Can Crude Oil Exploration Influence the Phytochemicals and Bioactivity of Medicinal Plants? A Case of Nigerian Vernonia amygdalina and Ocimum gratissimum

The Nigerian Niger-Delta crude oil exploration often results in spills that affect indigenous medicinal plant biodiversity, likely changing the phytochemical profile of surviving species, their bioactivity or toxicity. In crude oil-rich Kokori and crude oil-free Abraka, classic examples of indigenous plants occupying the medicine-food interface include Vernonia amygdalina (VAL) and Ocimum gratissimum leaves (OGL). These plants are frequently utilised during pregnancy and in anaemia. To date, no scientific investigation has been reported on the potential changes to the phytochemical or bioactivity of the study plants. To discuss the similarities and dissimilarities in antisickling bioactivity and phytochemicals in VAL and OGL collected from Kokori (VAL-KK and OGL-KK) and Abraka (VAL-AB and OGL-AB), in silico, in vitro and comparative UPLC-QTOF-MS analysis was performed. Nine unique compounds were identified in OGL-KK, which have never been reported in the literature, while differences in antisickling potentials were observed in VAL-KK, OGL-KK and, VAL-AB, OGL-AB. Our findings show that VAL-AB and OGL-AB are richer and more diverse in phytochemicals and displayed a slightly higher antisickling activity than VAL-KK and OGL-KK. Ligand-based pharmacophore modelling was performed to understand the potential compounds better; this study may provide a basis for explaining the effect of crude oil spills on secondary metabolites and a reference for further research.

Moringa oleifera Seed at the Interface of Food and Medicine: Effect of Extracts on Some Reproductive Parameters, Hepatic and Renal Histology

The lipid-rich Seed of Moringa oleifera has been promoted as an effective water clarifier. Aside its vital nutritional application as an emerging food additive, the seed has continued to gain a wider acceptance in various global ethnomedicines for managing several communicable and lifestyle diseases, howbeit, its potential toxic effect, particularly on fertility and pregnancy outcomes has remained uninvestigated; the effect of Moringa oleifera seed (MOSE) aqueous-methanol extracts on fertility and pregnancy outcome, was investigated in vivo using female Wistar rats that were divided into 50, 100, 300 and 500 mg per kilogram body weight. Group six was given Moringa oleifera seed treated water ad-libitum (ad-libitum group). Organs harvested for histological assessment included ovary, uterus, liver and kidney. In addition to HPLC fingerprint and a preliminary peptide detection, we determined the physico-chemical characteristics and mineral content of MOSE using standard methods. Data were analyzed with significance at p ≤ 0.05. There was no significant difference in the estrus cycle, mating index, gestation survival index, gestation index, fertility index and sex ratio among all groups. Gestation length was reduced in some groups. While the male pup birth weight was comparable among the different groups, female pups birth weights were significantly reduced in 50 and 100 mg groups. Anogenital distance indices of female pups in ad libitum group were significantly increased. Pathologies were observed in liver and kidneys of dams while kidneys of pups presented a dose dependent reduction in the number of glomeruli. There were no observed pathological changes in the ovary and uterus. This study showed for the first time in rodents, that the lipid-rich MOSE is unsafe to the kidney of rodents while the lipid-free MOSE appears to be safe at doses up to 300 mg/kg body weight. Findings from this study suggested that the female pups were masculinized. In conclusion, the lipid-rich seed extracts of MOSE appear to be unsafe during pregnancy, induce hepatic and renal toxicity while the lipid-free MOSE excludes inherent toxicity as the hydrophobic part has been linked to toxicity as observed in this study due to the developmental programming effect on female offspring in rodents.

Heavy Metals, Proximate Analysis and Brine Shrimp Lethality of Vernonia amygdalina and Ocimum gratissimum Growing in Crude Oil-Rich Delta State, Nigeria

Vernonia amygdalina (VA) and Ocimum gratissimum (OG) are among the most frequently consumed vegetables in Kokori and Abraka communities of Delta State, Nigeria. However, the continuous crude oil exploration and spillages in Kokori may threaten their safety for use as food and medicine. Twelve samples of VA and OG obtained from crude oil-rich and crude oil-free communities were comparatively analysed for proximate composition, heavy metals, and cytotoxicity. Data obtained were subjected to various multivariate statistical techniques, including principal component analysis (PCA), biplot, and analysis of variance (ANOVA), to investigate the correlations between the vegetables from the different communities and the effect of crude oil exploration and spill on plant biomass. Results obtained indicate a significant difference (p < 0.05) in the proximate composition of VA and OG and higher heavy metal content for VA from the crude oil-spill Kokori. Two VA collections from Kokori were exceptionally toxic to cellular crustaceans.

Morinda lucida Benth (Rubiaceae): A review of its ethnomedicine, phytochemistry and pharmacology

ETHNOMEDICINAL RELEVANCE

Natural products derived from plants have served the primary healthcare needs of millions of indigenous people for centuries, many of which have been documented and scientifically validated. Morinda lucida Benth (Rubiaceae), also referred to as brimstone tree, is an ethnomedicinal plant which has been widely used in traditional medicine for several decades, particularly in the African continent. Various parts of the plant, including stem bark, leaves and root, have been applied in traditional medicine for the management of various pathological conditions such as malaria, diabetes, hypertension, inflammation, typhoid fever, cancer, cognitive disorders, sickle cell disease, trypanosomiasis, onchocerciasis and various fevers. In this review, we critically evaluated the relationship between traditional uses, laboratory pharmacological activities and clinical studies on M. lucida so as to unveil opportunities for the development of relevant therapeutic agents against diseases that threaten mankind.

MATERIALS AND METHODS

A search for relevant data on M. lucida was done using scientific databases (Google Scholar, Mendeley, ScienceDirect, PubMed, Asian Science Citation Database, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, Chinese Scientific Journal Database, Chinese Science Citation Database, other web sources (such as The Plant List and PROTA), books and other literature sources.

RESULTS

A hundred compounds have been isolated from M. lucida. Many of the reported secondary metabolites include alkaloids, tannins, anthraquinones, sterols, saponins, polyphenols, terpenoids, phenols and cardiac glycosides. The in vitro and in vivo experimental studies on various extracts, fractions and isolated compounds of M. lucida support the acclaimed pharmacological activities of the plant, such as antimalarial, antidiabetic, hypotensive, anti-inflammatory, immunostimulatory, antioxidant, antimicrobial, antiproliferative, cognitive-enhancement, anti-sickling, anti-trypanosomal, anti-onchocercal, muscle relaxant, antifungal and anti-leishmanial activities. These evidence-based scientific reports lend credence to their traditional uses. However, the safety of extracts of M. lucida is a cause for concern following reported toxicities such as antispermatogenic effect, genotoxicity and in vitro inhibition of human cytochrome P450 3A subfamily.

CONCLUSION

Documented evidence suggests that M. lucida remains a rich source of extracts and chemical compounds with diverse bioactivities that are of therapeutic benefit to man and this justifies its traditional uses for the primary healthcare needs of indigenous populations across tropical Africa. Due to the fact that M. lucida extracts may not be safe at some reported doses, more in-depth studies on their toxicities are required to better understand safer approaches to their traditional uses. In addition, mechanistic studies on the isolated compounds with known pharmacological activities are quite limited, thus necessitating future research efforts to be focused on the mechanisms of action of these active principles in order to facilitate their potential enlistment for rational drug design.

In vitro antiviral activity of peptide-rich extracts from seven Nigerian plants against three non-polio enterovirus species C serotypes

Background

As frequent viral outbreaks continue to pose threat to public health, the unavailability of antiviral drugs and challenges associated with vaccine development underscore the need for antiviral drugs discovery in emergent moments (endemic or pandemic). Plants in response to microbial and pest attacks are able to produce defence molecules such as antimicrobial peptides as components of their innate immunity, which can be explored for viral therapeutics.

Methods

In this study, partially purified peptide-rich fraction (P-PPf) were obtained from aqueous extracts of seven plants by reverse-phase solid-phase extraction and cysteine-rich peptides detected by a modified TLC method. The peptide-enriched fractions and the aqueous (crude polar) were screened for antiviral effect against three non-polio enterovirus species C members using cytopathic effect reduction assay.

Results

In this study, peptide fraction obtained from Euphorbia hirta leaf showed most potent antiviral effect against Coxsackievirus A13, Coxsackievirus A20, and Enterovirus C99 (EV-C99) with IC₅₀ < 2.0 µg/mL and selective index ≥ 81. EV-C99 was susceptible to all partially purified peptide fractions except Allamanda blanchetii leaf.

Conclusion

These findings establish the antiviral potentials of plants antimicrobial peptides and provides evidence for the anti-infective use of E. hirta in ethnomedicine. This study provides basis for further scientific investigation geared towards the isolation, characterization and mechanistic pharmacological study of the detected cysteine-rich peptides.

Detection of cysteine-rich peptides in Tragia benthamii Baker (Euphorbiaceae) and in vivo antiinflammatory effect in a chick model

Tragia benthamii (TBM) commonly called the climbing nettle is a tropical plant claimed to have numerous anti inflammatory effects in sub Saharan African ethnomedicine which lacks scientific evidence. Aqueous extracts of TBM were further prepurified on a RP-C18 parked solid phase system to obtain 20% aqueous fraction. This fraction was enzymatically and chemically analyzed (by MALDI TOF MS and MS/MS) to contain interesting low molecular weight cysteine-rich stable peptides within the range of 2.5–3.2 KDa. The 20% aqueous fraction was further tested in vivo using carrageenan-induced foot edema (acute inflammation) in seven-day old chicks with diclofenac as reference drug. The cytotoxicity of this active fraction was investigated using the brine shrimp lethality assay. The brine shrimp cytotoxicity assay produced LC50 above 1000 μg/mL. Pretreatment with the TBM extract (30–300 mg/kg, i.p) dose dependently (P<0.01) reduced foot edema with maximal inhibition of 0.253 ± 0.180 (84.3%) at 300 mg/kg body weight, which was comparable to that of diclofenac with inhibition (P<0.05) of 0.410 ± 0.271 (74.5%) at 10 mg/kg body weight. The study has therefore shown for the first time, the detection of cysteine-rich biologically active peptides in T. benthamii and the stable peptide extracts from this ethnomedicinal plant, which is not toxic to Artemia salina, exhibits anti inflammatory activity in a chick in vivo model. This may provide scientific evidence for its use in the treatment of inflammation and pain in traditional medicine. Further in-depth vivo and in vitro studies will be required to investigate its anti inflammatory activity including effect on HUVEC-TERT, the possible inhibition of ICAM-1 surface expression and the mechanism of the anti inflammatory effect.

Evaluation of peptide-rich root extracts of Calliandria portoriscensis (Jacq.) Benth (Mimosaceae) for in vitro antimicrobial activity and brine shrimp lethality

BACKGROUND

Several Host defence peptides (HDPs) are low molecular weight (< 50 amino acids residues) peptides detected in several ethnomedicinal plants and have particularly gained research interest in recent times. Due to their wide range of bioactivity, occurrence, abundance and ability to induce very little resistance, they hold promising potentials in drug development. This study investigated the presence of bioactive peptides in the roots of Calliandra portoricensis (CPr) (Mimosaceae) and evaluated its antimicrobial activity against gram-negative and gram-positive bacteria.

METHODS

The crude peptide extract was obtained and pre-purified on pre-loaded tube of RP-C18 solid phase cartridges (strata giga tube C18-E; 5 g, 20 mL, Phenomenex, Germany). Peptide enriched fraction was chemically analysed for arginine-rich/aromatic amino acid-rich peptides using a modified G-250 analytical stain and ninhydrin on thin layer chromatography (TLC) for a preliminary screening. Furthermore, MALDI TOF/TOF peptidomics was used to detect the presence and masses of the peptides. Extracts from CPr were used to test the ability to inhibit microbial growth using p-INT (Para-iodonitrotetrazolium violet) dye, with 0.1% gentamycin as positive control. The concentration that inhibits the growth of microorganisms by 50% (IC50) were determined. Toxicity of the two extracts was accessed using freshly hatched nauplii of Artemia salina. Data analysis were evaluated using Microsoft excel and GraphPad Prism5.

RESULTS

Low molecular weight (LMW) peptides were detected in CPr using TLC and MALDI-TOF MS. Generally, the extracts exhibited good inhibition (70-95%) against the gram-negative and gram-positive bacteria, except MRSA6 typed strain. Enhanced activity was observed in the pre-purified peptide fraction than in the methanol crude, except on MRSA6. The greatest antimicrobial inhibition by pre-purified peptide fraction was against MRSA22 (IC50 = 0.69 ± 0.33 μg/mL). The crude methanol extract (LC50 = 5.13 μg/mL) was slightly more toxic than the peptide extract (LC50 = 6.12 μg/mL).

CONCLUSIONS

This is the first report on detection of bioactive LMW peptides in Mimosaceae family. These peptides appear to be rich in arginine and aromatic amino acids. The peptide extract, in its pre-purified form showed a lower Brine shrimp cytotoxicity and an enhanced antimicrobial activity against the tested gram-negative and gram-positive bacteria.

Cardioprotective Effects of Curcumin-Nisin Based Poly Lactic Acid Nanoparticle on Myocardial Infarction in Guinea Pigs

Myocardial infarction (MI) is the most prevalent cause of cardiovascular death. A possible way of preventing MI maybe by dietary supplements. The present study was thus designed to ascertain the cardio-protective effect of a formulated curcumin and nisin based poly lactic acid nanoparticle (CurNisNp) on isoproterenol (ISO) induced MI in guinea pigs. Animals were pretreated for 7 days as follows; Groups A and B animals were given 0.5 mL/kg of normal saline, group C metoprolol (2 mg/kg), groups D and E CurNisNp 10 and 21 mg/kg respectively (n = 5). MI was induced on the 7^th day in groups B-E animals. On the 9^th day electrocardiogram (ECG) was recorded, blood samples and tissue biopsies were collected for analyses. Toxicity studies on CurNisNp were carried out. MI induction caused atrial fibrillation which was prevented by pretreatment of metoprolol or CurNisNp. MI induction was also associated with increased expressions of cardiac troponin I (CTnI) and kidney injury molecule-1 (KIM-1) which were significantly reduced in guinea pig's pretreated with metoprolol or CurNisNp (P < 0.05). The LC₅₀ of CurNisNp was 3258.2 μg/mL. This study demonstrated that the formulated curcumin-nisin based nanoparticle confers a significant level of cardio-protection in the guinea pig and is nontoxic.

Ethnobotanical survey of Rinorea dentata (Violaceae) used in South-Western Nigerian ethnomedicine and detection of cyclotides

ETHNOPHARMACOLOGICAL RELEVANCE

People living in the tropical rain forest of South-Western Nigeria use Rinorea dentata (P. Beauv.) Kuntze (Violaceae) in ethno-veterinary medicine to facilitate parturition. There are no evidence-based pharmacological investigations for the uterotonic activity of this plant.

AIMS OF STUDY

(i) Collection of data about the ethnopharmacological uses of R. dentata and evaluation of its uses and applications in health care; (ii) determining potential uterotonic effects in vitro, and (iii) chemical characterization of R. dentata, which is a member of the Violaceae family known to express circular cystine-knot peptides, called cyclotides.

MATERIALS AND METHODS

The ethnopharmacological use of R. dentata in settlement camps within the area J4 of Omo forest has been investigated by semi-structured questionnaires and open interviews. Use index analysis has been performed by seven quantitative statistical models. Respondents' claim on the beneficial ethno-veterinary application of the plant to aid parturition has been investigated in vitro by myometrial contractility organ bath assays. The bioactive plant extract was screened by chemical derivatization and mass spectrometry-based peptidomics using reversed-phase HPLC fractionation and MALDI-TOF/TOF analysis.

RESULTS

Based on the survey analysis, medicinal preparations of R. dentata have been used for anti-microbial and anti-malaria purpose in humans, and for aiding parturition in farm animals. The latter application was mentioned by one out of six respondents who claimed to use this plant for any medicinal purpose. The plant extract exhibited a weak uterotonic effect using organ bath studies. The plant contains cyclotides and the peptide riden A has been identified by de novo amino acid sequencing using mass spectrometry.

CONCLUSION

Few dwellers around the settlement camps of the tropical forest of Omo (Nigeria) use R. dentata for various health problems in traditional veterinary and human medicine. The weak uterotonic effect of the cyclotide-rich extract is in agreement with the low use value index obtained for this plant. Cyclotides have been reported in the genus Rinorea confirming the ubiquitous expression of these stable bioactive plant peptides within the family of Violaceae.

Cyclotide discovery in Gentianales revisited--identification and characterization of cyclic cystine-knot peptides and their phylogenetic distribution in Rubiaceae plants

Cyclotides are a unique class of ribosomally synthesized cysteine-rich miniproteins characterized by a head-to-tail cyclized backbone and three conserved disulfide-bonds in a knotted arrangement. Originally they were discovered in the coffee-family plant Oldenlandia affinis (Rubiaceae) and have since been identified in several species of the violet, cucurbit, pea, potato, and grass families. However, the identification of novel cyclotide-containing plant species still is a major challenge due to the lack of a rapid and accurate analytical workflow in particular for large sampling numbers. As a consequence, their phylogeny in the plant kingdom remains unclear. To gain further insight into the distribution and evolution of plant cyclotides, we analyzed ∼300 species of >40 different families, with special emphasis on plants from the order Gentianales. For this purpose, we have developed a refined screening methodology combining chemical analysis of plant extracts and bioinformatic analysis of transcript databases. Using mass spectrometry and transcriptome-mining, we identified nine novel cyclotide-containing species and their related cyclotide precursor genes in the tribe Palicoureeae. The characterization of novel peptide sequences underlines the high variability and plasticity of the cyclotide framework, and a comparison of novel precursor proteins from Carapichea ipecacuanha illustrated their typical cyclotide gene architectures. Phylogenetic analysis of their distribution within the Psychotria alliance revealed cyclotides to be restricted to Palicourea, Margaritopsis, Notopleura, Carapichea, Chassalia, and Geophila. In line with previous reports, our findings confirm cyclotides to be one of the largest peptide families within the plant kingdom and suggest that their total number may exceed tens of thousands.

Uterine contractility of plants used to facilitate childbirth in Nigerian ethnomedicine

ETHNOPHARMACOLOGICAL RELEVANCE

Pregnant women in Nigeria use plant preparations to facilitate childbirth and to reduce associated pain. The rationale for this is not known and requires pharmacological validation.

AIM OF STUDY

Obtain primary information regarding the traditional use of plants and analyze their uterine contractility at cellular level.

MATERIALS AND METHODS

Semi-structured, open interviews using questionnaires of traditional healthcare professionals and other informants triggered the collection and identification of medicinal plant species. The relative traditional importance of each medicinal plant was determined by its use-mention index. Extracts of these plants were analyzed for their uterotonic properties on an in vitro human uterine cell collagen model.

RESULT

The plants Calotropis procera, Commelina africana, Duranta repens, Hyptis suaveolens, Ocimum gratissimum, Saba comorensis, Sclerocarya birrea, Sida corymbosa and Vernonia amygdalina were documented and characterized. Aqueous extracts from these nine plants induced significant sustained increases in human myometrial smooth muscle cell contractility, with varying efficiencies, depending upon time and dose of exposure.

CONCLUSION

The folkloric use of several plant species during childbirth in Nigeria has been validated. Seven plants were for the first time characterized to have contractile properties on uterine myometrial cells. The results serve as ideal starting points in the search for safe, longer lasting, effective and tolerable uterotonic drug leads.