Improvement in Flavonoids and Phenolic Acids Production and Pharmaceutical Quality of Sweet Basil (Ocimum basilicum L.) by Ultraviolet-B Irradiation.
Sweet basil (Ocimum basilicum Linnaeus) is aromatic herb that has been utilized in traditional medicine. To improve the phytochemical constituents and pharmaceutical quality of sweet basil leaves, ultraviolet (UV)-B irradiation at different intensities (2.30, 3.60, and 4.80 W/m²) and durations (4, 6, 8, and 10-h) was applied at the post-harvest stage. Total flavonoid content (TFC) and total phenolic content (TPC) were measured using spectrophotometric method, and individual flavonoids and phenolic acids were identified using ultra-high performance liquid chromatography. As a key enzyme for the metabolism of flavonoids, chalcone synthase (CHS) activity, was measured using a CHS assay. Antioxidant activity and antiproliferative activity of extracts against a breast cancer cell line (MCF-7) were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays, respectively. UV-B irradiation at an intensity of 3.60 W/m² increased TFC approximately 0.85-fold and also increased quercetin (0.41-fold), catechin (0.85-fold), kaempferol (0.65-fold) rutin (0.68-fold) and luteolin (1.00-fold) content. The highest TPC and individual phenolic acid (gallic acid, cinnamic acid and ferulic acid) was observed in the 3.60 W/m² of UV-B treatment. Cinnamic acid and luteolin were not detected in the control plants, production being induced by UV-B irradiation. Production of these secondary metabolites was also significantly influenced by the duration of UV-B irradiation. Irradiation for 8-h led to higher TFC, TPC and individual flavonoids and phenolic acids than for the other durations (4, 8, and 10-h) except for cinnamic acid, which was detected at higher concentration when irradiated for 6-h. Irradiation for 10-h significantly decreased the secondary metabolite production in sweet basil leaves. CHS activity was induced by UV-B irradiation and highest activity was observed at 3.60 W/m² of UV-B irradiation. UV-B treated leaves presented the highest DPPH activity and antiproliferative activity with a half-maximal inhibitory concentration (IC50) value of 56.0 and 40.8 µg/mL, respectively, over that of the control plants (78.0 and 58.2 µg/mL, respectively). These observations suggest that post-harvest irradiation with UV-B can be considered a promising technique to improve the healthy-nutritional and pharmaceutical properties of sweet basil leaves.
Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. alighasemzadeh@upm.edu.my.
Ali
A
Ghasemzadeh
Department of Agronomy and Plant Breeding, Yadegar-e-Imam Khomeini (RAH) Shahre Rey Branch, Islamic Azad University, Tehran, Iran. ashkani.sadegh@gmail.com.
Sadegh
S
Ashkani
Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. ali_baghdadi@yahoo.com.
Ali
A
Baghdadi
Department of Agronomy and Plant Breeding, Yadegar-e-Imam Khomeini (RAH) Shahre Rey Branch, Islamic Azad University, Tehran, Iran. pazoki_agri@yahoo.com.
Alireza
A
Pazoki
Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. hawazej@upm.edu.my.
Hawa Z E
HZ
Jaafar
Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. profasmah@gmail.com.
Asmah
A
Rahmat
D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects*; D005260:Female; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D062385:Hydroxybenzoates / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D061986:MCF-7 Cells; D018649:Ocimum basilicum / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*; D014466:Ultraviolet Rays
D000975:Antioxidants; D005419:Flavonoids; D062385:Hydroxybenzoates; C017616:phenolic acid
CHS activity; Ocimum basilicum L.; TFC; TPC; UV-B; antioxidant activity; antiproliferative activity