H.R. Raveesha’s research while affiliated with Bangalore University and other places

Andrographis lineata Nees is an erect herb and has been used as a traditional medicine against many diseases. The present study was to investigate the phytochemical analysis and antibacterial activity of A. lineata plant extracts. The methanolic extracts of A. lineata showed a variety of phytochemicals such as alkaloids, flavonoids, phenols, tannins, terpenoids etc. The quantitative estimation of major phytochemical constituents revealed maximum amount of phenolic content in the roots and alkaloids in both the stem and leaf. Correspondingly, the highest amount of tannins and terpenoids were recorded in the leaf and flavonoids in the root samples. Furthermore, the plant extracts of A. lineata showed antibacterial activity against both Gram-positive and Gram-negative bacterial strains. Comparatively, stem extract was effective against Streptococcus mutans (18.19±0.04 mm), leaf extract against Enterobacter faecalis (24.13±0.14 mm) and root extract against Bacillus subtilis (24.09±0.14 mm) at 30 μg/μL concentration. However, the leaf extract was more effective against Escherichia coli (25.13±0.16 mm), Pseudomonas aeruginosa (20.20±0.13 mm) and Klebsiella pneumoniae (18.18±0.17 mm) at 30 μg/μL concentration. The studies infer that the phytochemical constituents of A. lineata have antibacterial properties and these herbs may be considered as the medicinal plant for treating bacterial diseases.

Chonemorpha fragrans (Moon) Alston is a valuable medicinal plant with various applications in pharmaceuticals for various diseases. The current study was designed to examine the role of elicitors on biomass, camptothecin production and the antioxidant capacity of callus culture. The different elicitors such as chitosan, salicylic acid, yeast extract, and glycine were employed in this study. The phytoconstituents were characterized and quantified by GC-MS and LC-MS analysis. Antioxidant capacity was assessed by DPPH, ABTS, reducing power, and phosphmolybdenum assay. Maximum biomass was achieved in 100 mg/L Gl elicited callus on Gamborg's medium augmented with 0.5 mg/L of 2, 4-D, and BAP. The higher antioxidant and secondary metabolites were higher in the Ct elicited callus. GC-MS analysis revealed the presence of phytoconstituents like β – sitosterol, stigmasterol, and squalene. Higher Camptothecin (CPT) content was noticed in Ye supplemented callus. Therefore, our results are demonstrated that the elicitor supplements have the potential to enhance biomass and phytoconstituents in leaf-derived callus cultures of C. fragrans.

In the past decade, the development of metal nanoparticles in an eco-friendly manner has become an important aspect in the field of nanotechnology. Our present study reports the utilization of Urginea indica (U. indica) bulbs for the synthesis of copper (Cu) and copper oxide nanoparticles (Cu2O NPs). Cytotoxic activity against colon (HCT-116) carcinoma cell lines as well as their antibacterial and scavenging potential were determined. The green synthesized copper nanoparticles were confirmed using various analytical characterization techniques. The cytotoxic effect of the NPs was studied by MTT assay, and scavenging efficacy was assessed by DPPH and ABTS assays. Furthermore, green synthesized nanoparticles were evaluated for their antibacterial activity by the Agar disc diffusion method against multidrug-resistant bacterial strains. The nanoparticles were observed to be almost spherical in shape with an average diameter of 66.99nm as assessed by SEM analysis. Nanoparticles revealed dose-dependent antioxidant activity and antimicrobial activity against bacterial strains viz. Enterococcus faecalis, Bacillus cereus, Escherichia coli, Serratia marcescens, and also in vitro studies revealed dose-dependent cytotoxic effects treated against HCT-116 cell line with IC50 of 56.726 μg/mL. The data obtained in the study shows that Cu-Cu2O NPs obtained from U. indica bulbs have potent therapeutic value in the pharmaceutical industry.

Iron-based nanoparticles were synthesized using aqueous extracts of Alpinia galangal rhizoid by the green combustion method. A. galanga is an important medicinal plant and it has more medicinal value. In this study, we aim to characterize the synthesized iron oxide (α-Fe2O3) and different mole percent of copper doped nanoparticles (NPs) by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy-dispersive X-ray (EDX), UV-visible (UV-vis), Fourier transform infrared (FTIR) spectroscopy and their biological activity. From the XRD, it was found that the size of the NPs was 20 - 60 nm and it is evident from TEM image. The UV-visible absorption peaked at 278, 435 and 550 nm were observed due to the ligand to metal charge transfer transitions double excitation of an Fe³⁺ pair. IR bands at ∼ 535 and ∼450 cm⁻¹ were observed from FTIR spectra and is due to Fe–O vibrations. SEM results reveal the irregular spherical shape of the α-Fe2O3 and copper doped α-Fe2O3 NPs. There is no much variation in size and shape of the nanoparticles in between undoped and doped iron oxide. The antibacterial activity of synthesized undoped and copper doped α-Fe2O3 NPs was performed by a disc-diffusion and microtiter method against human pathogenic gram-negative and gram-positive bacteria. Maximum inhibition was observed against Serratia marcescens followed by Bacillus cereus in all samples. α-Fe2O3 NPs also exhibit anticancer activity against three human cancer cell lines like ovarian cancer cell line (SKOV3), metastatic breast cancer cell line (MDAMB-231), and colon cancer cell line (COLO-205). Significant antiproliferative activity was observed against ovarian cancer in MTT assay, induced cell cycle arrest, and cell death was noticed in SKOV3. The results revealed that undoped and copper doped α-Fe2O3 NPs have a wide range of antibacterial applications and also showed anticancer activity against ovarian cancer cell lines. This green synthesis approach is low-cost and eco-friendly and it can be applied in various fields. This indicates that the α-Fe2O3 NPs have the potential to serve as a green nano-oxide for pharmaceutical industries.

Nothapodytes nimmoniana (Graham) Mabb. (N. nimmoniana), gaining more attention for its wide range of medicinal uses and its pharmaceutical activities. The present study was designed to standardize the protocol for embryo culture, callus induction and its phytochemical and antioxidant activities. Mature embryos of N. nimmoniana were inoculated on L2 medium supplemented with cytokinins (2 mg/L of BAP and 1 mg/L of KIN). Callus induction was observed from nodal explants derived from regenerated shoots, when sub cultured on L2 medium fortified with BAP (0.5 mg/L) + NAA (1 mg/L) + 2,4-D (1 mg/L). Preliminary screening reveals the presence of various primary and secondary phytochemicals like alkaloids, flavonoids, polyphenols, steroids, saponins, tannins in leaf, bark, root, callus and in vitro root. Total alkaloids content (57.40 ± 0.50 µg of CE /mg) was found to be higher in methanolic extract of root. Whereas leaf extract revealed higher content of total flavonoids (87.91 ± 0.65 µg of QE /mg) and total tannins (35.36 ± 0.095 µg of TAE/mg). The total phenolics were found to be maximum in the callus extract (55.58 ± 0.28 µg of GAE/mg). Root extracts showed significant DPPH and ABTS scavenging activity with an IC 50 values of 51.52 ± 0.40 µg/mL and 26.64 ± 0.36 µg/mL respectively. Leaf extract demonstrated better total antioxidant and reducing power activity with an IC 50 value of 70.63 ± 0.38 µg of AAE/mg and 396.33 ± 1.53 µg/mL. Our study demonstrated that methanolic extract proves to be a better solvent for extraction of phytochemicals and antioxidant activity and further studies are required to isolate the bioactive compounds from the crude extract.

ZnO: Ag (0–20 mol%) hexagonal nanostructures were prepared via the phyto-synthesis route using Chonemorpha fragrans leaf extract. The structure, morphology, and compositions of the as-formed product were characterized by powder X-ray diffraction (PXRD), Field Emission Scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Surface-enhanced area diffraction (SEAD), and Raman spectroscopy. Further, prepared nanostructures were subjected to sensor and luminescence studies. PXRD pattern shows the formation of the hexagonal wurtzite system. The Rietveld refinement analysis is used to refine structural parameters. FESEM micrographs show the agglomeration of the nanoparticles. The TEM pictures reveal the hexagonal shaped nanoparticles. The average 30 - 35 nm ranged crystallite sizes were determined using Scherrer's method which is in good agreement with the TEM. An economical and naturally responsive strategy can be the use of plant extract in the synthesis of nanostructured products. Also, studies related to sensing of paracetamol were performed using ZnO: Ag (20 mol%) indicating that it is a promising electrode material for paracetamol sensing. The identified PL emission bands indicate favorable luminescence applications for ZnO: Ag nanopowders.

Decalepis arayalpathra is one of the important medicinal plants with milky latex, which grows on the exposed rocky slopes at an 800-1200 m elevation. It is endemic to the southern region of the Western Ghats chiefly in the Agasthyamalai region of Tamil Nadu. The plant has been used by traditional people to treat various diseases such as peptic ulcers, cancer like affliction, skin diseases etc. The moniliform tuberous roots have special fragrance like vanilla, because the roots contain different compounds such as α-amyrin acetate, ß-sitosterol, naringenin, kaempferol and aromadendrin especially in 2-hydroxy 4-methoxy benzaldehyde (2H4MB). The present study was aimed to examine the phytochemical screening and identification of bioactive compounds of Decalepis arayalpathra by GC-MS & HPLC analysis. The phytochemical analysis was carried out by using standard methods. Preliminary phytochemical screening showed major bioactive compounds such as alkaloids, flavonoids, proteins, steroids, terpenoids, quinones, resins, phenols, tannins, volatile oils and other phytocompounds. FTIR analysis identified various bioactive components and those were confirmed through GC-MS analysis. 2-hydroxy 4-methoxybenzaldehyde (2H4MB) and ß-sitosterol were quantified by HPLC analysis. Further studies have to be carried out in the in-vitro multiplication, isolation and characterization of compounds to enhance the root flavouring complexes for medicinal, food and beverage industries.

The present work is aimed to determine the chemical constituents in Baliospermum montanum methanolic extracts. An in vitro regenerated procedure was developed for the induction of callus from stem explant cultured on Murashige and Skoog (MS) medium fortified with various concentration and permutations of 2, 4-dichloro phenoxy acetic acid, 1-naphthalene acetic acid, 6-benzyl amino purine and gibberellic acid. FTIR & GC-MS analysis was done according to standard procedure. The quantitative estimation of β-sitosterol was done by HPLC method. Maximum fresh and dry weight of callus was estimated in the combination of GA3 (0.5 mg/L) + NAA (2 mg/L) compared to other concentration. The FTIR analysis showed various functional compounds with different characteristic peak values in the extracts. Major bioactive constituents were recognized in the GC-MS analysis. Root extract revealed the existence of 1-hexadecanol, pentanoic acid, 2-(aminooxy)- and 1-hexacosanol. Leaf extract showed the presence of propanoic acid, 2-oxo-, trimethylsilyl ester, 9,12-octadecadienoic acid (z,z)-, trimethylsilyl ester, docosane, 1,22-dibromo- and pentatriacontane. Stem and stem derived callus exhibit the presence of 1,6,3,4-dihydro-2-deoxy-beta-d-lyxo-hexopyranose, n-hexadecanoic acid and pentanoic acid, 2-(aminooxy). The methanolic extract of leaf exhibited 0.2149 % of β-sitosterol content. There were no peaks observed in the root, stem and stem derived callus. Further studies are necessary for the isolation and characterization of bioactive compounds from B. montanum.

The aim of the study was to develop an effective protocol for the in vitro shoot regeneration by direct organogenesis and to analyze its phytochemical and antioxidant activities of Chonemorpha fragrans. Shoot tip and nodal explants were inoculated on B5 medium supplemented with different concentrations of auxins and cytokinins individually as well as in combination for shoot induction. Maximum percentage of shoot initiation was observed in 1 mg/L of BAP. The excised in vitro shoots were transferred to the root induction medium and the roots were significantly induced in half strength B5 medium supplemented with 2 mg/L of IBA. The regenerated plants were transferred to sterilized sand, manure and soil rite (1:1:2) for acclimatization and hardening. About 80% of regenerated plants survived in the field conditions. The total phenols, flavonoids and tannin contents were found to be highest in leaf extracts and alkaloid content in stem extracts. The stem extracts showed higher antioxidant capacity and DPPH radical scavenging activity. Whereas, prominent reducing power activity was recorded in leaf extracts. Our results showed that efficient in vitro regeneration from shoot tip and nodal explants which helps to conserve this medicinally important plant from natural habitat. © 2020 Society for Biology and Biotechnology. All rights reserved.