https://hdl.handle.net/20.500.12809/134 2026-04-20T04:45:48Z https://hdl.handle.net/20.500.12809/10802 In Vitro and In Silico Evaluation of Anticholinesterase and Antidiabetic Effects of Furanolabdanes and Other Constituents from Graptophyllum pictum (Linn.) Griffith Tanko Metiefeng, Nathalie; Tamfu, Alfred Ngenge; Tagatsing, Maurice Fotsing; Küçükaydın, Selçuk Graptophyllum pictum is a tropical plant noticeable for its variegated leaves and exploited for various medicinal purposes. In this study, seven compounds, including three furanolabdane diterpenoids, i.e., Hypopurin E, Hypopurin A and Hypopurin B, as well as with Lupeol, β-sitosterol 3-O-β-d-glucopyranoside, stigmasterol 3-O-β-d-glucopyranoside and a mixture of β-sitosterol and stigmasterol, were isolated from G. pictum, and their structures were deduced from ESI-TOF-MS, HR-ESI-TOF-MS, 1D and 2D NMR experiments. The compounds were evaluated for their anticholinesterase activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BchE), as well as their antidiabetic potential through inhibition of α-glucosidase and α-amylase. For AChE inhibition, no sample had IC50 within tested concentrations, though the most potent was Hypopurin A, which had a percentage inhibition of 40.18 ± 0.75%, compared to 85.91 ± 0.58% for galantamine, at 100 µg/mL. BChE was more susceptible to the leaves extract (IC50 = 58.21 ± 0.65 µg/mL), stem extract (IC50 = 67.05 ± 0.82 µg/mL), Hypopurin A (IC50 = 58.00 ± 0.90 µg/mL), Hypopurin B (IC50 = 67.05 ± 0.92 µg/mL) and Hypopurin E (IC50 = 86.90 ± 0.76 µg/mL). In the antidiabetic assay, the furanolabdane diterpenoids, lupeol and the extracts had moderate to good activities. Against α-glucosidase, lupeol, Hypopurin E, Hypopurin A and Hypopurin B had appreciable activities but the leaves (IC50 = 48.90 ± 0.17 µg/mL) and stem (IC50 = 45.61 ± 0.56 µg/mL) extracts were more active than the pure compounds. In the α-amylase assay, stem extract (IC50 = 64.47 ± 0.78 µg/mL), Hypopurin A (IC50 = 60.68 ± 0.55 µg/mL) and Hypopurin B (IC50 = 69.51 ± 1.30 µg/mL) had moderate activities compared to the standard acarbose (IC50 = 32.25 ± 0.36 µg/mL). Molecular docking was performed to determine the binding modes and free binding energies of Hypopurin E, Hypopurin A and Hypopurin B in relation to the enzymes and decipher the structure-activity relationship. The results indicated that G. pictum and its compounds could, in general, be used in the development of therapies for Alzheimer's disease and diabetes. 2023-01-01T00:00:00Z https://hdl.handle.net/20.500.12809/10637 Characterization of Turkish Astragalus honeys according to their phenolic profiles and biological activities with a chemometric approach Küçükaydın, Selçuk; Tel-Çayan, Gülsen; Çayan, Fatih; Taş-Küçükaydın, Meltem; Eroğlu, Büşra; Duru, Mehmet Emin; Öztürk, Mehmet The genus of Astragalus provides a significant source of pollen and nectar for honeybees. In this study, 37 Astragalus honey samples in 8 different regions from Turkey were investigated for the phenolic compositions and antioxidant, antimicrobial, anti-quorum sensing, anti-inflammatory and enzyme inhibitory (urease, tyrosinase, butyrylcholinesterase (BChE), and acetylcholinesterase (AChE)) activities with chemometric approaches. Seventeen phenolic compounds and organic acids were detected using HPLC-DAD and levulinic, gallic, p-hydroxy benzoic, vanilic and p-coumaric acids were found to be common compounds in all studied Astragalus honey samples. The ET coded Astragalus honey sample from Erzurum showed the best antioxidant activity in DPPH• (IC50: 12.54 ± 0.25 mg/mL), ABTS•+ (IC50: 4.20 ± 0.12 mg/mL) and β-carotene linoleic acid (IC50: 3.85 ± 0.11 mg/mL) assays. Astragalus honey samples studied displayed moderate antimicrobial activity against Candida species, gram-negative and gram-positive bacteria while they showed high quorum sensing inhibition effects. The NB coded Astragalus honey sample from Niğde exhibited the highest anti-inflammatory activity against COX-1 (76.11 ± 0.80%) and COX-2 (55.98 ± 0.93%) enzymes. The studied Astragalus honey samples showed mild enzyme inhibitory activities against AChE, BChE, urease and tyrosinase. The chemometric characterization based on the botanical origin of Astragalus honey samples was determined using principal component analysis (PCA) and hierarchical cluster analysis (HCA). 2023-01-01T00:00:00Z https://hdl.handle.net/20.500.12809/10623 The Investigation of the Chemical Composition and Applicability of Gold Nanoparticles Synthesized with Amygdalus communis (Almond) Leaf Aqueous Extract as Antimicrobial and Anticancer Agents Baran , Mehmet Fırat; Keskin, Cumali; Baran, Ayşe; Eftekhari, Aziz; Omarova, Sabina; Kurt, Kadri The current work's main objective was to determine the chemical composition of Amygdalus communis (AC) leaf extract and examine the antibacterial and cytotoxic properties of biosynthesized gold nanoparticles (AuNPs). The chemical composition of AC leaf extract was determined using LC-ESI/MS/MS to detect compounds that may be responsible for the reducing, stabilizing, and capping steps in the synthesis of nanoparticles and their biological activities. The AC-AuNPs were spherical, with a particle size lower than 100 nm and a face-centered cubic structure. The EDX spectrum confirmed the formation of AuNPs and a negative zeta potential value (-27.7 mV) suggested their physicochemical stability. The in vitro cytotoxic efficacy of the AC-AuNPs against colorectal adenocarcinoma (Caco-2), glioma (U118), and ovarian (Skov-3) cancer cell lines and human dermal fibroblasts (HDFs) was evaluated by MTT assay. CaCo-2 cell proliferation was effectively inhibited by the AC-AuNPs at concentrations between 25 and 100 g mL-1. The AC-AuNPs exerted preeminent antimicrobial activity against Bacillus subtilis with an MIC of 0.02 μg/mL, whilst good activity was shown against Staphylococcus aureus bacteria and Candida albicans yeast with an MIC of 0.12 μg/mL. Ultimately, the results support the high antibacterial and anticancer potential of biosynthesized AuNPs from AC leaf extract. 2023-01-01T00:00:00Z https://hdl.handle.net/20.500.12809/10552 Cholinesterase, α-glucosidase, tyrosinase and urease inhibitory activities of compounds from fruits of Rinorea oblongifolia C.H. Wright (Violaceae) Küçükaydın, Selçuk; Munvera, Aristide Mfifen; Alfred Ngenge, Tamfu; Ouahouo, Blandine Marlyse Wache; Nyemb, Jean Noel From Rinorea oblongifolia fruits, 3-Nor-4β-friedelan-24-ol (1) and 3-decyl-6,7,8-trimethoxy-2H,5H-furo[4,3,2-de]isochromene-2,5-dione (4), new derivatives alongside, 28-hydroxyfriedelan-3-one (2), friedelin (3), 3,3’,4,4’,5’-pentamethylcoruleoellagic acid (5), hexamethylcoruleoellagic acid (6), 3’,4,4’,5,5’-pentamethylcoruleoellagic acid (7), and fatty compounds 8-11 were isolated and characterized using HRESIMS, EIMS, 1D and 2D NMR. In vitro enzyme inhibition of compounds 1, 2, 4, 5, 6 and 7 were evaluated on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-glucosidase, urease and tyrosinase. Against AChE and BChE, the phenolic compounds 4, 5, 6, and 7 had good activity probably due to the phenolic nature and methoxy substituents. Compounds 4, 5, 6 and 7 exhibited good α-glucosidase inhibition especially compound 4 whose IC50 = 42.45 ± 0.46 µg/mL was close that of acarbose (IC50 = 20.52 ± 0.84 µg/mL) standard drug. Urease and tyrosinase were appreciably inhibited by the compounds. Overall results of enzyme inhibitory assays indicate Rinorea oblongifolia, fruits and its constituents as potential remedy for enzymatic disorders. 2023-01-01T00:00:00Z