3. Chemical Composition and Antioxidant Activity of Tagetes minuta L. in Eastern Cape, South Africa

The purpose of this study was to determine the chemical composition of essential oils from Tagetes minuta from the Eastern Cape of South Africa and evaluate their antioxidant potential for medicinal end use. The essential oils were extracted by hydrodistillation method from fresh and dry parts (stem, leaves and flowers) of Tagetes minuta collected from Komga, Eastern Cape Province, South Africa and analyzed by gas chromatography coupled with mass spectrometry (GC-MS) and gas chromatography (GC). This analysis has led to the identification of 12, 31, 10, 37, 4 and 39 compounds representing 99.16, 98.07, 98.86, 98.30, 100 and 97.66% of fresh stem (TMFS), dry stem (TMDS), fresh leaves (TMFL), dry leaves (TMDL), fresh flower (TMFF) and dry flower (TMDF) essential oil respectively. The major components were identified to be cis-β-ocimene (38.03%) for TMFS; caryophyllene oxide (18.04%) for TMDS; trans, cis-alloocimene (25.35%) for TMFL; isopropyl tetradecanoate (17.02%) for TMDL; cis-β-ocimene (38.14%), for TMFF and trans-β-ocimene (37.03%), for TMDF. The dry parts (TMDS, TMDL and TMDF) essential oil were evaluated for antioxidant activity using DPPH and FRAP bioassays. Standard equivalent values from DPPH assay were between 6.74 ± 0.27 and 18.7 ± 0.35 μg/mL AAE with scavenging ability in descending order: TMDF > TMDL > TMDS. Standard equivalent values from FRAP assay were between 26.30 ± 0.41 and 113.0 ± 1.2 μg/mL AAE with antioxidant activity in descending order: TMDF > TMDL > TMDS. These results suggest that T. minuta may be used as a potential natural source of antioxidant.