Characterization of the volatile pattern and antioxidant capacity of essential oils from different species of the genus Ocimum.
The antioxidant capacity of essential oils obtained by steam hydrodistillation from five species of the genus Ocimum, namely Ocimum basilicum var. purpurascens, Ocimum basilicum, Ocimum gratissimum, Ocimum micranthum, and Ocimum tenuiflorum (syn. O. sanctum), were evaluated using a high-performance liquid chromatography-based hypoxanthine/xanthine oxidase and the DPPH assays. The yield of oils from the leaves of the five species was variable with the greater amount obtained from Ocimum gratissimum (3.5%) and the least from Ocimum basilicum var. purpurascens (0.5%). In the hypoxanthine/xanthine oxidase assay, strong antioxidant capacity was evident in all the oils but the greater was shown by that obtained from Ocimum tenuiflorum (syn. O. sanctum) (IC50 = 0.46 microL/mL) compared to Ocimum basilicum var. purpurascens (IC50 = 1.84 microL/mL). Antioxidant capacity was positively correlated (r = 0.92, p < 0.05) with a high proportion of compounds possessing a phenolic ring such as eugenol, while a strong negative correlation (r = -0.77, p > 0.1) with other major volatiles was observed. These correlations were confirmed to a large extent in the DPPH assay. The results of a 24 h experiment with Ocimum tenuiflorum (syn. O. sanctum) shows that the antioxidant capacity factor (amount of essential oil obtained x free radical scavenging capacity; mg x %/100) reaches a threshold between 10 and 12.00 h, corresponding to maximum sunlight intensity in Brasil and furthermore exhibits a clear diurnal variation. The data generated with Ocimum species indicates that essential oils obtained from various herbs and spices may have an important role to play in cancer chemoprevention, functional foods, and in the preservation of pharmacologic products.
Trevisan
Maria Teresa Salles
MT
Division of Toxicology and Cancer Risk Factors, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany.
Vasconcelos Silva
Maria Goretti
MG
Pfundstein
Beate
B
Spiegelhalder
Bertold
B
Owen
Robert Wyn
RW
D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D001713:Biphenyl Compounds; D002851:Chromatography, High Pressure Liquid; D005054:Eugenol / Q000032:analysis / Q000494:pharmacology; D019271:Hypoxanthine; D031339:Ocimum / Q000737:chemistry*; D018649:Ocimum basilicum / Q000737:chemistry; D009822:Oils, Volatile / Q000737:chemistry* / Q000494:pharmacology; D010851:Picrates; D018515:Plant Leaves / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry* / Q000494:pharmacology; D014835:Volatilization; D014969:Xanthine Oxidase
D000975:Antioxidants; D001713:Biphenyl Compounds; D009822:Oils, Volatile; D010851:Picrates; D010938:Plant Oils; D019271:Hypoxanthine; D005054:Eugenol; C004931:1,1-diphenyl-2-picrylhydrazyl; D014969:Xanthine Oxidase