An analytical framework combining online high-performance liquid chromatography methodologies and biological properties of different extracts of Leonurus cardiaca.

Little or no information is available concerning online high-performance liquid chromatography (HPLC) antioxidants and the antibiofilm effect of Leonurus cardiaca. Five distinct extractions of methanolic, ethyl acetate, dichloromethane, hexane, and water were obtained from L. cardiaca. In the online-HPLC-antioxidant analysis of all examined samples, rosmarinic acid emerged as the primary antioxidant, registering concentrations ranging from 6 to 15 ppm at wavelengths of 517 and 734 nm. Notably, the water extract exhibited robust antioxidant activity In vitro. Regarding acetylcholinesterase and butrylcholinesterase inhibition, the n-hexane extract exhibited superior inhibition with values of 3.08 and 5.83 galanthamine equivalent, respectively. Except for the water extract, all tested extracts (at a concentration of 20 µg/mL) exhibited substantial inhibitory activity against biofilm formation, in many cases superior to 80%, and reached even 94.52% against Escherichia coli. Although less vigorous, the extracts also acted against the mature biofilm (inhibition up 76.50% against Staphylococcus aureus). They could work against the metabolism inside an immature and mature biofilm, with inhibition percentages up to 93.18% (vs. Pseudomonas aeruginosa) and 76.50% (vs. Acinetobacter baumannii), respectively. Considering its significant antioxidants, enzyme inhibition, and antimicrobial activity, L. cardiaca emerges as a promising candidate for therapeutic potential.

HPLC-FRAP methodology and biological activities of different stem bark extracts of Cajanus cajan (L.) Millsp.

Cajanus cajan. (L.) Millsp. (C. cajan) (Family: Fabaceae) also known as pigeon pea, is a famous food and cover/forage crop bearing a high amount of key amino acids (methionine, lysine and tryptophan). This study investigated into the total phenolic (TPC), flavonoid content (TFC), antioxidant [2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity, total antioxidant capacity (TAC) (phosphomolybdenum) and metal chelating] activities and enzyme [α-amylase, α-glucosidase, tyrosinase, acetyl-(AChE), butyryl-(BChE) cholinesterase] inhibitory effects of four extracts (methanol, hexane, ethyl acetate, aqueous) prepared from C. cajan stem bark. Direct identification of antioxidants was also conducted using the high performance liquid chromatography-ferric reducing antioxidant power (HPLC-FRAP) system. The highest TPC and TFC were recorded with the methanolic (23.22 ± 0.17 mg GAE/g) and ethyl acetate extracts (19.43 ± 0.24 mg RE/g), respectively. The methanolic extract exhibited important antioxidant activity with DPPH (38.41 ± 0.05 mg Trolox equivalent (TE)/g), ABTS (70.49 ± 3.62 mg TE/g), CUPRAC (81.86 ± 2.40 mg TE/g), FRAP (42.96 ± 0.59 mg TE/g) and metal chelating (17.00 ± 1.26 mg ethylenediaminetetraacetic acid equivalent/g). p-coumaric and caffeic acid were the predominant antioxidants in the samples. Results from enzymatic assays showed the potential abilities of hexane extract in inhibiting the AChE, BChE, α-amylase and α-glucosidase enzymes. From the results obtained in this study, it can be concluded that C. cajan can be considered as a promising source of antioxidants and key enzyme inhibitors that can be exploited for future bioproduct development.