Biotransformation of selected natural products and phytochemistry of fermented Alnus sieboldiana and liverwort Conocephalum conicum / Nurunajah Ab Ghani

Biotransformation is a process by which organic compounds are transformed into its derivatives, aided by organisms such as fungi, bacteria and enzymes. Biotransformations are used as a valuable strategy to diversify chemistry of compounds particularly natural products. The aim of this work is to explore biotransformation on natural products using several concepts, in order to obtain varieties of natural entities. This thesis presents biotransformation studies on two classes of bioactive natural products represented by an anthraquinone and chalcones, followed by in-situ transformation of chemical constituents of male flowers by fungus, and changes in biosynthetic pathways when Japanese liverwort is grown under stressed condition. Small scale biotransformation of the bioactive anthraquinone nordamnacanthal 8 using 19 selected strains revealed its sturdy nature where only Absidia coerulea managed to convert the compound into lucidin 143. Then, in-labo biotransformation was pursued with microbial transformation of hydroxychalcones; 4'- hydroxychalcone 145 and 4-hydroxychalcone 146 by Aspergillus niger. After 7 days of fermentation, four dihydrochalcone derivatives were obtained. Isolated products were identified as 4'-hydroxydihydrochalcone 147, 4-hydroxydihydrochalcone 149, 3\4'-dihydroxydihydrochalcone 148 and 3,4-dihydroxydihydrochalcone 150, resulting from bioreduction at a,P-unsaturated double bond of hydroxychalcone and hydrogenation reaction at the activated phenyl rings. On the other hand, in-situ transformation of Alnus sieboldiana male flowers by fungus Penicillium sp. is of interest due to the common infection causing significant change in the smell. Infected male flowers were allowed to ferment for six months. Analysis of the volatile components of the fermented male flowers revealed P-phenylethyl cinnamate 174 (10%) as a major component followed by 2-phenylethanol 170 (8.7%). The level of 2- phenylethanol 170 in the fermented male flowers is three times higher as compared to the fresh male flowers (2.7%) which explained the unpleasant odor of fermented male flowers. Yashabushidiol A 72, yashabushidiol B 73 and naringenin 69, which were known to be original constituents of the fresh male flowers, were successfully isolated from the ethyl acetate extract of fermented male flowers. Additional transformation products isolated includes six flavonoids kaempferol 195, quercetin 196, pinocembrin dimethyl ether 197, /Lram-3-hydroxy-5,7-dimethoxyflavanone 198, galangin-5,7- dimethyl ether 199 and 5-methoxy-3,6,7-trihydroxyflavanone 200. Detailed analysis of the metabolic pathways of isolated compounds suggested flavanone-3-hydroxylase, flavonoid-3'-hydroxylase and plant-O-methyl-transferases enzymes were released due to the enzymatic action of fungus Penicillium sp. When Japanese liverwort Conocephalum conicum was grown under stressed condition, the biosynthesis pathways taking place in the plant seem to be affected resulting in confusions from chemotype perspective. Under normal growth conditions, (+)-bornyl acetate 94 is the major component in the type-II C. conicum while ds-methyl cinnamate 204 and transmethyl cinnamate 87 should not be present. However, when grown under stressed conditions, ^nms-methyl cinnamate 87 was found to be present as the major component instead of (+)-bornyl acetate 94, indicating activation of shikimate pathway along with mevalonic acid pathway. Thus, it is suggested that the stress C conicum to be categorized under Vnms-methyl cinnamate > bornyl acetate' subtype, since there were dual biogenetic pathways present at stressed condition

Flavanones from the flower of Macaranga triloba

Macaranga triloba belongs to the family of Euphorbiaceae. Investigation on the dichloromethane extract of flower of Macaranga triloba collected at Hulu Terengganu, Malaysia has yielded four flavanone compounds known as 6-prenyl-3’-methoxy-eriodictyol (1), nymphaeol-B (2), nymphaeol-C (3) and 6-farnesyl3’,4’,5,7-tetrahydroxyflavanone (4). The structures of these compounds were elucidated based on spectroscopic methods including nuclear magnetic resonance (NMR-1D and 2D), UV, IR as well as mass spectrometry. This is the first report of 6-prenyl-3’-methoxy-eriodictyol(1) and 6-farnesyl-3’,4’,5,7-tetrahydroxyflavanone (4) from the genus of Macaranga

Volatile components of Dillenia reticulata King (Dilleniaceae) essential oil and their cytotoxicity

ABSTRACT. This work aimed to investigate, for the first time, the chemical composition and cytotoxicity of Dillenia reticulata King’s essential oil. The essential oil was obtained through hydrodistillation, and its volatile components were analyzed through gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS) techniques. Twelve components, which constitutes more than 99.49% of oil content, were successfully identified. The most prominent components were bicyclogermacrene (44.18%), germacrene D (14.49%), β-gurjunene (12.59%), and elemol (12.25%). The cytotoxicity of essential oil was evaluated using an MTT assay. The essential oil exhibited cytotoxicity against three cancer cell lines which are HepG2, MCF7 and A549 with the IC50 values ranging from 61.5-68.5 μg/mL. The present study highlights the potential of using essential oil as an alternative for the development of chemopreventive or cosmetic agents for the pharmaceutical industry.   KEY WORDS: Dillenia reticulata, Dilleniaceae, Essential oil, Cytotoxicity, Bicyclogermacrene Bull. Chem. Soc. Ethiop. 2023, 37(1), 245-249.                                                                 DOI: https://dx.doi.org/10.4314/bcse.v37i1.19                                                       &nbsp

Chemical constituents of the leaves of Actinodaphne pruinosa

ABSTRACT. This study was designed to investigate the chemical constituents from Actinodaphne pruinosa growing in Malaysia. A phytochemical investigation of the leaves part resulted in the isolation of boldine (1), norboldine (2), laurotetanine (3), reticuline (4), syringaresinol (5), lupeol (6), and taraxerol (7). The structures of the isolated phytochemicals were established by analysis of their spectroscopic data, as well as the comparison with that of reported data. Notably, this is the first time to report the isolation and structural elucidation of the constituents from the leaves part of A. pruinosa.   KEY WORDS: Actinodaphne pruinosa, Aporphine, Lauraceae, Phytochemical   Bull. Chem. Soc. Ethiop. 2022, 36(4), 963-969.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i4.2

Secondary metabolites from endemic species Iris adriatica Trinajstic ex Mitic (Iridaceae)

This manuscript describes the first detailed chemical investigation of endemic species Iris adriatica, including isolation and structure elucidation. Chemical analyses of the rhizome CH2Cl2/MeOH (2:1) extract revealed fourteen secondary metabolites, mainly isoflavonoids. Among isoflavonoids, two groups have been found: nigricin-type and tectorigenin-type. Dominant group of the isolated compounds has been nigricin-type isoflavones: nigricin, nigricin-4'-(1-O-beta-D- glucopyranoside) and nigricin-4'-(1-O-beta-D-glucopyranosyl (1-6)-beta-D-glucopyranoside) with 2.5, 10 and 1% of the total extract, respectively. Irisxanthone - xanthone C-glucoside, beta-sitosterol, benzophenone and one of its derivatives have also been found. Nigricin-type isoflavonoids and irisxanthone can be considered as possible chemotaxonomic markers for I. adriatica. 5,3',5'-Trimethoxy-6,7-methylenedioxyisoflavone-4'-(1-O-beta-D-glucopyranoside) and benzophenone have been isolated from Iris species for the first time. Left-hand image of Iris adriatica (Adriatic potato) with redditsh purple flowersSupplementary material: [https://cer.ihtm.bg.ac.rs/handle/123456789/4469

Flavonoids from the Borneo Plant Species: Eusideroxylon zwageri Teijsm. & Binn.

A new flavonoid, 7,3ˊ-dihydroxy-3,5,4ˊ-trimethoxy flavone, along with two known flavonoids, 7-hydroxy-5,4ˊ-dimethoxyflavone and 7-hydroxy-3,5,4ˊ-trimethoxy flavone were isolated from the leaves ethyl acetate extract of Eusideroxylon zwageri Teijsm. & Binn. (Lauraceae). Structures were elucidated by spectroscopic techniques such as NMR, IR, and Orbitrap Mass Spectrometry

Secondary metabolites from endemic species <i>Iris adriatica</i> Trinajstić ex Mitić (Iridaceae)

<p>This manuscript describes the first detailed chemical investigation of endemic species <i>Iris adriatica</i>, including isolation and structure elucidation. Chemical analyses of the rhizome CH₂Cl₂/MeOH (2:1) extract revealed fourteen secondary metabolites, mainly isoflavonoids. Among isoflavonoids, two groups have been found: nigricin-type and tectorigenin-type. Dominant group of the isolated compounds has been nigricin-type isoflavones: nigricin, nigricin-4′-(1-<i>O</i>-<i>β</i>-D-glucopyranoside) and nigricin-4′-(1-<i>O</i>-<i>β</i>-D-glucopyranosyl (1–6)-<i>β</i>-D-glucopyranoside) with 2.5, 10 and 1% of the total extract, respectively. Irisxanthone – xanthone C-glucoside, <i>β</i>-sitosterol, benzophenone and one of its derivatives have also been found. Nigricin-type isoflavonoids and irisxanthone can be considered as possible chemotaxonomic markers for <i>I. adriatica</i>. 5,3′,5′-Trimethoxy-6,7-methylenedioxyisoflavone-4′-(1-<i>O</i>-<i>β</i>-D-glucopyranoside) and benzophenone have been isolated from <i>Iris</i> species for the first time.</p> <p>Left-hand image of <i>Iris adriatica</i> (Adriatic potato) with redditsh purple flowers © Miroslav Mitić. All Rights Reserved.</p

Phytoconstituents of <i>Endiandra kingiana</i>; antidiabetic effects and molecular docking studies on alpha-amylase and alpha-glucosidase

Phytochemical investigation on the bark of E. kingiana plant afforded ten compounds, including six polyketides namely kingianin A 1, kingianin B 2, kingianin E 3, kingianin F 4, kingianin K 5 and kingianin L 6, three endiandric acids; kingianic acid A 7, tsangibeilin B 8 and endiandric acid M 9, and one sesquiterpene; daibuoxide 10. All compounds were separated as racemic mixture by recycling high-performance liquid chromatography (RHPLC), except for daibuoxide. Their structures were elucidated by detailed spectroscopic and comparative literature data analysis. This is the first report on the presence of the sesquiterpene; daibuoxide in Endiandra genus. In vitro enzymatic bio-evaluation of the isolated compounds against α-amylase and α-glucosidase showed that 4 demonstrated the best α-amylase and α-glucosidase inhibitory activity with IC50 values of 181.54 ± 6.27 µg/mL and 237.87 ± 0.07 µg/mL, respectively. In addition, molecular docking analysis confirmed the α-amylase and α-glucosidase inhibitory activities demonstrated by 4.</p