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Environmental fate & pathways

Additional information on environmental fate and behaviour

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Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Publication which meets generally accepted scientific standards

Data source

Reference
Reference Type:
publication
Title:
Biotransformation of aliphatic and aromatic ketones, including several monoterpenoid ketones and their derivatives by five species of marine microalgae
Author:
Hook IL, Ryan S, Sheridan H
Year:
2003
Bibliographic source:
PMID:12657294 Phytochemistry 63(1):31-6

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Three saltwater green alga (Chlorella minutissima, Nannochlorus atomus, Dunaliella parva) und two red alga (Porphyridium pupureum, Isochrysis galbana) were allowed to grow for 7 days. Then the test substance was added to a final concentration of 100 mg/L and incubated under sterile conditions. The parent compound decrease and the amount of transformation product was follwed analytically.
GLP compliance:
no
Type of study / information:
Biotransformation in marine green and red alga

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Any other information on results incl. tables

The non-selective biotransformation of the diastereomeric mixture (±)-menthyl acetate to (±)-menthol was completed by two green alga (C. minutissima, N. atomus) and one red alga (P. purpureum) within a 24 h period. Cultures of one red alga (I. galbana) effected its biotransformation by the third day while the remaining green alga (D. parva) took 4 days to completely biotransform the substrate.

Table: Biotransformation percentrages after 5 days

C. minutissima   N. atomus  D. parva  P. purpureum  I. galbana
 100 %  100 %  100 %  100 %  100 %

Applicant's summary and conclusion

Conclusions:
The nonstereoselective 100 % transformation of menthyl acetate to menthol in five marine alga species (3 green alga and 2 red alga) was evidenced between 1 and 4 days.
Executive summary:

The biotransformation of the diastereomeric mixture (±)-menthyl acetate by three species of marine green algae (Chlorella minutissima, Nannochlorus atomus, Dunaliella parva) and two marine red alga (Porphyridium pupureum, Isochrysis galbana) was investigated. The publication reports an acceptable level of detail and is rated Klimisch 2 (reliable with restrictions).

Algal broth was obtained by culturing the algae in artificial sea water at 25 °C under illumination by cool white fluorescent light (20 W/m², 6 hours darkness / 18 hours light). The algal broth was then diluted and the test substance diluted in methanol (10 %) was added at a concentration of 100 mg/L or solvent control or control.

Dilutions of microalgae (1:5) were made in conical flasks (250 mL) to provide a 40 % flask fill (i.e. 20 mL algal broth into 80 mL artificial sea water. Algae were allowed to grow statically for 7 days at which stage a solution of substrate in methanol (1 mL) was added. Aliquots (10 mL) were taken from the culture flasks in triplicate at intervals of 24, 48, 72, 96 and 120 hours. These were extracted with equal volumes of distilled diethyl ether. The ether layer was separated, dried over Na2SO4, filtered and evaporated to dryness in vacuum. The residue was re-dissolved in diethyl ether (1 mL) and analyzed under standard GC conditions. The three replicates for a given data point of the time course experiment for each alga were combined. The algal cells were removed by filtration and the aqueous medium was extracted with diethyl ether. The components of the diethyl ether extracts were separated by column chromatography on silica gel. Products were visualized by UV light or by spraying with vanillin in concentrated H 2SO4 (l %) or freshly prepared iodoplatinate spray. Compounds were characterized by spectroscopic analysis and by comparison with authentic samples or literature values.

The non-selective biotransformation of the diastereomeric mixture (±)-menthyl acetate to (±)-menthol was completed by two green alga (C. minutissima, N. atomus) and one red alga (P. purpureum) within a 24 h period. Cultures of one red alga (I. galbana) effected its biotransformation by the third day while the remaining green alga (D. parva) took 4 days to completely biotransform the substrate.

In conclusion the nonstereoselective 100 % transformation of menthyl acetate to menthol in five marine alga species (3 green alga and 2 red alga) was evidenced between 1 and 4 days.