Effect of drying methods in the extraction of bioactive compounds from Chicozapote (Manilkara zapota): assessing antioxidant and antimicrobial activities

Abstract

Manilkara zapota “chicozapote” is an evergreen fruit tree belonging to the Sapotaceae family native to Yucatán and other areas adjacent to southern Mexico and Central America. In this research, different parts of chicozapote fruit (pulp, peel, and seeds) were submitted to different drying methods (lyophilization and oven-drying at 50°C) and compared to fresh samples to evaluate the effects the sample treatment has in the retrieve and extraction of bioactive compounds, as well as their significance in their antimicrobial and antioxidant activities. Sample characterization parameters were determined as follows: 76.24% in moisture, 19.51 in soluble solids, 4.46 in pH, 169.22 g average weight, 62.27 and 84.28 cm in diameter and length, 0.56 in titratable acidity, and 34.72 maturity index. A tracking of ripening for 6 days revealed that the acidity drops drastically at 5 days post-harvest, in contrast, soluble solids increase. 6 samples were obtained after the drying methods were applied (LPU: lyophilized pulp, OPU: Oven-dried pulp, LPE: lyophilized peel, OPE: Oven dried peel, LS: lyophilized seed, and OS: Oven-dried seed. Proximate composition was determined for each one of the samples, and ranges were as it follows in g/100g of DS: protein (4.34-5.1), ash (3.91-15.1), fat (0.71-16.09), total dietary fiber (31.61-64.88), and DC (7.12-45.92). Bioactive compounds extraction was performed by a solvent-mediated extraction with ethanol 70%. Yields (w/w, %) were between 79.5 and 5.69, being LPU the highest sample. Total phenolic content (TPC), total flavonoid content (TFC), and total condensed tannin (TCT) were determined. TPC GAE mg g-1 values were between 17.91 and 152.15; TFC QEE mg g-1 were from 9.3 to 202.37; and TCT +CAE mg g-1 were from 14.94 to 244.28, being LPE the richest in bioactive compounds in general. Antioxidant capacity through ABTS and DPPH assays were associated the bioactive compound content, which all samples ranged from 89.56 to 95.73% radical scavenger activity (RSA), except from seed samples. Minimal inhibitory concentrations (MIC) evaluated in the standard pathogens ranged from 198 to 1,000 µg/mL, except from seed, which had MICs > 1,000 in all microorganisms, LPE and FPE had the lowest average MIC with 330 and 397, respectively. Therefore, further studies were made with these two samples. Their antibiotic modulation effect and their synergistic interactions with different antibiotics (AB) were tested (ciprofloxacin, chloramphenicol, and tetracycline). Only FPE at MIC/4 probed a modulation effect of 5 in all AB, meaning that can decrease their MIC by 5 times. Additionally, it displayed a synergistic interaction with all of them, with a FIC of 0.45. Moreover, cellular assays to assess more extensively their potential. LPE demonstrated a selective cytotoxicity in Caco 2 cells (IC50 = 704 µg/mL), while both FPE and LPE were non-toxic in control cells. Furthermore, the cellular antioxidant activity indicated that both samples have a similar behavior towards their antioxidant capacity (IC50 = 177.3, and 133.1 µg/mL) for LPE and FPE, respectively. Finally, their anti-inflammatory potential was assessed, both samples were effective (IC50 = 24.91, and 24.85 µg/mL) for LPE and FPE, respectively. Therefore, sample treatment, especially drying method has a significant impact on their bioactive compounds profile and thereby affecting their biological activities.