Plectranthus species (Lamiaceae) have been employed in traditional medicine and this is now validated by the presence of bioactive abietane-type diterpenoids. Herein, sixteen Plectranthus acetonic extracts were prepared by ultrasound-assisted extraction and their biological activity was screened. The antimicrobial activity of each extract was screened against yeasts, and Gram-positive and Gram-negative bacteria. The P. hadiensis and P. mutabilis extracts possessed significant activity against Staphylococcus aureus and Candida albicans (microdilution method). Moreover, all extracts showed antioxidant activity using the DPPH method, with P. hadiensis and P. mutabilis extracts having the highest scavenging activities. Selected by the Artemia salina model, P. hadiensis and P.ciliatus possessed low micromolar anti-proliferative activities in human colon, breast, and lung cancer cell lines. Furthermore, the most bioactive extract of P. hadiensis leaves and the known abietane diterpene, 7α-acetoxy-6β-hydroxyroyleanone isolated from this plant, were tested against the aggressive type triple negative breast cancer (MDA-MB-231S). P. hadiensis extract reduced the viability of MDA-MB-231S cancer cell line cells, showing an IC50 value of 25.6 µg/mL. The IC50 value of 7α-acetoxy-6β-hydroxyroyleanone was 5.5 µM (2.15 µg/mL), suggesting that this lead molecule is a potential starting tool for the development of anti-cancer drugs.

The study of natural sources such as plants, microorganisms and marine organisms has developed interest among the scientific community in recent years for their extensive and diverse chemical composition and consequent biological potential. The search for antitumor compounds is among the lead causes that justify phytochemical studies. Although some natural products have served as FDA approved chemotherapeutic agents, there is still a demand for the search of compounds with those characteristics. The Plectranthus genus has long been used in traditional medicine, and scientific studies have already proven its undeniable value as a source of bioactive compounds. Diterpenes are the most prominent biologically active group of secondary metabolites present in this genus. In particular, abietane diterpenes have long been studied for their biological activities, namely their anti-tumoral potential. In this review, abietane diterpenes isolated from Plectranthus genus with antiproliferative, antitumoral or cytotoxic potential are reported. In addition, a correlation between this subclass of diterpenes with their mechanisms of cell death has been discussed.

Biopharmaceutical Sciences│Ciências BiofarmacêuticasBiomed Biopharm Res. , 2017; (14) 1: , 95-108 95 Biomedical and Biopharmaceutical Research J o r n a l d e I n v e s t i g a ç ã o B i o m é d i c a e B i o f a r m a c ê u t i c a Biological activity screening of seven Plectranthus species AbstractNatural products from Plectranthus spp. plants have an ethnopharmacological use, inspiring several scientific investigations. As such, this work aims to perform a biological activity screening in order to scientifically validate the use of these plants. Assays on in vitro acetylcholinesterase (AChE) inhibition, antioxidant effects, antimicrobial activity and Artemia salina lethality were performed on seven Plectranthus spp. extracts (P. swynnertonii, P. welwischii, P. woodii, P. cylindraceus, P. spicatus, P. ramosior and P. petiolaris). Acetonic extracts were obtained by sonication (10% w/v), where P. ramosior had the highest yield of dry extract (13.49% w/w). In the AChE inhibition assay, only P. cylindraceus extract decreased enzymatic activity (30.2 ± 3.78%). The antimicrobial activity was screened using the well diffusion method, against Gram positive and negative bacteria and yeast. P. ramosior extract showed not only an inhibition zone against S. aureus and C. albicans (15 and 11 mm, respectively), but also the highest scavenging activity (DPPH method, 36.4 ± 0.04%). On the lethality test in A. salina, P. swynnertonnii extract was the most toxic (LC50 = 0.036 mg/L). These preliminary results showed that P. cylindraceus, P. ramosior and P. swynnertonnii are potential bioactive extracts for further isolation and antimicrobial and cytotoxic studies.Keywords: Plectranthus, Acetylcholinesterase, Antioxidant, Antimicrobial, Toxicity ResumoOs produtos naturais das espécies de plantas Plectranthus têm um uso etnofarmacológico, suscitando vários estudos científicos. Neste trabalho pretendeu-se validar cientificamente estas plantas, realizando uma pesquisa de atividades biológicas. Extratos de sete espécies de Plectranthus (P. swynnertonii, P. welwischii, P. woodii, P. cylindraceus, P. spicatus, P. ramosior e P. petiolaris) foram testados na inibição da acetilcolinesterase in vitro (AChE), atividades antioxidante e antimicrobiana, e toxicidade em Artemia salina. Os extratos acetónicos foram obtidos por ultrassons (10% m/v), dos quais P. ramosior obteve o rendimento de extração mais elevado (13,49% m/m). Todos os extratos foram testados, no entanto apenas o P. cylindraceus obteve inibição da atividade da AChE (30,2 ± 3,78%). A atividade antimicrobiana foi avaliada usando o método de difusão em poços, contra bactérias Gram-positivas, -negativas e leveduras. P. ramosior revelou não só inibição contra S. aureus e C. albicans (15 e 11 mm, respetivamente), como também a mais elevada atividade antioxidante (método DPPH, 36,4 ± 0,04%). No ensaio em A. salina P. swynnertonnii foi o extrato mais tóxico (LC50 = 0,036 mg/L). Os resultados preliminares obtidos neste trabalho, revelam a potencial biotividade dos extratos de P. cyl...

: Diabetes mellitus greatly affects the quality of life of patients and has a worldwide prevalence. Insulin is the most commonly used drug to treat diabetic patients and is usually administered through the subcutaneous route. However, this route of administration is ineffective due to the low concentration of insulin at the site of action. This route of administration causes discomfort to the patient and increases the risk of infection due to skin barrier disturbance caused by the needle. The oral administration of insulin has been proposed to surpass the disadvantages of subcutaneous administration. In this review, we give an overview of the strategies to deliver insulin by the oral route, from insulin conjugation to encapsulation into nanoparticles. These strategies are still under development to attain efficacy and effectiveness that are expected to be achieved in the near future.