Autoimmune and infectious diseases are the major public health issues and have gained great attention in the last few years for the search of new agents with therapeutic benefits on the host immune functions. In recent years, natural products (NPs) have been studied broadly for their multi-targeted activities under pathological conditions. Interestingly, several attempts have been made to outline the immunomodulatory properties of NPs. Research on in-vitro and in-vivo models have shown the immunomodulatory activity of NPs, is due to their antiinflammatory property, induction of phagocytosis and immune cells stimulation activity. Moreover, studies on humans have suggested that phytomedicines reduce inflammation and could provide appropriate benefits either in single form or complex combinations with other agents preventing disease progression, subsequently enhancing the efficacy of treatment to combat multiple malignancies. However, the exact mechanism of immunomodulation is far from clear, warranting more detailed investigations on their effectiveness. Nevertheless, the reduction of inflammatory cascades is considered as a prime protective mechanism in a number of inflammation regulated autoimmune diseases. Altogether, this review will discuss the biological activities of plant-derived secondary metabolites, such as polyphenols, alkaloids, saponins, polysaccharides and so forth, against various diseases and their potential use as an immunomodulatory agent under pathological conditions.

Phytol (PYT) is a diterpene member of the long-chain unsaturated acyclic alcohols. PYT and some of its derivatives, including phytanic acid (PA), exert a wide range of biological effects. PYT is a valuable essential oil (EO) used as a fragrance and a potential candidate for a broad range of applications in the pharmaceutical and biotechnological industry. There is ample evidence that PA may play a crucial role in the development of pathophysiological states. Focusing on PYT and some of its most relevant derivatives, here we present a systematic review of reported biological activities, along with their underlying mechanism of action. Recent investigations with PYT demonstrated anxiolytic, metabolism-modulating, cytotoxic, antioxidant, autophagy- and apoptosis-inducing, antinociceptive, anti-inflammatory, immune-modulating, and antimicrobial effects. PPARs- and NF-κB-mediated activities are also discussed as mechanisms responsible for some of the bioactivities of PYT. The overall goal of this review is to discuss recent findings pertaining to PYT biological activities and its possible applications.

Treatment of Staphylococcus aureus infections has become complicated owing to growing antibiotic resistance mechanisms and due to the multitude of virulence factors secreted by this organism. Failures with traditional monovalent vaccines or toxoids have brought a shift towards the use of multivalent formulas and neutralizing antibodies to combat and prevent range of staphylococcal infections. In this study, we evaluated the efficacy of a fusion protein (r-ET) comprising truncated regions of staphylococcal enterotoxin A (SEA) and toxic shock syndrome toxin (TSST-1) in generating neutralizing antibodies against superantigen induced toxicity in murine model. Serum antibodies showed specific reactivity to both SEA and TSST-1 native toxins. Hyperimmune serum from immunized animals protected cultured splenocytes from non-specific superantigen induced proliferation completely. Passive antibody administration prevented tissue damage from acute inflammation associated with superantigen challenge from S. aureus cell free culture supernatants. Approximately 80% and 50% of actively and passively immunized mice respectively were protected from lethal dose against S. aureus toxin challenge. This study revealed that r-ET protein is non-toxic and a strong immunogen which generated neutralizing antibodies and memory immune response against superantigen induced toxic effects in mice model.

In this review, we examine the current status of Staphylococcus aureus vaccine development and the prospects for future vaccines. Examination of the clinical trials to date show that murine models have not predicted success in humans for active or passive immunization. A key factor in the failure to develop a vaccine to prevent S. aureus infections comes from our relatively limited knowledge of human protective immunity. More recent reports on the elements of the human immune response to staphylococci are analysed. In addition, there is some controversy concerning the role of antibodies for protecting humans, and these data are reviewed. From a review of the current state of understanding of staphylococcal immunity, a working model is proposed. Some new work has provided some initial candidate biomarker(s) to predict outcomes of invasive infections and to predict the efficacy of antibiotic therapy in humans. We conclude by looking to the future through the perspective of lessons gleaned from the clinical vaccine trials.