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Abstract The present study describes the antioxidant effect, glucose uptake activity and cytotoxicity of Melicope lunu-ankenda (ML) leaf extract using cell lines. Results of the study revealed that 60% ethanolic ML extract demonstrated the highest antioxidant activity with total phenolics and flavonoid contents of 354 mg GAE/g DW and 313 mg rutin equivalent (RE)/g DW, respectively. Ferric reducing antioxidant power (FRAP) was found to be 294.3 mM Fe (II) /g. The study showed that, ML leaf extract stimulated fluorescent d-glucose analog 2-[N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino]-2-deoxy-d-glucose (2-NBDG) uptakes by both 3t3-L1 adipocytes and HepG2 hepatocarcinoma cells, showing significant increase in a dose dependent way. Interestingly, cytotoxic activity of the extract conducted against 3t3-L1 adipocytes and HepG2 using the 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay, showed high activity against HepG2 hepatocarcinoma cells with IC 50 of 20.33 ± 1.5 μg/mL and 13.7 ± 2.1 μg/mL after exposure of 48 h and 72 h, respectively. However, ML extract was inactive against 3t3-L1 cell line with IC 50 values of 93 ± 3 μg/mL and 81 ± 2 μg/mL. The results ascertained the significance of ML as a medicinal plant with prodigious applications as an anti-diabetic as well as anti-cancer agent. [ABSTRACT FROM AUTHOR]

Five acetophenones bearing spiroketal-hexofuranoside rings, one di- C -glycosidic acetophenone and two benzopyrans, along with 16 known compounds were isolated from the leaves of Melicope pteleifolia . Structures of all the isolates were elucidated using extensive spectroscopic methods, including 1D, 2D-NMR and HRESIMS. All the isolates were also evaluated for their neuraminidase inhibitory activities against H1N1, H9N2, wild-type H1N1 and oseltamivir-resistant H1N1 (H274Y mutation) virus strains. Of the isolates, tamarixetin 3-robinobioside was found to exhibit the strongest enzymatic inhibition (IC 50 24.93 ± 3.46, 23.19 ± 5.41, 26.67 ± 5.16 and 40.16 ± 4.50 μ M, respectively). Selected candidates, kaempferol 3-robinobioside, kaempferol 3- O - β - d -glucopyranosyl (1 → 2)- α - d -xylopyranoside and tamarixetin 3-robinobioside, also showed moderate reductions in H1N1-induced cytopathic effects on MDCK cells. [ABSTRACT FROM AUTHOR]

Abstract: Seven new diglycosidic constituents, named pteleifosides A–G (1–7), along with ten known glycosides, were isolated from the roots and rhizomes of Melicope pteleifolia (Champ. ex Benth.) T. Hartley. The structures of the isolated compounds were established on the basis of chemical and spectroscopic methods, mainly 1D and 2D NMR data and mass spectrometry. [Copyright &y& Elsevier]

Abstract: Four novel geminally dialkylated, non-aromatic acetophenone derivatives 1–4 were isolated from Melicope coodeana. The compounds, related to hop bitter acids, were named Coodeanones A–C, where Coodeanone B was found in both E and Z configuration of the 6′‴–7′‴ double bond. Antibacterial, antifungal and antimalarial activities of the acetophenone derivaties were investigated, and Coodeanone C (4) was found to have activity toward Plasmodium falciparum (malaria) (IC50 =42.8μM). [Copyright &y& Elsevier]

Abstract: Six novel quinolinone alkaloids bearing a phenylpropanoid or a coumarin moiety, named melicodenines C–H (1–6), two new cinnamyl alcohol derivatives, named melicodins A (7) and B (8), and a new coumarinolignan, named melicodin C (9), were isolated from the leaves of Melicope denhamii (Seem.) T. G. Hartley. Their structures were established by spectroscopic analyses including extensive 2D-NMR experiments. Compounds 1–5 and 9 possess a cyclobutane ring and are hypothetically produced by a [2+2] cycloaddition, whereas compound 6 is presumed to form through a Diels–Alder cycloaddition followed by the elimination of an acetone molecule. Ten quinolinone alkaloids (1–6, 10–13) and a coumarinolignan (9) were tested for anti-proliferative activity against DLD-1 human colon cancer cells. Melicodenine G (5) showed the most potent inhibitory activity, causing the induction of apoptosis with an IC 50 value of 9.4±0.3 μM. [Copyright &y& Elsevier]

Abstract: A bioassay-guided investigation of Melicope ptelefolia Champ ex Benth (Rutaceae) resulted in the identification of an acyphloroglucinol, 2,4,6-trihydroxy-3-geranylacetophenone or tHGA, as the active principle inhibiting soybean 15-LOX. The anti-inflammatory action was also demonstrated on human leukocytes, where the compound showed prominent inhibitory activity against human PBML 5-LOX, with an IC50 value of 0.42μM, very close to the effect produced by the commonly used standard, NDGA. The compound concentration-dependently inhibited 5-LOX product synthesis, specifically inhibiting cysteinyl leukotriene LTC4 with an IC50 value of 1.80μM, and showed no cell toxicity effects. The anti-inflammatory action does not seem to proceed via redox or metal chelating mechanism since the compound tested negative for these bioactivities. Further tests on cyclooxygenases indicated that the compound acts via a dual LOX/COX inhibitory mechanism, with greater selectivity for 5-LOX and COX-2 (IC50 value of 0.40μM). The molecular features that govern the 5-LOX inhibitory activity was thus explored using in silico docking experiments. The residues Ile 553 and Hie 252 were the most important residues in the interaction, each contributing significant energy values of −13.45 (electrostatic) and −5.40kcal/mol (electrostatic and Van der Waals), respectively. The hydroxyl group of the phloroglucinol core of the compound forms a 2.56Å hydrogen bond with the side chain of the carboxylate group of Ile 553. Both Ile 553 and Hie 252 are crucial amino acid residues which chelate with the metal ion in the active site. Distorting the geometry of these ligands could be the reason for the inhibition activity shown by tHGA. The molecular simulation studies supported the bioassay results and served as a good model for understanding the way tHGA binds in the active site of human 5-LOX enzyme. [Copyright &y& Elsevier]

Abstract: The ethyl acetate extract of the leaves of Melicope vitiflora was separated by column chromatography and the resulting fractions tested for their bioactivity towards methicillin-resistant-Staphylococcus aureus (MRSA) and Micrococcus luteus (ML). The bioactive column chromatography fractions were further separated by preparative TLC and dereplication was carried out on them by first subjecting them to electrospray ionisation-ion trap mass spectrometry (ESI-MSn). The resulting molecular masses, their fragmentation patterns in addition to the chemnet database (www.chemnetbase.com) were used to aid in the structural elucidation of some of the compounds by permitting comparison with known structures of natural origin. Some molecular masses and the corresponding fragmentations were found that did not correlate with any known compounds thus revealing potentially novel natural products that could be investigated on a larger scale and could ultimately find application as new drugs against MRSA and other multi drug resistant microorganisms. Structures are also proposed for known compounds that have not been previously reported for M. vitiflora. [Copyright &y& Elsevier]

We screened more than 60 Malaysian plants against two species of insects and found that Melicope subunifoliolata (Stapf) T.G. Hartley (Rutaceae) showed strong feeding deterrent activity against Sitophilus zeamais Motsch. (Curculionidae) and very good larvicidal activity against Aedes aegypti L. (Diptera). One anti-insect compound, meliternatin (3,5-dimethoxy-3′,4′,6,7-bismethylendioxyflavone) (6) and six other minor polyoxygenated flavones were isolated from M. subunifoliolata. [Copyright &y& Elsevier]

Abstract: Two novel Diels–Alder type adducts, melicodenines A (1) and B (2), were isolated from the leaves of Melicope denhamii (Seem.) T. G. Hartley and their structures were established by spectroscopic analyses, including extensive 2D NMR experiments. Compound 1 is a bisquinolinone alkaloid comprised of two N-methylflindersines (3), while compound 2 is the first naturally occurring quinolinone–acetophenone conjugate composed of 3 and an evodionol methyl ether (4). [Copyright &y& Elsevier]