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Oceanic islands are unique in their species composition, which is defined by arrival of colonizers via long distance dispersal followed by establishment of species followed in some cases by adaptive radiation. Evolutionary biologists identified traits facilitating successful colonization of islands as including polyploidy, self‐compatibility, herbaceousness and ability for long‐distance dispersal. Successful establishment and evolutionary diversification of lineages on islands often involves shifts to woodiness and shifts in methods of outcrossing as well as changes in dispersal ability. The genus Melicope colonized numerous archipelagos throughout the Pacific including the Hawaiian Islands, where the lineage comprises currently 54 endemic species and represents the largest radiation of woody plants on the islands. The wide distributional range of the genus illustrates its high dispersibility, most likely due to adaption to bird dispersal. Here we investigate ploidy in the genus using flow cytometry and chromosome counting. We find the genus to be paleopolyploid with 2n = 4x = 36, a ploidy level characterizing the entire subfamily Amyridoideae and dating back to at least the Palaeocene. Therefore Hawaiian Melicope have not undergone recent polyploidization prior to colonization of the islands. Thus Melicope retained colonization success while exhibiting a combination of traits that typically characterize well established island specialists while lacking some traits associated to successful colonizers.

The genus Melicope (Rutaceae) occurs on most Pacific archipelagos and is perfectly suited to study Pacific biogeography. The main goal was to infer the age, geographic origin and colonization patterns of Melicope and its relatives. We sequenced three nuclear and two plastid markers for 332 specimens that represent 164 species in 16 genera of Rutaceae. Phylogenetic reconstruction, molecular dating, ancestral area reconstruction and diversification analyses were carried out. The two main clades (Acronychia-Melicope and Euodia) originated in Australasia and their crown ages are dated to the Miocene. Diversification rates differed among the subclades and were lowest in the Euodia lineage and highest in the Hawaiian Melicope lineage. The Malagasy and Mascarene species form a clade, which split from its SE Asian relatives in the Pliocene/Pleistocene. At least eight colonizations to the Pacific islands occurred. The timing of all colonizations except for the Hawaiian group is congruent with age of the island ages. Australia, New Guinea and New Caledonia have been the source of colonizations into the Pacific islands in the Melicope clade. Melicope shows high dispersability and has colonized remote archipelagos such as the Austral and Marquesas Islands each twice. Colonization of islands of the Hawaiian-Emperor seamount chain likely predates the ages of the current main islands, and the initial colonization to Kaua'i occurred after the splitting of the Hawaiian lineage into two subclades. Wider ecological niches and adaptations to bird-dispersal likely account for the much higher species richness in the Acronychia-Melicope clade compared to the Euodia clade.

Diabetes mellitus is normally characterized by chronic hyperglycemia associated with disturbances in the fat, carbohydrate, and protein metabolism. There is an increasing trend of using natural products instead of synthetic agents as alternative therapy for disorders due to their fewer side effects. In this study, antidiabetic and antioxidant activities of different Melicope lunu-ankenda (ML) ethanolic extracts were evaluated using inhibition of α-glucosidase and 2,2-diphenyl-l-picrylhydrazyl (DPPH) radicals scavenging activity, respectively; whereas, proton nuclear magnetic resonance ((1) H NMR) and ultra-high performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) techniques were used for metabolite profiling of ML leaf extracts at different concentrations of ethanol and water. Sixty percent of ethanolic ML extract showed highest inhibitory effect against α-glucosidase enzyme (IC50 of 37 μg/mL) and DPPH scavenging activity (IC50 of 48 μg/mL). Antidiabetic effect of ML extracts was also evaluated in vivo and it was found that the high doses (400 mg/Kg BW) of ML extract exhibited high suppression in fasting blood glucose level by 62.75%. The metabolites responsible for variation among ML samples with variable ethanolic levels have been evaluated successfully using (1) H-NMR-based metabolomics. The principal component analysis (PCA) and partial least squares(PLS) analysis scores depicted clear and distinct separations into 4 clusters representing the 4 ethanolic concentrations by PC1 and PC2, with an eigenvalue of 69.9%. Various (1) H-NMR chemical shifts related to the metabolites responsible for sample difference were also ascribed. The main bioactive compounds identified attributing toward the separation included: isorhamnetin, skimmianine, scopoletin, and melicarpinone. Hence, ML may be used as promising medicinal plant for the development of new functional foods, new generation antidiabetic drugs, as a single entity phytomedicine or in combinational therapy.

The treatment of Rutaceae in the Chinese flora chose to follow Engler in recognizing Rutoideae and Toddalioideae as two separate subfamilies. Morphological and chemical comparisons, however, suggested grouping those two subfamilies in one subfamily, Rutoideae. This move has received support from molecular phylogenetic analyses, which also showed that the Chinese taxa in Euodia should be placed in Tetradium and Melicope following Hartley. Investigations into the chemistry and molecular phylogeny of Murraya also indicated that the species in the section Bergera without yuehchukene should be removed from Murraya. These findings clearly show the value of molecular cladistics to the taxonomy of Rutaceae in China and also directions for further investigations.

Aim Pacific biogeographical patterns in the widespread plant genus Melicope J.R. Forst. & G. Forst. (Rutaceae) were examined by generating phylogenetic hypotheses based on chloroplast and nuclear ribosomal sequence data. The aims of the study were to identify the number of colonization events of Melicope to the Hawaiian Islands and to reveal the relationship of Hawaiian Melicope to the Hawaiian endemic genus Platydesma H. Mann. The ultimate goal was to determine if the Hawaiian Islands served as a source area for the colonization of Polynesia. Location Nineteen accessions were sampled in this study, namely eight Melicope species from the Hawaiian Islands, four from the Marquesas Islands, one species each from Tahiti, Australia and Lord Howe Island, two Australian outgroups and two species of the Hawaiian endemic genus Platydesma. To place our results in a broader context, 19 sequences obtained from GenBank were included in an additional analysis, including samples from Australia, Papua New Guinea, New Zealand, Southeast Polynesia and Asia. Methods DNA sequences were generated across 19 accessions for one nuclear ribosomal and three chloroplast gene regions. Maximum parsimony analyses were conducted on separate and combined data sets, and a maximum likelihood analysis was conducted on the combined nuclear ribosomal and chloroplast data set. A broader nuclear ribosomal maximum parsimony analysis using sequences obtained from GenBank was also performed. Geographic areas were mapped onto the combined chloroplast and nuclear ribosomal tree, as well as onto the broader tree, using the parsimony criterion to determine the dispersal patterns. Results Phylogenetic analyses revealed that Platydesma is nested within Melicope and is sister to the Hawaiian members of Melicope. The Hawaiian Melicope + Platydesma lineage was a result of a single colonization event, probably from the Austral region. Finally, Marquesan Melicope descended from at least one, and possibly two, colonization events from the Hawaiian Islands. Main conclusions These data demonstrate a shifting paradigm of Pacific oceanic island biogeography, in which the patterns of long-distance dispersal and colonization in the Pacific are more dynamic than previously thought, and suggest that the Hawaiian Islands may act as a stepping stone for dispersal throughout the Pacific.

Investigation of leaves of Melicope ptelefolia afforded 18 2,2-dimethyl-2H-1-benzopyrans, consisting of 14 new members, including one benzodipyran and four known compounds. Their structures were established by mass and NMR spectroscopy, especially NOE and HMBC experiments. © 1997 Elsevier Science Ltd. All rights reserved

The investigation of the leaves of Melicope ptelefolia (Rutaceae) afforded, besides N-methylflindersine, two new bisquinolinone alkaloids named melicobisquinolinone A and B. Their structures were established by MS and NMR spectroscopy, especially NOE and HMBC experiments.

The crystal structure determinations of two crystalline components of the hexane extract of the fruit of the indigenous Australian tree Melicope ellyrana have shown them to be polymorphs of the same compound, namely the flavonoid 4′,5-di­hydroxy-3,3′,8-tri­methoxy-7-(3-methyl­but-2-enyl­oxy)­flavone [systematic name: 5-hydroxy-2-(4-hydroxy-3-methoxy­phenyl)-3,8-di­methoxy-7-(3-methyl­but-2-enyl­oxy)-4H-1-benzo­pyran-4-one], C23H24O8. The two polymorphs, one monoclinic (polymorph A) and the other triclinic (polymorph B), show significant conformational differences, particularly in the enyl­oxy side chain, while only one (polymorph A) shows intermolecular hydrogen bonding.

Die optisch aktiven 5.7.4′-Trihydroxy-flavanon-4′-[γ.γ-dimethyl-allylather] (5) (Selinon) aus Selinum vaginatum Clarke und 5.4′-Dihydroxy-7.3′-dimethoxy-flavanon-4′[γ.γ-dimethylallyl-ather] (8) aus Melicope sarcococca Laut. wurden durch partielle Synthese der racemischen Verbindungen in ihrer Struktur bestatigt. Phloracetophenon-4-0-β-neohesperidosid wurde mit 4-[γ.γ-Dimethyl-allyloxy]-benzaldehyd (2) bzw. 3-Methoxy-4[γ.γ-dimethyl-allyloxy]-benzaldehyd (3) zum Chalkonglykosid kondensiert, zum Flavanonglykosid (4 bzw. 6) isomerisiert und enzymatisch zum Aglykon (±)-Selinon (5) bzw. (±)-5.7-Dihydroxy-3′-methoxy-4′-[γ.γ-dimethyl-allyloxy]-flavanon (7) hydrolysiert. 7 wurde mit Diazomethan zu (±)-5-Hydroxy-7.3′-dimethoxy-4′-[γ.γ-dimethyl-allyoxy]-flavanon (8) methyliert. Synthesis of the Naturally Occurring 4′-(γ.γ-Dimethylallyl) Ethers of 5.7.4′-Trihydroxyflavanone (Selinone) and 5.4′-Dihydroxy-7.3′-dimethoxyflavanone The structures of the optically active 5.7.4′-trihydroxyflavanone 4′-(γ.γ-dimethylallyl) ether (5) (Selinone) from Selinum vaginatum Clarke and 5.4′-dihydroxy-7.3′-dimethoxyflavanone 4′-(γ.γ-dimethylallyl) ether (8) from Melicope sarcococca Laut. were confirmed by partial synthesis of the corresponding racemic compounds. Phloracetophenone 4-0-β-neohesperidoside was condensed with 4-(γ.γ-dimethylallyloxy) benzaldehyde (2) and 3-methoxy-4-(γ.γ-dimethyl-allyloxy) benzaldehyde (3) to form the chalcone glycosides which were isomerised to the flavanone glycosides 4 and 6, respectively. Subsequent enzymic hydrolysis of the two compounds gave (±)-selinone (5) and (±)-5.7-dihydroxy-3′-methoxy-4′-(γ.γ-dimethylallyloxy)-flavanone (7). The latter on methylation with diazomethane yielded (±)-5-hydroxy-7.3′-dimethoxy-4′-(γ.γ-dimethylallyloxy)flavanone (8).