Phytochemical analysis and antioxidant profiling of ornamental flowers

Abstract

The present study entitled was undertaken with the objective of studying the physico-chemical, phytochemical and antioxidant properties, anti-nutritional factors and bioactive compounds of selected ornamental flowers viz., red hibiscus (both single and double), I. coccinea, I. singaporensis, R. damascena, marigold (T. erecta and T. patula), N. nucifera, N. rubra and C. sulphureus. The physico-chemical properties such as moisture, protein, fat, fibre, vitamin C, total ash and mineral contents (sodium, magnesium, calcium, iron, phosphorus and potassium) of the selected flowers were ascertained. Moisture content ranged from 45.51 (C. sulphureus) to 87.53 per cent (N. rubra). Protein content ranged between 2.03 (I. singaporensis) to 11.79 per cent (T. patula). Fat content of the ornamental flowers varied from 0.77 (single typed red hibiscus) to 10.77 per cent (T. erecta). The mean fibre content varied between 9.66 (single typed red hibiscus) to 20.00 (N. nucifera) per cent in the flowers. Ascorbic acid content of the ornamental flowers was observed to be in the range of 58.93 (T. patula) to 154.13 mg/100 g of DW (R. damascena). Total ash content of ornamental flowers studied ranged from 2.83 (N. rubra and C. sulphureus) to 10.00 per cent (N. nucifera). Sodium content of ornamental flowers ranged from 13.83 (double typed red hibiscus) to 16.23 mg/100 g of dry weight (single typed red hibiscus). Magnesium content varied from 5.61 (T. erecta) to 12.89 mg/100 g (single typed red hibiscus) in the flowers studied. Calcium content was in the range of 6.84 (R. damascena) to 31.24 mg per 100 g of DW (N. nucifera). Iron content of flowers ranged from 0.43 (R. damascena) to 2.31 mg/100 g (T. patula). Phosphorus content of the ornamental flowers ranged from 7.80 (I. coccinea) to 22.40 mg/100 g DW (T. patula). The mean potassium content varied from 40.86 (R. damascena) to 104.66 mg/100 g (N. nucifera). Phytochemicals in ornamental flowers such as carotenoids, anthocyanins, total flavonoids and phenols were also estimated. Total carotenoid content of the ornamental flowers ranged from 0.20 (R. damascena) to 8.13 mg per 100 g of DW (T. erecta). Anthocyanin content of ornamental flowers was in the range of 6.56 (T. erecta) to 187.43 mg/100 g (R. damascena). Flavonoid content ranged between 33.33 (N. nucifera) to 104.16 mg/100 g of DW (T. erecta). Phenol content of the ornamental flowers varied between 6.52 (R. damascena) to 49.80 mg/100 g of DW (C. sulphureus). Quantitative estimation of anti-nutritional factors such as tannin, oxalates and nitrates were done in the selected ornamental flowers. Tannin content of ornamental flowers ranged between 8.50 (N. nucifera) to 53.10 mg/100 g (R. damascena). Oxalate content was found to vary from 23.23 (N. nucifera) to 687.30 mg per 100 g of DW (single typed red hibiscus) of the flowers. Nitrate content varied between 6.30 (T. erecta) to 201.03 mg per 100 g DW (C. sulphureus) of the flowers. Free radical scavenging activity of the ten ornamental flowers was studied using DPPH and ABTS assays. Value of the DPPH assay ranged from 38.26 (R. damascena) to 269.32 µg/ml (double typed red hibiscus). ABTS radical scavenging activity ranged from 47.92 (R. damascena) to 738.60 µg/ml (T. patula). Estimation of physicochemical, phytochemical, anti-nutritional and antioxidant properties and bioactive compounds of the selected ornamental flowers revealed that the petals of N. nucifera recorded maximum fibre (20.00 %), total ash (10.00 %), magnesium (11.49 mg), calcium (31.24 mg) and potassium (104.66 mg) contents per 100 g DW with minimum anti-nutritional constituents such as tannins (8.50 mg) and oxalates (23.23 mg). T. patula recorded highest protein (11.79 %), fat (10.43 mg), sodium (15.30 mg), magnesium (10.61 mg), iron (2.31 mg), phosphorus (22.40 mg), potassium (79.40 mg) and flavonoid (101.00 mg) contents per 100 g DW but with lowest antioxidant properties in DPPH (257.57 µg/ml) ABTS (738.60 µg/ml) assay. Highest content of fat (10.77 mg), sodium (15.86 mg), carotenoids (8.13 mg) and flavonoids (104.16 mg) with lowest nitrate (6.30 mg) values per 100 g DW were noticed in T. erecta. R. damascena registered maximum sodium (15.23 mg), vitamin C (154.13 mg), anthocyanins (187.43 mg/100 g DW) and antioxidant properties in DPPH (38.26 µg/ml) as well as ABTS (47.92 µg/ml) assay, but having high tannin content (53.10 mg) per 100 g DW. H. rosa-sinensis (single) showed highest quantity of sodium (16.23 mg), magnesium (12.89 mg) and anthocyanins (184.82 mg) but with maximum oxalate content (687.30 mg) per 100 g DW. H. rosasinensis (double) showed highest quantity of magnesium (11.30 mg) and anthocyanins (186.63 mg) per 100 g DW but with least antioxidant property (269.32 µg/ml) as revealed in the DPPH assay. Petals of N. rubra registered maximum moisture content (87.53 %) and antioxidant properties in DPPH assay (47.04 µg/ml) with lowest nitrate (7.73 g) content per 100 g of DW. Cosmos recorded highest quantity of sodium (14.80 mg), iron (1.85 mg) and phenols (49.80 mg) but with maximum quantity nitrates (201.03 mg) per 100 g DW. I. coccinea recorded maximum sodium content (15.43 mg/100 g DW) among the ornamental flowers tested. GC-MS analysis of ten ornamental flowers revealed the various compounds present in its methanol extracts. Flowers of I. singaporensis contained more compounds (18) compared to rest of the flowers. The most abundant compound in I. singaporensis was (1R, 3R, 4R, 5R)-(-)-Quinic acid (70.60 %) whereas in I. coccinea, it was stigmast-5-en-3-ol, 3.beta (45.33 %). The most abundant compound in C. sulphureus was benzene, 1-chloro4-methoxy- (34.22 %) while in T. erecta -amyrin (42.37 %). Damask rose and red water lily contained eight compounds each. The most prevalent compound in Damask rose was 1, 2-benzenedicarboxylic acid (37.74 %) whereas in red water lily, it was heptacosane (44.27 %). Flowers of both single and double petalled hibiscus were found to contain seven -amyrin (83.41 %) was found in single petalled red hibiscus while 9-octadecenoic acid, 12-(acetyloxy) (25.56 %) and 9-octadecadienoic acid (25.51 %) were the most abundant in double petalled red hibiscus. Six different compounds were found in methanol extracts of both sacred lotus and T. patula. Most abundant compounds in the flower extracts of lotus were 9, 12, octadecadien-1-ol (34.74 %) and 9-octadecenoic acid, 12-(acetyloxy)-, methyl ester, [r-(z)]- (22.70 %). The predominant compound in T. patula was vitamin E (59.67 %). The present study revealed that the selected ornamental flowers are having nutritional value with high antioxidant properties and low anti-nutritional contents. The GC-MS analysis of ornamental flowers showed that they contained a variety of beneficial compounds that can act as nematicide, pesticide, anti-cancerous, antimicrobial, antifungal, antioxidant and anti-inflammatory agents. Some compounds identified in this study were reported to have anti-xanthine oxidase and anti-tyrosinase potentials. The compounds identified in the flowers could be used for the development of novel drugs also.