BackgroundBegonia sect. Diploclinium is a ‘dust-bin’ section for species retaining pleisiomorphic characters and lacking novel synapomorphic characters used to delimit other Asian sections in Begonia. Part of this large and polymorphous section is transferred to Begonia sect. Baryandra in a move towards a more natural classification for the genus.ResultsPhylogenetic analysis of nuclear ribosomal ITS DNA sequences show a strongly supported monophyletic group containing Philippine and Bornean species previously in Begonia sect. Diploclinium, and the type of Begonia sect. Baryandra, B. oxysperma. This clade forms the basis for the now much-expanded Begonia sect. Baryandra, which as defined here contains 49 species and has its centre of diversity in the Philippines.ConclusionsA natural classification for a much expanded Begonia sect. Baryandra has been provided. This paper highlights the feasibility of moving towards a natural classification of Asian Begonia step by step as information comes to light through building upon previous framework phylogenies with denser sampling.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-38) contains supplementary material, which is available to authorized users.

Two tetrahydroxanthene-1,3(2H)-dione metabolites, valderramenols A (1) and B (2), were isolated from the Philippine endemic Annonaceous species Uvaria valderramensis. Planar structures of the rac-xanthene-1,3-(2H)-diones 1 and 2 were established by MS and NMR measurements. Their enantiomers were separated by chiral HPLC, and the absolute configurations of the separated enantiomers were determined by comparison of the HPLC-ECD spectra with computed TDDFT-generated spectra. A TDDFT-ECD study of the known grandiuvarone (3) allowed the revision of its absolute configuration as S. Compound 1 showed antitubercular activity (MIC 10 μg/mL), while 3 and 4 had weaker activities (MIC 32 μg/mL). Oxepinone 3 exhibited cytotoxic activity against KB-562, a chronic myeloid leukemia cell line.

Background:The Philippines is home to some ethnomedicinal Apocynaceae that has been used to cure common ailments. They are perceived to be safe, but misidentification can lead to substitution and adulteration. Morphological characters are primarily utilized to identify these species but a new method utilizing molecular characters called DNA barcoding has emerged. In this study, the efficiency of matK, rbcL, trnH-psbA, and trnL-F to molecularly authenticate selected Apocynaceae species were tested.Materials and Methods:Genomic DNA from silica-dried leaf samples were isolated and used as a template for generating DNA barcodes. Pair-wise sequence divergence using Kimura-2-Parameter was used to analyze inter-specific and intraspecific variations among the barcodes, whereas basic local alignment search tool (BLAST) and neighbor-joining (NJ) analyses were employed to examine discrimination success.Results:The results show that matK is the best barcode for Apocynaceae as it has the highest amplification and sequencing success together with rbcL while having high inter-specific and low intra-specific divergence relative to the other candidate barcodes. Furthermore, matK provided the highest discrimination both in BLAST and NJ analyses.Conclusion:This study proposes the use of matK as the principal barcode for Apocynaceae.SUMMARY Both matK and rbcL have higher universality compared to trnH-psbA and trnL-FmatK has relatively high inter-specific divergence and very minimal intra-specific divergencematK is the best barcode to molecularly authenticate Apocynaceae with either trnH-psbA or trnL-F as supplements. Abbreviations used: K2P: Kimura-2-parameter, BLAST: Basic local alignment search tool, NJ: Neighbor-joining.

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