Establishment of adventitious root cultures in Labisia pumila for the production of secondary metabolities with antioxidative properties

Labisia pumila (Kacip Fatimah) is a herbaceous plant traditionally used for facilitating childbirth and post-natal recovery. L. pumila are highly demanded for commercial production, thus there is a need to establish a new in vitro cultivation system that produce large amounts of biomass with increased accumulation of secondary metabolites. Adventitious root culture is a promising technique to be applied in L. pumila for the rapid production of its secondary products. Therefore, this study was carried out to establish adventitious root cultures for biomass and secondary metabolite production from three varieties of L. pumila namely as var. alata, var. pumila and var. lanceolata. The root culture was initiated by selecting in vitro source materials from each variety. Optimisation of plant growth regulators, MS medium strength, sugars and elicitors were subsequently carried out to enhance root biomass and metabolites production. Shoot buds induction from adventitious root explants of L. pumila was also investigated. Out of 50 clones for each variety; var. alata line 30 (LPA30), var. pumila line 28 (LPP28) and var. lanceolata line 32 (LPL32) were selected as superior in vitro plantlets that had the highest DPPH radical scavenging activity (35.01±2.56 mg Trolox/g DW, 34.17±1.83 mg Trolox/g DW and 33.22±1.41 mg Trolox/g DW, respectively). LPA30 also had the highest ferric reducing ability (5.84±0.06 mg Trolox/g DW) and total phenolics (8.32±0.22 mg gallic acid/g DW) and flavonoids (3.99±0.07 mg quercetin/g DW) content as compared to LPP28 (4.71±0.11 mg Trolox/g DW, 6.77±0.22 mg gallic acid/g DW, 3.54±0.02 mg quercetin/g DW) and LPL32 (2.39±0.02 mg Trolox/g DW, 4.45±0.08 mg gallic acid/d DW, 2.35±0.08 mg quercetin/g DW), respectively. Optimisation of plant growth regulators revealed that 1 mg/L NAA was the best auxin for biomass production with the highest yield of phenolics and flavonoids in LPA30, LPP28 and LPL32 root cultures. The combination of 1 mg/L NAA with cytokinin (BAP and KN at 0.1, 0.5, 1 mg/L) failed to produced roots with high biomass and metabolite accumulation. Furthermore, full strength MS medium and 3% (w/v) sucrose provided the highest metabolite yields and biomass production in all root cultures. The elicitation of chitosan and salicylic acid in LPA30 root cultures failed to enhance phenolics and flavonoids production. In contrast, metabolite accumulation was enhanced in both LPP28 and LPL32 roots using 10 mg/L chitosan and 5 mg/L salicylic acid, respectively, although biomass formation was hindered. LPP28 and LPL32 roots elicited with 10 mg/L chitosan enhanced up to 1.5 and 2.2 folds phenolics, and 1.2 and 1.9 folds flavonoids content, respectively. Meanwhile, LPP28 and LPL32 roots elicited with 5 mg/L salicylic acid enhanced up to 1.9 and 2.5 folds phenolics, and 1.5 and 2.2 folds total flavonoids content, respectively. The HPLC analysis showed gallic acid and myricetin were detected in adventitious roots and in vitro plantlets. Quercetin was only detected in in vitro plantlets. Positive correlations were observed between TPC and TFC with DPPH and FRAP assay in L. pumila samples. Treatment of 3 mg/L TDZ successfully induced shoot buds formation in LPA30 adventitious root explants (14.81±6.24%), as compared to 5 mg/L TDZ for LPP28 (40.74±6.42%) and LPL32 (85.19±12.83%). Those explants with shoot buds were transferred into MS media without hormone for preliminary study. From this study, LPA30, LPP28 and LPL32 were selected as plantlets with high antioxidative properties. Adventitious root cultures of the plantlets were established in liquid shake culture system for phenolics and flavonoids production. Shoot regeneration from adventitious root explants of L. pumila can be further studied in the future. Keywords: Labisia pumila

Stem Cell Therapy for Neurodegenerative Diseases: How Do Stem Cells Bypass the Blood-Brain Barrier and Home to the Brain?

Blood-brain barrier (BBB) is a term describing the highly selective barrier formed by the endothelial cells (ECs) of the central nervous system (CNS) homeostasis by restricting movement across the BBB. An intact BBB is critical for normal brain functions as it maintains brain homeostasis, modulates immune cell transport, and provides protection against pathogens and other foreign substances. However, it also prevents drugs from entering the CNS to treat neurodegenerative diseases. Stem cells, on the other hand, have been reported to bypass the BBB and successfully home to their target in the brain and initiate repair, making them a promising approach in cellular therapy, especially those related to neurodegenerative disease. This review article discusses the mechanism behind the successful homing of stem cells to the brain, their potential role as a drug delivery vehicle, and their applications in neurodegenerative diseases