Phytotoxic Effects and Phytochemical Fingerprinting of Hydrodistilled Oil, Enriched Fractions, and Isolated Compounds Obtained from Cryptocarya massoy (Oken) Kosterm. Bark

The hydrodistilled oil of Cryptocarya massoy bark was analysed by means of GC and GC-MS, highlighting the presence of unusual C10 massoia lactone (56.2%), C12 massoia lactone (16.5%), benzyl benzoate (12.7%), C8 massoia lactone (3.4%), δ-decalactone, (1.5%) and benzyl salicylate (1.8%) as key constituents. The phytotoxic activities of the oil, of three enriched fractions (lactone-rich, ester-rich, sesquiterpene-rich) and four constituents (δ-decalactone, δ-dodecalactone, benzyl salicylate, benzyl benzoate) were screened on Lycopersicon esculentum and Cucumis sativus seeds and seedlings. At 1000 μl/L the essential oil and the massoia lactone-rich fraction caused a complete inhibition of germination in both assays and when applied on tomato plantlets induced an 85% and 100% dieback respectively. Performances exceeded well-known phytotoxic essential oils Syzygium aromaticum and Cymbopogon citratus, already used in commercial products for weed and pest management. The same substances were also evaluated against 4 phytopathogenic bacteria and 10 phytopathogenic fungi, providing EC50 in the 100-500 μl/L range for essential oil and in the 10-50 μl/L range for δ-dodecalactone and massoia lactone-rich fraction. The phytotoxic behavior is related mainly to massoia lactones and benzyl esters, while a greater amount of δ-dodecalactone may infer a good activity against some phytopathogenic fungi. Further investigations of these secondary metabolites are warranted to evaluate their use as natural herbicides.