The brown seaweed, Sargassum linearifolium (Turner) C. Agardh, 1820 is commonly available along the south-east coast of India. Its compound fucosterol was isolated and confirmed through spectral characterisation and chemical transformation methods. The antiplasmodial effect of the isolated fucosterol was investigated against the 3D7 chloroquine sensitive Plasmodium falciparum strain, parasitaemia percentage was determined at 48 h and morphological change was studied through microscopic examination after Giemsa staining. A perceptible antiplasmodial effect was produced by fucosterol compound against the P. falciparum and positive control, chloroquine with the IC₅₀ values (μg/mL) of 7.48 and 12.81, respectively. Fucosterol showed higher antiplasmodial activity as compared to chloroquine. It is inferred that both the fucosterol and chloroquine could have inhibited the schizont stage of the parasite during the intra-erythrocyte asexual development. The findings underline the usefulness of the seaweed-based fucosterol and further studies are warranted.

The main objective of the present research work is to assess the biological properties of the aqueous plant extract (ACAE) synthesised silver nanoparticles from the herbal plant Ageratum conyzoides, and their biological applications. The silver nanoparticle syntheses from Ageratum conyzoides (Ac-AgNPs) were optimised with different parameters, such as pH (2, 4, 6, 8 and 10) and varied silver nitrate concentration (1 mM and 5 mM). Based on the UV–vis spectroscopy analysis of the synthesised silver nanoparticles, the concentration of 5 mM with the pH at 8 was recorded as the peak reduction at 400 nm; and these conditions were optimized were used for further studies. The results of the FE-SEM analysis recorded the size ranges (~30–90 nm), and irregular spherical and triangular shapes of the AC-AgNPs were captured. The characterization reports of the HR-TEM investigation of AC-AgNPs were also in line with the FE-SEM studies. The antibacterial efficacies of AC-AgNPs have revealed the maximum zone of inhibition against S. typhi to be within 20 mm. The in vitro antiplasmodial activity of AC-AgNPs is shown to have an effective antiplasmodial property (IC₅₀:17.65 μg/mL), whereas AgNO₃ has shown a minimum level of IC₅₀: value 68.03 μg/mL, and the Ac-AE showed >100 μg/mL at 24 h of parasitaemia suppression. The α-amylase inhibitory properties of AC-AgNPs have revealed a maximum inhibition similar to the control Acarbose (IC₅₀: 10.87 μg/mL). The antioxidant activity of the AC-AgNPs have revealed a better property (87.86% ± 0.56, 85.95% ± 1.02 and 90.11 ± 0.29%) when compared with the Ac-AE and standard in all the three different tests, such as DPPH, FRAP and H₂O₂ scavenging assay, respectively. The current research work might be a baseline for the future drug expansion process in the area of nano-drug design, and its applications also has a lot of economic viability and is a safer method in synthesising or producing silver nanoparticles.

Objectives: To analyse the phytochemicals and evaluate the antioxidant and anti-proliferative ability of Turbinaria ornata (Turner) J. Agardh, 1848. Methods: A phytochemical analysis of the T. ornata-hexane extract (To-HE) and T. ornata-aqueous extract (To-AE) was performed. T. ornata extracts were analysed by gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR) and high-performance liquid chromatography (HPLC). The antioxidant properties of To-HE and To-AE were determined by 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH) and ferric ion reducing power (FRAP) assays. In addition, the in vitro anti-proliferative properties of To-HE and To-AE were assessed in kidney epithelial cells from the African green monkey (Vero) and in adenocarcinomic human alveolar basal epithelial cells (A549) using the MTT (3-(4,5-dimethylthiazol- 2yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole) assay. Results: The phytochemical screening of T. ornata revealed the presence of saponin, alkaloids, amino acids, fixed oil and fat and phenolic compounds (tannins, flavonoids and total phenol). A higher antioxidant ability was found in To-HE than in To-AE. The anti-proliferative efficacy values (μg/mL) of To-HE and To-AE for A549 and Vero cells were 62.91 and 93.00 and 72.64 and 106.6, respectively. The FTIR analysis revealed the presence of functional groups such as alcohols, amides, aromatics, amines, alkyl halides, alkynes, alkanes and carboxylic acids. The GC-MS analysis of To-HE revealed the presence of 13 active compounds. Conclusion: Owing to its recorded anti-proliferative effect, further pharmaceutical studies on the development of this anticancer drug are merited.