Varietal similarities and differences in the polycyclic isopentenoid composition of sorghum

The intraspecific similarities and differences among the various polycyclic isopentenoids (sterols and pentacyclic triterpenes) which occur in leaf tissue and surface wax from three varieties of flowering Sorghum bicolor; G499 GBR, BOK 8 and IS 809, have been determined. The three varieties exhibited differences in phenotypic characters (e.g. shoot height) and pest resistance. While sterol and pentacyclic amyroid compositions were similar in the three varieties, significant differences were evident in the qualitative distribution of the migrated hopanoids. One variety, IS 809, which is phenotypically short and resistant, contained a single migrated hopanoid, sorghumol Alternatively, the other two varieties, both phenotypically tall and one-G 499 GBR-resistant, the other-BOK 8-susceptible, contained a mixture of four Δ⁹⁽¹¹⁾-migrated hopanoids, i.e. sorghumol and three of its stereoisomers, and the Δ⁵⁽⁶⁾-migrated hopanoid simiarenol. While ketones corresponding to the Δ⁹⁽¹¹⁾-migrated hopanoids were detected in the three varieties, the ketone of the Δ⁵⁽⁶⁾-migrated hopanoid was apparently absent. In contrast to other graminaceous plants, the predominant C-3 derivatives did not include the C-3 methyl ethers, but did include esters and polar conjugates. Significant differences apparent in amounts of pentacyclic triterpenes were not apparent in the total amount of sterols extracted from the leaves (including surface wax) of the three varieties. Since S. bicolor varietal differences occurred only among the migrated hopanoids (found in mature leaves) it would appear that pentacyclic triterpenes, unlike sterols, have greater applicability as chemotaxonomic indices for intraspecific relationships in sorghum.     

Biosynthesis of sterols and triterpenes in Pelargonium hortorum

Although all parts of the geranium plant (Pelargonium hortorum) are capable of synthesizing sterols and triterpenes and their esters in vitro from mevalonic acid-[2-¹⁴C], the aerial portions are more active than other tissues. All plant parts were shown to incorporate mevalonic acid-[2-¹⁴C] into isoprenoids for at least 3 days. The leaves and petioles had the greatest incorporation on a wet weight basis. Chopped preparations showed comparable incorporations of mevalonate whereby rootlets incorporated about one half as much as most parts; the flower petals incorporated five times the average amount. In leaves the principal sterol synthesized was sitosterol. Metabolic studies with isolated leaves indicated a fairly rapid conversion of free tetracyclic triterpenes to 4-desmethyl-sterols, while β-amyrin was synthesized at a different rate than α-amyrin. Esterified tetracyclic triterpenes exhibited only a slight amount of conversion to 4-desmethylsterols.     

Iguesterin,a new quinonoid triterpene from Catha cassinoides

β-Amyrin, sitosterol, celastrol, pristimerin, tingenone and a new hydroxymethylene quinonoid dinor-triterpene iguesterine were isolated from the root bark of Catha cassinoides. The structure of iguesterine was determined spectroscopically and by synthesis from tingenone. Tentative assignments are given for the chemical shifts of the methyl groups of iguesterin, tingenone and some of their derivatives.     

Lanostane triterpenes of Canscora decussata

From the aerial parts of Canscora decussata Schult (Gentianaceae), five triterpenes, viz. gluanone, canscoradione, friedelin, fridelan-3-β-ol, and β-amyrin, three sterols, viz. sitosterol, stigmasterol, and campesterol, besides liberal amount of a mixtures of n-alkanes (C₂₇-C₃₁) and n-alkanols (C₂₆-C₃₂) have been isolated. The identity of the compounds has been established by chemical transformations, spectral evidence, and by direct comparison, where possible, with authentic reference materials. Gluanone and canscoradione have not been encountered before in nature.     

3-Oxo-friedelan-20α-OIC acid from gymnosporia emarginata

3-Oxo-friedelan-20α-oic acid, named as maytenonic (polpunonic) acid, has been isolated along with β-amyrin and sitosterol from Gymnosporia emarginata. ¹H and ¹³C NMR signals have been assigned for the structure. X-ray analysis of the single crystal confirmed that the carboxylic acid is α-oriented at C-20 and the D/E rings of this D:A-friedo-oleanane are in chair-chair conformation. ¹³C NMR data of the present compound also enabled the assignment of the C-20α- and β-methyl carbons in friedelin.     

The biosynthesis,metabolism and translocation of β-amyrin in Sorghum bicolor

The biosynthesis of [¹⁴C] β-amyrin and three other labelled 3β-hydroxypentacyclic triterpenes from [2-^14C] acetate in leaves of Sorghum bicolor was demonstrated. Evidence for the metabolism of [¹⁴C] β-amyrin to the corresponding C-3 ketone (β-amyrone) and for the transport of [¹⁴C] β-amyrin in leaves was also obtained.     

铜锤玉带草三萜酯化学成分分析

脂肪酸广泛分布于自然界各种生物之间,但是脂肪酸与多萜类化合物,尤其是三萜类化合物,结合形成多萜酯,极为少见。我们自云南民间中草药铜锤玉带草中分离得到3个高级脂肪酸三萜酯;其中2个经鉴定为:棕榈酸-β-香树酯,珠光脂酸-β-香树酯,并运用化学和光谱学的方法对他们的化学结构进行了解析。     

Triterpenoids from Hyptis suaveolens roots

A new natural triterpenoid, 3β-hydroxylup-12-en-28-oic acid, has been isolated from the roots of Hyptis suaveolens in addition to α- and β-amyrin.     

Triterpenoids of Cnidosculus urens

The ethanol extract of Cnidosculus urens yielded β-amyrin cinnamate and germanicol acetate. Also, using ¹³C NMR spectroscopy, mixtures of β-amyrin, germanicol and lupeol as well as their acetates were identified.     

Cyclitols from Croton celtidifolius

Croton celtidifolius has been found to contain 1l-1-O-methyl-myo-inositol, neo-inositol and sitosterol. Structure of 1l-1-O-methyl-myo-inositol pentaacetate, elaborated by NMR decoupling technique, is described.