Antimicrobial, antioxidant and cytotoxic activites and chemical profile of species of Miconia Ruiz Pav., Clidemia D. Don and Tibouchina Aubl. (Melastomataceae)

Abstract

The resistance of microorganisms to current antimicrobials, and the deleterious effects caused by the excessive free radical manufacturing in the human body and their relationship with increasing global incidence of cancer, has led to a continuous search for new chemical agents that can contribute to the fight against these ills. The objective of the present work was to evaluate the antimicrobial, antioxidant and cytotoxic activities and determine the chemical profile of ethyl acetate extract of ten species of the family Melastomataceae. Antimicrobial activity was assessed by the methods of disk diffusion in agar and microdilution in broth (MIC-µg/mL). Antioxidant activity was measured by DPPH free radical capture assay while toxicity was evaluated with Artemia salina Leach. Cytoxicity was evaluated by in vitro tests with THP-1-cells. Identification of the classes of metabolites was performed using chemical reagents, while quantification of total phenols (EGA/g) and total flavonoids (EQ/g) was done by spectrophotometry. The extract of Clidemia capitellata exhibited activity against Micrococcus luteus with MIC = 62.5-μg/mL. The extract of C. hirta had the highest sequestering activity of DPPH free radicals (63.54-%). The toxicological assay revealed high toxicity for Miconia alborufescens extract (CL 50 61.6-μg/mL). Cytotoxic activity of extracts for THP-1-cells was observed through visualization of apoptotic bodies and cell death. Phytochemical analysis detected the presence of condensed tannins, terpenes, steroids and polyphenols, and the absence of alkaloids. The assays performed provided promising results, suggesting the continuation of new chemical-pharmacological evaluations and the isolation of the active principle of the extracts.

Phytochemical composition and biological activities of extracts from ten species of the family Melastomataceae Juss

“…Phytochemical evaluations of species of Melastomataceae have revealed the presence of phenolic compounds, triterpenes, steroids, anthocyanins, saponins, organic acids, tannins, anthraquinones and benzoquinones among their constituents as secondary metabolites (Jones et al, 1980;Santos and Tavares, 2003;Serna and Martínez, 2015;Bomfim et al, 2020). The solvent and extractive method used can influence variation in the levels of total phenols and total flavonoids present in extracts (Oliveira et al, 2016), as well as in biological activity.…”

“…The absorbance reading of the samples was performed at 620 nm with a UV-Vis spectrophotometer. The same preparation conditions were used to construct the calibration curve for gallic acid (y = 3.8883x + 0.11141; R 2 = 0.9954) (Bomfim et al, 2020). The results were expressed in milligrams of gallic acid per gram of crude extract (mg EAG/g of extract).…”

“…The content of total flavonoids was measured at 492 nm with a UV-Vis spectrophotometer and expressed in milligrams of quercetin per gram of crude extract (mg EQ/g of extract). The standard quercetin curve was obtained under the same sample preparation conditions (y = 1.2078x -0.1175; R 2 = 0.9889) (Bomfim et al, 2020).…”

“…Studies of the biological potential of the family Melastomataceae have demonstrated that its species have analgesic, antioxidant, antimicrobial, anti-inflammatory activities (Vasconcelos et al, 2006;Andreo et al, 2006;Sobrinho et al, 2017;Bomfim et al, 2020). These activities may be associated with the presence of several secondary metabolites such as flavonoids, tannins, terpenes and anthocyanidins (Calderón et al, 2002;Serna and Martínez, 2015;Bomfim et al, 2020) which are synthesized by plants in response to environmental conditions and often during specific stages of their development. Polyphenols can act by damaging and altering the permeability of the bacterial cell membrane (Cushnie and Lamb, 2005) and combating oxidative stress.…”

Estudo morfoanatômico de Clidemia hirta (L.) D. Don.

“…Another study, carried out by Narasimham, et al (2017), demonstrated anti-cancer activity of diluted ethanolic extract of Clidemia hirta leaves against cells of the Dalton Lymphoma Ascites (DLA) lineage. Bomfim, et al (2020) verified antimicrobial activity by the disk diffusion test of the ethyl acetate extract of the aerial parts of C. hirta against M. luteus, S. aureus, and P. aeruginosa, with halos of 13.0 ± 1.02, 9.0 ± 0.57, and 10.0 ± 1.52 mm, respectively, antioxidant activity by the DPPH method (63.54 ± 1.46%) and high toxicity against Artemia salina (LC50 75.8 μg / ml).…”