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Unantimycin A, a new neoantimycin analog isolated from a microbial metabolite fraction library

Lim CL, Nogawa T, Okano A, Futamura Y, Kawatani M, Takahashi S, et al.

J Antibiot (Tokyo), 2016 06;69(6):456-8.
PMID: 26648115 DOI: 10.1038/ja.2015.124
Anti-cholinesterase potential of diverse botanical families from Malaysia: Evaluation of crude extracts and fractions from liquid-liquid extraction and acid-base fractionation

Amir Rawa MS, Hassan Z, Murugaiyah V, Nogawa T, Wahab HA

J Ethnopharmacol, 2019 Dec 05;245:112160.
PMID: 31419500 DOI: 10.1016/j.jep.2019.112160

ETHNOPHARMACOLOGICAL RELEVANCE: Enhancement of cholinergic functions in the brain via acetylcholinesterase inhibition is one of the main therapeutic strategies to improve symptoms associated with Alzheimer's or related cognitive deficits. There is a pathophysiological correlation between Alzheimer's and Diabetes Mellitus, as well as inflammation and oxidative stress that may cause cognitive decline.
AIM OF THE STUDY: The present study was intended to evaluate anti-cholinesterase potential of 177 Malaysian plant extracts from 148 species known to have related ethnomedicinal uses such as anti-inflammatory, anti-oxidant, anti-diabetic, epilepsy, headache, memory enhancement and anti-aging.
MATERIALS AND METHODS: Anti-cholinesterase screening against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes was performed on the basis of in-vitro colorimetric 96-well microplate-based assay method. Potent active plant extracts were subjected to liquid-liquid extraction and acid-base fractionation for further analysis.
RESULTS: Fifty-seven plant extracts exhibited potent anti-cholinesterase activities (50-100% inhibition) at 200 μg/ml. Majority of the active plants originated from Fabaceae family. Coccoloba uvifera (L.) L. stem extract manifested the lowest IC50 of 3.78 μg/ml for AChE and 5.94 μg/ml for BChE. A few native species including Tetracera indica (Christm. & Panz.) Merr., Cyrtostachys renda Blume and Ixora javanica (Blume) DC. showed cholinesterase inhibition despite limited local medical applications. Further anti-AChE evaluation (50 μg/ml) of 18 potent plant extracts harbored active polar components in butanol and water fractions, except Senna pendula (Willd.) H.S.Irwin & Barneby (leaves and stems), Acacia auriculiformis Benth. (leaves), Artocarpus altilis (Parkinson ex F.A.Zorn) Fosberg (leaves), and Macaranga tanarius (L.) Mull.Arg. (leaves) that showed inhibitory activity in less polar fractions. The acidic extraction of these four plant species improved their inhibition level against AChE.
CONCLUSION: This study rendered a preliminary overview of anti-cholinesterase activity from diverse Malaysian botanical families in which provided the medical relevance toward these native plant species, especially ones with limited ethnobotanical record or practice.
Fulltext Potential Anti-Acetylcholinesterase Activity of Cassia timorensis DC

Azman NAN, Alhawarri MB, Rawa MSA, Dianita R, Gazzali AM, Nogawa T, et al.

Molecules, 2020 Oct 04;25(19).
PMID: 33020403 DOI: 10.3390/molecules25194545

Seventeen methanol extracts from different plant parts of five different Cassia species, including C. timorensis, C. grandis, C. fistula, C. spectabilis, and C. alata were screened against acetylcholinesterase (AChE). C. timorensis extracts were found to exhibit the highest inhibition towards AChE whereby the leaf, stem, and flower methanol extracts showed 94-97% inhibition. As far as we are aware, C. timorensis is one of the least explored Cassia spp. for bioactivity. Further fractionation led to the identification of six compounds, isolated for the first time from C. timorensis: 3-methoxyquercetin (1), benzenepropanoic acid (2), 9,12,15-octadecatrienoic acid (3), β-sitosterol (4), stigmasterol (5), and 1-octadecanol (6). Compound 1 showed moderate inhibition towards AChE (IC50: 83.71 μM), while the other compounds exhibited poor to slightly moderate AChE inhibitory activity. Molecular docking revealed that the methoxy substitution of 1 formed a hydrogen bond with TYR121 at the peripheral anionic site (PAS) and the hydroxyl group at C5 formed a covalent hydrogen bond with ASP72. Additionally, the OH group at the C3' position formed an interaction with the protein at the acyl pocket (PHE288). This possibly explains the activity of 1 in blocking the entry of acetylcholine (ACh, the neurotransmitter), thus impeding the hydrolysis of ACh.
Fulltext Antioxidant, Anti-Inflammatory, and Inhibition of Acetylcholinesterase Potentials of Cassia timoriensis DC. Flowers

Alhawarri MB, Dianita R, Razak KNA, Mohamad S, Nogawa T, Wahab HA

Molecules, 2021 Apr 29;26(9).
PMID: 33946788 DOI: 10.3390/molecules26092594

Despite being widely used traditionally as a general tonic, especially in South East Asia, scientific research on Cassia timoriensis, remains scarce. In this study, the aim was to evaluate the in vitro activities for acetylcholinesterase (AChE) inhibitory potential, radical scavenging ability, and the anti-inflammatory properties of different extracts of C. timoriensis flowers using Ellman's assay, a DPPH assay, and an albumin denaturation assay, respectively. With the exception of the acetylcholinesterase activity, to the best of our knowledge, these activities were reported for the first time for C. timoriensis flowers. The phytochemical analysis confirmed the existence of tannins, flavonoids, saponins, terpenoids, and steroids in the C. timoriensis flower extracts. The ethyl acetate extract possessed the highest phenolic and flavonoid contents (527.43 ± 5.83 mg GAE/g DW and 851.83 ± 10.08 mg QE/g DW, respectively) as compared to the other extracts. In addition, the ethyl acetate and methanol extracts exhibited the highest antioxidant (IC50 20.12 ± 0.12 and 34.48 ± 0.07 µg/mL, respectively), anti-inflammatory (92.50 ± 1.38 and 92.22 ± 1.09, respectively), and anti-AChE (IC50 6.91 ± 0.38 and 6.40 ± 0.27 µg/mL, respectively) activities. These results suggest that ethyl acetate and methanol extracts may contain bioactive compounds that can control neurodegenerative disorders, including Alzheimer's disease, through high antioxidant, anti-inflammatory, and anti-AChE activities.
A new peptaibol, RK-026A, from the soil fungus Trichoderma sp. RK10-F026 by culture condition-dependent screening

Rawa MSA, Nogawa T, Okano A, Futamura Y, Nakamura T, Wahab HA, et al.

Biosci Biotechnol Biochem, 2021 Jan 07;85(1):69-76.
PMID: 33577647 DOI: 10.1093/bbb/zbaa051

A new peptaibol, RK-026A (1) was isolated from a fungus, Trichoderma sp. RK10-F026, along with atroviridin B (2), alamethicin II (3), and polysporin B (4) as a cytotoxic compound, which was selected by principal component analysis of the MS data from 5 different culture conditions. The structure of 1 was determined as a new atroviridin B derivative containing Glu at the 18th residue instead of Gln by NMR and HR-MS analyses including the investigation of detailed MS/MS fragmentations. 1 showed cytotoxicity toward K562 leukemia cells at an IC50 value of 4.1 µm.
Opantimycin A, a new metabolite isolated from Streptomyces sp. RK88-1355

Nogawa T, Okano A, Lim CL, Futamura Y, Shimizu T, Takahashi S, et al.

J Antibiot (Tokyo), 2017 02;70(2):222-225.
PMID: 27599762 DOI: 10.1038/ja.2016.113
Zealpeptaibolin, an 11-mer cytotoxic peptaibol group with 3 Aib-Pro motifs isolated from Trichoderma sp. RK10-F026

Rawa MSA, Nogawa T, Okano A, Futamura Y, Wahab HA, Osada H

J Antibiot (Tokyo), 2021 08;74(8):485-495.
PMID: 34163024 DOI: 10.1038/s41429-021-00429-y

Six new 11-mer peptaibols designed as zealpeptaibolins, A - F were isolated from the soil fungus, Trichoderma sp. RK10-F026, based on the principal component analysis of the MS data from five different culture compositions. Previously, 20-mer peptaibols from the same fungal strain were identified; 11-mer peptaibols in contrast were discovered from a different culture condition, signifying peptaibol production was culture condition-dependent. These peptaibols contained three Aib-Pro motifs in the sequence. The structures were established by NMR and HR-MS experiments including detailed MS/MS fragmentations. The absolute configurations were determined by Marfey's analysis. Zealpeptaibolin F exhibited the strongest cytotoxicity toward K562 leukemia cells with an IC50 value of 0.91 µM.
RK-1355A and B, novel quinomycin derivatives isolated from a microbial metabolites fraction library based on NPPlot screening

Lim CL, Nogawa T, Uramoto M, Okano A, Hongo Y, Nakamura T, et al.

J Antibiot (Tokyo), 2014 Apr;67(4):323-9.
PMID: 24496142 DOI: 10.1038/ja.2013.144

Two novel quinomycin derivatives, RK-1355A (1) and B (2), and one known quinomycin derivative, UK-63,598 (3), were isolated from a microbial metabolites fraction library of Streptomyces sp. RK88-1355 based on Natural Products Plot screening. The structural elucidation of 1 and 2 was established through two-dimensional NMR and mass spectrometric measurements. They belong to a class of quinomycin antibiotics family having 3-hydroxyquinaldic acid and a sulfoxide moiety. They are the first examples for natural products as a quinoline type quinomycin having a sulfoxide on the intramolecular cross-linkage. They showed potent antiproliferative activities against various cancer cell lines and they were also found to exhibit moderate antibacterial activity.