NMR reassignment of stictic acid isolated from a Sumatran lichen Stereocaulon montagneanum (Stereocaulaceae) with superoxide anion scavenging activities.

The phytochemical study of Stereocaulon montagneanum harvested in Sumatra (Indonesia) led to the isolation of 11 known compounds including two metabolites not previously described in the genus Stereocaulon, peristictic acid (8) and menegazziaic acid (10). The complete 1H and 13C NMR spectral assignments of stictic acid derivatives are reported with some revisions. Five depsidones belonging to the stictic acid chemosyndrome were superoxide anion scavengers as potent as ascorbic acid and with no toxicity on two human cell lines.

Crystal structure of olivetolic acid: a natural product from Cetrelia sanguinea (Schaer.).

The title compound, C12H16O4 (systematic name: 2,4-dihy-droxy-6-pentyl-benzoic acid) is a natural product isolated from C. sanguinea (Schaer.) and is reported to have various pharmacological activities. The mol-ecule is approximately planar (r.m.s. deviation for the non-H atoms = 0.096 Å) and features an intra-molecular O-H⋯O hydrogen bond. In the crystal, each olivetolic acid mol-ecule is connected to three neighbours via O-H⋯O hydrogen bonds, generating (10-1) sheets. This crystal is essentially isostructural with a related resorcinolic acid with a longer alkyl chain.

Enhancement of a Novel Isolate of Serratia plymuthica as Potential Candidate for an Antianthracnose.

BACKGROUND AND OBJECTIVE: A new rhizobacteria isolate of Serratia plymuthica (strain UBCR_12) exhibited a promising potential as a biocontrol agent for anthracnose causing agent Colletotrichum gloeosporioides. The aim of this study was to characterize its antagonistic activity and explore the factors contributing to a higher inhibition activity. MATERIALS AND METHODS: The antifungal effect of UBCR_12 against C. gloeosporioides was assayed under various pH values and nutritional sources. Culture supernatant obtained from UBCR_12 and C. gloeosporioides co-culture was also tested for its inhibitory activity. In addition, the antagonistic range of this isolate was examined against Sclerotium rolfsii and Fusarium oxysporum. Statistical analysis was done using one way analysis of variance and further processed using Fisher's Least Significant Difference (LSD) test with a p<0.05. RESULTS: The UBCR_12 induced inhibition was shown to be stable over time at pH 7, while peptone addition led to a faster induction (2 days after treatment) and glucose treatment to a higher activity. Of all these modifications, preliminary co-culture experiments with fungal cells resulted in the best antagonistic activity of UBCR_12 culture supernatant of about 30.66%. This isolate also showed a wide range of antagonistic activity due to its high suppression against S. rolfsii and F. oxysporum from soybean. CONCLUSION: Both environmental and biotic manipulations contributed an elevated inhibition rate of UBCR_12 against C. gloeosporioides. A proportional combination of the factors stimulating antagonistic activity of this strain is recommended to be utilized for the development of this strain as an antianthracnose. The enhanced antifungal effects of UBCR_12 resulted under each type of modification were varied indicating the difference of cell responses. It suggests that certain antifungal mechanism could be generated by modifying the environmental factor required for its induction. In addition, the application of cell-free culture supernatant provides an alternative solution in the utilization of biocontrol agents. For large scale application, it could minimize the risk of population outbreaks and harmful effects due to the living cells application.

Lobarin from the Sumatran lichen, Stereocaulon halei.

The diphenyl ether, lobarin (1) (syn. lobariol carboxylic acid) related to lobaric acid was isolated for the first time as a natural product along with five known compounds from Stereocaulon halei, a fruticose lichen collected in Indonesia. The structure of lobarin was elucidated by spectroscopic data analysis and its most stable conformers were determined by molecular mechanic dynamic calculations. A marked superoxide anion scavenging was found for compound 1 while no cytotoxicity on the B16 murine melanoma and HaCaT human keratinocyte cell lines was observed.

rac-Eudesm-7(11)-en-4-ol.

The isolation and structural determination of rac-eudesm-7(11)-en-4-ol, C15H26O, from the steam distillate of the flowers of Dipterocarpus cornutus Dyer (Dipterocarpaceae) is described. The structure was determined from spectroscopic data and a single-crystal X-ray study. Two similar independent molecules comprise the asymmetric unit of the structure.