Eksplorasi Senyawa Fenolik Baru dan Uji Aktivitas Penghambatan Radikal Bebas dari Beberapa Tumbuhan Tropis

SURAT KEPUTUSAN REKTOR UNIVERSITAS AIRLANGGA, NOMOR 886/UN3/2018, PELAKSANAAN PENELITIAN INTERNAL UNIVERSITAS AIRLANGGA, HIBAH RISET MANDAT, PENELITIAN UNGGULAN FAKULTAS DAN PENELITIAN DOSEN PEMULA TAHUN 201

(-)-Ampelopsin F, Dimerstilbene, Compound From Dryobalanopsoblongifolia And Antimalarian Activity Test.

The Dipterocarpaceae (dipterocarp) is one of a large family comprising 16 genera, about 600 species of which are widely distributed (76%) in Malaysia and Indonesia. Dryobalanops comprises a small number of species. This genus is locally named kayu kapur [1, 2]. As other genus in Dipterocarpacea, Dryobalanops has been known to be a rich source of phenolic compounds, especially stilbene oligomers [3,4,5,6] but there has never been a report on their antimalarial activity. Previous studies have identified stilbene oligomers from Dryobalanops oblongifolia Dyer, namely (–)-ampelopsin A, a compound of dimer stilbenoid, and two compounds of trimer stilbenoid, namely cis- and trans-diptoindonesin B [3, 4]. This paper reports on a compound of dimer stilbene, (–)-ampelopsin F, from the acetone extract of the tree bark of D. oblongifolia. Test of its antimalarial activity showed an IC50 value of 0.001 μg/mL, which makes it promising as an antimalarial compound. The structure of (–)-ampelopsin F (1) was determined based on physical data and spectroscopic data, including UV, MS, NMR, 2D NMR, and also by comparison with published data. The antimalarial activity test was carried out according to the method of Trager and Jensen [7]. The melting point was determined on a micro melting-point apparatus, UV spectra was measured using a UV-Vis Shimadzu spectrometer in MeOH, and 1H and 13C NMR spectra were recorder on a JEOL J-500 spectrometer operating at 500 MHz (1H) and 125 MHz (13C) using TMS as an internal standard. Optical rotatory was measured using a PerkinElmer 341 polarimeter. Gravitation column chromatography (GCC) was carried out using Merck Si gel 60 (70–200 mesh), vacuum liquid chromatography (VLC) and radial chromatography using Merck Si gel 60 GF254, and thin-layer chromatography (TLC) using procoated Si gel plates (Merck kieselgel 60 F254 0.25 mm). Solvents used in this research were of analytical and technical grade and were distilled before use. The tree bark of D. oblongifolia Dyer was obtained from Gunung Mali, Tempunak, Sintang, West Kalimantan, in December 2012. The specimen was identified at Biological Research Center, LIPI, Bogor, Indonesia, and a voucher specimen has been deposited at the herbarium. The powdered tree bark of Dryobalanops oblongifolia (5 kg) was macerated with acetone for 2 × 24 h and then concentrated under reduced pressure to give a gummy brownish extract. The extract was divided into acetone–diethyl ether soluble and insoluble fractions. The acetone-diethyl ether soluble fraction (48 g) was fractionated using VLC (n-hexane–ethyl acetate, increasing polarity) to give four major fractions A–D. From TLC analysis, fraction D (3.2 g) was chosen for further analysis. Fraction D was GCC refractionated repeatedly using n-hexane–ethyl acetate 5:5 – ethyl acetate 100% to yield fractions D1–D3. Fraction D1, on repeated purification using radial chromatography with chloroform–methanol (9:1), yielded compound 1 (14.8 mg). Compound 1 was obtained as an amorphous brown solid, mp 220–222°C (dec), [α] 25D –2°. The molecular formula, C28H22O6, of compound 1 was established based on HR-FAB-MS (m/z 454.1416 [M]+), corresponding to a resveratrol dimer. The UV spectra of compound 1 showed absorption at 220 and 282 nm, typical for oligomeric stilbene chromophores. The 13C NMR spectra of compound 1 showed 22 distinct signals, which represented 28 atoms of carbon. The 1H NMR spectra of compound 1 exhibited four signals of an ortho-coupled aromatic hydrogen at δ 7.02, 6.72, 6.69, and 6.50 (each 2H, d), indicating the presence of two units of 4-hydroxyphenyl. Four signals of a meta-coupled aromatic hydrogen at δ 6.38, 6.36, 6.08, and 6.01 (each 1H, d) indicated the presence of two units of 1,2-substituted-3,5-dihydroxyphenyl. Four signals of an aliphatic methane hydrogen singlet appeared at δ 4.08, 4.03, 3.56, and 3.23.The chemical shift values of the four aliphatic methine hydrogens indicated that this structure did not form an oxygen heterocyclic ring. The four methine hydrogens appearing as a singlet signal showed that all the dihedral angles of the vicinal hydrogen approach 90°, so that the small values of the vicinal coupling constants prevented the four methine hydrogens did not undergo splitting [8, 9]. The relation of inter-units shown in compound 1 was confirmed by analysis of 1H–13C long-range couplings on the HMBC spectrum (Fig. 1). The HMBC spectrum of compound 1 showed some correlations between H-7/C-8, H-7/C-10a, H-8/C-10, H-8/C-10a, H-8a/C-10a, H-8a/C-10, and H-8a/C-9a; it showed that rings A2 and B2 were connected by C-7, C-8, and C-8a. Moreover, the correlations between H-7a/C-9, H-8a/C-8, H-8/C-8a, H-8/C-10a, and H-7/C-7a proved that C-7a formed a bicyclo ring between C-8 and C-8a. The aliphatic methine hydrogens at δ 3.56, 4.03, and 4.08 were long-range coupled with the aromatic hydrogens at δ 6.69, 6.36, and 7.02, respectively. In addition, the methine hydrogen at δ 3.23 with another methine hydrogen at δ 4.03 displayed w-relationships of the proton system [8, 9]. Based on the analysis of NMR and 2D NMR and comparation of the NMR spectroscopic data between compound 1 and the published data of (+)-ampelopsin F that was isolated from Ampelopsis brevipedunculata [9], it was concluded that this compound has the (–)-ampelopsin F structure. (–)-Ampelopsin F (1), amorphous brown solid, mp 220–222°C (dec); [α] 25D –2° (c 0.1; MeOH). UV spectrum (MeOH, λmax, nm): 220 and 282. HR-FAB-MS m/z [M]+ 454.1416 (calcd for C28H22O6, 454.1410). 1H NMR (500 MHz, CD3OD, δ, ppm, J/Hz): 7.02 (2H, d, J = 8.6, H-2, 6), 6.72 (2H, d, J = 6.9, H-3, 5), 6.69 (2H, d, J = 8.3, H-2a, 6a), 6.50 (2H, d, J = 6.7, H-3a, 5a), 6.38 (1H, d, J = 2, H-14), 6.36 (1H, d, J = 2.3, H-14a), 6.08 (1H, d, J = 2.6, H-12a), 6.01 (1H, d, J = 2, H-12), 4.08 (1H, s, H-7), 3.56 (1H, s, H-7a), and 3.23 (1H, s, H-8). 13C NMR (125 MHz, CD3OD, δ, ppm): 158.5 (C-13), 158.1 (C-11a), 157.2 (C-13a), 156.1 (C-4, 4a), 153.2 (C-11), 147.9 (C-9a), 147.5 (C-9), 139.1 (C-1), 136.1 (C-1a), 130.1 (C-2, 6), 129.4 (C-2a, 6a), 128.7 (C-10), 115.8 (C-3, 5), 115.6 (C-3a, 5a), 114.2 (C-10a), 105.8 (C-14a), 104.4 (C-14), 102.0 (C-12, 12a), 59.3 (C-8), 50.9 (C-7a), 49.9 (C-8a), 47.6 (C-7). The antimalarial activity of compound 1, expressed as IC50, is the sample concentration required to inhibit parasite growth by 50%. The antimalarial activity was tested by introducing a series of samples with different concentrations containing complete medium (RPMI 1640 medium with 10% serum O) + erythrocyte into microwell plates and then adding a suspension of Plasmodium falciparum (chloroquine sensitive strain, 3D7) [10]. Pyrimethamine was used as positive control. The percent average parasitemia and the percent average inhibition of parasite growth were determined by counting the amount of infected erythrocytes in every 1000 erythrocytes. The value of IC50 was obtained by analyzing the data of the antimalarial activity test result using probit analysis of the SPSS program. The antimalarial activity test of (–)-ampelopsin F against P. falciparum gave an IC50 value of 0.001 μg/mL (with pyrimethamine as a positive control, IC50 0.03 μg/mL). This result showed that (–)-ampelopsin F has promise as an antimalarial agent

4- Etoksi-3- Metoksifenol dan Metil-3,4-Dihidroksibenzoat, Dua Senyawa Turunan Fenolik Dari Ekstrak Etil Asetat Kulit Umbi Gadung (Dioscorea hispida Dennst) Dan aktivitas Antioksidan Ekstrak Etil Asetat

Two phenolic compoundnamely 4-ethoxy-3-methoxyphenol and methyl-3,4-dihydroxybenzoic have been isolated fromDioscorea hispida Dennst. The isolation of phenolic compounds was done by maceration methods using methanol, followed by partition with n-hexane and ethyl acetate. The process of separation and purification used various chromatography techniques including vacuum liquid chromatography, column chromatography, and radial chromatography. The structure of isolated compounds were determined by spectroscopic methods including UV-Vis, IR, 1D and 2D NMR. The ethyl acetate extract was evaluated for DPPH free radical scavenging activity assay. The IC50of ethyl acetate extract was 415 ppm. The result of this assay indicated that ethyl acetate extract has a potential as an antioxidant

Batatasin III a derivative of dihydrostilbene compound from Yam Peel of Uwi Tuban and Its Antioxidant Activity

A dihydrostilbene derivative compound, namely 3,3-dihydroxy-5-methoxybibenzyl or batatasin III (1) was isolated from the yam peel of Dioscorea alata L. The structure of compound 1 has been elucidated based on spectroscopy UV-Vis, 1D and 2D NMR Analysis. The IC50 of DPPH radical scavenging of this compound (206.82 μg/mL) lower than ethyl acetate extract (109.99 μg/mL), but higher than methanol extract (893.59 μg/mL)

Cytotoxic Prenyl and Geranyl Coumarins from the Stem Bark of Casimiroa edulis

Phytochemical investigation of the methanolic extract of the stem bark of Casimiroa edulis afforded four coumarins. Various spectroscopic experiments were used to characterize the isolated coumarins. The structures were identified as auraptene (K-1), suberosin (K-2), 5-geranyloxypsoralen (bergamottin) (K-3), and 8-geranyloxypsoralen (K-4), based on the chemical and spectral analysis. Among these compounds, suberosin (K-2) and 5-geranyloxypsoralen (bergamottin) (K-3) were isolated for the first time from this genus, and auraptene (K-1) was isolated from this plant for the first time. Cytotoxicity of pure compound K-4 and sub-fraction MD-3 was evaluated against HeLa and T47D cell lines and moderate activity was found with an IC50 value in the range 17.4 to 72.33 μg/mL

Cytotoxicity of Heterophyllene A, the Derivative of Arylbenzofuran from Stem Bark of Artocarpus calophyl

Exploration of secondary metabolites was the focus of this research, especially of Artocarpus calophylla species to look for a potential cytotoxic agent. An arylbenzofuran derivative compound, namely heterophyllene A was isolated from the stem bark of Artocarpus calophylla. Structure determination of this compound has been elucidated using UV-Vis spectroscopy, 1D, and 2D NMR analysis. This compound has a lower IC50 than ethyl acetate extract. The IC50 of this compound (57,54 µg/mL) to HeLa and (25,80 µg/mL) to T47D cells, ethyl acetate extract (>100 µg/mL) to HeLa and (84,16 µg/mL) to T47D cells

Sesquiterpene from Myanmar Medicinal Plant (<em>Curcuma comosa</em>)

Curcuma comosa (Zingiberaceae) is widely grown in tropical and subtropical areas of Asia, like Thailand, Indonesia, Malaysia, and Myanmar. In Myanmar, the rhizome of Curcuma comosa is called Sa-nwin-ga, and local people had used it as a traditional medicine for stomach ache, diabetes mellitus, and hypertension. This species produces secondary metabolites of phenolic and nonphenolic groups. Phenolic groups like diarylheptanoids and flavonoids. While nonphenolics are terpenoids, especially sesqui- and monoterpenes. In this chapter, the group of sesquiterpene compounds from Curcuma comosa starts from the isolation technique, followed by the elucidation of the molecular structure, and their activity tests have been discussed

Cytotoxic Carbazole Alkaloid from the Root of Clausena cxcavata on Hela Cell L

In a search for bioactive constituents from Myanmar medicinal plants, a carbazole alkaloid, named 7hydroxy heptaphylline (1) was isolated from the root of Clausena excavata. The structure of isolated compound was elucidated based on spectrophotometric data such as UV-vis, FT-IR, NMR and HRMS data. The cytotoxicity of the isolated compound (1) was evaluated by MTT assay against on HeLa cancer cells. The compound (1) exhibited moderate inhibition activity with IC50 41.4 µg/ml

A new pyrano coumarin from Clausena excavata roots displaying dual inhibition against α-glucosidase and free radical

A new pyrano coumarin, identified as excavatin A (1) together with two known compounds nordentatin (2) and binorpocitrin (3) was isolated from the 95% EtOH extract of Clausena excavata. All structures were elucidated by using spectroscopy methods such as extensive NMR and HR-FAB-MS spectrometry. All the isolated compounds were tested on antidiabetes activity by using α-glucosidase inhibition assay and the antioxidant activity by DPPH assay. Compounds 1-3 showed antioxidant activity with IC50 values 0.286, 0.02, 0.278 mM. Among them, 2 exhibited inhibition activity against maltase (IC50 5.45 µM) and sucrase (IC50 43.57 µM). However, compounds (1) and (3) displayed inhibition on yeast α-glucosidase with IC50 values 1.92 and 5.58 mM

Phytoconstituents of Genus Micromelum and Their Bioactivity—a Review.

The genus Micromelum belongs to the Rutaceae family. As its rich bioactive constituents its stems, flowers, leaves, and roots have been used in traditional medicine, for the treatment of various diseases from ancient time. Phytochemically, many bioactive compounds, including coumarins, polyoxygenated flavonoids, phenylpropanoic acid derivatives, quinolone alkaloids, and also carbazole alkaloids, have been reported as secondary metabolites of the Micromelum spp. including many new compounds. Therefore, Micromelum spp. are considered potential for drug leads. In this article, we present an overview of secondary metabolites isolated from genus Micromelum and their bioactivities that have been reported between 1982 and 2019