Polyoxygenated seco -cyclohexenes and other constituents from Uvaria valderramensis

Tetrahydroxanthene-1,3(2H)-diones and Oxidized Hexadiene Derivatives from Uvaria leptopoda and Their Biological Activities

The first phytochemical investigation of the twig extract of Uvaria leptopoda resulted in the isolation and identification of three new tetrahydroxanthene-1,3(2H)-diones, uvarialeptones A-C, two new oxidized hexadiene derivatives, uvarialeptols A and B, together with ten known compounds. Their structures were elucidated by spectroscopic techniques and mass spectrometry. Uvarialeptones A and B were unprecedented tetrahydroxanthene-1,3(2H)-dione dimers which exhibited a cyclobutane ring via [2 + 2] cycloaddition from uvarialeptone C and 9a-O-methyloxymitrone, respectively. The structure of uvarialeptone A was confirmed by X-ray diffraction analysis using Mo Kα radiation. Compound 3 inhibited NO production at an IC50 value of 6.7 ± 0.1 μM.

Essential oils of Uvaria boniana - chemical composition, in vitro bioactivity, docking, and in silico ADMET profiling of selective major compounds

Phytochemical investigation applying GC (gas chromatography)-MS (mass spectrometry)/GC-FID (flame ionization detection) on the hydro-distilled essential oils of the Vietnamese medicinal plant Uvaria boniana leaf and twig lead to the detection of 35 constituents (97.36%) in the leaf oil and 52 constituents (98.75%) in the twig oil. Monoterpenes, monoterpenoids, sesquiterpenes, and sesquiterpenoids were characteristic of U. boniana essential oils. The leaf oil was represented by major components (E)-caryophyllene (16.90%), bicyclogermacrene (15.95%), α-humulene (14.96%), and linalool (12.40%), whereas four compounds α-cadinol (16.16%), epi-α-muurolol (10.19%), α-pinene (11.01%), and β-pinene (8.08%) were the main ones in the twig oil. As compared with the leaf oil, the twig oil was better in antimicrobial activity. With the same MIC value of 40 mg/mL, the twig oil successfully controlled the growth of Gram (+) bacterium Bacillus subtilis, Gram (-) bacterium Escherichia coli, fungus Aspergillus niger, and yeast Saccharomyces cerevisiae. In addition, both two oil samples have induced antiinflammatory activity with the IC₅₀ values of 223.7-240.6 mg/mL in NO productive inhibition when BV2 cells had been stimulated by LPS. Docking simulations of four major compounds of U. boniana twig oil on eight relevant antibacterial targets revealed that epi-α-muurolol and α-cadinol are moderate inhibitors of E. coli DNA gyrase subunit B, penicillin binding protein 2X and penicillin binding protein 3 of Pseudomonas aeruginosa with similar free binding energies of -30.1, -29.3, and -29.3 kJ/mol, respectively. Furthermore, in silico ADMET studies indicated that all four docked compounds have acceptable oral absorption, low metabolism, and appropriated toxicological profile to be considered further as drug candidates.

Antibacterial and COX-2 Inhibitory Tetrahydrobisbenzylisoquinoline Alkaloids from the Philippine Medicinal Plant Phaeanthus ophthalmicus

Phaeanthus ophthalmicus (Roxb. ex G.Don) J.Sinclair (previously known as P. ebracteolatus (Presl) Merr) is a Philippine medicinal plant occurring as evergreen shrub in the lowland forests of Luzon islands. It is used traditionally by Filipinos to treat bacterial conjunctivitis, ulcer and wound infections. Based on previous investigations where cyclooxygenase-2 (COX-2) functions as immune-linked factor in infectious sensitivities to bacterial pathogens by triggering pro-inflammatory immune-associated reactions, we investigated the antimicrobial and COX inhibitory activities of the extracts and tetrahydrobisbenzylisoquinoline alkaloids of P. ophthalmicus in vitro and in silico to validate its ethnomedicinal uses. Thus, the dichloromethane-methanol (DCM-MeOH) crude extract and alkaloid extracts exhibiting antibacterial activities against drug-resistant bacterial strains such as methicillin-resistance Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Klebsiella pneumoniae + CRE and Pseudomonas aeruginosa + MBL afforded (+)-tetrandrine (1) and (+)-limacusine (2) as the major biologically active tetrahydrobisbenzylisoquinoline alkaloidal constituents after purification. Both tetrahydrobisbenzylisoquinoline alkaloids 1 and 2 showed broad spectrum antibacterial activity with strongest inhibition against the Gram-negative bacteria MβL-Pseudomonas aeruginosa Klebsiella pneumoniae + CRE. Interestingly, the alkaloid limacusine (2) showed selective inhibition against ovine COX-2 in vitro. These results were ascertained by molecular docking and molecular dynamics simulation experiments where alkaloid 2 showed strong affinity in the catalytic sites of Gram-negative bacterial enzymes P. aeruginosa elastase and K. pneumoniae KPC-2 carbapenemase (enzymes involved in infectivity mechanisms), and of ovine COX-2. Overall, our study provides credence on the ethnomedicinal use of the Philippine medicinal plant P. ophthalmicus as traditional plant-based adjuvant to treat bacterial conjunctivitis and other related infections. The antibacterial activities and selective COX-2 inhibition observed for limacusine (2) point to its role as the biologically active constituent of P. ophthalmicus. A limited number of drugs with COX-2 inhibitory properties like celecoxib also confer antibacterial activity. Thus, tetrahydrobisbenzyl alkaloids, especially 2, are promising pharmaceutical inspirations for developing treatments of bacterial/inflammation-related infections.

Antitubercular and cytotoxic polyoxygenated cyclohexane derivatives from Uvaria grandiflora

Chromatographic purification of the DCM sub-extract of Uvaria grandiflora led to the isolation and characterization of a new polyoxygenated cyclohexane derivative, grandifloranol (1), together with five known compounds. Among the compounds isolated, zeylenone (3) showed moderate antitubercular activity against Mycobacterium tuberculosis H₃₇Rv with MIC₉₀ value of 51.2 μM and antiproliferative or cytotoxic activity against human myeloid leukaemia (K-562) and HeLa cells with IC₅₀ values of 2.3 and 18.3 μM, respectively.

Alkaloids and styryllactones from Goniothalamus cheliensis

Eight previously undescribed compounds, including four alkaloids and five styryllactones together with 36 known compounds were isolated from the twig and leaf extracts of Goniothalamus cheliensis. Their structures were elucidated by extensive analysis of their spectroscopic data. The absolute configuration of (-)-(4S,5S,6R,7S,8S)-goniochelienlactone and (-)-(4S,5S,6R,7S,8S)-7-acetylgoniochelienlactone were established from single crystal X-ray analysis using Cu Kα radiation. The absolute configurations of the other related compounds were identified by comparisons of their ECD spectra with those of related known compounds. Most of the isolated compounds were evaluated for their cytotoxicities against human colorectal cancer cells (HCT-116). Griffithazanone A was the most potent with an IC₅₀ value of 2.39 μM.

Potent α-glucosidase inhibitory activity of compounds isolated from the leaf extracts of Uvaria hamiltonii

The phytochemical investigation of the leaf extracts of Uvaria hamiltonii (Annonaceae) led to the isolation and identification of ten compounds including a new seco-cyclohexene (1) together with nine known compounds (2-10). Their structures were elucidated by intensive analysis by spectroscopic methods and comparisons of their spectroscopic data with those of compounds reported in the literature. Compounds 2, 8, and 9 showed potent α-glucosidase inhibitory activity with the IC₅₀ values ranging from 2.6-7.1 µM.

Antitubercular and Cytotoxic Chlorinated seco-Cyclohexenes from Uvaria alba

Two new chlorine-containing polyoxygenated seco-cyclohexenes, albanols A (1) and B (2), along with the oxepinone metabolite grandiuvarone (3) were isolated from the endemic Philippine Annonaceae plant Uvaria alba. Both new compounds exhibited modest antitubercular activity. Compound 1 showed cytostatic activity (ranging from 1-50 μM) against HeLa cells and weak antiproliferative activity against HUVEC and K-562 cells with GI₅₀ values of 106 and 81 μM, respectively.