Rinchen Yangzom - Academia.edu (original) (raw)

Papers by Rinchen Yangzom

Natural Product Communications, 2021

Five flavonol O-glycosides and 4 C-glycosylflavones were isolated from the flowers of the Himalay... more Five flavonol O-glycosides and 4 C-glycosylflavones were isolated from the flowers of the Himalayan Megacodon stylophorus (Gentianaceae). They were characterized as quercetin 3- O-glucoside (1), quercetin 3- O-rutinoside (2), kaempferol 3- O-glucoside (3), isorhamnetin 3- O-glucoside (4) and kaempferol 3,7-di- O-glucoside (5) (flavonols), and isovitexin (6), isoorientin (7), isovitexin X″- O-arabinoside (8) and isovitexin 4′- O-glucoside (9) ( C-glycosylflavones) by ultraviolet, liquid chromatography-mass spectrometry, acid hydrolysis, nuclear magnetic resonance, and/or high-performance liquid chromatography and thin-layer chromatography comparisons with authentic samples. On the other hand, 5 C-glycosylflavones were isolated from the leaves and identified as 6, 7, 9, vitexin (10), and orientin (11). Although many C-glycosylflavones and xanthones have been reported from Gentianaceae species, flavonols are minor occurrence in the family. Flavonoids were reported from the Megacodon sp...

Supplemental material, Supplementary Material 1, for Flavonoids From the Flowers and Leaves of th... more Supplemental material, Supplementary Material 1, for Flavonoids From the Flowers and Leaves of the Himalayan <i>Megacodon stylophorus</i> (Gentianaceae) by Tsukasa Iwashina, Rinchen Yangzom, Hari Prasad Devkota and Takayuki Mizuno in Natural Product Communications

Biochemical Systematics and Ecology, 2021

Sibbaldia: the Journal of Botanic Garden Horticulture, 2017

The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet... more The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet and northern Myanmar seems to be one of the last frontiers not only for Meconopsis hunting but also for other botanical exploration. Although there remain political difficulties for foreigners to approach the unsettled border between India and China, including the famous Tsari valley with its prominently rich flora, which was visited by Frank Ludlow, George Sherriff, Frank Kingdon-Ward and a few other plant hunters before 1950, some botanical and horticultural treasures in this region have gradually been revealed to recent travellers. As a result of examining the photographs taken by these travellers and our own botanical field research in eastern Bhutan in 2014, accompanied by subsequent herbarium studies, two species new to science are described. The first, from eastern Bhutan and adjacent Arunachal Pradesh and Tibet, has long been cultivated under the names M. grandis or M. grandis G...

Flower pigments of Black Pea (Thermopsis barbata) sampled from alpine zone in western Bhutan were... more Flower pigments of Black Pea (Thermopsis barbata) sampled from alpine zone in western Bhutan were surveyed. Major anthocyanins of the blackish flowers were delphinidin 3-O-glucoside, cyanidin 3-O-glucoside and petunidin 3-O-glucoside together with some minor anthocyanins and other flavonoids. Interestingly, chlorogenic acid was also found from the flowers. Contribution of each compound to flower coloration and other ecological functions are discussed.

Phytochemistry, 2021

Two undescribed anthocyanins and two undescribed flavonols were isolated from the flowers of Prim... more Two undescribed anthocyanins and two undescribed flavonols were isolated from the flowers of Primula ×polyantha Mill., along with five known anthocyanins and four known flavonols. The two undescribed anthocyanins and the two undescribed flavonols were determined to be hirsutidin 3-O-β-galactopyranoside-5-O-β-glucopyranoside, 7-O-methyl-petunidin 3-O-β-galactopyranoside-5-O-β-glucopyranoside, quercetin 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside], and kaempferol 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside] using chemical and spectroscopic methods. They were also found in the flowers of the Himalayan wild species, Primula primulina (Spreng.) H. Hara except for quercetin 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside]. The flower color variations of P. ×polyantha cultivars, reflected by the hue values (b*/a*) of the colors, were due to th...

The Global Register of Introduced and Invasive Species (GRIIS) presents validated and verified ch... more The Global Register of Introduced and Invasive Species (GRIIS) presents validated and verified checklists (inventories) of introduced (alien) and invasive alien species at the country, territory, and associated island level. Phase 1 of the project focused on developing validated and verified checklists of countries that are Party to the Convention on Biological Diversity (CBD). Phase 2 which is on-going, aims to achieve global coverage including non-party countries and all overseas territories of countries e.g. Netherlands, France and United Kingdom. Species belonging to all Kingdoms are covered as well as occurring in all Environment/systems. Country/ Territory/ Island checklists are reviewed and verified by networks of country or species experts. Verified checklists/ species records as well as those under review are presented on the online GRIIS website (www.griis.org). Individual species records are flagged with a ‘yes’ for verification. Only verified checklists/ species records ...

Sibbaldia: the International Journal of Botanic Garden Horticulture, 2017

The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet... more The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet and northern Myanmar seems to be one of the last frontiers not only for Meconopsis hunting but also for other botanical exploration. Although there remain political difficulties for foreigners to approach the unsettled border between India and China, including the famous Tsari valley with its prominently rich flora, which was visited by Frank Ludlow, George Sherriff, Frank Kingdon-Ward and a few other plant hunters before 1950, some botanical and horticultural treasures in this region have gradually been revealed to recent travellers. As a result of examining the photographs taken by these travellers and our own botanical field research in eastern Bhutan in 2014, accompaniedby subsequent herbarium studies, two species new to science are described. The first, from eastern Bhutan and adjacent Arunachal Pradesh and Tibet, has long been cultivated under the names M. grandis or M. grandis GS...

Biochemical Systematics and Ecology, 2019

Blue flowers of six Bhutani Meconopsis species, M. bhutanica, M. bella, M. horridula, M. simplici... more Blue flowers of six Bhutani Meconopsis species, M. bhutanica, M. bella, M. horridula, M. simplicifolia, M. primulina and M. polygonoides, were surveyed for anthocyanins and other flavonoids. Four anthocyanins were isolated and identified as cyanidin 3-O-sambubioside-7-O-glucoside (1), cyanidin 3-O-[xylosyl-(1 → 2)-(6″-malonylglucoside)]-7-O-glucoside (2), cyanidin 3-O-sambubioside (4) and cyanidin 3-O-[xylosyl-(1 → 2)-(6″-malonylglucoside)] (5). On the other hand, 12 flavonols were isolated from their Meconopsis species with various combination and characterized as kaempferol 3-O-glycosides (8-12), kaempferol 3,7-O-glycosides (13-16), quercetin 3-Oglycosides (17 and 18) and isorhamnetin 3-O-glycoside (19). Of six Meconopsis species which were surveyed in this experiment, anthocyanin and flavonol composition of five species except for M. horridula was clarified for the first time. Their Meconopsis species showed the different flavonoid profiles, respectively, and flavonoid diversity within the glycosylation level of Meconopsis flowers were indicated.

Natural Product Communications, 2018

Three anthocyanins were isolated from the red flowers of Meconopsis wallichi in Bhutan. They were... more Three anthocyanins were isolated from the red flowers of Meconopsis wallichi in Bhutan. They were characterized as cyanidin 3- O-glucoside, cyanidin 3- O-sambubioside and cyanidin 3- O-(succinylsambubioside) by UV-VIS, LC-MS, acid hydrolysis, alkaline saponification, and HPLC comparisons with authentic samples. The latter anthocyanin was reported in nature for the first time. However, flavonoids except for anthocyanins were not found in the flowers, showing that the red color is due to three cyanidin glycosides alone, without copigments and metals. Although the anthocyanins were reported from the blue flowers of three Meconopsis species, those of red flower Meconopsis species were characterized for the first time.

Biochemical Systematics and Ecology, 2018

Two flavonol glycosides were isolated from the yellow flowers of Bhutani Himalayan Meconopsis pan... more Two flavonol glycosides were isolated from the yellow flowers of Bhutani Himalayan Meconopsis paniculata, together with other two minor flavonol glycosides. They were identified as 6-hydroxykaempferol 3-O-glucoside and 6-hydroxykaempferol 3-O-sophoroside by UV, LC-MS, acid hydrolysis and 1 H and 13 C NMR. Two minor flavonol glycosides were identified as kaempferol 3-O-glucoside and kaempferol 3-O-sophoroside. Although herbacetin (8-hydroxykaempferol) 3-O-glucoside has been reported from M. paniculata as a yellow pigment by Harborne (1969), 6-hydroxykaempferol 3-O-glucoside and 3-O-sophoroside were found in this survey. The latter flavonoid was reported in nature for the first time. On the other hand, four flavonol glycosides were isolated from the yellow flowers of M. integrifolia and characterized as quercetin 3-O-gentiobioside and three 3-O-(acetylgentiobiosides). Thus, it was proved that the yellow flower colour of two Meconopsis species, M. paniculata and M. integrifolia, are due to flavonol glycosides.

Journal of Biogeography, 2017

In this paper, a novel two-level framework was proposed and applied to solve the output average c... more In this paper, a novel two-level framework was proposed and applied to solve the output average consensus problem over heterogeneous multi-agent systems. This approach is mainly based on the recent technique of system abstraction. For given multi-agent systems, we first constructed their abstractions as the upper level and solved their average consensus problem by leveraging well-known results for single integrators. Then the control protocols for physical agents in the lower level were synthesized in a hierarchical way by embedding the designed law for abstractions into an interface between two levels. In this way, the complexity coming from heterogeneous dynamics of agents is totally decoupled from that of the coordination task and the communication topologies. An example was given to show its effectiveness.

Edinburgh Journal of Botany, 2017

A new species of Roscoea is described and illustrated. Roscoea megalantha Tosh.Yoshida & R.Yangzo... more A new species of Roscoea is described and illustrated. Roscoea megalantha Tosh.Yoshida & R.Yangzom occurs in the Eastern Zone of Bhutan and neighbouring Arunachal Pradesh in India. A distribution map and an IUCN conservation assessment are given. A key to the three species of Roscoea found in Bhutan is provided.

Natural Product Communications, 2021

Five flavonol O-glycosides and 4 C-glycosylflavones were isolated from the flowers of the Himalay... more Five flavonol O-glycosides and 4 C-glycosylflavones were isolated from the flowers of the Himalayan Megacodon stylophorus (Gentianaceae). They were characterized as quercetin 3- O-glucoside (1), quercetin 3- O-rutinoside (2), kaempferol 3- O-glucoside (3), isorhamnetin 3- O-glucoside (4) and kaempferol 3,7-di- O-glucoside (5) (flavonols), and isovitexin (6), isoorientin (7), isovitexin X″- O-arabinoside (8) and isovitexin 4′- O-glucoside (9) ( C-glycosylflavones) by ultraviolet, liquid chromatography-mass spectrometry, acid hydrolysis, nuclear magnetic resonance, and/or high-performance liquid chromatography and thin-layer chromatography comparisons with authentic samples. On the other hand, 5 C-glycosylflavones were isolated from the leaves and identified as 6, 7, 9, vitexin (10), and orientin (11). Although many C-glycosylflavones and xanthones have been reported from Gentianaceae species, flavonols are minor occurrence in the family. Flavonoids were reported from the Megacodon sp...

Supplemental material, Supplementary Material 1, for Flavonoids From the Flowers and Leaves of th... more Supplemental material, Supplementary Material 1, for Flavonoids From the Flowers and Leaves of the Himalayan <i>Megacodon stylophorus</i> (Gentianaceae) by Tsukasa Iwashina, Rinchen Yangzom, Hari Prasad Devkota and Takayuki Mizuno in Natural Product Communications

Biochemical Systematics and Ecology, 2021

Sibbaldia: the Journal of Botanic Garden Horticulture, 2017

The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet... more The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet and northern Myanmar seems to be one of the last frontiers not only for Meconopsis hunting but also for other botanical exploration. Although there remain political difficulties for foreigners to approach the unsettled border between India and China, including the famous Tsari valley with its prominently rich flora, which was visited by Frank Ludlow, George Sherriff, Frank Kingdon-Ward and a few other plant hunters before 1950, some botanical and horticultural treasures in this region have gradually been revealed to recent travellers. As a result of examining the photographs taken by these travellers and our own botanical field research in eastern Bhutan in 2014, accompanied by subsequent herbarium studies, two species new to science are described. The first, from eastern Bhutan and adjacent Arunachal Pradesh and Tibet, has long been cultivated under the names M. grandis or M. grandis G...

Flower pigments of Black Pea (Thermopsis barbata) sampled from alpine zone in western Bhutan were... more Flower pigments of Black Pea (Thermopsis barbata) sampled from alpine zone in western Bhutan were surveyed. Major anthocyanins of the blackish flowers were delphinidin 3-O-glucoside, cyanidin 3-O-glucoside and petunidin 3-O-glucoside together with some minor anthocyanins and other flavonoids. Interestingly, chlorogenic acid was also found from the flowers. Contribution of each compound to flower coloration and other ecological functions are discussed.

Phytochemistry, 2021

Two undescribed anthocyanins and two undescribed flavonols were isolated from the flowers of Prim... more Two undescribed anthocyanins and two undescribed flavonols were isolated from the flowers of Primula ×polyantha Mill., along with five known anthocyanins and four known flavonols. The two undescribed anthocyanins and the two undescribed flavonols were determined to be hirsutidin 3-O-β-galactopyranoside-5-O-β-glucopyranoside, 7-O-methyl-petunidin 3-O-β-galactopyranoside-5-O-β-glucopyranoside, quercetin 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside], and kaempferol 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside] using chemical and spectroscopic methods. They were also found in the flowers of the Himalayan wild species, Primula primulina (Spreng.) H. Hara except for quercetin 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside]. The flower color variations of P. ×polyantha cultivars, reflected by the hue values (b*/a*) of the colors, were due to th...

The Global Register of Introduced and Invasive Species (GRIIS) presents validated and verified ch... more The Global Register of Introduced and Invasive Species (GRIIS) presents validated and verified checklists (inventories) of introduced (alien) and invasive alien species at the country, territory, and associated island level. Phase 1 of the project focused on developing validated and verified checklists of countries that are Party to the Convention on Biological Diversity (CBD). Phase 2 which is on-going, aims to achieve global coverage including non-party countries and all overseas territories of countries e.g. Netherlands, France and United Kingdom. Species belonging to all Kingdoms are covered as well as occurring in all Environment/systems. Country/ Territory/ Island checklists are reviewed and verified by networks of country or species experts. Verified checklists/ species records as well as those under review are presented on the online GRIIS website (www.griis.org). Individual species records are flagged with a ‘yes’ for verification. Only verified checklists/ species records ...

Sibbaldia: the International Journal of Botanic Garden Horticulture, 2017

The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet... more The region from eastern Bhutan to Arunachal Pradesh of India and the adjacent south-eastern Tibet and northern Myanmar seems to be one of the last frontiers not only for Meconopsis hunting but also for other botanical exploration. Although there remain political difficulties for foreigners to approach the unsettled border between India and China, including the famous Tsari valley with its prominently rich flora, which was visited by Frank Ludlow, George Sherriff, Frank Kingdon-Ward and a few other plant hunters before 1950, some botanical and horticultural treasures in this region have gradually been revealed to recent travellers. As a result of examining the photographs taken by these travellers and our own botanical field research in eastern Bhutan in 2014, accompaniedby subsequent herbarium studies, two species new to science are described. The first, from eastern Bhutan and adjacent Arunachal Pradesh and Tibet, has long been cultivated under the names M. grandis or M. grandis GS...

Biochemical Systematics and Ecology, 2019

Blue flowers of six Bhutani Meconopsis species, M. bhutanica, M. bella, M. horridula, M. simplici... more Blue flowers of six Bhutani Meconopsis species, M. bhutanica, M. bella, M. horridula, M. simplicifolia, M. primulina and M. polygonoides, were surveyed for anthocyanins and other flavonoids. Four anthocyanins were isolated and identified as cyanidin 3-O-sambubioside-7-O-glucoside (1), cyanidin 3-O-[xylosyl-(1 → 2)-(6″-malonylglucoside)]-7-O-glucoside (2), cyanidin 3-O-sambubioside (4) and cyanidin 3-O-[xylosyl-(1 → 2)-(6″-malonylglucoside)] (5). On the other hand, 12 flavonols were isolated from their Meconopsis species with various combination and characterized as kaempferol 3-O-glycosides (8-12), kaempferol 3,7-O-glycosides (13-16), quercetin 3-Oglycosides (17 and 18) and isorhamnetin 3-O-glycoside (19). Of six Meconopsis species which were surveyed in this experiment, anthocyanin and flavonol composition of five species except for M. horridula was clarified for the first time. Their Meconopsis species showed the different flavonoid profiles, respectively, and flavonoid diversity within the glycosylation level of Meconopsis flowers were indicated.

Natural Product Communications, 2018

Three anthocyanins were isolated from the red flowers of Meconopsis wallichi in Bhutan. They were... more Three anthocyanins were isolated from the red flowers of Meconopsis wallichi in Bhutan. They were characterized as cyanidin 3- O-glucoside, cyanidin 3- O-sambubioside and cyanidin 3- O-(succinylsambubioside) by UV-VIS, LC-MS, acid hydrolysis, alkaline saponification, and HPLC comparisons with authentic samples. The latter anthocyanin was reported in nature for the first time. However, flavonoids except for anthocyanins were not found in the flowers, showing that the red color is due to three cyanidin glycosides alone, without copigments and metals. Although the anthocyanins were reported from the blue flowers of three Meconopsis species, those of red flower Meconopsis species were characterized for the first time.

Biochemical Systematics and Ecology, 2018

Two flavonol glycosides were isolated from the yellow flowers of Bhutani Himalayan Meconopsis pan... more Two flavonol glycosides were isolated from the yellow flowers of Bhutani Himalayan Meconopsis paniculata, together with other two minor flavonol glycosides. They were identified as 6-hydroxykaempferol 3-O-glucoside and 6-hydroxykaempferol 3-O-sophoroside by UV, LC-MS, acid hydrolysis and 1 H and 13 C NMR. Two minor flavonol glycosides were identified as kaempferol 3-O-glucoside and kaempferol 3-O-sophoroside. Although herbacetin (8-hydroxykaempferol) 3-O-glucoside has been reported from M. paniculata as a yellow pigment by Harborne (1969), 6-hydroxykaempferol 3-O-glucoside and 3-O-sophoroside were found in this survey. The latter flavonoid was reported in nature for the first time. On the other hand, four flavonol glycosides were isolated from the yellow flowers of M. integrifolia and characterized as quercetin 3-O-gentiobioside and three 3-O-(acetylgentiobiosides). Thus, it was proved that the yellow flower colour of two Meconopsis species, M. paniculata and M. integrifolia, are due to flavonol glycosides.

Journal of Biogeography, 2017

In this paper, a novel two-level framework was proposed and applied to solve the output average c... more In this paper, a novel two-level framework was proposed and applied to solve the output average consensus problem over heterogeneous multi-agent systems. This approach is mainly based on the recent technique of system abstraction. For given multi-agent systems, we first constructed their abstractions as the upper level and solved their average consensus problem by leveraging well-known results for single integrators. Then the control protocols for physical agents in the lower level were synthesized in a hierarchical way by embedding the designed law for abstractions into an interface between two levels. In this way, the complexity coming from heterogeneous dynamics of agents is totally decoupled from that of the coordination task and the communication topologies. An example was given to show its effectiveness.

Edinburgh Journal of Botany, 2017

A new species of Roscoea is described and illustrated. Roscoea megalantha Tosh.Yoshida & R.Yangzo... more A new species of Roscoea is described and illustrated. Roscoea megalantha Tosh.Yoshida & R.Yangzom occurs in the Eastern Zone of Bhutan and neighbouring Arunachal Pradesh in India. A distribution map and an IUCN conservation assessment are given. A key to the three species of Roscoea found in Bhutan is provided.