الهام کاکائی

Increasing prevalence of nosocomial infections, due to arbitrary use of antibiotics, has caused serious health problems. Natural compounds have been used for many years for the treatment of many infections. Rare actinobacteria are one of the main sources used for discovery and isolation of natural compounds with pharmaceutical properties. The main purpose of this review article was to study new metabolites derived from rare actinobacteria, and evaluate their medicinal and pharmaceutical applications.

This study included over 183 peer-reviewed papers from the databases of Scopus, PubMed, Web of Science and ScienceDirect from 2015 to 2021.

In this study chemical structure and biological activity of 113 new compounds isolated from rare actinobacteria were evaluated. This study also showed that rare actinobacteria have the capability to produce a variety of compounds such as alkaloids, flavonoids, terpenes and polyketides with a diverse range of biological activities including antibacterial, antifungal, antiviral and anticancer properties.

The results of this study revealed that rare actinobacteria can be considered as an excellent source for the production of natural active compounds with high potentials for therapeutic and applied medical, pharmaceutical and agricultural biotechnology. It also showed the key role of these compounds in the development of necessary drugs for humans in the near future

Over recent years, nosocomial infections, and the morbidity and mortality associated with pathogenic bacteria have dramatically increased due to antibiotic resistance and imposed significant burdens on the global health system. Critical shortage of effective therapeutics against multidrug-resistant bacteria highlights the need for development of novel antibiotics. Actinobacteria are well-known sources of natural bioactive compounds, especially antibiotics. Nearly two-thirds of the antibiotics on the market have actinobacterial origins. Endophytic actinobacteria residing within plants contribute to the plant growth and survival by producing plethora of secondary metabolites. Therefore, isolation, cultivation, and identification of new strains, as well as their potential to produce antimicrobial compounds, are of great importance. Lack of published research in this field highlights the importance of this review in Iran. The aim of this review was to present the latest methods for the isolation and identification of endophytic actinobacteria and introducing relevant databases. We also studied the most recent isolated strains, chemical structure of 51 newly identified secondary metabolites, and their potential medical-pharmaceutical applications. This study revealed that endophytic actinobacteria are prolific sources of bioactive secondary metabolites with high levels of structural diversity and potent pharmaceutical and medicinal applications.

The most important treatment for celiac disease is a gluten-free diet throughout the lifetime of the patient. Corn flour is one of the alternatives for wheat flour in baking of bread and bakery products that are of high nutritional value and because of lack of gluten are suitable for people with celiac disease. Moreover, potato flour is one of the best wheat flour alternatives in bread-making and is consistent with that; and now, not only in production of bread but also in production of other bakery products. Hydrocolloids are a branch of additives which are widely used in food industry. One of the most widely used gum in food industry and bakery is hydroxy propyl methyl cellulose gum, which is a derivative of cellulose. Considering the above mentioned facts; the aim of this study was to prepate baguette bread with a mixture of equal parts of corn and potato flour with hydroxy propyl methyl cellulose gum. In this regard, the effect of different levels of gum on qualitative properties of produced baguette bread was investigated.
Treatments included an equal mix of corn flour and potato flour with 0.25, 0.5, 0.75, 1% hydroxy propyl methyl cellulose gum were prepared. Different chemical tests such as moisture content determination, ash, proteins, fiber and pH measurement were performed on samples of corn and potato flour and after baking on baguettes bread. Yield of dough and bread was calculated in order to determine the strength of dough, porosity and hollow of bread. To evaluate the organoleptic characteristics of baguette bread samples, the analysis of properties of bread with the five senses were using. Staling test based on sense and instrument method at intervals 24, 48, 72 hours after baking was performed on all samples of gluten-free baguettes. Simon Henry method was used for determining the volume of the sample bread. In order to analyze the results of test, a completely randomized design with three replications was used and the means by Duncan's multiple range test, in probability level a=1% by SPSS software in 16 versions compared.
According to results, addition of hydroxy propyl methyl cellulose gum causes yield of dough to increase significantly comparing to the control sample. Generally, gums are hydrophilic compoundsand usually they are interacting with water to reduce the spreadability and stability of the presence of water in the system. Also, adding HPMC gum, decreases yield percent of baguette gluten free bread comparing to contrl samples. Reason of diminishing returns of bread samples containing gum is structural nature of HPMC gum that is capable of properly maintaining carbon dioxide. But there was no significant difference in ash and protein that it was for structure of used gum. By adding HPMC gum, water content of samples in compared to C treatment increased due to the high water holding capacity of used gum. Also adding HPMC gum will increase the amount of fiber in samples containing gum compared to instance treatment. Moreover, HPMC gum increases the volume and improve the color appearance of baguette bread samples containing gum in compare to instance treatment (C) but there was no significant difference in uniformity characteristics of back of gluten-free baguettes samples. Its reason is because of gum hydrophilic property which by increasing the viscosity can keep gas in dough and bread. Color improvement of baguette bread samples containing gum is increasing browning reaction because of adding gum. According to the results, HPMC gum at level of 0.75 and 1% of weight had positive impact on internal characteristics of baguette. Increasing porosity of baguette bread containing gum and improving their hole and seeds shape is for gum ability to maintenance of carbon dioxide and increase bread volume, also this gum prevent dry and hardening of bread texture due to water absorption. Aroma of bread is depend on maylard and caramelization reaction, so scent in bread with suitable browning reactions, increased and as gums are effective in increasing browning reactions of maylard so has desired effect on bread aroma. Also more used gum, will reduce water consumption, improve freshness and softening of bread tissue due to the interaction of hydrocolloids with water and reducing water retention during cooking and was thus a positive effect on the texture of bread. According to results, adding HPMC gum in level of 0.75 and 1% causes the staling time to reduce in three 24, 48 and 72 hours after cooking baguette bread containing gum (by sensory and device) compare to the treatment C. Furthermore, adding HPMC gum increases the volume of baguette bread samples containing gum compare to the instance treatment (C). Volume increasing is because of hydrophilic properties of gum that improve dough spread and maintenance of CO2 gas.
According to the results, treatments containing 1% HPMC gum had the highest water content and fiber. The amount of ash and protein in the samples containing hydroxy propyl methyl cellulose to the instance samples had a slight increase, but this difference was not significant. On the other hand treatment containing 1% gum had the highest dough yields and the control sample had the lowest. Also, yields decreased with increasing gum than the control bread. Other treatments containing 1% gum had the highest privilege organoleptic than other treatments. Also according to the staling test results in sensory and device method, at intervals 24, 48 and 72 hours after baking, treatment with 1% gum has the lowest time of staling. Also treatment containing 1% gum had the most volume and the control the lowest one.