EVALUATION OF PHYTOCHEMICAL COMPOSITION AND ANTIOXIDANT ACTIVITY OF OCIMUM BASILICUM L. UNDER DIFFERENT ENVIRONMENTAL CONDITIONS

Abstract

Background and purpose: The balance of carbon allocation and the number of secondary metabolites produced in edible and medicinal crops can be influenced by environmental factors. This manuscript outlines an example of a controlled light intensity experiment done on sweet basil (Ocimum basilicum L.) to illustrate the coherent procedure for assessing total phenolics, total flavonoids, antioxidant activity, targeted phenolic compound profiles and relations among them in one experimental process.

Methods: A database was created for four different full spectrum LED photon-flux treatments (600, 450, 300 and 180 µmol m-2 s-1) with 3 independent biological replicates per treatment. Established spectrophotometric assays for TPC, TFC, DPPH, ABTS, and FRAP were used to model the leaf extracts, as well as a targeted HPLC-DAD panel to model major phenolic constituents. Data were analyzed with one-way ANOVA with Tukey HSD and Pearson correlation.

Results:  As light intensity increased, there was monotonic increase in the dataset for TPC, TFC, DPPH, ABTS, FRAP and all the phenolics targeted. TPC ranged from 25.61 ± 0.69 to 32.84 ± 0.91 mg GAE/g dry weight, while TFC ranged from 11.92 ± 0.35 to 15.68 ± 0.42 mg QE/g. DPPH scavenging ranged from 73.26 ± 0.94% to 82.35 ± 1.02%, ABTS from 78.01 ± 1.03% to 88.72 ± 1.15%, and FRAP from 370.2 ± 9.7 to 455.8 ± 11.8 µmol Fe²⁺ equivalents/g. All five main response variables had significant treatment differences (ANOVA p ≤ 0.0056) and high positive Pearson correlation values were found between the phytochemical and antioxidant parameters (r = 0.920–0.990).

Conclusion: In this context, light availability, and phenolics accumulation and antioxidant capacity increases with light availability. The pattern is similar to what was reported with light environment modulating basil secondary metabolism.