KEY FINDINGS: Majority of antimicrobials have been discovered from prokaryotes and those which are of eukaryotic origin are derived mainly from fungal and plant sources. With this in mind, it is important to note that pests, such as cockroaches come across pathogenic bacteria routinely, yet thrive in polluted environments. Other animals, such as snakes thrive from feeding on germ-infested rodents. Logically, such species must have developed an approach to protect themselves from these pathogens, yet they have largely been ignored as a potential source of antimicrobials despite their remarkable capability to fight disease-causing organisms.
SUMMARY: Animals living in polluted environments are an underutilized source for potential antimicrobials, hence it is believed that several novel bioactive molecule(s) will be identified from these sources to counter increasingly resistant bacterial infections. Further research will be necessary in the development of novel antimicrobial(s) from these unusual sources which will have huge clinical impact worldwide.
MATERIALS AND METHODS: MTG and SRM was analyzed for their reducing power ability, ABTS radical inhibition and 1,1-diphenyl-2-picryl hydrazylfree radicals scavenging activities. Furthermore, the antiproliferation efficacy was evaluated using MTT assay on K 562 and HCT116 cancer cell lines versus NIH/3T3 and CCD18-Co normal cell lines respectively.
RESULTS: SRM and MTG demonstrate moderate antioxidant value with ABTS assay (Trolox equivalent antioxidant capacity (TEAC): 2.25±0.02 mmol trolox / mmol and 1.96±0.04 mmol trolox / mmol respectively) and DPPH (IC50=3.75±0.04 mg/mL and IC50=2.28±0.02 mg/mL respectively). Both MTG and SRM demonstrate equal potency (IC50=25.20±1.53 and IC50= 22.19±1.06 respectively) towards K 562 cell lines, comparable to control, betulinic acid (BA) (IC5024.40±1.26). Both compounds showed concentration-dependent cytototoxicity effects and exert profound antiproliferative efficacy at concentration > 100 μM towards HCT 116 and K 562 cancer cell lines, comparable to those of BA and 5-FU (5-Fluorouracil). Furthermore, both MTG and SRM exhibit high selectivity towards HCT 116 cell lines with selective indexes of 3.14 and 2.93 respectively compared to 5-FU (SI=0.60).
CONCLUSIONS: These findings revealed that the medicinal and nutitional values of mitragynine obtained from ketum leaves that growth in tropical forest of Southeast Asia and its analogues does not limited to analgesic properties but could be promising antioxidant and anticancer or chemopreventive compounds.
OBJECTIVES: This review exhaustively gathers available information on ethnopharmacological uses, phytochemistry, and bioactivity studies on more than 20 species of Premna and critically analyzes the reports to provide the perspectives and directions for future research for the plants as potential source of drug leads and pharmaceutical agents.
METHODS: A literature search was performed on Premna species based on books of herbal medicine, major scientific databases including Chemical Abstract, Pubmed, SciFinder, Springerlink, Science Direct, Scopus, the Web of Science, Google Scholar, and ethnobotanical databases.
RESULTS: More than 250 compounds have been isolated and identified from Premna species, comprising of diterpenoids, iridoid glycosides, and flavonoids as the most common secondary metabolites, followed by sesquiterpenes, lignans, phenylethanoids, megastigmanes, glyceroglycolipids, and ceramides. Many in vitro and in vivo studies have been conducted to evaluate the biological and pharmacological properties of the extracts, and isolated compounds of Premna species with antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, antihyperglycaemia, and cytotoxic activities.
CONCLUSION: The bioactive compounds responsible for the bioactivities of most plants have not been well identified as the reported in vivo pharmacological studies were mostly carried out on the crude extracts. The isolated bioactive components should also be further subjected to more preclinical studies and elaborate toxicity study before clinical trials can be pursued.
AIM OF THIS REVIEW: The present study is a critical assessment of the state-of-the-art concerning the traditional uses, the phytochemistry and the pharmacology of species belonging to the genus Hedyosmum to suggest further research strategies and to facilitate the exploitation of the therapeutic potential of Hedyosmum species for the treatment of human disorders.
MATERIALS AND METHODS: The present review consists of a systematic overview of scientific literature concerning the genus Hedyosmum published between 1965 and 2018. Moreover, an older text, dated from 1843, concerning the traditional uses of H. bonplandianum Kunth has also been considered. Several databases (Francis & Taylor, Google Scholar, PubMed, SciELO, SciFinder, Springer, Wiley, and The Plant List Database) have been used to perform this work.
RESULTS: Sixteen species of the genus Hedyosmum have been mentioned as traditional remedies, and a large number of ethnomedicinal uses, including for the treatment of pain, depression, migraine, stomach-ache and ovary diseases, have been reported. Five species have been used as flavouring agents, tea substitutes or foods. Sesterterpenes, sesquiterpene lactones, monoterpenes, hydroxycinnamic acid derivatives, flavonoids, and neolignans have been reported as the most important compounds in these species. Studies concerning their biological activities have shown that members of the Hedyosmum genus possesses promising biological properties, such as analgesic, antinociceptive, antidepressant, anxiolytic, sedative, and hypnotic effects. Preliminary studies concerning the antibacterial, antioxidant, antiplasmodial, and antifungal activities of these plants as well as their cytotoxic activities against different tumour cell lines have been reported. Some active compounds from the Hedyosmum genus have been used as starting points for the innovative and bioinspired development of synthetic molecules. A critical assessment of these papers has been performed, and some conceptual and methodological problems have been identified regarding the materials and methods and the experimental design used in these studies, including a lack of ethnopharmacological research.
CONCLUSIONS: The present review partially confirms the basis for some of the traditional uses of Hedyosmum species (mainly H. brasiliense) through preclinical studies that demonstrated their antinociceptive and neuroprotective effects. Due to promising preliminary results, further studies should be conducted on 13-hydroxy-8,9-dehydroshizukanolide and podoandin. Moreover, several essential oils (EOs) from this genus have been preliminarily investigated, and the cytotoxic and antibacterial activities of H. brasiliense and H. sprucei EOs certainly deserve further investigation. From the promising findings of the present analysis, we can affirm that this genus deserves further research from ethnopharmacological and toxicological perspectives.