Characterization of the Volatile Pattern and Antioxidant Capacity of Essential Oils from Different Species of the Genus Ocimum

• Published in: Journal of agricultural and food chemistry Vol. 54; no. 12; pp. 4378 - 4382
• Main Authors: Salles Trevisan, Maria Teresa, Vasconcelos Silva, Maria Goretti, Pfundstein, Beate, Spiegelhalder, Bertold, Owen, Robert Wyn
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14.06.2006
• Subjects: antioxidant activity; antioxidants; Antioxidants - analysis; Antioxidants - pharmacology; Aroma and flavouring agent industries; basil; Biological and medical sciences; Biphenyl Compounds; chemical composition; Chromatography, High Pressure Liquid; essential oils; Eugenol - analysis; Eugenol - pharmacology; Food industries; Fundamental and applied biological sciences. Psychology; gas chromatography; Hypoxanthine; mass spectrometry; Ocimum; Ocimum - chemistry; Ocimum basilicum; Ocimum basilicum - chemistry; Ocimum basilicum var. purpurascens; Ocimum gratissimum; Ocimum micranthum; Ocimum tenuiflorum; Oils, Volatile - chemistry; Oils, Volatile - pharmacology; phenolic compounds; Picrates; Plant Leaves - chemistry; Plant Oils - chemistry; Plant Oils - pharmacology; Volatilization; Xanthine Oxidase; Volatile compound; Oxygen; Ocimum; Enzyme; HPLC chromatography; Antioxidant; Characterization; Labiatae; Dicotyledones; Angiospermae; reactive oxygen species; Hypoxanthine; Xanthine oxidase; Spermatophyta; Essential oil; Oxidoreductases; Species; Mass spectrometry; HPLC
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf060181+

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 μL/mL) compared to Ocimum basilicum var. purpurascens (IC50 = 1.84 μL/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 × free radical scavenging capacity; mg × %/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. Keywords: HPLC; hypoxanthine; mass spectrometry; Ocimum; reactive oxygen species; xanthine oxidase