Effect of solvent ratio, temperature and time on extraction of bioactive compounds and their antioxidant potential from callus, leaf and peel extracts of Citrus pseudolimon Taraka

Abstract

Galgal or Hill lemon (Citrus pseudolimon Taraka) is a lesser known variety of Citrus indigenous to northern India with potential medicinal benefits. The objective of the research was to optimize extraction conditions for achieving maximum recovery of total phenolic content (TPC), total flavonoid content (TFC) and antioxidant potential in terms of radical scavenging activity (RSA) from ethanolic extracts of in vitro callus cultures, leaf and peel tissues of galgal. The callus was obtained from the seeds germinated under in vitro conditions. MS medium supplemented with 2,4-D (4.0 mgL^− 1) + Kinetin (0.5 mgL^− 1) was found to be the best medium for callus induction. The extracts from callus, leaves and peel were different concentrations of ethanol/water solution at different temperatures and extraction times. The maximum TPC and TFC were achieved in extracts prepared using treatment with E:W ratio 50 at 50 °C for 30 min in leaf (TPC 6.86 ± 0.04 mg gallic acid g^− 1 dw and TFC 3.16 ± 0.02 mg rutin g^− 1dw) and peel (TPC 9.88 ± 0.03 mg gallic acid g^− 1 and TFC 4.81 ± 0.02 mg rutin g^− 1dw) extracts and E:W ratio 25 at 50 °C for 30 min for callus extract (TPC 4.9 ± 0.04 mg gallic acid g^− 1 dw and TFC 2.57 ± 0.03 mg rutin g^− 1dw). The maximum RSA was observed in extract prepared using E:W ratio 50 at 50 °C for 30 min (45.5 ± 1.3%, 40.2 ± 0.2% and 23.2 ± 0.8%in peel, leaves and callus respectively). The correlation analysis revealed positive correlation among TPC, TFC and RSA of peel, leaf and callus extracts. Thus, various tissues of galgal along with their callus cultures could act as sources of bioactive compounds which could be used for medicinal purposes.