In the present study, the phenolic (Folin-Dennis) and flavonoid (colorimetric assay) constituents, antioxidant [2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) assay] and cytotoxic activities of an aqueous extract (AE) of Centella asiatica leaves were investigated. The aqueous extract (50 g/L) was obtained by infusion followed by cold maceration for 24 h. The levels of phenolic and flavonoid compounds were 2.86 g/100 g and 0.361 g/100 g, respectively. The AE showed elevated DPPH scavenging activity, with an IC₅₀ value of 31.25 μg/mL. The AE had a promising activity against mouse melanoma (B₁₆F₁), human breast cancer (MDA MB-231) and rat glioma (C₆) cell lines, with IC₅₀ values of 698.0, 648.0 and 1000.0 μg/mL, respectively. A positive correlation was established between the level of flavonoids, antioxidant and antitumor activities.

Proteinases play a fundamental metabolic role during the life cycle in the plant kingdom. By interacting with endogenous or exogenous inhibitors, the proteolytic activity is modulated to meet metabolic requirements. By probing proteolytic enzymes with their inhibitors, it is possible to identify novel functions unrelated to their proteolytic activity. A group of plant proteolytic enzymes stands as a line of defence against environmental changes as their activation is triggered following various types of stress. On the other hand, plants also contain proteinase inhibitors as countermeasures for their protection against insects and pests. Both proteinases and inhibitors emerge as useful tools to combat human diseases. This review focuses on the biochemical characterization of plant proteinases, their inhibitors, the pharmacological potential of proteinases and inhibitors, and new putative emerging functions of proteolytically inhibited proteinases.

The phytochemical study of hexane, chloroform and methanol extracts from leaves of Psychotria viridis resulted in the identification of: the pentacyclic triterpenes, ursolic and oleanolic acid; the steroids, 24-methylene-cycloartanol, stigmasterol and β-sitosterol; the glycosylated steroids 3-O-β-D-glucosyl-β-sitosterol and 3-O-β-D-glucosyl-stigmasterol; a polyunsaturated triterpene, squalene; the esters of glycerol, 1-palmitoylglycerol and triacylglycerol; a mixture of long chain hydrocarbons; the aldehyde nonacosanal; the long chain fat acids hentriacontanoic, hexadecanoic and heptadenoic acid; the ester methyl heptadecanoate; the 4-methyl-epi-quinate and two indole alkaloids, N,N-dimethyltryptamine (DMT) and N-methyltryptamine. The chemical structures were determined by means of spectroscopic (IR, ¹H and ¹³C NMR, HSQC, HMBC and NOESY) and spectrometric (CG-MS and LCMS-ESI-ITTOF) methods. The study of biologic properties of P. viridis consisted in the evaluation of the acetylcholinesterase inhibition and cytotoxic activities. The hexane, chloroform, ethyl acetate and methanol extracts, the substances 24-methylene-cycloartanol, DMT and a mixture of 3-O-β-D-glucosyl-β-sitosterol and 3-O-β-D-glucosyl-stigmasterol showed cholinesterase inhibiting activity. This activity induced by chloroform and ethyl acetate extracts was higher than 90%. The methanol and ethyl acetate extracts inhibit the growth and/or induce the death of the tumor cells strains B16F10 and 4T1, without damaging the integrity of the normal cells BHK and CHO. DMT also demonstrated a marked activity against tumor cell strains B16F10 and 4T1.