Abstract

Thai basil is a renowned medicinal plant and a rich source of bioactive antioxidant compounds with several health benefits, with actions to prevent of cancer, diabetes and cardiovascular disease. Plant cell and tissue culture technologies can be routinely established as an important, sustainable and low-cost biomass source to produce high-value phytochemicals. The current study aimed at developing an effective protocol to produce Thai basil leaf-derived callus cultures with sustainable and high production of biomass and antioxidants as an alternative of leaves production. MS basal medium with various concentrations of plant growth regulators (PGRs) compatible with nutraceutical applications (i.e., gibberellic acid (GA3) and 6-benzylaminopurine (BAP) either alone or in combination with naphthalene acetic acid (NAA)) were evaluated. Among all tested PGRs, the combination BAP:NAA (5 mg/L:1 mg/L) yields the maximum biomass accumulation (fresh weight (FW): 190 g/L and dry weight (DW): 13.05 g/L) as well as enhanced phenolic (346.08 mg/L) production. HPLC quantification analysis indicated high productions of chicoric acid (35.77 mg/g DW) and rosmarinic acid (7.35 mg/g DW) under optimized callus culture conditions. Antioxidant potential was assessed using both in vitro cell free and in vivo cellular antioxidant assays. Maximum in vitro antioxidant activity DPPH (93.2% of radical scavenging activity) and ABTS (1322 µM Trolox equivalent antioxidant capacity) was also observed for the extracts from callus cultures grown in optimal conditions. In vivo cellular antioxidant activity assay confirmed the effective protection against oxidative stress of the corresponding extract by the maximum inhibition of ROS and RNS production. Compared to commercial leaves, callus extracts showed higher production of chicoric acid and rosmarinic acid associated with higher antioxidant capacity. In addition, this biological system also has a large capacity for continuous biomass production, thus demonstrating its high potential for possible nutraceutical applications.

Highlights

  • The genus Ocimum (Family Lamiaceae) includes almost 150 species of herbs and shrubs that inhabit the semi tropical and tropical regions of America (Central and South), Asia and Africa [1,2]

  • In line with this observation, our results show that the phenolic acids chicoric acid and rosmarinic acid can be modulated by plant growth regulators (PGRs) in vitro callus cultures of Thai basil

  • A protocol is proposed for the effective production of leaf-derived callus cultures of Thai basil with sustainable and elevated productions of both biomass and antioxidant phenolics

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Summary

Introduction

The genus Ocimum (Family Lamiaceae) includes almost 150 species of herbs and shrubs that inhabit the semi tropical and tropical regions of America (Central and South), Asia and Africa [1,2]. Thai basil is a reservoir of a pharmaceutically important metabolite, such as rosmarinic acid and chicoric acid [5,6,7] These plant specialized metabolites play a pivotal role in plant–environment interactions, provide biotic and abiotic stress tolerance and are used as pharmaceutical agents because they have a variety of antioxidant, anticancer, antimicrobial or anti-diabetic activities [8,9,10,11]. Culture extracts were further analyzed for total phenolic production, HPLC quantification of chicoric acid, rosmarinic acid, and caffeic acid, as well as antioxidant capacity using both in vitro cell-free (DPPH, ABTS and FRAP assays) and cellular assays. These values were compared with those obtained from commercial leaves for extraction. Our findings clearly illustrate the great significance of the optimized biological system, which has a wide capacity for continuous biomass production, demonstrating its high potential for future nutraceutical applications

Callus Induction and Biomass Production
Production of Phenolic Compounds
Evaluation of Simple
In Vitro Cell-Free Antioxidant Assays
Cellular Antioxidant Activity
Chemicals and Reagents
Plant Materials and Callus Culture Establishment
Sample Extraction
HPLC Analysis
DPPH Assay
ABTS Assay
Cellular Antioxidant Assay
Statistical Analysis
Conclusions
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