Diabetes Mellitus is an endocrine disorder which causes insulin deficiency. Medicinal plants are documented to be efficacious in the management of the disease. The current research set to determine the phytochemicals present, anti-oxidant activity and investigate the potency of Eriobotrya japonica against α-amylase inhibition. The leaves of the plant were extracted sequentially. The different extracts were evaluated for the presence of phytochemicals and their potential anti-oxidant and α-amylase inhibition activity. Methanol with the highest polarity, gave the highest yield of 20% and hexane with the lowest polarity have the lowest yield of 2.09%. This trend resembled that observed for the total flavanoid and total phenolic content analysis which gave values of 0.3822 mg QAE/mg and 3.810 mg GAE/mg respectively for methanolic and hexane extracts. The extracts of methanol recorded higher DPPH free radical scavenging activity of 87% and gave the lowest IC 50 of 0.5336 which was below that of ascorbic acid used as a control. Hexane extract had a higher α-amylase inhibitory activity of 24% at 1 μg/ml as compared to other extracts. Generally hexane extracts of Eriobotrya japonica exhibits mild inhibitory activity against α-amylase enzyme which is recommended than the conventional therapy which maximally inhibits the enzyme causing major side effects. The results obtained herein support the use of the plant as an anti-diabetic agent at higher concentrations.

The resistance of microorganisms towards antibiotics remains a big challenge in medicine. Silver nanoparticles (AgNPs) received attention recently for their characteristic nanosized features and their ability to display antimicrobial activities. This work reports the synthesis of AgNPs using the Citrus sinensis peels extract in their aqueous, mild, and less hazardous conditions. The effect of concentration variation (1%, 2%, and 3%) of the plant extracts on the size and shape of the AgNPs was investigated. The antimicrobial activities were tested against gram-positive Staphylococcus aureus and gram-negative Klebsiella pneumoniae. Absorption spectra confirmed the synthesis by the surface Plasmon resonance peaks in the range 400–450 nm for all the AgNPs. FTIR spectra confirmed that Citrus sinensis peels extract acted as both reducing and surface passivating agent for the synthesized AgNPs. TEM revealed spherical AgNPs with average size of 12 nm for 3% concentration as compared to the agglomeration at 1% and 2%. All the AgNPs synthesized using Citrus sinensis peels extracts (1%, 2%, and 3%) exhibited antimicrobial activity against both gram-positive and negative bacteria. These results indicated a simple, fast, and inexpensive synthesis of silver nanoparticles using the Citrus sinensis peels extract that has promising antibacterial activity.