Evaluation of the antifungal effect of plant extracts on oral Candidaspp. - a critical methodological analysis of the last decade

INTRODUCTION

In 2022, the World Health Organization published a report encouraging researchers to focus on Candida spp. to strengthen the global response to fungal oral infections and antifungal resistance. In the context of innovative research, it seems pertinent to investigate the antifungal potential of natural extracts of plants and the methodology involved in the recent reports. The aim of this systematic review is to identify the current state of in vitro research on the evaluation of the ability of plant extracts to inhibit Candida spp.

MATERIAL AND METHODS

A bibliographic search has been developed to on a 10-year period to identify which plant extracts have an antifungal effect on the Candida spp. found in the oral cavity.

RESULTS

A total of 20 papers were reviewed and fulfilled all the selection criteria and were included in the full data analysis.

DISCUSSION

Plants have been tested in a wide range of states - whole extracts, extraction of particular components such as flavonoids or polyphenols, or even using the plant to synthesize nanoparticles. Of forty-five plants tested, five of them did not show any effect against Candida spp., which weren't part of the same family. There is a wide range of plant that exhibit antifungal proprieties.

CONCLUSION

Many plants have been tested in a wide range of states - whole extracts, extraction of components such as flavonoids or polyphenols, or even using the plant to synthetize nanoparticles. The combination of plants, the addition of plants to a traditional antifungal and the interference with adhesion provided by some plants seem to be promising strategies. Nonetheless, on contrary to drugs, there is a critical lack of standardization on methodologies and protocols, which makes it difficult to compare data and, consequently, to conclude, beyond doubts, about the most promising plants to fight Candida spp. oral infections.

Candida glabrata's recurrent infections: biofilm formation during Amphotericin B treatment

Candida species are responsible for recurrent human infections, mostly in immunocompromised patients, due to their high vulnerability. Candida glabrata has a major role in systemic candidiasis and Amphotericin B (AmB), a polyene only used in hospitals, is frequently used to treat this disease. Lately, however, clinical evidences of Candida recurrent infections during these treatments are being described, probably due to biofilm (re)formation during this therapy. Thus, this work aims at inferring if C. glabrata biofilms are still being formed during AmB treatment. For that, C. glabrata biofilms were formed in the presence of AmB and analysed by dry weight. Matrix composition was analysed quantifying carbohydrates and, specifically, β-1,3 glucans. Results demonstrated that, although in a lesser extent, C. glabrata is able to develop biofilms in the presence of AmB, with a thick extracellular matrix, with an increase on carbohydrates, especially β-1,3 glucans. Therefore, it is confirmed that complex biofilms of C. glabrata can be formed during an AmB treatment.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study shows new insights regarding recurrent candidiasis. The authors demonstrated that Amphotericin B did not totally prevent the development of biofilms during Candida glabrata's infection treatment and that the change in the biofilm matrices may have a high responsibility for the fail in the treatment of systemic candidiasis.

Beta hydroxy beta methylbutyrate supplementation impairs peripheral insulin sensitivity in healthy sedentary Wistar rats

AIM

Investigate, in healthy sedentary rats, the potential mechanisms involved on the effects of beta hydroxy beta methylbutyrate (HMB) supplementation upon the glycaemic homeostasis, by evaluating the insulin sensitivity in liver, skeletal muscle, and white adipose tissue.

METHODS

Rats were supplemented with either beta hydroxy beta methylbutyrate (320 mg kg(-1)  BW) or saline by gavage for 4 weeks. After the experimental period, the animals were subjected to the glucose tolerance test (GTT) and plasma non-esterified fatty acids (NEFA) concentration measurements. The soleus skeletal muscle, liver and white adipose tissue were removed for molecular (western blotting and RT-PCR) and histological analysis.

RESULTS

The beta hydroxy beta methylbutyrate supplemented rats presented: (i) higher ratio between the area under the curve (AUC) of insulinaemia and glycaemia during glucose tolerance test; (ii) impairment of insulin sensitivity on liver and soleus skeletal muscle after insulin overload; (iii) reduction of glucose transporter 4 (GLUT 4) total and plasma membrane content on soleus; (iv) increased hormone-sensitive lipase (HSL) mRNA and protein expression on white adipose tissue and plasma NEFA levels and (v) reduction of fibre cross-sectional area of soleus muscle.

CONCLUSION

The data altogether indicate that beta hydroxy beta methylbutyrate supplementation impairs insulin sensitivity in healthy sedentary rats, which, in the long-term, could lead to an increased risk of developing type 2 diabetes.

Drug-delivery systems of green tea catechins for improved stability and bioavailability

Numerous studies in humans, animal models and cell lines have suggested the potential benefits from the consumption of green tea polyphenols, including prevention of cancer and heart diseases. However these potential effects have been strongly limited by green tea catechins low bioavailability, which hinders the development of therapeutic applications. In this review formulations that are being proposed for delivery of green tea catechins are discussed. New delivery systems are presented as valid alternatives to overcome the limitations such as green tea catechins poor stability or intestinal absorption.

Candida glabrata: a review of its features and resistance

Candida species belong to the normal microbiota of the oral cavity and gastrointestinal and vaginal tracts, and are responsible for several clinical manifestations, from mucocutaneous overgrowth to bloodstream infections. Once believed to be non-pathogenic, Candida glabrata was rapidly blamable for many human diseases. Year after year, these pathological circumstances are more recurrent and problematic to treat, especially when patients reveal any level of immunosuppression. These difficulties arise from the capacity of C. glabrata to form biofilms and also from its high resistance to traditional antifungal therapies. Thus, this review intends to present an excerpt of the biology, epidemiology, and pathology of C. glabrata, and detail an approach to its resistance mechanisms based on studies carried out up to the present.

Profile of serum IL-1beta and IL-10 shortly after ovariectomy and estradiol replacement in rats

Ovariectomy leads to progressive and significant increases in body weight gain and osteoporosis and is related to changes in serum and tissue cytokine profiles, such as observed in other models of overweight. We aimed to evaluate serum interleukin-1beta and interleukin-10 shortly after ovariectomy, before the establishment of overweight in rats. Female Wistar rats were submitted to ovariectomy, ovariectomy and estradiol replacement, or sham operation and compared with intact controls. Rats were killed 3, 6, 9, or 13 d after ovariectomy. Body mass and retroperitoneal fats were significant higher only 13 d after ovariectomy, and estradiol replacement to ovariectomized rats impaired both body mass and retroperitoneal fat gain. Shortly after ovariectomy (at 3 d) serum interleukin-1beta levels significantly increased in ovariectomized rats, treated or not with estradiol, while serum interleukin-10 levels increased only 9 d after ovariectomy. Our results suggest the existence of an important interplay between the immune system and ovarian function. This interplay occurs regardless of significant changes in adipose tissue compartment, as ovarian excision leads to short-term changes in the pattern of interleukin-1beta and interleukin-10 cytokine production that precede body weight gain and are not reverted by estradiol replacement.

The deep plantar arch in humans: constitution and topography

The integrity of the various structures within the feet depends on their blood supply. Lesions of the feet often require revascularization, which if successful avoids the need for amputation. To provide greater anatomical detail to aid vascular surgery and imaging, the anatomy and constitution of the deep plantar arch was studied in 50 adult cadaveric feet. The arteries of the foot were injected with red neoprene latex and dissected under magnification. The deep plantar arch, present in all feet, was the result of anastomosis between the deep plantar artery and the deep branch of the lateral plantar artery. The deep plantar artery was predominant in 72% of specimens (Type I arches) and the lateral plantar artery in 22% (Type II), with the contribution being equal in 6% (Type III). The medial plantar artery contributed to the medial segment of the deep plantar arch by its deep branch in 12% of specimens. The distance between the deep plantar arch and each interdigital commissure was generally constant, averaging 29% of total foot length. The deep plantar arch was located in the middle third of the foot in all specimens, being in the distal part of this third in 90%. The deep plantar arch is, therefore formed mainly by the deep plantar artery, a branch of the dorsal artery of foot; its location can be estimated if foot length is known.

Unilateral absence of the thoracic part of the trapezius muscle

The absence of some muscles, such as pectoralis major, serratus anterior and quadratus femoris have been described, however the absence of trapezius, either in isolation or in association with other structures, is not often observed. In this case study, we present a case of partial absence of the left trapezius muscle in an adult black male cadaver, which had a large aponeurosis replacing the ascending fibres and some of the transverse fibres of the muscle. Histological analysis showed the presence of a few muscle fibres in the aponeurosis. From a functional viewpoint, it is possible that this individual would have had difficulty in moving his shoulder, especially during flexion, abduction and circumduction of the arm.

Biometric study of the relationships between palmar neurovascular structures, the flexor retinaculum and the distal wrist crease

During surgical exposure of the carpal tunnel it is possible to injure the neurovascular structures closely related to the flexor retinaculum, such as the superficial palmar arch and the communicating branch between the ulnar and median nerves. Because of the importance of these structures and with the purpose of increasing knowledge of anatomical details concerning to their location, a biometric study was performed on the retinaculum and the communicating branch, and between the communicating branch and the distal wrist crease, as well as between the retinaculum and the superficial palmar arch. We dissected 56 hands from 28 Brazilian formalin-preserved cadavers of both sexes (24 male) at the Federal University of São Paulo-Escola Paulista de Medicina, Brazil. The communicating branch was observed in 96.4% of cases and the superficial palmar arch in 78.6%. The communicating branch was found between the common palmar digital nerve of the 4th interosseous space (from the ulnar nerve) to the homonymous nerve of the 3rd interosseous space (from the median nerve). In males, the distance between the distal wrist crease and the site where the communicating branch originates from the ulnar component had an average of 33.9 +/- 5.5 mm on the right side and 30.2 +/- 8.2 mm on the left. The distance between the distal wrist crease and the junction of the communicating branch with the common palmar digital nerve of the 3rd interosseous space was 43.6 +/- 6.9 mm on the right and 40.2 +/- 6.2 mm on the left side. Conversely, in 14.8% of cases (1 female), the communicating branch was observed to emerge from the common palmar digital nerve of the 3rd interosseous space. The distance between the retinaculum and the superficial palmar arch in the axial line of the 4th metacarpal bone was on average 7.3 +/- 4.3 mm on the right and 8.3 +/- 3.5 mm on the left side. At the same level, the distance between the retinaculum and the communicating branch was 6.2 +/- 3.7 mm on the right side and 5.1 +/- 2.8 mm on the left. These results can be used as a reference during surgical procedures in the palmar region.

Abnormal disposition of a branch of the ulnar nerve in the flexor retinaculum

The most frequent disposition of the structures within the ulnar tunnel is for the ulnar nerve to be located medial or posteromedial to the ulnar artery. The structures within the ulnar tunnel are closely related to the medial part of the flexor retinaculum. Lesions of the ulnar nerve and artery during endoscopic decompression of the carpal tunnel have been reported (Agee et al. 1992; Lee et al. 1992; Nath et al. 1993; De Smets & Fabry, 1995). An adequate anatomical knowledge of such structures and their variations is therefore important. During a study of the palmar region, we found that a special branch originated from the ulnar nerve in relation to the flexor retinaculum. Documentation of this variation will contribute to the knowledge of the anatomy of the ulnar nerve and its distal branches.

The ulnar tunnel: a rare disposition of its contents

The ulnar tunnel is located at the proximal part of the hand radial to the pisiform bone and to the proximal part of the carpal tunnel. Inside it lie the ulnar nerve and artery. Compression of the ulnar nerve in this tunnel is often reported. Cysts, occupational trauma, fractures and muscle variations are among the main causes (Schjelderup, 1964; Kleinert & Hayes, 1971). Damage to the ulnar nerve and artery during the endoscopic decompression of the carpal tunnel has been reported recently (Agee et al. 1992; Nath et al. 1993; De Smets & Fabry, 1995). The structures within the ulnar tunnel are closely related to the medial part of the flexor retinaculum, in particular the ulnar artery which is located lateral to the ulnar nerve. During a study of this region we found a rare disposition of the contents of this tunnel. We believe that knowledge of this variation is important for the surgical anatomy of this region.