Contribution to The Study of Gracilaria and relative genera (Gracilariales, Rhodophyta) from Vietnam

More than 1500 specimens of Gracilaria sensu lato (Gracilaria, Gracilariopsis, and Hydropuntia) collecting by previous authors along the coast of Vietnam and our new material, which are deposited in the herbaria of the Institute of Oceanography, Nhatrang (ION), Institute of Material Science, Nhatrang Branch (IMS) and Institute of Oceanology, Hai Phong Branch (IOH), have been studied. We re-examined almost herbarium specimens of 33 Gracilaria taxa had been published by Dawson (1954); Pham Hoang Ho (1969), Nguyen Huu Dinh (1992), Nguyen Huu Dinh et al (1993) and Nguyen Van Tien (1994). Some of them were misidentified or misapplied names. In this paper, 19 Vietnamese species of Gracilaria sensu lato were discussed and critically adjusted. The structure of male and female reproductive organs, particularly the formation of spermatangia has been studied carefully. Five of the nineteen were added for the flora: Gracilaria rubra, G. cuneifolia, G. longirostric, G. yamamotoi, and Hydropuntia divergens

HỢP CHẤT STEROID VÀ FLAVONE TỪ THÂN RỄ THIÊN NIÊN KIỆN LÁ LỚN (Homalomena pendula)

Phytochemical investigation of the rhizomes of Homalomena pendula resulted in the isolation of one flavone and three steroids. These compounds were determined as tangeretin (1), ergosterol peroxide (2), sitoindoside I (3), and stigmasterol (4) on the basis of 1D and 2D NMR data and in comparison with the available data in the literature. Compounds 1‒3 were found for the first time from the genus Homamomena. The n-hexane and ethyl acetate extracts show NO production inhibitory activity in RAW 264.7 macrophage cells with IC50 values of 46.8 and 75.52 µg·mL–1.Hợp chất flavone, tangeretin (1), và ba hợp chất steroid: ergosterol peroxide (2), sitoindoside I (3) và stigmasterol (4) đã được phân lập từ thân rễ của cây thiên niên kiện lá lớn (Homalomena pendula). Cấu trúc hóa học của chúng được xác định dựa trên phân tích dữ liệu phổ cộng hưởng từ hạt nhân (1D và 2D NMR) và so sánh với các tài liệu đã công bố. Các hợp chất (1-3) được phân lập lần đầu tiên từ chi Homalomena. Cao chiết n-hexane và ethyl acetate của cây này có hoạt tính ức chế sản sinh NO trên đại thực bào RAW 264.7 kích thích bằng lipopolysaccharide với các giá trị IC50 là 46,80 và 75,52 µg·mL–1

Contribution to The Study of Gracilaria and relative genera (Gracilariales, Rhodophyta) from Vietnam

More than 1500 specimens of Gracilaria sensu lato (Gracilaria, Gracilariopsis, and Hydropuntia) collecting by previous authors along the coast of Vietnam and our new material, which are deposited in the herbaria of the Institute of Oceanography, Nhatrang (ION), Institute of Material Science, Nhatrang Branch (IMS) and Institute of Oceanology, Hai Phong Branch (IOH), have been studied. We re-examined almost herbarium specimens of 33 Gracilaria taxa had been published by Dawson (1954); Pham Hoang Ho (1969), Nguyen Huu Dinh (1992), Nguyen Huu Dinh et al (1993) and Nguyen Van Tien (1994). Some of them were misidentified or misapplied names. In this paper, 19 Vietnamese species of Gracilaria sensu lato were discussed and critically adjusted. The structure of male and female reproductive organs, particularly the formation of spermatangia has been studied carefully. Five of the nineteen were added for the flora: Gracilaria rubra, G. cuneifolia, G. longirostric, G. yamamotoi, and Hydropuntia divergens

CHEMICAL CHARACTERISTICS AND GELLING PROPERTIES OF AGAR EXTRACTED FROM RED ALGAE GROWING AT VIETNAM COAST

CHEMICAL CHARACTERISTICS AND GELLING PROPERTIES OF AGAR EXTRACTED FROM RED ALGAE GROWING AT VIETNAM COAS

Checklist of the marine macroalgae of Vietnam

Despite a rich seaweed flora, information about Vietnamese seaweeds is scattered throughout a large number of often regional publications and, hence, difficult to access. This paper presents an up-to-date checklist of the marine macroalgae of Vietnam, compiled by means of an exhaustive bibliographical search and revision of taxon names. A total of 827 species are reported, of which the Rhodophyta show the highest species number (412 species), followed by the Chlorophyta (180 species), Phaeophyceae (147 species) and Cyanobacteria (88 species). This species richness is comparable to that of the Philippines and considerably higher than Taiwan, Thailand or Malaysia, which indicates that Vietnam possibly represents a diversity hotspot for macroalgae. A comparison of the species composition with neighbouring countries yielded surprisingly low similarities. Rather than an indication of a biogeographical pattern, we are of the opinion that the low similarity with neighbouring countries is primarily an artifact resulting from taxonomic inconsistencies. The checklist presented here could serve as a valuable tool to reveal the seaweed diversity in Vietnam and to stimulate intraregional comparative research

Characteristics and Relationships between Total Polyphenol and Flavonoid Contents, Antioxidant Capacities, and the Content of Caffeine, Gallic Acid, and Major Catechins in Wild/Ancient and Cultivated Teas in Vietnam

Vietnam has diverse and long-established tea plantations but scientific data on the characteristics of Vietnamese teas are still limited. Chemical and biological properties including total polyphenol and flavonoid contents (TPCs and TFCs), antioxidant activities (DPPH, ABTS, FRAP, and CUPRAC), as well as the contents of caffeine, gallic acid, and major catechins, were evaluated for 28 Vietnamese teas from North and South Vietnam. Higher values of TPCs and TFCs were found for green (non-oxidised) and raw Pu’erh (low-oxidised) teas from wild/ancient tea trees in North Vietnam and green teas from cultivated trees in South Vietnam, as compared to oolong teas (partly oxidised) from South Vietnam and black teas (fully oxidised) from North Vietnam. The caffeine, gallic acid, and major catechin contents depended on the processing, geographical origin, and the tea variety. Several good Pearson’s correlations were found (r2 > 0.9) between TPCs, TFCs, the four antioxidant capacities, and the content of major catechins such as (–)-epicatechin-3-gallate and (–)-epigallocatechin-3-gallate. Results from principal component analysis showed good discriminations with cumulative variances of the first two principal components varying from 85.3% to 93.7% among non-/low-oxidised and partly/fully oxidised teas, and with respect to the tea origin