Facile syntheses of methyl α-D-altropyranoside and its 3,4-and 4,6-O-isopropylidene derivatives

An L-arabino-D-glucurono-D-xylan isolated from the mature stalk of the reed Arundo donax contained the neutral sugars D-xylose, L-arabinose, and D-glucose in molar proportions 8.9:1:traces. 2-O-(4-O-Methyl-α-D-glucopyranosiduronic acid)-D-xylose was also present. The results of methylation analysis showing the presence of 2,3,4-tri-, 2,3-di-, 2-, and 3-O-methyl-D-xylose together with 2,3,5-tri-O-methyl-L-arabinose were determined by the gas-liquid chromatography-mass spectrometry technique and were in good agreement with those of the periodate oxidation. The D-xylan has an average degree of polymerization of about 80 and is essentially linear. The polysaccharide has structural features similar to those of polysaccharides isolated from other Gramineae.     

A new water-soluble polysaccharide from the seeds of Cassia multijuga

A polysaccharide consisting of D-galactose, D-mannose, and D-xylose in the molecular ratios 5:1:2 has been isolated from the defatted seeds of Cassia multijuga. Methylation analysis yielded 2,3-di-O-methyl-D-galactose (2 mol), 2,3,6-tri-O-methyl-D-galactose (4 mol), 2,3,4,6-tetra-O-methyl-D-galactose (4 mol), 2,3-di-O-methyl-D-mannose (2 mol), 2-O-methyl-D-xylose (1 mol), 2,3-di-O-methyl-D-xylose (2 mol), and 2,3,4-tri-O-methyl-D-xylose (1 mol). Periodate oxidation indicated 32.4% of end-groups and methylation indicated 31.2%. Partial hydrolysis with acid gave 6-O-α-D-galactosyl-D-galactose, 6-O-α-D-galactosyl-D-mannose, 4-O-β-D-galactosyl-D-xylose, and 3-O-β-D-xylosyl-D-xylose, together with monosaccharides. The polysaccharide is highly branched, consisting of galactosyl, mannosyl, and xylosyl residues in the main chain, with (1→4)-β linkages, and galactosyl and xylosyl end-groups.     

The structure of Lannea humilis gum

Lannea humilis trees exude a water-soluble gum polysaccharide containing galactose (75%), arabinose (11%), rhamnose (2%), and uronic acids (12%). Three aldobiouronic acids are present (chromatographic analysis), namely 4-O-(α-D-galactopyranosyluronic acid)-D-galactose, 6-O-(β-D-glucopyranosyluronic acid)-D-galactose, and 6-O-(4-O-methyl-β-D-glucopyranosyluronic acid)-D-galactose. Linkage analysis of degraded gums A and B, obtained by controlled, acid hydrolysis, gave (chromatographic analysis) 3-O-β-L-arabinofuranosyl-L-arabinose, 3-O-β-L-arabinopyranosyl-L-arabinose, 3-O-α-D-galactopyranosyl-L-arabinose, 3-O-β-D-galactopyranosyl-D-galactose, and 6-O-β-D-galactopyranosyl-D-galactose. Degraded gums A and B were examined by methylation analysis, and the former was subjected to a Smith-degradation, giving degraded gum C, which was studied by linkage and methylation analysis. The O-methyl derivative of the whole gum was prepared (a) by the Haworth and Purdie procedures, and (b) by the sodium hydride-methyl iodide-methyl sulphoxide technique. Both products were examined, after methanolysis, by g.l.c.: 2,3,4-tri-O-methyl-L-rhamnose; 2,3,5- and 2,3,4-tri- and 2,5-di-O-methyl-L-arabinose; 2,3,4,6-tetra-, 2,3,6-, 2,4,6- and 2,3,4-tri-, 2,6- and 2,4-di-, and 2-O-methyl-D-galactose; 2,3,4-tri-O-methyl-D-glucuronic acid and 2,3,4-tri-O-methyl-D-galacturonic acid were identified. The whole gum was subjected to four successive Smith-degradations giving Polysaccharides I–IV, which were examined by linkage and methylation analysis. Polysaccharide IV is a branched galactan; the arabinose-containing sidechains in L. humilis gum therefore do not contain more than four residues, and only a few of that length occur. The evidence obtained indicates that the gum molecules are very highly branched. The galactan framework consists of short chains of β-(1→3)-linked D-galactose residues, branched and interspersed with β-(1→6)-linkages. To positions 3 and 6 of this framework are attached either single D-galactose end-groups or short side-chains of D-galactose or of L-arabinose residues, and three aldobiouronic acids. A possible structural fragment that shows these features is proposed.     

2��-O Methylation of Internal Adenosine by Flavivirus NS5 Methyltransferase

RNA modification plays an important role in modulating host-pathogen interaction. Flavivirus NS5 protein encodes N-7 and 2′-O methyltransferase activities that are required for the formation of 5′ type I cap (m⁷GpppAm) of viral RNA genome. Here we reported, for the first time, that flavivirus NS5 has a novel internal RNA methylation activity. Recombinant NS5 proteins of West Nile virus and Dengue virus (serotype 4; DENV-4) specifically methylates polyA, but not polyG, polyC, or polyU, indicating that the methylation occurs at adenosine residue. RNAs with internal adenosines substituted with 2′-O-methyladenosines are not active substrates for internal methylation, whereas RNAs with adenosines substituted with N⁶-methyladenosines can be efficiently methylated, suggesting that the internal methylation occurs at the 2′-OH position of adenosine. Mass spectroscopic analysis further demonstrated that the internal methylation product is 2′-O-methyladenosine. Importantly, genomic RNA purified from DENV virion contains 2′-O-methyladenosine. The 2′-O methylation of internal adenosine does not require specific RNA sequence since recombinant methyltransferase of DENV-4 can efficiently methylate RNAs spanning different regions of viral genome, host ribosomal RNAs, and polyA. Structure-based mutagenesis results indicate that K61-D146-K181-E217 tetrad of DENV-4 methyltransferase forms the active site of internal methylation activity; in addition, distinct residues within the methyl donor (S-adenosyl-L-methionine) pocket, GTP pocket, and RNA-binding site are critical for the internal methylation activity. Functional analysis using flavivirus replicon and genome-length RNAs showed that internal methylation attenuated viral RNA translation and replication. Polymerase assay revealed that internal 2′-O-methyladenosine reduces the efficiency of RNA elongation. Collectively, our results demonstrate that flavivirus NS5 performs 2′-O methylation of internal adenosine of viral RNA in vivo and host ribosomal RNAs in vitro.     

G.L.C.-M.S. of partially methylated and acetylated derivatives of 3-deoxyoctitols

Partially methylated and acetylated 3-deoxyoctitols were prepared from derivatives of 3-deoxy-d-manno-2-octulosonic acid (KDO), and identified as the d-glycero-d-talo and d-glycero-d-galacto isomers by g.l.c.-m.s. Mono- and oligosaccharide derivatives of KDO were subjected in sequence to methylation, carboxyl-reduction, hydrolysis, carbonyl-reduction, and acetylation to yield 1,2,6-tri-O-acetyl-3-deoxyoctitol derivatives. Carboxyl-reduction and then methylation gave the series of 2,6-di-O-acetyl derivatives. Oligosaccharides with KDO at the reducing end, e.g., β-d-ribofuranosyl-(1→7)-KDO, α-l-glycero-d-manno-heptopyranosyl-(1→5)-KDO, and α-KDOp-(2→4)-KDO, yielded, after carbonyl-reduction, methylation, carboxyl-reduction, hydrolysis, and acetylation, the 1,7-, 1,5-, and 1,4-di-O-acetyl derivatives, whereas remethylation after carboxyl-reduction gave the 7-, 5-, and 4-O-acetyl derivatives of 3-deoxyoctitol. General rules for the fragmentation of 3-deoxyoctitols during e.i.-m.s. were established.     

Structure of the 3-deoxy-d-manno-octulosonic acid-containing polysaccharide (K6 antigen) from escherichia coli LP 1092

The acidic polysaccharide (K6) antigen from Escherichia coli LP 1092 contains d-ribose and 3-deoxy-d-manno-octulosonic acid in the molar ratio of 2:1, respectively. Spectroscopic data (¹³C- and ¹H-n.m.r.), methylation analyses, and periodate oxidation indicate that the polysaccharide is composed of the foregoing components essentially in the following trisaccharide sequence: →2)-β-d-Ribf-(1→2)-β-d-Ribf-(1→7)-α-d-KDO-(2→The polysaccharide also contains O-acetyl substituents (～0.2–0.3 mol per KDO residue).     

The final structure of robinin and biorobin and their total synthesis

Robinin has been proved by total synthesis and by methylation analysis using GC-MS to be kaempferol-3- O-(6-O-α-l-rhamnopyranosyl -β-d-galactopyranoside)-7-O-α-l-rhamnopyranoside and not, as claimed by Maksjutina et al., a mixture of 4 glycosides containing the 7-O-rhamnosyl moiety in the α- and β-furanoside as well as in the α- and β-pyranoside forms. The assumption that the 3-O-rhamnosido -galactose moiety contained furanoid rings was also disproved.     

Effects of pyrogallol on O-methylation of dopamine and salsolinol

In the cultured cells of Corydalis pallida var. tenuis, the formation of 6-O-methylated metabolites (6-D₄ and 6-D₇) from salsolinol-D₄ (2-D₄) was reduced by pyrogallol. The production of 3-O-methylated derivatives (10 and 10-D₃) from dopamine was almost not affected by pyrogallol. Similar results were obtained in intact plants, though the effect of pyrogallol on methylation of C-6-OH of salsolinol in plants is smaller than that in the cultured cells. These results show that the effects of pyrogallol on the methylation of C-6-OH of salsolinol and that on the methylation of C-3-OH of dopamine are different, suggesting that the O-methylating enzymes of salsolinol and dopamine are different in C. pallida var. tenuis. The production of 3-O-methyldopamine in the presence of pyrogallol was reduced in intact plants of Cynanchum vincetoxicum, but not in the cultured cells. The effect of pyrogallol on the methylation of salsolinol was uncertain in Cyn. vincetoxicum. Both 6- and 7-O-methylations of salsolinol occur in Cyn. vincetoxicum, while only 6-O-methylation occurs in C. pallida var. tenuis. This could reveal that the O-methylating enzymes at C-6 and C-7 are different.     

Methylation analysis of carrageenans from the seaweed Iridaea undulosa

Two carrageenans from Iridaea undulosa, isolated by precipitation of the crude polysaccharide at O.70–1.05 M and 1.55–1.65 M KCl concentrations, were studied by methylation analysis. Acid hydrolysis of the methylated derivative of the less soluble carrageenan (molar ratio galactose: 3,6-anhydrogalactose: sulphate 1.00: 0.50: 1.20) yielded major amounts of 2,6-di-O-methylgalactose (51.3 mol %), 4,6-di-O-methylgalactose (25.6%) and 4-O-methylgalactose (51.3mol%), 4,6-di-O-methylgalactose (25.6%) and 4-O-methylgalactose (13.4%). Minor quantities of 3-O-methylgalactose (4.6%) and 6-O-methylgalactose (3.2%) were found together with traces of 2,3,6- and/or 2,4,6-tri-O-methylgalactose, 2-O-methylgalactose and galactose. Oxidative acid hydrolysis produced 3,6-anhydro-2-O-methylgalactonic acid and 3,6-anhydrogalactonic acid in a molar ratio 3.5-4.0:1.0. The methylated derivative of the more soluble carrageenan (molar ratio galactose:3,6-anhydrogalactose:sulphate 1.00:0.04:1.43) gave on acid hydrolysis, 2,3,4,6-tetra-O-methylgalactose (4.6%), 2,3,6-tri-O-methylgalactose (4.2%), 2,4,6-tri-O-methylgalactose (10.7%), 4,6-di-O-methylgalactose (24.1%), 3,6-di-0-methylgalactose (8.0%), 2,3-di-O- methylgalactose (3.4%), 2,4-di-O-methylgalactose (4.6%), 2,6-di-O-methylgalactose (4.2%), 3-O-methylgalactose (19.5%),4-O-methylgalactose (9.6%),6-O-methylgalactose(3.1%),galactose (3.4%)and traces of 2-O-methylgalactose.     

Structural investigations on two hemicellulosic polysaccharides from groundnut (Arachis hypogea) seed endosperm

A highly branched xylan and a linear, β-d-(1→4)-linked glucomannan are the two hemicellulosic components isolated from the endosperms of groundnut (Arachis hypogea). Electrophoretic, sedimentation, and sugar analysis indicate the polysaccharides to be fairly homogeneous. The O-methyl derivatives of the polysaccharides were analysed, after reduction and O-acetylation, by gas-liquid chromatography and g.l.c.-mass spectrometry. 2,3,4-Tri-O-methyl-d-xylose (3.6 mol), 2,3-di-O-methyl-d-xylose (21.0 mol), 3-O-methyl-d-xylose (2.8 mol), and d-xylose (4.2 mol) were detected in the xylan, whereas 2,3,4,6-tetra-O-methyl-d-glucose and/or mannose (1.6 mol), 2,3,6-tri-O-methyl-d-mannose (5.6 mol), and 2,3,6-tri O-methyl-d-glucose (21.2 mol) were found in the glucomannan. Periodate and Smith-degradation studies substantiate the results of methylation analysis on the xylan. A glucose: mannose ratio of 3:1 for the glucomannan, however, suggests that this fraction may be an aggregate of true glucomannan and glucan or degraded cellulose.     

Studies of polysaccharide structures. II. Characteristic fragments of a modified Smith-degradation: synthesis of some new methyl ethers of tetritols

Syntheses of 1-O-methyl-D-erythritol, 1-O-methyl-L-threitol, 1,4-di-O-methyl-erythritol, and 1,4-di-O-methyl-L-threitol are described. These compounds are obtained by a modified Smith-degradation, which involves methylation prior to acid hydrolysis, and reveals the presence of (1→4)- and (1→4,1→6)-linked hexose residues.     

The structure of bael (Aegle marmelos) gum

Purified, bael-gum polysaccharide containsd-galactose (71%),l-arabinose (12.5%),l-rhamnose (6.5%), andd-galacturonic acid (7%). Hydrolysis of one mole of the fully methylated polysaccharide gave: (a) from the neutral part, 2,3,4-tri-O-methyl-l-rhamnose (2 moles), 2,3,5-tri-O-methyl-l-arabinose (4 moles), 2,3,4,6-tetra-O-methyl-d-galactose (8 moles), 3,4-di-O-methyl-l-rhamnose (2 moles), 2,5-di-O-methyl-l-arabinose (1 mole), 2,4,6-tri-O-methyl-d-galactose (10 moles), 2,3-di-O-methyl-l-arabinose (1 mole), 2,4-di-O-methyl-d-galactose (14 moles), and 2-O-methyl-d-galactose (2 moles); and (b) from the acidic part, 2,3,4-tri-O-methyl-d-galacturonic acid (1 mole), 2,4,6-tri-O-methyl-3-O-(2,3,4-tri-O-methyl-d-galactopyranosyluronic acid)-d-galactose (2.6 moles), and 2,4,6-tri-O-methyl-3-O-[2,4,6-tri-O-methyl-3-O-(2,3,4-tri-O-methyl-d-galactopyranosyluronic acid)-d-galactopyranosyl]-d-galactose (1 mole). Mild hydrolysis of the whole gum yielded oligosaccharides from which 3-O-β-d-galactopyranosyl-l-arabinose, 5-O-β-d-galactopyranosyl-l-arabinose, 3-O-β-d-galactopyranosyl-d-galactose, and 6-O-β-d-galactopyranosyl-d-galactose could be isolated and characterized. The results of methylation, periodate oxidation, Smith degradation, Barry degradation, and graded hydrolysis studies were employed for the elucidation of the structure of the whole gum.     

Identification of N, O-diacetyl-, N-acetyl- and N-glycolylneuraminyl-(2 → 3)-lactose in rat urine

The structure of three neuraminyl-oligosaccharides isolated from rat urine-have been studied by chromatographic and mass spectrometric analyses of different hydrolysis and methylation products. The structures of the oligosaccharides were identifies as O-α-N-acetyl(O-acetyl)neuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose, O-α-N-acetylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose and O-α-N-glycolylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose.     

Phenolic Glycosides with antiproteasomal activity from Centaurea urvillei DC. subsp. urvillei

A new flavanone glycoside, naringenin-7-O-β-d-glucuronopyranoside, and a new flavonol glycoside, 6-hydroxykaempferol-7-O-β-d-glucuronopyranoside were isolated together with 12 known compounds, 5 flavone glycoside; hispidulin-7-O-β-d-glucuronopyranoside, apigenin-7-O-β-d-methylglucuronopyranoside, hispidulin-7-O-β-d-methylglucuronopyranoside, hispidulin-7-O-β-d-glucopyranoside, apigenin-7-O-β-d-glucopyranoside, a flavonol; kaempferol, two flavone; apigenin, and luteolin, a flavanone glycoside; eriodictyol-7-O-β-d-glucuronopyranoside, and three phenol glycoside; arbutin, salidroside, and 3,5-dihydroxyphenethyl alcohol-3-O-β-d-glucopyranoside from Centaurea urvillei subsp. urvillei. The structure elucidation of the new compounds was achieved by a combination of one- (¹H and ¹³C) and two-dimensional NMR techniques (G-COSY, G-HMQC, and G-HMBC) and LC-ESI-MS. The isolated compounds were tested for their antiproteasomal activity. The results indicated that kaempferol, a well known and widely distributed flavonoid in the plant kingdom, was the most active antiproteasomal agent, followed by apigenin, eriodictyol-7-O-β-d-glucuronopyranoside, 3,5-dihydroxyphenethyl alcohol-3-O-β-d-glucopyranoside, and salidroside, respectively.     

Structural studies on the polysaccharide of mahua (Madhuca indica) flowers

Graded hydrolysis of purified mahua polysaccharide, PS-AI, afforded four neutral and three acidic oligosaccharides, together with monosaccharides. These oligosaccharides were characterized through hydrolysis, methylation, and reduction with lithium aluminum hydride. On methylation, Smith-degraded PS-AI gave 2,3,4,6-tetra-O-methyl-d-galactose (5.5 mol), 2,3,4-tri-O-methyl-d-galactose (1 mol), 2,4,6-tri-O-methyl-d-galactose (2.2 mol), and 2,3,4-tri-O-methyl-l-arabinose (0.9 mol). Based on these results, and those obtained from methylation, periodate oxidation, and chromium trioxide oxidation studies on the polysaccharide PS-AI, a tentative structure has been assigned to the average repeating-unit in the polysaccharide.     

Sesquiterpenoids and flavonoids from Pteris multifida Poir.

Phytochemical research of Pteris multifida Poir. led to the isolation of fifteen compounds, including six flavonoids (1–6) and nine sesquiterpenoids (7–15). Their structures were characterized by NMR, MS, ORD and CD data. Compounds kaempferol 3-O-α-L-rhamnoside-7-O-β-D-glucoside (1), myricetin 3-O-β-D-glucoside (2), kaempferol 3-O-β-D-glucoside (4), luteolin-7-O-β-D-rutinoside (5), quercetin-3-O-α-L-rhamnopyranoside (6), (2S,3S)-12-hydroxypterosin Q (7), (2S,3S)-pterosin Q (8), 2-hydroxypterosin C (9) and (2S)-12-hydroxypterosin A (10) were first isolated from P. multifida, and compounds 1–2 and 10 were first isolated from the family Pteridaceae. Furthermore, the chemotaxonomic significance of the isolates was discussed.     

Two new flavonol glycosides from the leaves of Cleome viscosa L.

From the leaves of Cleome viscosa L., two new flavonol glycosides, named visconoside A (1) and visconoside B (2), together with six known flavonol glycosides, vincetoxicoside A (3), vincetoxicoside B (4), kaempferitrin (5), kaempferide 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (6), kaempferol 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (7), and isorhamnetin 3-O-β-d-glucopyranoside (8) were isolated by various chromatography methods. Its chemical structure was elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and compared with literatures.     

Stress Responses in Alfalfa (Medicago sativa L.) : V. Constitutive and Elicitor-Induced Accumulation of Isoflavonoid Conjugates in Cell Suspension Cultures

The isoflavonoid conjugates medicarpin-3-O-glucoside-6″-O-malonate (MGM), afrormosin-7-O-glucoside (AG), and afrormosin-7-O-glucoside-6″-O-malonate (AGM) were isolated and characterized from cell suspension cultures of alfalfa (Medicago sativa L.), where they were the major constitutive secondary metabolites. They were also found in alfalfa roots but not in other parts of the plant. The phytoalexin medicarpin accumulated rapidly in suspension cultured cells treated with elicitor from Colletotrichum lindemuthianum, and this was subsequently accompanied by an increase in the levels of MGM. In contrast, net accumulation of afrormosin conjugates was not affected by elicitor treatment. Labeling studies with [¹⁴C]phenylalanine indicated that afrormosin conjugates were the major de novo synthesized isoflavonoid products in unelicited cells. During elicitation, [¹⁴C]phenylalanine was incorporated predominantly into medicarpin, although a significant proportion of the newly synthesized medicarpin was also conjugated. Treatment of ¹⁴C-labeled, elicited cells with l-α-aminooxy-β-phenylpropionic acid, a potent inhibitor of PAL activity in vivo, resulted in the initial appearance of labeled medicarpin of very low specific activity, suggesting that the phytoalexin could be released from a preformed conjugate under these conditions. Our data draw attention to the involvement of isoflavone hydroxylases during the constitutive and elicitor-induced accumulation of isoflavonoids and their conjugates in alfalfa cell cultures.     

Synthesis of 2-acetamido-2-deoxy-4-O-β-d-galactopyranosyl-3-O-methyl-d-glucopyranose (N-acetyl-3-O-methyllactosamine) and its benzyl α-glycoside

Benzyl 2-acetamido-2-deoxy-3-O-methyl-α-d-glucopyranoside (3) was obtained by deacetalation of its 4,6-O-benzylidene derivative (2). Compound 2 was prepared by methylation of benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside with methyl iodide-silver oxide in N,N-dimethylformamide. Diol 3 was selectively benzoylated and p-toluenesulfonylated, to give the 6-benzoic and 6-p-toluenesulfonic esters (4 and 5, respectively). Displacement of the sulfonyl group of 5 with sodium benzoxide in benzyl alcohol afforded the 6-O-benzyl derivative (6). Glycosylation of 4 with 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide (7) in dichloromethane, in the presence of 1,1,3,3-tetramethylurea, furnished the disaccharide derivative 8. Similar glycosylation of compound 6 with bromide 7 gave the disaccharide derivative 10. O-Deacetylation of 8 and 10 afforded disaccharides 9 and 11. The structure of compound 9 was established by ¹³C-n.m.r. spectroscopy. Hydrogenolysis of the benzyl groups of 11 furnished the disaccharide 2-acetamido-2-deoxy-4-O-β-d-galactopyranosyl-3-O-methyl-d-glucopyranose (N-acetyl-3-O-methyllactosamine).     

Phenylpropanoid and flavonoid glycosides from the leaves of Clerodendrum infortunatum (Lamiaceae)

Clerodendrum infortunatum L. (syn.: Clerodendrum viscosum Vent.), a member of the Lamiaceae, yielded one undescribed jasmonic acid derivative, ten acteosides, and two flavonoids. The jasmonic acid derivative was identified as 6'-O-caffeoyl-12-glucopyranosyloxyjasmonic acid. The acteosides were identified as isoacteoside, acteoside, 2''-O-acetyl-martyonside, 3''-O-acetyl-martyonside, martynoside, brachynoside, leucosceptoside A, jionoside C, jionoside D, incanoside C. The flavonoids were identified as apigenin 7-O-glucuronide and acacetin 7-O-glucuronide. The structures of the isolated components have been identified by UHPLC-HRMS, 1D and 2D NMR spectroscopic analyses, spectrometric techniques, and in comparison with published NMR data. The absolute sugar configuration was determined by GLC-MS/MS analysis of the octylated derivative of the sugar moiety after hydrolysis. Among the known compounds, ten are reported for the first time from this species, while the acteoside leucosceptoside A and the two flavonoids have been isolated for the first time from the genus Clerodendrum. The chemophenetic significance of the compounds obtained from C. infortunatum is summarized in comparison to those found in other Clerodendrum species.