A novel approach for development and characterization of effective mosquito repellent cream formulation containing citronella oil

Quality by Design Perspective for Designing Foam-based Formulation: Current State of Art

Foam-based delivery systems contain one or more active ingredients and dispersed solid or liquid components that transform into gaseous form when the valve is actuated. Foams are an attractive and effective delivery approach for medical, cosmetic, and pharmaceutical uses. The foams-based delivery systems are gaining attention due to ease of application as they allow direct application onto the affected area of skin without using any applicator or finger, hence increasing the compliance and satisfaction of the patients. In order to develop foam-based delivery systems with desired qualities, it is vital to understand which type of material and process parameters impact the quality features of foams and which methodologies may be utilized to investigate foams. For this purpose, Quality-by-Design (QbD) approach is used. It aids in achieving quality-based development during the development process by employing the QbD concept. The critical material attributes (CMAs) and critical process parameters (CPPs) were discovered through the first risk assessment to ensure the requisite critical quality attributes (CQAs). During the initial risk assessment, the high-risk CQAs were identified, which affect the foam characteristics. In this review, the authors discussed the various CMAs, CPPs, CQAs, and risk factors associated in order to develop an ideal foam-based formulation with desired characteristics.

Challenges encountered by natural repellents: Since obtaining until the final product

Vector-borne diseases, particularly the arboviruses dengue, Zika, chikungunya, and yellow fever caused by the Aedes aegypti mosquito, have been driving the use of repellents worldwide. The most representative synthetic repellent, DEET stands out as the market's oldest and most efficient repellent. It is considered a reference standard but presents considerable toxicity, not recommended for children up to 6 months old and pregnant women. For this reason, alternatives have been sought, and natural repellents derived mainly from essential oils have been studied, highlighting the essential oils of lemon (Corymbia citriodora), citronella (Cympobogon sp.), Andiroba (Carapa guianensis). However, the development and commercialization of products containing natural repellents are significantly lower when compared to DEET and other synthetic repellents. In order to understand the reasons, aspects related to safety, mechanism of action, efficacy as well development and complexity of the products were evaluated. It is concluded that, as for safety, there is lacking information in the literature regarding the effects on non-target organisms and robust toxicity data. The mechanism of action is based on theories, with less information on the exact mode of action, molecular targets, and interaction with the olfactory and taste receptors of insects. Despite being a current trend to search for actives from natural sources highly present in essential oils, however they reduced action time because due to rapid evaporation after application to the skin, thus requiring repellent vehicles. The development and complexity related to these products bring challenging aspects, beginning on the plant cultivation and extraction processes to produce essential oils with a more homogeneous chemical composition towards the formulation stabilization processes due to fast evaporation and short action time, with the use of pharmaceutical technology such as encapsulation techniques.

Stability Profile and Clinical Evaluation of an Innovative Hydrogel Containing Polymeric Micelles as Drug Delivery Systems with Oregano Essential Oil against Fibroepithelial Polyps

Skin tags, also known as fibroepithelial polyps (FPs) or acrochordons, are soft, pigmented excrescences, with a prevalence of 50-60% in the population, occurring especially in the fourth decade of life. To date, FPs have been efficiently eliminated using minimum invasive methods such as surgical removal, cauterization, laser irradiation, and cryosurgery. Over-the-counter treatments are also of interest for patients due to their non-invasive character, but their clinical efficiency has not been clearly demonstrated. This study was designed in order to evaluate the efficacy of a modern-pharmaceutical-formulation-type poloxamer-based binary hydrogel, having Origanum vulgare L. essential oil (OEO-PbH) as an active ingredient in the management of FPs. The formulation has been shown to possess good qualities in terms of stability and sterility. Non-invasive measurements revealed changes in some physiological skin parameters. An increase in transepidermal water loss (TEWL) and erythema index was noted, while skin surface water content (SWC) decreased during eight weeks of treatment. The macroscopic evaluation revealed that the FPs dried and shrunk after topical treatment with OEO-PbH. Clinically, patients presented a lowering of the number of lesions on the treated area of 20-30% after one month of treatment and around 50% after the second month. Histopathological examination suggests that topical treatment with OEO-PbH may induce histological changes in the epidermis, dermis, and fibrovascular cores of FPs, including a loss of thickness, reduced size and number of blood vessels, and low cellularity. These changes may contribute to the observed reduction in size of FPs after treatment with OEO-PbH.

A combination of linalool and linalyl acetate synergistically alleviates imiquimod-induced psoriasis-like skin inflammation in BALB/c mice

Introduction: Psoriasis is a chronic inflammatory skin disorder characterized by keratinocyte hyperproliferation and differentiation with increased immune cell infiltration. The anti-psoriatic effect of lavender oil has been reported. However, its phytoconstituents, linalool (L) and linalyl acetate (LA), showed a distinctive affinity with psoriasis targets.

Objectives: This investigation was aimed to determine the combined effect of L and LA in ameliorating psoriasis-like skin inflammation and its safety in long-term topical uses.

Methods: The combined effect of L and LA was compared with their individual effects. The anti-psoriatic activity was performed using imiquimod (IMQ)-induced psoriasis in BALB/c mice and evaluated to reduce PASI and CosCam scores and Th-1 and Th-17 cell-specific cytokine levels. The acute and repeated dose dermal toxicities were investigated as per the OECD guidelines.

Results: L and LA combination (LLA) in the 1:1 w/w ratio at 2% concentration showed a synergistic effect. The combination showed 76.31% and 71.29% recovery in PASI and CosCam Scores; however, L2% and LA2% showed 64.28% and 47.61% recovery in PASI and 64.75 and 56.76% recovery in CosCam scores, respectively. It showed >90% and >100% recovery in Th-17 and Th-1 cell-specific cytokines, respectively, and restored epidermal hyperplasia and parakeratosis toward normal compared with psoriatic mice. A marked reduction in NF-κB, cck6, and the IL-17 expression was also observed in the LLA-treated group. This combination was safe in a therapeutically effective dose for 28 days as no significant changes were observed in organ and body weights, liver and kidney parameters, and differential leukocyte counts.

Conclusion: This study proves the synergy between L and LA in a 1:1 w/w ratio at 2% in the treatment of psoriasis-like skin inflammation and provides strong scientific evidence for its safe topical use.

Formulation and Physicochemical Evaluation of Green Cosmeceutical Herbal Face Cream Containing Standardized Mangosteen Peel Extract

The widely reported adverse effects of synthetic ingredients encourage the development of green cosmeceuticals to achieve Sustainable Development Goal (SDG) 3. The waste product of mangosteen (mangosteen peel) was utilized in the formulation to reduce waste production corresponding to SDG 12, in addition to its anti-aging and pigmentation control effects. This study aimed to formulate and evaluate novel herbal face creams containing standardized mangosteen peel extract. The mangosteen creams were formulated using natural ingredients and were evaluated for their organoleptic characteristics, rheology, spreadability and pH. Furthermore, an accelerated stability study, freeze–thaw stability study and centrifugation test were conducted. In addition, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays were conducted to assess its antioxidant effects, whereas tyrosinase inhibitory assay was conducted to determine its anti-tyrosinase activity. The formulated creams appeared light yellowish-brown and homogenous without phase separation. The creams displayed shear-thinning behavior and optimal pH which was ideal for topical application. The creams were stable after being subjected to various stability tests and were shown to have antioxidant and anti-tyrosinase activity. In conclusion, the development of mangosteen-based green cosmeceutical face cream is in line with SDG 3 and 12. It is expected to be used as a safe and effective alternative to synthetic products.

Host-Guest Inclusion Complexes of Natural Products and Nanosystems: Applications in the Development of Repellents

Repellents are compounds that prevent direct contact between the hosts and the arthropods that are vectors of diseases. Several studies have described the repellent activities of natural compounds obtained from essential oils. In addition, these chemical constituents have been pointed out as alternatives to conventional synthetic repellents due to their interesting residual protection and low toxicity to the environment. However, these compounds have been reported with short shelf life, in part, due to their volatile nature. Nanoencapsulation provides protection, stability, conservation, and controlled release for several compounds. Here, we review the most commonly used polymeric/lipid nanosystems applied in the encapsulation of small organic molecules obtained from essential oils that possess repellent activity, and we also explore the theoretical aspects related to the intermolecular interactions, thermal stability, and controlled release of the nanoencapsulated bioactive compounds.

Essential oils used in dermocosmetics: Review about its biological activities

INTRODUCTION

Currently, the demand for the use of constituents of natural origin in cosmetic formulations in detriment of synthetic compounds is noticeable. Several studies assess the potential of essential oils when incorporated into various cosmetic formulations and study their biological activities. This work intends to prepare a literature review on essential oils tested in dermocosmetic formulations and whose biological activities were evaluated through in vitro and/or in vivo tests. The main objectives for this study were as follows: to identify the essential oils that have been used in cosmetic formulations; and compile information on the main biological activities tested in cosmetic formulations.

METHODS

A search was carried out until 2021 in the scientific databases PubMed and Web of Science, using different search terms, and several scientific articles from in vitro and in vivo studies in animals and clinical trials were selected and analyzed of involving development dermocosmetic formulations containing essential oils and the analysis of their biological activities.

RESULTS

These studies demonstrate that the antimicrobial activity (antibacterial and antifungal) is the one most studied, mainly through in vitro tests. In vivo studies were also carried out either in animals or in clinical studies showing different effects, such as repellent action, inhibition of hair growth, and action against migraine. Regarding formulations, it was evident that creams are the most used.

CONCLUSIONS

There is enormous potential for the use of essential oils in future formulations in the cosmetic and pharmaceutical industry, in particular as preservatives, exploring their other biological activities.

Ligusticum sinense Nanoemulsion Gel as Potential Repellent against Aedes aegypti, Anopheles minimus, and Culex quinquefasciatus (Diptera: Culicidae)

Ligusticum sinense Oliv. cv. is a species of Umbelliferae (Apiaceae), a large plant family in the order Apiales. In this study, L. sinense hexane extract nanoemulsion gel (LHE-NEG) was investigated for mosquito repellency and compared to the standard chemical, N,N-diethyl-3-methylbenzamide (DEET), with the goal of developing a natural alternative to synthetic repellents in protecting against mosquito vectors. The results demonstrated that LHE-NEG afforded remarkable repellency against Aedes aegypti, Anopheles minimus, and Culex quinquefasciatus, with median protection times (MPTs) of 5.5 (4.5-6.0), 11.5 (8.5-12.5), and 11.25 (8.5-12.5) h, respectively, which was comparable to those of DEET-nanoemulsion gel (DEET-NEG: 8.5 (7.0-9.0), 12.0 (10.0-12.5), and 12.5 (10.0-13.5) h, respectively). Evaluation of skin irritation in 30 human volunteers revealed no potential irritant from LHE-NEG. The physical and biological stability of LHE-NEG were determined after being kept under heating/cooling cycle conditions. The stored samples of LHE-NEG exhibited some changes in appearance and differing degrees of repellency between those kept for 3 and 6 heating/cooling cycles, thus providing slightly shorter MPTs of 4.25 (4.0-4.5) and 3.25 (2.5-3.5) h, respectively, when compared to those of 5.0 (4.5-6.0) h in fresh preparation. These findings encourage commercially developed LHE-based products as an alternative to conventional synthetic repellents in preventing mosquito bites and helping to interrupt mosquito-borne disease transmission.

Composición fitoquímica del extracto de raíz de Ichthyothere terminalis de dos regiones geográficas diferentes de Colombia

Se reporta el análisis fitoquímico de dos extractos de raíz de Ichthyothere terminalis, colectadas en las localidades de Cumaral (Meta) y Abrego (Norte de Santander), Colombia. Los extractos se obtuvieron en etanol por destilación a presión reducida y fueron caracterizados por pruebas cualitativas, así como por cromatografía de gases acoplada a espectrometría de masas (GC-MS). El análisis GC-MS reveló diferencias en los compuestos en Ichthyothere terminalis de acuerdo al lugar de procedencia. Las plantas procedentes de Cumaral contienen saponinas, cumarinas y taninos, mientras que las procedentes de Abrego contienen alcaloides taninos, cumarinas y flavoniodes. El extracto etanólico de Abrego presenta principalmente octadecandien-1-ol (53,5%), oxido de cariofileno (30,8%), hexadecanol (24,0%), trans-β-cariofileno (13,6%), cicloisolongifoleno (11,6%), germancreno D (6,0%) y 9-octadecen-1-ol (8,0%). Las plantas de Cumaral presentan principalmente citronelal (46,4%), p-cimeno (6,4%), geraniol (5,0%) y citronelol (4,6%). Entre los compuestos químicos encontrados, varios poseen propiedades repelentes de acuerdo a los reportes etnobotánicos de la region Amazónica. Estudios adicionales podrán determinar la efectividad como repelente de los extractos de raíz de I. terminalis.

Sustained release formulations of citronella oil nanoemulsion using cavitational techniques

Nanoemulsion synthesis has proven to be an effective way for transportation of immobile, insoluble bioactive compounds. Citronella Oil (lemongrass oil), a natural plant extract, can be used as a mosquito repellent and has less harmful effects compared to its available market counterpart DEET (N, N-Diethyl-meta-toluamide). Nanoemulsion of citronella oil in water was prepared using cavitation-assisted techniques while investigating the effect of system parameters like HLB (Hydrophilic Lipophilic Balance), surfactant concentration, input energy density and mode of power input on emulsion quality. The present work also examines the effect of emulsification on release rate to understand the relationship between droplet size and the release rate. Minimum droplet size (60nm) of the emulsion was obtained at HLB of 14, S/O¹ ratio of 1.0, ultrasound amplitude of 50% and irradiation time of 5min. This study revealed that hydrodynamic cavitation-assisted emulsification is more energy efficient compared to ultrasonic emulsification. It was also found that the release rate of nanoemulsion enhanced as the droplet size of emulsion reduced.

The use of mosquito repellents at three sites in India with declining malaria transmission: surveys in the community and clinic

Background

Repellents such as coils, vaporizers, mats and creams can be used to reduce the risk of malaria and other infectious diseases. Although evidence for their effectiveness is limited, they are advertised as providing an additional approach to mosquito control in combination with other strategies, e.g. insecticide-treated nets. We examined the use of repellents in India in an urban setting in Chennai (mainly Plasmodium vivax malaria), a peri-urban setting in Nadiad (both P. vivax and P. falciparum malaria), and a more rural setting in Raurkela (mainly P. falciparum malaria).

Methods

The use of repellents was examined at the household level during a census, and at the individual level in cross-sectional surveys and among patients visiting a clinic with fever or other symptoms. Factors associated with their use were examined in a multivariate analysis, and the association between malaria and the use of repellents was assessed among survey- and clinic participants.

Results

Characteristics of participants differed by region, with more people of higher education present in Chennai. Use of repellents varied between 56–77 % at the household level and between 32–78 % at the individual level. Vaporizers were the main repellents used in Chennai, whereas coils were more common in Nadiad and Raurkela. In Chennai and Nadiad, vaporizers were more likely to be used in households with young male children. Vaporizer use was associated with higher socio-economic status (SES) in households in Chennai and Nadiad, whereas use of coils was greater in the lower SES strata. In Raurkela, there was a higher use of coils among the higher SES strata. Education was associated with the use of a repellent among survey participants in Chennai and clinic study participants in Chennai and Nadiad. Repellent use was associated with less malaria in the clinic study in Chennai and Raurkela, but not in the surveys, with the exception of the use of coils in Nadiad.

Conclusions

Repellents are widely used in India. Their use is influenced by the level of education and SES. Information on effectiveness and guidance on choices may improve rational use.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1709-9) contains supplementary material, which is available to authorized users.