An Evaluation of the Novel Biological Properties of Diterpenes Isolated from Plectranthus ornatus Codd. In Vitro and In Silico

Plectranthus ornatus Codd, the genus Plectranthus of the Lamiaceae family, has been used as traditional medicine in Africa, India and Australia. Pharmacological studies show the use of this plant to treat digestive problems. In turn, leaves were used for their antibiotic properties in some regions of Brazil to treat skin infections. The present study examines the anti-inflammatory, antioxidant and cytotoxic effects of the halimane and labdane diterpenes (11R*,13E)-11-acetoxyhalima-5,13-dien-15-oic acid (HAL) and 1α,6β-diacetoxy-8α,13R*-epoxy-14-labden-11-one (PLEC) and the forskolin-like 1:1 mixture of 1,6-di-O-acetylforskolin and 1,6-di-O-acetyl-9-deoxyforskolin (MRC) isolated from P. ornatus on lung (A549) and leukemia (CCRF-CEM) cancer cell lines, and on normal human retinal pigment epithelial (ARPE-19) cell line in vitro. Additionally, molecular docking and computational approaches were used. ADMET properties were analysed through SwissADME and proTox-II—Prediction. The results indicate that all tested compounds significantly reduced the viability of the cancer cells and demonstrated no cytotoxic effects against the non-neoplastic cell line. The apoptosis indicators showed increased ROS levels for both the tested A549 and CCRF-CEM cancer cell lines after treatment. Furthermore, computational studies found HAL to exhibit moderate antioxidant activity. In addition, selected compounds changed mitochondrial membrane potential (MMP), and increased DNA damage and mitochondrial copy number for the CCRF-CEM cancer cell line; they also demonstrated anti-inflammatory effects on the ARPE-19 normal cell line upon lipopolysaccharide (LPS) treatment, which was associated with the modulation of IL-6, IL-8, TNF-α and GM-CSF genes expression. Docking studies gave indication about the lowest binding energy for 1,6-di-O-acetylforskolin docked into IL-6, TNF-α and GM-CSF, and 1,6-di-O-acetyl-9-deoxyforskolin docked into IL-8. The ADMET studies showed drug-likeness properties for the studied compounds. Thus, halimane and labdane diterpenes isolated from P. ornatus appear to offer biological potential; however, further research is necessary to understand their interactions and beneficial properties.

Anticancer Properties of Plectranthus ornatus-Derived Phytochemicals Inducing Apoptosis via Mitochondrial Pathway

Since cancer treatment by radio- and chemotherapy has been linked to safety concerns, there is a need for new and alternative anticancer drugs; as such, compounds isolated from plants represent promising candidates. The current study investigates the anticancer features of halimane (11R*,13E)-11-acetoxyhalima-5,13-dien-15-oic acid (HAL) and the labdane diterpenes 1α,6β-diacetoxy-8α,13R*-epoxy-14-labden-11-one (PLEC) and forskolin-like 1:1 mixture of 1,6-di-O-acetylforskolin and 1,6-di-O-acetyl-9-deoxyforskolin (MRC) isolated from Plectranthus ornatus in MCF7 and FaDu cancer cell lines. Cytotoxicity was assessed by MTT assay, ROS production by Di-chloro-dihydro-fluorescein diacetate assay (DCFH) or Red Mitochondrial Superoxide Indicator (MitoSOX) and Mitochondrial Membrane Potential (MMP) by fluorescent probe JC-1 (5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide). In addition, the relative amounts of mitochondrial DNA (mtDNA) were determined using quantitative Real-Time-PCR (qRT-PCR) and damage to mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) by semi-long run quantitative Real-Time-PCR (SLR-qRT-PCR). Gene expression was determined using Reverse-Transcription-qPCR. Caspase-3/7 activity by fluorescence was assessed. Assessment of General In Vivo Toxicity has been determined by Brine Shrimp Lethality Bioassay. The studied HAL and PLEC were found to have a cytotoxic effect in MCF7 with IC₅₀ = 13.61 µg/mL and IC₅₀ = 17.49 µg/mL and in FaDu with IC₅₀ = 15.12 µg/mL and IC₅₀ = 32.66 µg/mL cancer cell lines. In the two tested cancer cell lines, the phytochemicals increased ROS production and mitochondrial damage in the ND1 and ND5 gene regions and reduced MMP (ΔΨm) and mitochondrial copy numbers. They also changed the expression of pro- and anti-apoptotic genes (Bax, Bcl-2, TP53, Cas-3, Cas-8, Cas-9, Apaf-1 and MCL-1). Studies demonstrated increase in caspase 3/7 activity in tested cancer cell lines. In addition, we showed no toxic effect in in vivo test for the compounds tested. The potential mechanism of action may have been associated with the induction of apoptosis in MCF7 and FaDu cancer cells via the mitochondrial pathway; however, further in vivo research is needed to understand the mechanisms of action and potential of these compounds.

Curcuma longa and Curcuma mangga leaves exhibit functional food property

Although leaves of Curcuma mangga and Curcuma longa are used in food preparations, the bioactive components in it are not known. In this study, antioxidant, antiinflammatory and anticancer activities of leave extracts and its isolates were investigated using established bioassay procedures in our laboratory. The leaf extracts of both plants gave similar bioassay and chromatographic profiles. The methanolic and water extracts of C. mangga (CMM and CMW) and C. longa (CLM and CLW), at 100 μg/mL, inhibited lipid peroxidation (LPO) by 78%, 63%, 81% and 43%, cyclooxygenase enzymes COX-1 by 55%, 33%, 43% and 24% and COX-2 by 65%, 55%, 77% and 69%, respectively. At same concentration, CMM, CMW, CLM and CLW showed growth inhibition of human tumour cell lines by 0-46%. Therefore, a bioassay-guided isolation of water and methanolic extracts of C. longa was carried out and afforded nine isolates. At 25 μg/mL, these compounds inhibited LPO by 11-87%, COX-1 and -2 enzymes by 0-35% and 0-82% and growth of human tumour cells by 0-36%, respectively.