Profiling bioactive compounds in avocado (Persea americana Mill.) cultivars and freeze dried fruit powders and investigating its potential in Cancer cell lines

Abstract

The research work entitled “Profiling bioactive compounds in avocado (Persea americana Mill.) cultivars and freeze dried fruit powders, and investigating its potential in cancer cell lines.” was conducted at College Of Agriculture, Vellayani during 2017-2019, with the objectives to ascertain bioactive compounds in fresh fruits and freeze dried powders of avocado (Persea americana Mill.) cultivars and to investigate anti proliferation activities of freeze dried powder in cancer cell lines. Four cultivars selected for the study were Pollock, Kallar Round, Purple Hybrid and Fuerte. Quantitative estimation of phytochemicals showed that, glutathione content of fresh avocado fruits was in the range of 15.3mg/100g-18.3 mg/100g and was found to be higher in the cultivar Pollock (18.33mg/100g) and which was on par with Fuerte (18.13mg/100g). Folic acid, vitamin E, total carotenoids and total phenol content were observed in fresh fruits of avocado cultivars to be in the range of 79.30mg/100g-80.33mg/100g, 2.04 -2.52mg/100g, 2.55/100g-2.94mg/100g, and 12.24mg/100g -13.84mg/100g respectively. The Cultivar Pollock recorded highest content of folic acid (18.33mg/100g), vitamin E (2.52mg/100g), total carotenoids (2.94mg/100g) and total phenol (13.84mg/100g).Vitamin K and total phytosterols present in the four cultivars were in the range of 0.013mg/100g-0.019mg/100g and 62.30mg/100g-68.60mg/100g respectively. Lutein content was found to be more in the cultivar Fuerte (0.206mg/100g). Purple Hybrid was found to be superior in the case of total flavonoid content (21.07mg/100g). Mineral analysis of fresh fruits of avocado cultivars revealed that iron content was found to be higher in Fuerte (0.403mg/100g). Calcium, sodium, potassium, magnesium, zinc and selenium contents were found to be more in Pollock

(9.3mg/100g, 6.12mg/100g, 394.47 mg/100g, 22.20mg/100g, 0.473mg/100g and 0.500μg/100g respectively). The cultivars Pollock and Fuerte contained the same amount of copper (0.146mg). Phosphorus content was found to be almost the same in all the four cultivars noted in the range of 32.13/100g-34.90mg/100g. In the case of total antioxidant activity in fresh avocado cultivars, Pollock was found to be superior (234.50mg/100g) and was found to have no significant difference with Purple hybrid (230.66mg). The findings revealed that the cultivar Purple Hybrid had the highest DPPH radical scavenging activity with an IC50 value of 34.03µg/ml. Higher Hydroxyl radical scavenging activity was noted in the in the cultivar Kallar Round (27.03µg/ml) and the lowest Hydroxyl radical scavenging activity was observed in the cultivar Pollock (38.86µg/ml). Super oxide radical scavenging activity (IC50) was observed to be higher in the cultivar Kallar Round (12.12µg/ml). Estimation of phytochemicals in freeze dried powders showed more glutathione content in Pollock (45.50mg/100g). Folic acid, vitamin K and lutein content in freeze dried form of the four avocado cultivars ranged from 180.70mg/100g-197.90mg/100g, 0.179mg/100g-0.185mg, and 0.423mg/100g0.503mg/100g respectively. Total phytosterols was found to be more in Kallar Round (173.80mg/100g) and Total flavonoid content was found higher in Pollock (45.27mg/100g) and Purple Hybrid (45mg/100g).The carotenoid content was observed higher in the cultivar Pollock (8.15mg/100g) and which was found to be on par with Purple Hybrid (8.07mg/100g). Mineral estimation in the freeze dried form of avocados highlighted the iron content to be higher in Fuerte (2.87mg/100g). Calcium content was in the range of 104mg/100g-142.5mg/100g and was found to be higher for Purple Hybrid and lower for Pollock. Sodium content was found to be higher in Purple Hybrid (14.40mg/100g). Phosphorus and Magnesium contents were found to be more in

Pollock (76.07mg/100g and 42.13mg/100g respectively). Potassium content was found to be superior in Purple Hybrid (623mg/100g) and was on par with Pollock (622.76mg/100g) and Kallar Round (618.76mg/100g). Zinc content was found to be higher in the cultivar Kallar Round (4.66mg/100g) and less in Fuerte (2.11mg/100g). Copper and selenium contents were found to be almost same in all the four cultivars and in the range of 3mg/100g-3.23mg/100g and 8.07µg/100g-8.90μg/100g respectively. Total antioxidant activity was observed to be superior in the freeze dried powder of the cultivar Pollock (461.90mg/100g) and possessed no significant difference with Purple hybrid (460.33mg/100g). The findings revealed that the cultivar Purple hybrid had the highest DPPH radical scavenging activity with an IC50 value of 90.80µg/ml. Regarding the IC50 values for hydroxyl radical scavenging activity of freeze dried avocado cultivars, highest activity was noted in the freeze dried powder of Fuerte (69.25µg/ml). Lowest activity was observed in the freeze dried powder of Pollock (86.60µg/ml). Super oxide Radical Scavenging Activity (IC50) was observed higher in the freeze dried powder of Fuerte (24.47µg/ml). Based on the assessment of phytochemicals, minerals and antioxidant activities in fresh and freeze dried avocado powder, Pollock was found to be the superior cultivar. Hence freeze dried fruit powder of the cultivar Pollock was selected for cell line study. Cytotoxicity of freeze dried powder of Pollock was estimated by MTT assay on Human colon cancer cells (HCT 116). Assay was done with different concentrations of avocado extract (10μg, 20μg, 50μg, 100μg, and 200μg). Growth inhibition noted were, 27 %, 30 %, 33%, 45 %, and 71 % for 10 μg, 20 μg, 50 μg, 100 μg and 200 μg respectively. Percentage of viable cell decreased with increase in extract concentration while percentage cytotoxicity increased with increase in concentration of avocado extract. 50 % growth inhibition (GI50) of cancer cells were shown at 120μg/ml of fruit extract. 29 percent of cells were found to be viable after exposure of extract (200μg).

Recordings of the present study revealed that avocado fruit contains many bioactive components such as glutathione, folic Acid, vitamin K, vitamin E, lutein, carotenoids, phenols, phytosterols, and flavonoids which possessed potent antioxidant activities. Among the fresh and freeze dried form of avocado cultivars, Pollock was found to be superior and had noticeable anti-carcinogenic properties Findings of the present study add to the growing evidence, supporting the promising role of avocado fruit as an anti-cancer agent. Therefore, avocado fruit may represent a valuable therapeutic fruit for the treatment of cancer.