Kien-Thai Yong

Macroline, akuammiline, sarpagine, and ajmaline alkaloids from Alstonia macrophylla

A total of seventeen alkaloids, comprising six macroline (including alstofolinine A, a macroline indole incorporating a butyrolactone ring-E), two ajmaline, one sarpagine, and eight akuammiline alkaloids, were isolated from the stem-bark and leaf extracts of the Malayan Alstonia macrophylla. The structure and relative configurations of these alkaloids were established using NMR, MS and in several instances, confirmed by X-ray diffraction analysis. Six of these alkaloids were effective in reversing multidrug-resistance (MDR) in vincristine-resistant KB cells.

New National and Regional Bryophyte Records, 49

Paper presents couple of new national and regional bryophyte records accross the world, including our new record of Pseudocalliergon lycopodioides in the Carpathians (Czarny Dunajec); the only recent record for the Carpathians.

Comparative morphological and photosynthetic studies on three Malaysian species of Pogonatum from habitats of varying light irradiances

Abstract Comparative morphological and physiological studies were carried out on three species of Malaysian Pogonatum collected from habitats exposed to different light intensities ranging from 28±4 W/m2 for P. cirratum subsp. macrophyllum (Dozy & Molk.) Hyvönen, to 230±39 W/m2 for P. subtortile (Müll.Hal.) A. Jaeger to 751±45 W/m2 for P. neesii (Müll.Hal.) Dozy. Total chlorophyll and beta-carotene content were higher in P. cirratum subsp. macrophyllum and P. subtortile than in P. neesii when calculated on a fresh weight basis. However, soluble protein content was higher in the sun species compared to its shade-adapted counterparts, and the soluble protein to total chlorophyll ratio was highest in P. neesii. The chloroplasts in the leaves of P. cirratum subsp. macrophyllum were significantly larger than those in the other two species, and had more grana and thylakoids per chloroplast profile. The numbers of starch grains in P. cirratum subsp. macrophyllum and P. subtortile were more than double that observed in P. neesii. Morphological studies of the leaves showed specific differences in the shapes and heights of the lamellae found on the adaxial surfaces of the leaves. The lamellae of P. cirratum subsp. macrophyllum were rudimentary whilst those of P. subtortile were 2–3 cells high and P. neesii possessed lamellae 5–7 cells high. These findings indicate a direct correlation between the height of the lamellae and the light irradiances received by the plants. Determination of the in vitro Photosystem II photochemical rates, with an oxygen electrode, of chloroplasts isolated from these plants, showed that P. neesii and P. subtortile exhibited higher rates than P. cirratum subsp. macrophyllum. Similarly in vivo light saturation studies with an infrared gas analyzer showed that CO2 assimilatory rates were highest in P. neesii, even at low light intensities, suggesting a relationship between photosynthesis and light irradiance in these mosses that is different from vascular plants.

New national and regional bryophyte records, 52

Circumpolar boreal-montane moss Buxbaumia aphylla is a new species for Croatia. We have found 58 capsules and 12 setae at the three sites: the smallest population (10 specimens) was located at Sokolina ; at the two other sites B. aphylla was more abundant (Svinjarevac: 29 specimens, Konjska smrt: 31 specimens). Ricciocarpos natans is reported from several localities. It was discovered during extensive surveys of the macrophytic vegetation throughout Croatia. Based on our recent findings, the species occurs in northern and eastern Croatia, mostly in backwaters, or areas subject to inundation, of the large rivers Danube, Drava and Mura. According to our observations, the species in Croatia occupies relatively small and rather shallow eutrophic stagnant waters.

Phylogenetic study of the genus Aptychella (Pylaisiadelphaceae, Musci)

Abstract The relationships among species of the epiphytic genus Aptychella (Broth.) Herzog and Clastobryopsis M. Fleisch. were inferred based on phylogenetic analyses of plastid (rpl16, rps4, and trnL-F) and mitochondrial (nad5) gene sequences as well as morphological features. One of the Asian members, Aptychella robusta (M. Fleisch.) M. Fleisch., exhibits much genetic variation and differentiation among populations, which may reflect the presence of cryptic species. The distinctiveness of Asian members characterized by unicostate leaves, A. brevinervis (M. Fleisch.) M. Fleisch., A. pseudobrevinervis H. Akiyama and A. oblongifolia H. Akiyama, are confirmed. On the contrary, Aptychella proligera, the sole member of the genus known from South and Central America, is shown to have a close relationship to the A. brevinervis complex and preserves low genetic variation among samples collected from geographically remote localities. This lack of variation might be caused by a recent immigration from Asian populations. The Asiatic genus Clastobryopsis is treated as a synonym of Aptychella based on the present phylogenetic analyses. One new combination is proposed—Aptychella imbricata (H. Akiyama et al.) H. Akiyama comb. nov.

Biologically active vallesamine, strychnan, and rhazinilam alkaloids from Alstonia: Pneumatophorine, a nor-secovallesamine with unusual incorporation of a 3-ethylpyridine moiety

Four alkaloids comprising two vallesamine, one strychnan, and one pyranopyridine alkaloid, in addition to 32 other known alkaloids were isolated from two Malayan Alstonia species, Alstonia pneumatophora and Alstonia rostrata. The structures of these alkaloids were determined using NMR and MS analyses, and in one instance, confirmed by X-ray diffraction analysis. The nor-6,7-secovallesamine alkaloid, pneumatophorine, is notable for an unusual incorporation of a 3-ethylpyridine moiety in a monoterpenoid indole. The rhazinilam-type alkaloids (rhazinicine, nor-rhazinicine, rhazinal, and rhazinilam) showed strong cytotoxicity toward human KB, HCT-116, MDA-MB-231, and MRC-5 cells, while pneumatophorine, the uleine alkaloid undulifoline, and the strychnan alkaloids, N4-demethylalstogustine and echitamidine, induced concentration dependent relaxation in phenylephrine-precontracted rat aortic rings.

Macromitrium larrainii, a New Species of Macromitrium (Orthotrichaceae, Bryophyta) from New Caledonia

Abstract The moss Macromitrium larrainii sp. nov. from Mt Panié, the highest summit of New Caledonia, is described and illustrated. This species is characterised by 1) the hairy appearance of branches due to the long aristate leaves arranged irregularly, not spirally, 2) the narrow leaf lamina asymmetrical above, 3) leaf cells consistently smooth, and 4) upper leaf cells irregular in shape and basal ones linear with a straight lumen. Comparison with similar Macromitrium species in neighbouring countries confirms that it is a new species, likely endemic.

New Records of Bazzania Species (Marchantiophyta: Lepidoziaceae) in Peninsular Malaysia with Identification Key

Abstract This paper is the first attempt to understand the genus Bazzania Gray (Marchantiophyta: Lepidoziaceae) in Peninsular Malaysia. Eleven new records for Peninsular Malaysia are reported. They are Bazzania albifolia Horik., B. angustitipula N.Kitag., B. asymmetrica (Steph.) N. Kitag., B. bicrenata N.Kitag., B. bidentula (Steph.) Steph. exYasuda, B. erosa (Reinw., Blume & Nees) Trevis., B. friabilis N. Kitag. & T. Kodama, B. horridula Schiffner, B. pseudovittata N.Kitag. & T.Kodama, B. serpentina (Nees) Trevis. and B. uncigera (Reinw., Blume & Nees) Trevis. The first five species are new to the country, Malaysia. An identification key for all the Bazzania species reported for Peninsular Malaysia is provided.

Taxonomy and distribution of Cheilolejeunea larsenii Mizut. (Marchantiophyta, Lejeuneaceae), with special reference to three new synonyms

Cheilolejeunea exinnovata E.W.Jones, a rare and poorly known liverwort from Africa and Brazil, C. ghatensis G.Asthana, S.C.Srivast. & A.K.Asthana, previously endemic to India, and C. adnata (Kunze ex Lehm.) Grolle var. autoica Gradst. & Ilk.-Borg. reported only from French Guiana are proposed as new synonyms of the Asian Cheilolejeunea larsenii Mizut., so far known only from China and Thailand. Cheilolejeunea larsenii is characterized by its rounded leaf apex, a small and strongly inflated leaf lobule that possesses a distinctively long and unicellular lobule tooth, and an absence of gynoecial innovations. A detailed description, taxonomic notes, new localities, distribution map, and illustrations of C. larsenii are provided.

Ajmaline, Oxindole, and Cytotoxic Macroline–Akuammiline Bisindole Alkaloids from Alstonia penangiana

Examination of the EtOH extract of the Malayan Alstonia penangiana resulted in the isolation of 10 new alkaloids, comprising two ajmaline (1, 2), four macroline oxindole (3-6), and four macroline-akuammiline bisindole alkaloids (7-10). The structures of these alkaloids were determined based on analysis of the spectroscopic data and, in the case of the oxindole 6 and the bisindole alkaloid 7, also confirmed by X-ray diffraction analysis. The bisindole alkaloids 7 and 8 showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, HCT 116, and A549 cells with IC50 values in the 0.3-8.3 μM range.