Plant regeneration through somatic embryogenesis in protoplast cultures of sandalwood (Santalum album L.)

Summary Protoplasts were isolated from embryogenic cell suspension cultures derived from proliferating shoot segments of a 20-year-old sandalwood tree (Santalum album Linn.). Under appropriate conditions, isolated protoplasts divided in liquid culture medium and produced embryogenic cell aggregates and globular embryos. Plating of cell aggregates on a fresh medium facilitated the differentiation of somatic emryos which further developed into plantlets.Abbreviations BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ Gibberellic acid - IAA indoleacetic acid - IBA indolebutrytic acid - MES 2-(N-morpholino)ethane sulfonic acid - MS Murashige and Skoog's medium as modified in the text     

Ab initio Molecular Electrostatic Potential Grid Maps for Quantitative Similarity Calculations of Organic Compounds

The program MolSim designed to calculate the similarity of different molecules quantitatively in a fast and easy way is described. The molecular similarity is estimated for the molecular shape as well as for the electrostatic potentials of the molecules derived from ab initio calculations. A grid-based method is used to determine the steric and electrostatic similarities between a lead compound and the corresponding test set by calculating the Spearman correlation coefficient. The superpositioning of the molecules was accomplished with the SEAL algorithm incorporating a Monte Carlo simulated annealing approach while preserving the conformational flexibility of the calculated structures.The ability of the program was tested on a set of Sandalwood odour compounds, a class of substances that is difficult to analyse with respect to its structure-activity relationship because of the structural diversity of Sandalwood odour compounds, in contrast to their high selectivity and pronounced structural specificity. The application of the program on a small test set of these compounds showed that the program is able to explain the Sandalwood odour activity correctly.Electronic Supplementary Material available.     

Identification and structural characterization of a new pro-apoptotic cyclic octapeptide cyclosaplin from somatic seedlings of Santalum album L.

Small cyclic peptides exhibiting potent biological activity have great potential for anticancer therapy. An antiproliferative cyclic octapeptide, cyclosaplin was purified from somatic seedlings of Santalum album L. (sandalwood) using gel filtration and RP-HPLC separation process. The molecular mass of purified peptide was found to be 858 Da and the sequence was determined by MALDI-ToF-PSD-MS as ‘RLGDGCTR’ (cyclic). The cytotoxic activity of the peptide was tested against human breast cancer (MDA-MB-231) cell line in a dose and time-dependent manner. The purified peptide exhibited significant antiproliferative activity with an IC₅₀ 2.06 μg/mL. In a mechanistic approach, apoptosis was observed in differential microscopic studies for peptide treated MDA-MB-231 cells, which was further confirmed by mitochondrial membrane potential, DNA fragmentation assay, cell cycle analysis and caspase 3 activities. The modeling and docking experiments revealed strong affinity (kcal/mol) of peptide toward EGFR and procaspase 3. The co-localization studies revealed that the peptide sensitizes MDA-MB-231 cells by possibly binding to EGFR and induces apoptosis. This unique cyclic octapeptide revealed to be a favorable candidate for development of anticancer agents.     

StructureOdor Relationships of Semisynthetic β‐Santalol Analogs

A series of eleven β‐santalol analogs, including nine new derivatives, was prepared by semisynthesis from natural (?)‐(Z)‐β‐santalol and studied by gas chromatography‐olfactometry (GC‐O) to characterize their olfactory properties and potencies. These compounds and 45 others selected in the literature were used to build three olfactophores by molecular modelling. Three models were obtained that gather structural and physicochemical constraints that will be useful for further design of new sandalwood odorants.     

Recent developments in the chemistry of sandalwood odorants

Natural sandalwood oil, a unique and valuable ingredient in fine perfumery, has been the focus of scientific interest for many years. Due to its scarcity and its high price, the search for novel synthetic raw materials imitating the characteristic odor profile of sandalwood oil is as challenging as ever. In this context, the preparation of the novel sandalwood odorants 26, 33, and 39 will be discussed, including their sensory properties and structure-odor relationship.     

Regional genetic differentiation in Western Australian sandalwood (<Emphasis Type="Italic">Santalum spicatum</Emphasis>) as revealed by nuclear RFLP analysis

Western Australian sandalwood, Santalum spicatum, is widespread in the semi-arid and arid regions of Western Australia, and there is some morphological variation suggestive of two ecotypes. The level and structuring of genetic diversity within the species was investigated using anonymous nuclear RFLP loci. Santalum spicatum showed moderate levels of genetic diversity compared to other Australian tree species. The northern populations in the arid region showed greater levels of diversity and less population differentiation than the southern populations in the semi-arid region due to differences in the distribution of rare alleles. Equilibrium between drift and gene flow in the northern populations indicated that they have been established for a long period of time with stable conditions conducive to gene flow. In contrast, the southern populations showed a relationship between drift and gene flow indicative of a pattern of fragmentation and isolation where drift has greater effect than gene flow. The different patterns of diversity suggest that the ecotypes in the two regions have been subject to differences in the relative influences of drift and gene flow during their evolutionary history.Communicated by D.B. Neale     

Geographic and Phenotypic Variation in Heartwood and Essential‐Oil Characters in Natural Populations of Santalum austrocaledonicum in Vanuatu

Phenotypic variation in heartwood and essential‐oil characters of Santalum austrocaledonicum was assessed across eleven populations on seven islands of Vanuatu. Trees differed significantly in their percentage heartwood cross‐sectional area and this varied independently of stem diameter. The concentrations of the four major essential‐oil constituents (α‐santalol, β‐santalol, (Z)‐β‐curcumen‐12‐ol, and cis‐nuciferol) of alcohol‐extracted heartwood exhibited at least tenfold and continuous tree‐to‐tree variation. Commercially important components α‐ and β‐santalol found in individual trees ranged from 0.8–47% and 0–24.1%, respectively, across all populations, and significant (P<0.05) differences for each were found between individual populations. The Erromango population was unique in that the mean concentrations of its monocyclic ((Z)‐β‐curcumen‐12‐ol and cis‐nuciferol) sesquiterpenes exceeded those of its bi‐ and tricyclic (α‐ and β‐santalol) sesquiterpenes. Heartwood colour varied between trees and spanned 65 colour categories, but no identifiable relationships were found between heartwood colour and α‐ and β‐santalol, although a weak relationship was evident between colour saturation and total oil concentration. These results indicate that the heartwood colour is not a reliable predictive trait for oil quality. The results of this study highlight the knowledge gaps in fundamental understanding of heartwood biology in Santalum genus. The intraspecific variation in heartwood cross‐sectional area, oil concentration, and oil quality traits is of considerable importance to the domestication of sandalwood and present opportunities for the development of highly superior S. austrocaledonicum cultivars that conform to the industry's International Standards used for S. album.     

Two aurone glycosides from heartwood of Pterocarpus santalinus

Two new aurone glycosides, 6 hydroxy 5 methyl 3',4',5' trimethoxy aurone 4-O-alpha-L-rhamnopyranoside and 6,4' dihydroxy aurone 4-O-rutinoside have been isolated from the ethanolic extract of the wood of Pterocarpus santalinus. Their structures were determined on the basis of chemical and spectroscopic analysis (UV, IR, EIMS, (1)H and (13)C NMR).     

Sesquiterpenes from the east African sandalwood Osyris tenuifolia

The essential oil of the east African sandalwood Osyris tenuifolia was investigated by chromatographic and spectroscopic methods. Beside several already known sesquiterpenes four new compounds could be isolated by preparative gas chromatography and their structures investigated by mass spectroscopy and NMR techniques. Two of the new compounds--tenuifolene (17) and ar-tenuifolene (15)--show a new sesquiterpene backbone. 2,(7Z,10Z)-Bisabolatrien-13-ol (23) and the cyclic ether lanceoloxide (21) belong to the bisabolanes.     

Evaluation of larvicidal enhanced activity of sandalwood oil via nano-emulsion against Culex pipiens and Ades aegypti

Mosquito control with essential oils is a trending strategy using aqueous oil nano-emulsions to expand their performance. Sandalwood essential oil and its prepared nano-emulsion used to estimate their larvicidal activities against the 3rd instar larvae of Culex pipiens and Aedes aegypti and their effects on larval tissue detoxifying enzymes. Sandalwood nano-emulsion was characterized by homogeneous, stable, average particles size (195.7 nm), polydispersity index (0.342), and zeta potential (?20.1 mV). Morphologically showed a regular spherical shape in size ranged from 112 to 169 nm that confirmed via scanning electron microscopy. Oil analysis identified sesquiterpene alcohols, mainly santalols, terpenoids, aromatic compounds, fatty acid methyl esters, and phenolic compounds. Larvicidal activities of the oil and its nano-emulsion indicated dose, formulation, and exposure time-related mortality after 24 and 48 h in both species. After 24 h, 100% mortality was detected at 1000 ppm for the nano-emulsion with LC₅₀ of 187.23 and 232.18 ppm and at 1500 ppm for the essential oil with an LC₅₀ of 299.47 and 349.59 ppm against the 3rd larvae Cx. pipiens and Ae. aegypti, respectively. Meanwhile, an enhanced significant effect of the nano-emulsion was observed compared to oil exposure in decreasing total protein content and the activities of alkaline phosphatase and β-esterase enzymes, and increasing α-esterase and glutathione S-transferase activities in larval body tissues. Results demonstrated the enhanced larvicidal potential of sandalwood oil nano-emulsion over that of oil. The effect involved alterations in the detoxifying enzymes based on the existing natural active ingredients against Cx. pipiens and Ae. aegypti larvae.