)-4,5-dihydro-1H-pyrazol-3-yl)-2H-chromen-2-one derivatives 3a–j were synthesized through microwave assisted thermal annulation of corresponding a,b-unsaturated ketones (chalcones) 2a–j via hydrazinolysis. Chalcones 2a–j were prepared from 3-acetyl-coumarin 1 which was previously accessed by Pechmann condensation reaction of salicylaldehyde. The series of pyrazoline-based coumarin motifs 3a–j synthesized, were structurally confirmed by analytical and spectral data. They were then evaluated for their antimicrobial activities using agar diffusion method. The result showed that microwave assisted method (MAM) for the reaction was remarkably successful and gave the targeted products 3a–j in higher yields at shorter reaction times compared to conventional synthetic method (CSM). The results showed that these skeletal frameworks exhibited marked potency as antibacterial agents. The most active antibacterial agent was 3-(5-(4- (diethylamino) phenyl)-4,5-dihydro-1H-pyrazol-3-yl)-2H-chromen-2-one 3j with MIC and MBC values of 3.92 ± 0.22 mg/mL and 7.82 ± 0.43 mg/mL respectively.The World Academy of Sciences (TWAS)https://www.tandfonline.com/loi/tabs20am2020Chemistr

Facile Synthesis, Characterization and <i>in vitro</i> Antibacterial Efficacy of Functionalized 2-Substituted Benzimidazole Motifs

A series of functionalized 2-substituted benzimidazole motifs was designed and successfully synthesized via thermal cyclization of 1,2-diaminobenzene on COOH end of L- leucine to achieve benzimidazole derivatives 6 as the essential precursor. The coupling of the precursor 6 with benzaldehyde derivatives a-h, ketone series i-k, and aryl sulfonyl chlorides l-n led to the formation of the targeted 2-substituted benzimidazole motifs 7a-n in improved yields. The targeted benzimidazole motifs were structurally authenticated through their spectral data and microanalytical parameters. The targeted final moieties were investigated for potential antimicrobial activity using the agar diffusion method with gentamicin as the clinical standard. All the compounds had a broad spectrum of activity with compound 7k having the highest remarkable activity with MIC of 0.98 ± 0.02 µg/mL and MBC value of 3.91 ± 0.10 µg/mL. These findings suggest that compound 7k containing camphor might be a good candidate for the design of new antimicrobial small-molecule drugs

Antibacterial and cytotoxic activities of undescribed cassiaric acid and other constituents from Cassia arereh stem barks

Please read abstract in the article.The South African Medical Research Council Self-Initiated Research (SAMRC) and the National Research Foundation Thuthuka.https://www.tandfonline.com/loi/gnpl20hj2023BiochemistryChemistryGeneticsMicrobiology and Plant Patholog

Antibacterial and antioxidant activities of the extract and some flavonoids from aerial parts of Echinops Gracilis O. Hoffm. (Asteraceae)

Mortality due to microbial diseases continues to be a major problem in many developing countries. The present study aims to evaluate the antibacterial and antioxidant activities of the ethyl acetate extract and some isolated compounds from aerial parts of Echinops gracilis. The phytochemical study resulted in the isolation of a new flavonoid derivative named apigenin-7-O-(4″-feruloyl)-β-D-glucoside (1), together with 2 known compounds: apigenin-7-O-(4″-trans-p-hydroxycinnamoyl)-β-D-glucoside (2), and apigenin-7-O-glucoside (3). Their chemical structures were determined using a combination of NMR and IR spectroscopic and MS techniques, as well as by comparison with literature data. The extract and isolates were evaluated for their antibacterial and antioxydant properties. The EtOAc extract and compounds 1 and 2 showed the ability to scavenge 2,2′-zino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS) with scavenging concentration (SC50) values of 13.6 ± 0.8 µg/mL, 108.2 ± 4.3 µg/mL, and 28.5 ± 2.2 µg/mL, respectively. In addition, compound 1 displayed significant activity against Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia, with minimum inhibition concentration (MIC) values of 31.2, 15.6, and 31.2 µg/mL respectively.https://journals.sagepub.com/home/npxhj2022Chemistr