Plectranthus Species with Anti-Inflammatory and Analgesic Potential: A Systematic Review on Ethnobotanical and Pharmacological Findings

The use of medicinal plants to treat inflammatory conditions and painful processes has attracted the attention of scientists and health professionals due to the evidence that natural products can promote significant therapeutic benefits associated with fewer adverse effects compared to conventional anti-inflammatory drugs. The genus Plectranthus is composed of various plants with pharmacological potential, which are used to treat various diseases in traditional communities worldwide. The present study systematically reviewed Plectranthus species with anti-inflammatory and analgesic potential. To this end, a systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. The search was conducted on the following databases: PubMed, ScienceDirect, SciVerse Scopus, and Web of Science. Different combinations of search terms were used to ensure more excellent article coverage. After the selection, a total of 45 articles were included in this review. This study identified twelve Plectranthus species indicated for the treatment of different inflammatory conditions, such as wounds, fever, bronchitis, abscess, asthma, hepatitis, labyrinthitis, tonsillitis, and uterine inflammation. The indications for pain conditions included headache, sore throat, heartburn, menstrual cramp, colic, toothache, stomachache, migraine, chest pain, abdominal pain, local pain, labor pain, and recurring pain. Among the listed species, ten plants were found to be used according to traditional knowledge, although only four of them have been experimentally studied. When assessing the methodological quality of preclinical in vivo assays, most items presented a risk of bias. The SR results revealed the existence of different Plectranthus species used to treat inflammation and pain. The results of this systematic review indicate that Plectranthus species have the potential to be used in the treatment of diseases with an inflammatory component, as well as in the management of pain. However, given the risk of biases, the experimental analysis of these species through preclinical testing is crucial for their safe and effective use.

Nootkatone Inhibits Acute and Chronic Inflammatory Responses in Mice

Nootkatone (NTK) is a sesquiterpenoid found in essential oils of many species of Citrus (Rutaceae). Considering previous reports demonstrating that NTK inhibited inflammatory signaling pathways, this study aimed to investigate the effects of this compound in mice models of acute and chronic inflammation. Murine models of paw edema induced by carrageenan, dextran, histamine, and arachidonic acid, as well as carrageenan-induced peritonitis and pleurisy, were used to evaluate the effects of NTK on acute inflammation. A murine model of granuloma induced by cotton pellets was used to access the impact of NTK treatment on chronic inflammation. In the acute inflammation models, NTK demonstrated antiedematogenic effects and inhibited leukocyte recruitment, which was associated with decreased vascular permeability, inhibition of myeloperoxidase (MPO), interleukin (IL)1-β, and tumor necrosis factor (TNF)-α production. In silico analysis suggest that NTZ anti-inflammatory effects may also occur due to inhibition of cyclooxygenase (COX)-2 activity and antagonism of the histamine receptor type 1 (H₁). These mechanisms might have contributed to the reduction of granuloma weight and protein concentration in the homogenates, observed in the chronic inflammation model. In conclusion, NTK exerted anti-inflammatory effects that are associated with inhibition of IL1-β and TNF-α production, possibly due to inhibition of COX-2 activity and antagonism of the H1 receptor. However, further studies are required to characterize the effects of this compound on chronic inflammation.