Green Synthesis of Silver Nanoparticles Using Novel Launaea Procumbens Leaves Extract and Screening Its Antibacterial Activity

Plants are emerging as a cost-effective and ecofriendly method for green synthesis of nanoparticles. The plant extract Launaea procumbens was used as a reduction agent in the green synthesis of silver nanoparticles. UV-Visible spectroscopy, HR-TEM, SAED, FE-SEM, EDAX, DLS, and FT-IR were used to study the green synthesized silver nanoparticles. UV-Vis spectroscopy of a prepared silver solution revealed maximum absorption at 435 nm. The synthesized silver nanoparticles were found to be spherical in shape with a size in the range of 24.28 to 31.54 nm. DLS analysis was used to determine the size of the green synthesized silver nanoparticles, which showed outstanding antibacterial action against Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus, as well as Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Gram-positive Bacillus subtilis had a maximum zone of inhibition of 20 mm, Staphylococcus aureus had a zone of inhibition of 19 mm, and Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa had zones of inhibition of 13 mm.

Phytopharmacognostical and Chromatographic Evaluation of Leaves of Launaea procumbens

Launaea procumbens leaves are galactagogue, diuretic, antifungal, anorexic, anti-arthritic and hepatoprotective according to Ayurvedic texts as well as modern research. Launaea species, particularly L. pinnatifida, is mentioned as one of the sources of Gojihva, regarding which there is controversy with respect to its true botanical identity. However, no detailed anatomical, phytochemical or chromatographic investigation is available for leaf of L. procumbens which can differentiate it from L. pinnatifida. The aim of this work is to develop standardization parameters of L. procumbens leaves by performing its pharmacognostical evaluation, preliminary phytochemical screening, HPTLC and GC-MS fingerprints. Pharmacognostic investigation of the leaves was performed by its morphological study, qualitative and quantitative microscopy as well as powder microscopy. Extraction of leaves was done by maceration using methanol. This extract was used for preliminary phytochemical screening and chemoprofiling by GC-MS, as well as for developing its HPTLC fingerprint. A mobile phase system was developed by pilot TLC, following which an HPTLC fingerprint was performed using the solvent system chloroform: methanol: ethyl acetate (3:7:6). Diagnostic microscopic characters identified in powder include unicellular covering trichome, xylem vessels, anomocytic stomata, and prisms of calcium oxalate crystal. Phytochemical screening revealed the presence of phytoconstituents classes like phenolics, anthraquinones, saponin glycosides, carbohydrates, sterols, triterpenoids and flavonoids. HPTLC fingerprinting detected 6 peaks with Rf 0.25, 0.37, 0.41, 0.50, 0.65, 0.78 at 254nm and 4 peaks with Rf 0.32, 0.37, 0.50, 0.66 at 366nm. GC-MS fingerprint revealed presence of propanoic acid anhydride, valeric anhydride, 2- Pyrrolidine acetic acid, phthalan, 5- (Hydroxy methyl)-2-(dimethoxy methyl) furan, vanillin, methyl β-l-Arabino pyranoside, 1,6-anhydro-β-D-Gluco pyranose and 6-Methyl-2-Heptanone, 6-(3,5-dimethyl-2-furanyl). Present study will be very useful for herbal industry in differentiating Launaea procumbens from other species of the genus Launaea, particularly L. pinnatifida (Gojihva) as well as for authentication, standardization and detection of adulteration in the leaf formulations of Launaea procumbens.