华南大戟科植物的增补

作者清理采自中国南部大戟科标本过程,发现一些需增补的分类群,现报道其中２个新种：分布于广东封开县的印禅铁苋菜Ａｃａｌｙｐｈａｗｕｉ和印禅三宝木Ｔｒｉｇｏｎｏｓｔｅｍｏｎｗｕｉ;２个新纪录种：分布于云南勐海县的短序白桐树Ｃｌａｏｘｙｌｏｎｓｕｂｓｅｓｓｉｌｉｆｌｏｒｕｍ和生长于海南南沙群岛的南沙大戟Ｅｕｐｈｏｒｂｉａｒｅｎｉｆｏｒｍｉｓ;１个近代生长于广东、贵州和四川的归化种－桃叶猩猩草Ｅｕｐｈｏｒｂｉａｈｅｔｅｒｏｐｈｙｌｌａ,而将依据四川渡口的标本命名的柳叶大戟Ｅ．ｅｐｉｌｉｂｉｉｆｏｌｉａ作为它的新异名．     

Terpenoids from Euphorbia helioscopia and Their Cytotoxic Activities against H1975 Cells

Three previously undescribed diterpenoids, helioscopnoids A–C, and eight known compounds were isolated from the whole plants of Euphorbia helioscopia. Their structures were established by extensive analysis of spectra and data comparison with previous literatures. Among them, compound 4 was identified as 24,24-dimethoxy-25,26,27-trinoreuphan-3β-ol with revised configurations of C-13, C-14, and C-17 (13R*, 14R*, 17R*). Cytotoxicity assays revealed that all compounds exhibited varying levels of cytotoxicity against H1975 cells, with compound 9 displaying the most potent activity, as indicated by cell viability rates of 18.13 % and 20.76 % at concentrations of 20 μM and 5 μM, respectively. This study expands the understanding of E. helioscopia terpenoids’ structural diversity and biological activities, contributing to the exploration of potential therapeutic applications.     

Sapatoxins,aliphatic ester tigliane diterpenes from Sapium indicum

From the unripe fruits of Sapium indicum, three aliphatic esters of the tigliane nucleus were isolated. These compounds were derivatives of 4-deoxyphorbol. Sapatoxin A was identified as 12-O-[n-deca-2,4,6-trienoyl]-4-deoxyphorbol-13-acetate, B as 12-O-[n-deca-2,4,6-trienoyl]-4-deoxy-5-hydroxyphorbol-13-acetate and C as 12-O-[n-deca-2,4,6-trienoyl]-4,20-dideoxy-5-hydroxyphorbol-13-acetate, by spectroscopic analysis and hydrolysis reactions.     

The involvement of sucrose,glucose and other metabolites in the synthesis of triterpenes and dopa in the laticifers of Euphorbia lathyris

A quantitative triterpene analysis was made of latex stem tissue of Euphorbia lathyris. Young plants seedlings of E. lathyris were incubated with various labelled precursors. Incorporation into triterpenes was obtained from [2-¹⁴C]mevalonic acid, [1-¹⁴C]acetate, [3-¹⁴C]pyruvate, [U-¹⁴C]sucrose, [U-¹⁴C]glucose, [U-¹⁴C]xylose, [U-¹⁴C]glyoxylate, [2,3-¹⁴C]succinic acid, [1-¹⁴C]glycerol [U-¹⁴C]serine. Both sugars tyrosine appeared to be effective precursors in DOPA synthesis inside the laticifers. Exogenously supplied mevalonic acid was only involved in triterpene synthesis outside the laticifers. GC-RC of triterpenes synthesized from [U-¹⁴C]glucose revealed the origin of these compounds in the latex. The labelled triterpenes obtained after incorporation of the other mentioned labelled precursors were only partly synthesized in the laticifers. For quantitative data on latex triterpene synthesis seedlings were incubated with [U-¹⁴C]sucrose, [U-¹⁴C]glucose, [U-¹⁴C]xylose [1-¹⁴C]acetate in the presence of increasing amounts of unlabelled substrate. From the amount of ¹⁴C incorporated into the triterpenes the amount of substrate directly involved in triterpene synthesis was calculated, as was the absolute triterpene yield. Sucrose showed the highest triterpene yield, equivalent to the daily increase of the triterpene content of growing seedlings. The possible significance of the other precursors in triterpene synthesis in the laticifers is discussed.     

Ingenol esters from the pro-inflammatory fraction of Euphorbia kamerunica

A series of unstable mono- and di-esters of the tetracyclic diterpene ingenol were isolated from the pro-inflammatory ether-soluble fraction of the latex of Euphorbia kamerunica. The esters were isolated by a neutral process involving column and thin-layer chromatography. The monoesters were identified by spectroscopic methods and hydrolysis reactions as ingenol-3-decanoate, ingenol-3-dodecanoate, ingenol-5-hexadienoate and ingenol-5-octenoate and the diesters as 20-acetyl-ingenol-3-octenoate and 20-acetyl-ingenol-3-angelate.     

Yield components in Hevea brasiliensis– theoretical considerations

Abstract A theoretical analysis of yield components of Hevea brasiliensis is attempted in this paper. The effect of the major yield components, i.e. initial flow rate per unit length of tapping cut, length of the cut, percentage rubber content and plugging index on rubber yield is represented by the formula Variation in yield within and between clones can be ascribed to variation to any one of the above components. The importance of high growth rate for maintaining high yield throughout the life cycle of the tree is theoretically elucidated. While the present contention of a theoretical maximum yield of 9.5 t ha^?1 with a stand of 350 trees is questioned, the theoretical possibility of attaining that yield by increasing the stand per ha to 600 is analysed.     

Precursors of ricinine in the castor bean plant

Isotopic tracer experiments confirmed that glycerol and succinic acid are good precursors of the pyridine ring of ricinine in castor bean plants. Tritium from C-2 was lost from tritiated glycerol while tritium from C-1 was retained. Thus a derivative of dihydroxyacetone is likely to be intermediate. By simultaneous feeding of glycerol-1-(3)-[³H] and succinic acid-2(3)-[¹⁴C], it was hoped to find precursors of ricinine containing both labels, but none could be found. There was no evidence for the appearance of labeled quinolinic acid, which is presumed to be a precursor of ricinine.     

The amino acid sequences of plastocyanin from Mercurialis perennis and Capsella bursa-pastoris

The amino acid sequences of the plastocyanins from Mercurialis perennis and Capsella bursa-pastoris have been determined. The amides at positions 64 and 68 in the Mercurialis sequence were positioned by ‘homology’ Both proteins are single polypeptide chains of 99 residues and are closely related to other higher plant plastocyanins.     

3-methoxy-4,6-dihydroxymorphinandien-7-one,an alkaloid from Croton bonplandianum

A new alkaloid, 3-methoxy-4,6-dihydroxymorphinandien-7-one, and norsinoacutine have been isolated from extracts of Croton bonplandianum.