Asian Journal of Biology

Non-Hemolytic Effect and Antiplasmodial Activity of Cassia sieberiana Root Bark on Plasmodium falciparum Isolates

2026-07-15T07:50:29+00:00

Introduction: Malaria remains endemic in Côte d’Ivoire, and Plasmodium falciparum is the predominant species associated with malaria attacks.

Aims: This study evaluated the phytochemical composition, haemolytic effect, and antiplasmodial activity of an aqueous extract of Cassia sieberiana root bark against P. falciparum isolates.

Methods: The aqueous extract was prepared by decoction, and selected secondary metabolites were identified using colorimetric methods. Haemolytic activity was assessed using uninfected O+ red blood cells, with phosphate-buffered saline and Triton X-100 serving as the negative and positive controls, respectively. Antiplasmodial activity was evaluated against 30 P. falciparum isolates, with quinine used as the reference antimalarial molecule.

Results: The extract contained alkaloids, saponins, polyphenols, flavonoids, and catechic tannins, whereas gallic tannins, sterols and terpenes, and quinones were not detected. The measured haemolysis percentage was 0.619%. Antiplasmodial activity increased across the tested concentrations. At the highest tested concentration, the minimum and maximum IC50 values were 1.11 ± 0.00 μg/mL and 4.33 ± 0.00 μg/mL, respectively.

Conclusion: Under the reported in vitro conditions, the aqueous root-bark extract showed low haemolytic activity and inhibited P. falciparum isolates. These findings provide preliminary evidence that water-extractable constituents of C. sieberiana root bark may contribute to the observed antiplasmodial activity. Further standardised studies are required to confirm the dose-response relationship, cytotoxicity, selectivity, active constituents, and possible mechanisms.

Valorization of Ripe Plantain Peel Waste in Aquaculture: Acute Toxicity, Behavioural Responses and Tissue Alterations in Juvenile African Catfish (Clarias gariepinus) (Burchell, 1822)

2026-07-28T07:58:50+00:00

This study evaluated the acute toxicity, behavioural responses, water-quality variations, and histopathological alterations in the gills and liver of juvenile Clarias gariepinus exposed to an ethanolic extract of ripe plantain (Musa paradisiaca) peels. Fish were exposed to extract concentrations of 0, 20, 25, 30, and 35 mg/L for 96 hours under static bioassay conditions. Behavioural responses, mortality, and water-quality parameters were monitored throughout the experiment, while histological examinations of the gill and liver tissues were conducted at the end of the exposure period. Exposed fish exhibited concentration-dependent behavioural abnormalities, including erratic swimming, respiratory distress, vertical erection, air gulping, and escape attempts. Mortality increased progressively with increasing extract concentration, with the highest mortality recorded at 35 mg/L. The 96-hour LC₅₀ was estimated at 35 mg/L (log concentration = 1.54), indicating moderate toxicity. Significant variations were observed in dissolved oxygen, pH, temperature, and conductivity across the concentrations and exposure periods. Histological examination of the gills revealed predominantly normal architecture, with only mild focal epithelial degeneration and haemorrhage at 20 mg/L. Liver tissues exhibited concentration-dependent alterations, including macrovesicular steatosis, inflammatory-cell infiltration, cytoplasmic vacuolation, vascular congestion, and sinusoidal congestion. The findings indicate that the ethanolic extract induced physiological and histopathological stress in juvenile C. gariepinus at higher concentrations, with the liver showing greater responsiveness than the gills. However, the absence of severe tissue necrosis suggests low-to-moderate toxicity within the tested concentration range. These results provide baseline information for evaluating the potential utilisation of ripe plantain peel-derived products in aquaculture.

Field Validation of Fungicides for the Management of Rice Brown Spot Disease (Bipolaris oryzae)

2026-07-29T09:39:46+00:00

Brown spot, caused by Bipolaris oryzae, is an important constraint to rice production under favourable disease conditions. This study evaluated the field efficacy of eight fungicides against brown spot and assessed disease severity among rice genotypes cultivated in farmers’ fields. A randomised complete block design with three replications was established at Rampur, Chitwan, using the susceptible cultivar Sankharika. Eight fungicide treatments and an untreated control were compared following three foliar applications at seven-day intervals. Disease severity and the area under the disease progress curve (AUDPC) were determined, and grain yield was correlated with AUDPC. A roving survey was also conducted at 21 locations in Chitwan and Nawalparasi districts. All fungicide treatments reduced final disease severity relative to the untreated control. Metalaxyl 8% + mancozeb 64% WP recorded the lowest mean AUDPC (436.85), followed by carbendazim (470.50) and hexaconazole (482.20). Hexaconazole recorded the lowest final disease severity (28.90%), whereas the untreated control recorded 45.20%. The association between grain yield and AUDPC was weak and not statistically significant (r = −0.031). The survey identified six genotypes, with maximum severity of 78% in Samba Mansuli and Sabitri and minimum severity of 26% in Kalo Basmati. These findings indicate differential fungicide performance and genotype responses under the evaluated field conditions and support further multilocation and multiseason validation.

An Economic Analysis of Pacific White Shrimp Farming under Intensive Culture Bore Water in Winter Season

2026-08-01T09:31:45+00:00

This study evaluated intensive culture under bore-water conditions during the winter season in Alakapuram, Andhra Pradesh. Three ponds measuring 0.5, 0.5, and 0.4 ha were stocked with PL₁₀ at densities of 24, 25, and 25 post-larvae m^-2, respectively. Water-quality parameters were monitored fortnightly at 07:00 from August to November. Shrimp were fed commercial diets containing 35-42% protein. Survival rates were 58.7%, 88.6%, and 93.0% in Ponds A2, B3, and B4, respectively. The corresponding final average body weights were 19.90, 20.20, and 16.66 g, while total production was 1,403, 1,790, and 1,550 kg. Total feed use was 2,082, 2,304, and 2,040 kg, resulting in feed conversion ratios of 1.48, 1.29, and 1.32. The culture periods were 88, 82, and 72 days. Pond B3 produced the highest biomass and average body weight and had the lowest feed conversion ratio, whereas Pond B4 recorded the highest survival. Economic analysis indicated reported profits of Rs. 100, Rs. 120, and Rs. 110 kg^-1 for Ponds A2, B3, and B4, respectively.

Algae and Cyanobacteria-Mediated Biosynthesis of Metal and Metal Oxide Nanoparticles: Mechanisms, Characterisation, and Applications in Sustainable Agriculture and Environmental Remediation

2026-07-22T13:18:36+00:00

The biogenic synthesis of metal and metal oxide nanoparticles using algae and cyanobacteria has emerged as a candidate alternative to physical and chemical fabrication routes, which typically depend on hazardous reagents, high energy inputs, and toxic by-products. This critical narrative review synthesises the accessible peer-reviewed literature on algal and cyanobacterial nanoparticle biosynthesis, with particular attention to the biochemical mechanisms underlying metal ion reduction and capping, the analytical techniques used to confirm nanoparticle formation, and the evidence supporting applications in sustainable agriculture and environmental remediation. Evidence indicates that both intracellular and extracellular synthesis routes are biochemically plausible, mediated principally by NAD(P)H-dependent oxidoreductases, sulphated polysaccharides, phycobiliproteins, and phenolic metabolites, although the relative contribution of each pathway remains incompletely resolved and appears to vary by taxon, growth phase, and reaction condition. Characterisation practice is reasonably consistent across studies, relying on ultraviolet-visible spectroscopy, transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy, but methodological heterogeneity and limited replication constrain cross-study comparison. In agriculture, algal and cyanobacterial nanoparticles show consistent short-term benefits for seed germination, seedling vigour, and antimicrobial protection in laboratory and greenhouse trials, but field-scale and life-cycle evidence remains sparse. In environmental remediation, biosynthesised nanoparticles demonstrate measurable efficacy in heavy metal adsorption, dye photodegradation, and pollutant sequestration, though reported removal efficiencies vary widely with experimental design and are rarely benchmarked against conventional adsorbents under comparable conditions. Across both application domains, confidence in translational readiness is limited by inconsistent reporting of nanoparticle stability, scale-up feasibility, and ecotoxicological risk. The review identifies methodological standardisation, mechanistic elucidation through omics approaches, and rigorous field- and life-cycle-level evaluation as priority research needs. It concludes that while algal and cyanobacterial biosynthesis constitutes a scientifically credible and environmentally motivated alternative to conventional nanoparticle production, the current evidence base supports cautious optimism rather than confirmed practical readiness for large-scale agricultural or remediation deployment.