Light-mediated biosynthesis of phenylpropanoid metabolites and antioxidant potential in callus cultures of purple basil (Ocimum basilicum L. var purpurascens)

International audienceOcimum basilicum L. var purpurascens (purple basil) contains medicinally valuable metabolites. Light greatly influences the physiological processes, including biomass accumulation and secondary metabolites production in medicinal plants. Herein, we investigated the influence of different spectral lights on the biosynthesis of phenylpropanoid metabolites in purple basil callus cultures. Growth kinetics was ostudied for a total of 49 days, with 7 days of sampling time. Among the various treatments, blue light resulted in maximum biomass accumulation, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant DPPH, FRAP and ABTS activities, as compared to controls. Moreover, blue light also encouraged higher superoxide dismutase activity while the red light was found effective for enhanced peroxidase activity. HPLC analysis revealed enhanced rosmarinic acid (87.62 mg/g DW) and anthocyanins (cyanidin: 0.15 mg/g DW and peonidin: 0.13 mg/g DW) contents under dark grown callus cultures which were almost 1.55, 1.25 and 1.18-fold greater than controls, respectively. Conversely, red light caused maximum production of cichoric acid (14.65 mg/g DW). Moreover, a positive correlation occurred among the accumulation of phenolic and flavonoids and antioxidant activities. These results suggest that light quality strongly influences medicinally valuable phenylpropanoid metabolites biosynthesis along with antioxidant potential in in vitro cultures of purple basil

<i>Isodon rugosus</i> (Wall. ex Benth.) Codd In Vitro Cultures: Establishment, Phytochemical Characterization and In Vitro Antioxidant and Anti-Aging Activities

Isodon rugosus (Wall. ex Benth.) Codd accumulates large amounts of phenolics and pentacyclic triterpenes. The present study deals with the in vitro callus induction from stem and leaf explants of I. rugosus under various plant growth regulators (PGRs) for the production of antioxidant and anti-ageing compounds. Among all the tested PGRs, thidiazuron (TDZ) used alone or in conjunction with &#945;-napthalene acetic acid (NAA) induced highest callogenesis in stem-derived explants, as compared to leaf-derived explants. Stem-derived callus culture displayed maximum total phenolic content and antioxidant activity under optimum hormonal combination (3.0 mg/L TDZ + 1.0 mg/L NAA). HPLC analysis revealed the presence of plectranthoic acid (373.92 &#181;g/g DW), oleanolic acid (287.58 &#181;g/g DW), betulinic acid (90.51 &#181;g/g DW), caffeic acid (91.71 &#181;g/g DW), and rosmarinic acid (1732.61 &#181;g/g DW). Complete antioxidant and anti-aging potential of extracts with very contrasting phytochemical profiles were investigated. Correlation analyses revealed rosmarinic acid as the main contributor for antioxidant activity and anti-aging hyaluronidase, advance glycation end-products inhibitions and SIRT1 activation, whereas, pentacyclic triterpenoids were correlated with elastase, collagenase, and tyrosinase inhibitions. Altogether, these results clearly evidenced the great valorization potential of I. rugosus calli for the production of antioxidant and anti-aging bioactive extracts for cosmetic applications

Molecular characterisation of <i>Bacillus</i> chitinase for bioconversion of chitin waste

<div><p>In this work chitin was extracted chemically from shrimp shells. Seventeen <i>Bacillus</i> isolates were screened for chitinolytic activity. The chitinolytic strains of <i>Bt</i>. were screened at different temperatures and pHs for their hydrolytic potentials. By using a pair of specific primers, <i>endochitinase</i> gene was amplified from SBS Bt-5 strain through PCR, and then cloned into pTZ57 TA cloning vector and transferred in <i>Escherichia coli</i> DH5α strain. The sequenced gene (GenBank Accession No: HE995800) consists of 2031 nucleotides capable of encoding 676 residues. The protein consisted of three functional domains with a calculated molecular mass of 74.53 kDa and a pI value of 5.83. The amino acid sequence of <i>chi</i> gene showed 99% similarity to the genes of <i>Bt</i> MR11 <i>endochitinase</i>, <i>Bt</i><i>serovar kurstaki</i> chitinase (<i>kch</i>i), <i>Bt</i> strain MR21 <i>endochitinase</i> and <i>Bacillus cereus</i> B4264.</p></div