Banca de DEFESA: RAFAEL FERREIRA DOS SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : RAFAEL FERREIRA DOS SANTOS
DATE: 22/01/2026
TIME: 09:00
LOCAL: UFRRJ-IQ-Programa de Pós-graduação em Química
TITLE:

Chemical and Biological Study of Melipona mondury Geopropolis and the Synthesis of Analogous Chalcones: Isolation, Characterization, and Structure–Activity Relationships

KEY WORDS:

C-Methylated Flavanones, Phytochemical Characterization, Chalcone Synthesis, and Biological Activity

PAGES: 200
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Química dos Produtos Naturais
SUMMARY:

Propolis is a natural resin produced by Africanized honeybees and stingless bees (SB), playing an essential role in the protection and organization of colonies. In the genus Melipona, this material is known as geopropolis, as it results from the combination of plant resins, waxes, salivary secretions, and inorganic materials such as soil and/or clay. This complex matrix acts in sealing crevices, reinforcing nest structure, mummifying intruders, and maintaining an aseptic internal environment, thereby contributing to colony health (Cardozo et al., 2015; Sousa et al., 2019).

Since antiquity, bee products have been used in traditional medicine, mainly due to their therapeutic properties. Among these products, geopropolis has attracted increasing scientific interest because of the wide range of biological activities attributed to it, including antioxidant (De Souza et al., 2013; Dutra et al., 2014), anti-inflammatory (Franchin et al., 2012; 2013), gastroprotective (Ribeiro-Junior et al., 2015), antiviral (Coelho et al., 2015), antimicrobial (Sousa et al., 2019; Novaes & Torres, 2024), and antiproliferative activities (Cunha et al., 2013; Campos et al., 2014). Despite this potential, systematic studies on Brazilian geopropolis only began in the late 1990s, which explains the still limited knowledge regarding its chemical composition, biosafety, pharmacological properties, and possible biomarkers (Bankova et al., 1998; Cardozo et al., 2015).

The chemical composition of (geo)propolis is notoriously complex and variable, being influenced by factors such as surrounding vegetation, seasonality, climatic conditions, soil type, and the genetic characteristics of the producing bees. In the case of stingless bees, this variability is even more pronounced due to the high diversity of species and the scarcity of consolidated data on the botanical sources exploited, which hinders the detailed chemical characterization of this matrix (Menezes, 2005).

Previous studies have reported the presence of different classes of organic substances in the geopropolis of Melipona species, including prenylated benzophenones, phenolic compounds, di- and triterpenes, free and glycosylated flavonoids, phenolic acids, terpenic acids, saponins, aldehydes, and alcohols, as well as minerals derived from the soil incorporated into the matrix (Cardozo et al., 2015; Sousa et al., 2019; Silva et al., 2020). However, there are still few studies that systematically address the isolation, structural elucidation, and biological evaluation of the compounds responsible for the pharmacological activities attributed to geopropolis, especially that produced by Melipona mondury (Dos Santos et al., 2017; Dos Santos et al., 2025).

In this context, the isolation and characterization of bioactive compounds from geopropolis are fundamental strategies to correlate specific metabolites with their possible botanical sources, thereby expanding the understanding of the plants visited by bees during resin collection. Moreover, the identification of these substances allows a more accurate assessment of their biological and biotechnological properties, providing support for the standardization of geopropolis, the establishment of quality and safety criteria, and its potential therapeutic and industrial applications.

Advancing the chemical knowledge of geopropolis may also guide sustainable hive management practices and encourage the conservation of resin-producing plant species, promoting benefits for both biodiversity and meliponiculturists. However, the isolation of substances from this natural matrix poses significant challenges, as geopropolis is produced in limited quantities and exhibits high compositional variability, which hampers the reproducibility of isolation processes and the acquisition of sufficient amounts for structural and pharmacological studies (Magalhães & Venturieri, 2010; Gemim & Silva, 2017).

Given these limitations, the synthesis of natural products and their analogues emerges as a strategic alternative in Natural Products Chemistry, enabling the production of larger quantities of bioactive compounds and the introduction of structural modifications aimed at studying structure–activity relationships. In this regard, chalcones—recognized as biosynthetic precursors of flavonoids and characterized by broad structural versatility and biological relevance—are promising synthetic models for investigating the mechanisms underlying the observed activities.

Accordingly, this thesis is organized into two chapters. Chapter 1 addresses the isolation, chemical characterization, and evaluation of the biological properties of substances obtained from the geopropolis of the stingless bee Melipona mondury, collected in Bosque da Barra, Rio de Janeiro State, Brazil. Chapter 2 focuses on the synthesis of chalcones analogous to the flavonoids isolated from this matrix, aiming to investigate structure–activity relationships and to broaden the understanding of the mechanisms associated with the observed biological activities.

COMMITTEE MEMBERS:
Presidente - 1177598 - ROSANE NORA CASTRO
Interna - 1979542 - RENATA BARBOSA LACERDA
Interno - 3292567 - EDUARDO HILLMANN WANDERLIND
Externa à Instituição - WANDA PEREIRA ALMEIDA - UNICAMP
Externa à Instituição - GILDA GUIMARÃES LEITÃO - UFRJ
Externo à Instituição - DAVYSON DE LIMA MOREIRA - JBRJ
Externa à Instituição - THATYANA ROCHA ALVES VASCONCELOS - UFF