Chemical profiling of Ocimum americanum using external flavonoids

Targeting purine metabolism-related enzymes for therapeutic intervention: A review from molecular mechanism to therapeutic breakthrough

Purines are ancient metabolites with established and emerging metabolic and non-metabolic signaling attributes. The expression of purine metabolism-related genes is frequently activated in human malignancies, correlating with increased cancer aggressiveness and chemoresistance. Importantly, under certain stimulating conditions, the purine biosynthetic enzymes can assemble into a metabolon called "purinosomes" to enhance purine flux. Current evidence suggests that purine flux is regulated by a complex circuit that encompasses transcriptional, post-translational, metabolic, and association-dependent regulatory mechanisms. Furthermore, purines within the tumor microenvironment modulate cancer immunity through signaling mediated by purinergic receptors. The deregulation of purine metabolism has significant metabolic consequences, particularly hyperuricemia. Herbal-based therapeutics have emerged as valuable pharmacological interventions for the treatment of hyperuricemia by inhibiting the activity of hepatic XOD, modulating the expression of renal urate transporters, and suppressing inflammatory responses. This review summarizes recent advancements in the understanding of purine metabolism in clinically relevant malignancies and metabolic disorders. Additionally, we discuss the role of herbal interventions and the interaction between the host and gut microbiota in the regulation of purine homeostasis. This information will fuel the innovation of therapeutic strategies that target the disease-associated rewiring of purine metabolism for therapeutic applications.

Exploring of Chemical Profile and Biological Activities of Three Ocimum Species From Comoros Islands: A Combination of In Vitro and In Silico Insights

Ocimum species have a great interest in different traditional medicinal systems. This study examined the chemical composition, antioxidant properties, enzyme inhibitory effects, and antibacterial and antifungal activities of the aerial parts of Ocimum gratissimum, Ocimum americanum, and Ocimum basilicum from the Comoros Islands. The extracts were analyzed using high-performance liquid chromatography-mass spectrometry (HPLC-MS) to determine their chemical composition. Antioxidant activity was assessed using 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP), chelating ability, and phosphomolybdenum radical scavenging assays. Enzyme inhibitory activities against acetylcholinesterase (AChE), butrylcholinesterase (BChE), tyrosinase, amylase, and glucosidase were evaluated using spectrophotometric methods. Antibacterial and antifungal activities were tested using the broth microdilution method against selected pathogenic microorganisms. The selected enzymes and proteins were evaluated using in silico methods with biomolecules from these plants. In addition, 111 different metabolites were identified in the tested extracts using advanced HPLC/MS techniques. The most significant number of detected compounds were derivatives of hydroxycinnamic acids, followed by flavonoid glycosides and aglycones and derivatives of hydroxybenzoic acids. All three Ocimum species exhibited significant antioxidant activities, O. gratissimum exhibited the best-reducing abilities in CUPRAC and FRAP assays. In addition, enzyme inhibitory assays revealed that O. americanum had the most potent inhibitory effect on tyrosinase (48.01 ± 3.89 mg kojic acid equivalent [KAE]/g), and amylase (1.08 ± 0.02 mmol acarbose equivalent [ACAE]/g). Antibacterial and antifungal tests demonstrated that the extracts possess broad-spectrum activity. Molecular docking results showed that compounds exhibited remarkable binding energies with target enzymes and proteins. The molecular dynamics simulations identified chicoric acid with MurE of Staphylococcus aureus complex as the most promising drug candidate. These findings support their traditional medical and nutraceutical uses and suggest possibilities for natural functional applications.

Evaluation of Antimicrobial Activity, Cytotoxicity, and Phytochemical Composition of Ocimum americanum L. (Lamiaceae)

Background

Herbal plants are a natural source of novel biomolecules used widely in ethnomedicine. The present study was intended to examine the antimicrobial properties, cytotoxicity, and phytoconstituents of Ocimum americanum L., an herb traditionally used by the people of Swahili (Kenya) against microbial infections.

Methods

The aerial parts of Ocimum americanum L. were sourced, dried, milled, and extracted using three solvents: aqueous, acetonic, and 70% hydroethanolic. Additionally, fractions of chloroform and ethyl acetate were obtained from all crude extracts of the plant. The antimicrobial property was evaluated using agar well diffusion and microdilution techniques against human opportunistic pathogens including S. aureus, E. coli, and C. albicans. The brine shrimp cytotoxicity test was used to analyze the lethality of the extracts and fractions. Phytochemical screening was used to qualitatively assay the presence of phytoconstituents.

Results

The phytochemical assay confirmed the presence of alkaloids, phenols, flavonoids, tannins, saponins, terpenoids, reducing sugars, anthraquinones, and glycosides. The lethality test demonstrated that all the extracts and fractions were toxic against Artemia salina nauplii with LC₅₀ values ranging from 0.59 to 559.71 µg/ml. Chloroformic fraction of the hydroethanolic extract had the highest lethality with an LC₅₀ value of 0.59 µg/ml. Two of the extracts and their fractions displayed antimicrobial activity against the Gram-positive bacteria (B. cereus and S. aureus) and fungus (C. albicans), while the same extracts had no activity against the Gram-negative bacteria (E. coli and K. pneumoniae). The highest antimicrobial activity was seen in the ethyl acetate fraction of the hydroethanolic extract at 250 mg/ml against Bacillus cereus which had an inhibition zone of 26.00 ± 0.00 and MIC value of 62.5 mg/ml.

Conclusion

In the current study, we report that Ocimum americanum L. demonstrated moderate antimicrobial activity, contains numerous phytocompounds, and is highly cytotoxic; thus, further research is needed for bioprospecting a novel compound.

Effects of sweet basil leaves (Ocimum basilicum L) addition on the chemical, antioxidant, and storage stability of roselle calyces (Hibiscus sabdariffa) drink

Consumers expect greater functionality from food and beverage products. Celebrated for a range of health benefits, polyphenols have been linked to a preventive role for chronic diseases and viral infections and have the ability to relieve oxidative stress. A drink made with roselle calyces (Hibiscus sabdariffa) and sweet basil leaves (Ocimum basilicum L) may provide therapeutic or preventive effects against chronic and infectious diseases. Damage caused by oxidative stress may be alleviated by the polyphenols found in roselle calyces and sweet basil leaves. The roselle-basil samples at different blend ratio were analysed for pH, total soluble solids, total titratable acidity, vitamin C, lycopene, total phenolic contents, antioxidant properties, and storage stability at different temperature (4 and 29 °C). The incorporation of sweet basil leaves to roselle calyces slightly decreased the vitamin C and lycopene content of the processed drink but increased the total carotenoid and antioxidant activities (ABTS and ORAC) of the drink. The radical scavenging properties of the processed drink increased with the addition of the dried sweet basil leaves and samples kept at a higher temperature of 29 °C showed a rise in antioxidant activities compared to samples stored at 4 °C. The increase in the free radical scavenging power of the drinks show that the roselle-basil drink may serve as health drink and addition of sweet basil leaves up to 5% may be suitable to produce roselle-basil drink.

The Botanical, Chemical and Ethnobotanical Diversity of Southern African Lamiaceae

The Lamiaceae is undoubtedly an important plant family, having a rich history of use that spans the globe with many species being used in folk medicine and modern industries alike. Their ability to produce aromatic volatile oils has made them valuable sources of materials in the cosmetic, culinary, and pharmaceutical industries. A thorough account of the taxonomic diversity, chemistry and ethnobotany is lacking for southern African Lamiaceae, which feature some of the region’s most notable medicinal and edible plant species. We provide a comprehensive insight into the Lamiaceae flora of southern Africa, comprising 297 species in 42 genera, 105 of which are endemic to the subcontinent. We further explore the medicinal and traditional uses, where all genera with documented uses are covered for the region. A broad review of the chemistry of southern African Lamiaceae is presented, noting that only 101 species (34%) have been investigated chemically (either their volatile oils or phytochemical characterization of secondary metabolites), thus presenting many and varied opportunities for further studies. The main aim of our study was therefore to present an up-to-date account of the botany, chemistry and traditional uses of the family in southern Africa, and to identify obvious knowledge gaps.

Traditional Foods and Sustainable Rural Development: Exploiting the Case of the Comoros Tea as a Potential Source of Bioactive Compounds

Although modern medicine is available in many developing countries, such as the Comoros Islands, the primary health-care needs of the local population are based on traditional foods and beverages derived from natural resources and medicinal plants for cultural and historical reasons. Aphloia theiformis (Vahl) Benn. (‘Mfandrabo’), Cinnamomum verum J.Presl (‘Mani yamdrara’), Ocimum gratissimum L. (‘Roulé’), Plectranthus amboinicus (Lour.) Spreng. (‘Ynadombwe’), Cymbopogon nardus (L.) Rendle (‘Sandze monach’) and Ocimum americanum L. (‘Kandza’) are six wild plants that are largely utilised to treat many diseases. The leaves of these plants are used in the traditional Comorian tea (aqueous infusion). This study aimed to identify and quantify the main health-promoting compounds in the traditional formulation of Comorian tea by HPLC profiling together with a preliminary assessment of antioxidant capacity to confirm the traditional use of these plants by the local population. The single plants were also studied. The Comoros tea presented a total polyphenolic content (TPC) of 4511.50 ± 74.41 mgGAE/100 g DW, a value higher than the TPCs of the different plants included in the Comorian tea. Moreover, the Comorian tea showed an antioxidant capacity (AOC) of 578.65 ± 6.48 mmol Fe2+/Kg DW, a value higher if compared to all the AOC values obtained in the single plants. The polyphenolic fraction (771.37 ± 35.76 mg/100 g DW) and organic acids (981.40 ± 38.38 mg/100 g DW) were the most important phytochemical classes in the Comorian tea (40.68% and 51.75% of the total phytocomplex, respectively), followed by the monoterpenes (5.88%) and vitamin C (1.67%), while carotenoids were detected in trace (0.02%). The Comorian tea could be important in meeting the high demand in the Comoros Islands and other developing countries for cost-effective and natural health-promoting foods and/or beverages to be produced by agri-food industries and used by the local population. This study may promote traditional foods in rural communities in the Comoros Islands and contribute to sustainable rural development and a commercial valorisation of these plants for health-promoting and food applications.

Isolation and Biological Properties of the Natural Flavonoids Pectolinarin and Pectolinarigenin-A Review

Flavonoids are metabolites widely distributed in plants and commonly present in foods, such as fruits and vegetables. Pectolinarin, which belongs to the flavone subclass, has attracted considerable attention due to its presence in many medicinal plants. It has turned out to be a good biological agent especially due to its antioxidant, anti-inflammatory, antidiabetic, and antitumor activities, evaluated both in vitro and in vivo. Its aglycone, the metabolite pectolinarigenin, is also known for a series of biological properties including anti-inflammatory and antidiabetic effects. In the first overview on the two metabolites here presented, their collection, isolation and the results of their biological evaluation are reported.

Cytotoxicity to Five Cancer Cell Lines of the Respiratory Tract System and Anti-inflammatory Activity of Thai Traditional Remedy

A Thai traditional remedy called Benchalokawichian (BLW) consists of 5 plant species, Ficus racemosa, Capparis micracantha, Clerodendrum petasites, Harrisonia perforata, and Tiliacora triandra. It has long been used in Thai traditional medicine to reduce fever in respiratory tract infection, but there is no report on either cytotoxicity against cancer cell lines of the respiratory tract system or anti-inflammatory effect. Thus, the objectives of this research were to investigate the cytotoxic activity of the ethanolic and water extracts of BLW, its single plant ingredients and its isolated compounds against 5 cancer cell lines of the respiratory tract, by SRB assay. Anti-inflammatory activity of all extracts and compounds was also tested by using lipopolysaccharide-induced nitric oxide (NO) in RAW 264.7 cells. The main compounds were isolated by high-performance liquid chromatography and compared with BLW and plant ingredients. A major compound of BLW and H. perforata ethanolic extracts is perforatic acid, which inhibited the growth of 2 lung cancer cell lines, A549 and H226, with IC50 values of 6.7 and 13.2 µg/mL. The ethanolic extract of BLW and T. triandra showed cytotoxic activity against all cancer cell lines with IC50 values in the range of 10.1 to 45.2 µg/mL. In contrast, all EtOH extracts showed moderate anti-inflammatory activity, but the water extract had no inhibitory effect on either activity. Pectolinarigenin and O-methyllaloptaeroxyrin, 2 minor compounds, exhibited NO inhibitory effect with IC50 values of 7.1 and 7.9 µg/mL, respectively, whereas perforatic acid was inactive (>50 µg/mL). Moreover, pectolinarigenin showed high cytotoxic activity against all cancer cell lines of the respiratory system with IC50 values in the range of 1.9 to 9.1 µg/mL. As a result, these 2 minor compounds can be used as markers for quality control of BLW for anti-inflammatory activity. Perforatic acid and pectolinarigenin are of interest for further study on their cytotoxic mechanism. Remarkably, T. triandra, one of the plant components of BLW, is possibly the source of the active cytotoxic compounds.

Phenolic compounds of herbal infusions obtained from some species of the Lamiaceae family

The present investigation was to estimate the total phenolic content and composition of flavonoids and hydroxycinnamic acids in herbal infusions obtained from aerial parts of three Lamiaceae species (Dracocephalum moldavica, Ocimum americanum and Satureja hortensis). The total phenolic content of herbal infusions was determined using a spectrophotometric method, whereas the individual phenolics were assessed by high-performance liquid chromatography (HPLC). The HPLC method was developed and validated. The total phenolic content was measured by applying the Folin-Ciocalteu method with reference to gallic acid. Results were in the range from 29.39 to 65.38 mg estimated as gallic acid equivalents per gram of dry herb. The phenolic profile was, in turn, analysed by HPLC and consisted of gallic acid, hydroxycinnamic acids (caffeic, chlorogenic, ferulic, and rosmarinic) and flavonoids (rutin, hyperoside, quercitrin, quercetin, apigenin, apigenin-7-glucoside and catechin) in different concentrations. Rosmarinic acid was the predominant component among the hydroxycinnamic acids in herbal infusions of all three plants. This was found to be in the range of 3.64 to 5.28 mg per gram of dry herb. Apigenin-7-glucoside, quercitrin and hyperoside were the prevailing flavonoid components of the infusions.

Review: DNA Barcoding and Chromatography Fingerprints for the Authentication of Botanicals in Herbal Medicinal Products

In the last two decades, there has been a tremendous increase in the global use of herbal medicinal products (HMPs) due to their claimed health benefits. This has led to increase in their demand and consequently, also, resulted in massive adulteration. This is due to the fact that most of the traditional methods cannot identify closely related species in a process product form. Therefore the urgent need for simple and rapid identification methods resulted in the discovery of a novel technique. DNA barcoding is a process that uses short DNA sequence from the standard genome for species identification. This technique is reliable and is not affected by external factors such as climates, age, or plant part. The difficulties in isolation of DNA of high quality in addition to other factors are among the challenges encountered using the DNA barcoding in the authentication of HMP. These limitations indicated that using DNA barcoding alone may ineffectively authenticate the HMP. Therefore, the combination of DNA barcoding with chromatographic fingerprint, a popular and generally accepted technique for the assessment and quality control of HMP, will offer an efficient solution to effectively evaluate the authenticity and quality consistency of HMP. Detailed and quality information about the main composition of the HMPs will help to ascertain their efficacy and safety as these are very important for quality control.

Ethnomedicinal uses of plants for the treatment of malaria in Soon Valley, Khushab, Pakistan

ETHNOPHARMACOLOGICAL RELEVANCE

To best of our knowledge this is the first quantitative ethno-medicinal study with the aim of documenting the indigenous knowledge and practices of using plants for malarial therapy in Soon Valley, Khushab, Pakistan. In this Valley, malaria is among the major public health problems but, until now, the population still mostly relies on herbal medicine for treatment.

MATERIALS AND METHODS

Ethno-medicinal data were documented from 63 informants by using semi-structured questionnaires and interviewing the informants about their knowledge of plants regarding malaria and related symptoms. Documented data were evaluated using the quantitative ethno-botanical indices of frequency citation (FC), relative frequency of citation (RFC), percentage of respondents having knowledge (PRK) and Jaccard index (JI).

RESULTS

A total of 70 plant species belonging to 62 genera and 34 families were recorded as anti-malarial in the study area. Solanaceae was found to be the most cited family with 7 species, followed by Fabaceae, Rutaceae and Lamiaceae with 5 species each. Ocimum americanum and Solanum incanum were the species with the highest relative frequency of citation (RFC =0.25 each) and percentage of respondents having knowledge (PRK =25.4% each), followed by Grewia tenax (RFC =0.23, PRK =23.8%), which indicates that these plants are the best species with anti-malarial properties. The most highly cited life form was found to be herbs (56%). The dominant plant part used in preparations were leaves (49%). The main mode of utilization was decoction (47%) followed by infusion (29%). In comparison, maximum similarity index is found in our study with JI (16.83) followed by (13.13). Similarity percentage of plants uses ranges from 0.81 to 16.83 while dissimilarity percentage varies from 0% to 17.65%.

CONCLUSIONS

To the best of our knowledge seven plant species, viz. Withania coagulans, Fagonia cretica, Carthamus oxyacantha, Ehretia obtusifolia, Helianthus annuus, Olea ferruginea and Vitex trifolia, are reported from this region for the first time for the treatment of malaria. This first ethno-medicinal study highlights potential sources for the development of new antimalarial drugs from indigenous knowledge of medicinal plants found in the Soon Valley, Pakistan. Such investigations could be a subject for in vitro and in vivo anti-plasmodial screening to develop new plant-based antimalarial drugs and can also be evaluated for other biological activities and novel drug discoveries.

Health Promotion Potential of Vegetables Cultivated in Northern Thailand: A Preliminary Screening of Tannin and Flavonoid Contents, 5α-Reductase Inhibition, Astringent Activity, and Antioxidant Activities

Many of scientific evidences suggest that regular consumption of fruits and vegetables can prevent chronic diseases. In Northern Thailand, there are many vegetables that are usually consumed by local people. In this study, 17 local vegetables were selected and extracted with 95% ethanol. The extracts were screened for 5α-reductase inhibitory activity, total tannin and flavonoid contents, astringent and antioxidant activities. The results showed that Spondias pinnata and Ocimum americanum had the highest tannin and flavonoid content, respectively. Neptunia oleracea was the most potent 5α-reductase inhibitor. For antioxidant activities, S pinnata was the most potent ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenger and the most potent ferric reducer. Polygonatum odoratum was the most potent hydrogen peroxide scavenger and Leucaena leucocephala was the most potent DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenger among the tested samples. This suggests that local vegetables in Northern Thailand have a health promotion potential, which can be further developed as nutritional supplements, preventive medicines, and topical products for cosmetic purposes.

The Influence of Cultivars and Phenological Phases on the Accumulation of Nevadensin and Salvigenin in Basil {Ocimum basilicum)

According to the earlier literature the optimum harvest time for basil is at the full flowering stage if accumulation of essential oil is taken into account. In this research we have investigated our gene-bank stored basil accessions to determine whether the harvest timing is variety specific or not considering their flavonoid accumulation pattern. In our work we have determined by HPLC the content of two main flavonoid compounds, salvigenin and nevadensin, of eight different gene bank accessions from 2013 of Ocimum basilicum L. Data were analysed with the nonparametric Kruskal-Wallis test. Multiple pairwise comparisons were made using the Conover-Iman procedure where the significance level was 5%. We have observed that the optimum harvest time is at the full flowering stage in the case of accessions ‘Genovese’ and ‘Piros’, but this was not verified for the others. The result of our experiment has shown that the maximum salvigenin and nevadensin content was detected both at the full- and early flowering period. Almost in all phenological phases the accession ‘M. Grimes’ accumulated the highest level of nevadensin, while accession ‘Lengyel’ produced the lowest results in all phenological phases. Generally it could be observed that compared with nevadensin more salvigenin is accumulated, and it is independent of the phenological phases. In the case of salvigenin, ‘M. Grimes’ accession produced the largest quantity and accession ‘Dark Opal’ showed the lowest values. Our analyses demonstrated that harvest at different phenological phases may result in different amounts of active agents according to the cultivar.

Inhibitory Effect on β -Hexosaminidase Release from RBL-2H3 Cells of Extracts and Some Pure Constituents of Benchalokawichian, a Thai Herbal Remedy, Used for Allergic Disorders

Introduction. Benchalokawichian (BCW), a Thai traditional herbal formulation, has long been used as antipyretic and to treat skin disorders. It comprises roots from five herbs: Ficus racemosa, Capparis micracantha, Clerodendrum petasites, Harrisonia perforata, and Tiliacora triandra. This polyherbal remedy has recently been included in the Thailand National List of Essential Medicines (Herbal Products list). Methodology. A Bioassay-guided fractionation technique was used to evaluate antiallergy activities of crude extracts, and those obtained by the multistep column chromatography isolation of pure compounds. Inhibitory effect on the release of β-hexosaminidase from RBL-2H3 cells was used to determine antiallergic activity. Results. Two pure compounds from BCW formulation showed higher antiallergic activity than crude or semipure extracts. Pectolinarigenin showed the highest antiallergic activity, followed by O-methylalloptaeroxylin, with IC50 values of 6.3 μg/mL and 14.16 μg/mL, respectively. Moreover, the highest activities of pure compounds were significantly higher than chlorpheniramine (16.2 μg/mL). Conclusions. This study provides some support for the use of BCW in reducing itching and treatment of other skin allergic disorders. The two isolated constituents exhibited high antiallergic activity and it is necessary to determine their mechanism of action. Further phytochemical and safety studies of pure compounds are required before development of these as antiallergy commercial remedies.

Application of chemometrics in authentication of herbal medicines: a review

INTRODUCTION

Herbal medicines (HM) and their preparations have been widely used for hundreds of years all over the world. However, they have not been officially recognised due to a lack of adequate or accepted research methodology for their evaluation.

OBJECTIVE

To present a concise overview of the recent applications of chemometrics in solving the ambiguity of herbal medicine authentication during the last two decades.

METHODOLOGY

Studies involving the applications of chemometric analysis in combination with different analytical methods were classified according to the method of analysis used including chromatographic (HPLC, GC and CE), spectroscopic (NMR, IR, UV and ICP) and genetic analysis (RAPD). The purpose of each of these studies was classified into one of three main categories: taxonomic discrimination, quality assessment or classification between plants of different geographic origins.

RESULTS

This review comprises over 150 studies, covering the past two decades, emphasising the significance of chemometric methods in the discrimination of many herbs from closely related species and from adulterants, based on the principal bioactive components and phytochemical diversity. Furthermore, the differentiation between varieties and hybrids was achieved in addition to the prediction of the active components by quantitative methods of analysis. Discrimination according to geographical origin and localities, processing methods, DNA profiling and metabolomics were also efficiently investigated.

CONCLUSION

Chemometric methods have provided an efficient and powerful tool for the quality control and authentication of different herbs.

Devil's Claw-a review of the ethnobotany, phytochemistry and biological activity of Harpagophytum procumbens

ETHNOPHARMACOLOGICAL RELEVANCE

Harpagophytum procumbens subps. procumbens (Burch.) DC. ex Meisn. (Pedaliaceae) is an important traditional medicine growing in the Kalahari region of southern Africa where it is consumed as a general health tonic and for treating diverse ailments including arthritis, pain, fever, ulcers and boils.

AIM OF THE REVIEW

To provide a comprehensive overview of the ethnobotany, phytochemistry and biological activity of H. procumbens and possibly make recommendations for further research.

MATERIALS AND METHODS

Peer-reviewed articles on H. procumbens were acquired on Scopus, ScienceDirect and SciFinder, there was no specific timeline set for the search. A focus group discussion was held with different communities in Botswana to further understand ethnobotanical uses of the plant.

RESULTS

Harpogophytum procumbens is used for a wide variety of health conditions in the form of infusions, decoctions, tinctures, powders and extracts. In addition to the common local use for arthritis and pain, other ethnomedicinal uses include dyspepsia, fever, blood diseases, urinary tract infections, postpartum pain, sprains, sores, ulcers and boils. Scientific studies revealed that H. procumbens exhibits analgesic, anti-oxidant, anti-diabetic, anti-epileptic, antimicrobial and antimalarial activities amongst others. Iridoid glycosides and phenylpropanoid glycosides have been the focus of phytochemical investigations as the biological activity has been ascribed to the iridoid glycosides (such as harpagoside and harpagide), which are common in nature and are known to possess anti-inflammatory activity. In addition, it has been shown that the hydrolysed products of harpagoside and harpagide have more pronounced anti-inflammatory activity when compared to the unhydrolysed compounds. Harpagophytum zeyheri is a close taxonomic ally of H. procumbens but H. procumbens is the favoured species of commerce, and contains higher levels of the pharmacologically active constituents. The two are used interchangeably and H. procumbens raw material is often intentionally adulterated with H. zeyheri and this may impact on the efficacy of inadequately controlled health products. The main exporter of this highly commercialised plant is Namibia. In 2009 alone, Harpagophytum exports were worth approximately €1.06 million. The high demand for health products based on this plant has led to over-harvesting, raising concerns about sustainability. Although only the secondary tubers are utilised commercially, the whole plant is often destroyed during harvesting.

CONCLUSIONS

Harpagophytum procumbens is used to treat a wide range of ailments. Some of the ethnobotanical claims have been confirmed through in vitro studies, however, when the constituents deemed to be the biologically active compounds were isolated the efficacy was lower than that of the whole extract. This necessitates the use of a different approach where all the metabolites are considered using a robust method such as spectroscopy; the phytochemical data can then be superimposed on the biological activity. Furthermore, there is a need to develop rapid and efficient quality control methods for both raw materials and products because the orthodox methods in current use are time-consuming and labour intensive.

A set of regioselective O-methyltransferases gives rise to the complex pattern of methoxylated flavones in sweet basil

Polymethoxylated flavonoids occur in a number of plant families, including the Lamiaceae. To date, the metabolic pathways giving rise to the diversity of these compounds have not been studied. Analysis of our expressed sequence tag database for four sweet basil (Ocimum basilicum) lines afforded identification of candidate flavonoid O-methyltransferase genes. Recombinant proteins displayed distinct substrate preferences and product specificities that can account for all detected 7-/6-/4'-methylated, 8-unsubstituted flavones. Their biochemical specialization revealed only certain metabolic routes to be highly favorable and therefore likely in vivo. Flavonoid O-methyltransferases catalyzing 4'- and 6-O-methylations shared high identity (approximately 90%), indicating that subtle sequence changes led to functional differentiation. Structure homology modeling suggested the involvement of several amino acid residues in defining the proteins' stringent regioselectivities. The roles of these individual residues were confirmed by site-directed mutagenesis, revealing two discrete mechanisms as a basis for the switch between 6- and 4'-O-methylation of two different substrates. These findings delineate major pathways in a large segment of the flavone metabolic network and provide a foundation for its further elucidation.

Characterization of Yew Tree (Taxus) Varieties by Fingerprint and Principal Component Analyses

The composition of varieties of Taxus growing in Estonia was analyzed by capillary electrophoresis with diode array detection (CE-DAD) for the separation of phenolic compounds, and by high performance liquid chromatography-mass spectrometry (HPLC-MS) for the determination of taxoids. The main purpose of this study was the chemotaxonomic differentiation of varieties of Taxus by using data from these analyses. Fingerprints scanned at 214 nm on the basis of CE separation at pH 9.3 were used to characterize seven varieties of yew. The contents of four key taxoids (10-deacetylbaccatin, baccatin III, cephalomannine and paclitaxel) in six Taxus varieties were comparatively determined by HPLC-MS. The set of electropherograms/chromatograms of the various Taxus extracts were subjected to principal component analysis (PCA), using the peak areas of 16 phenolic compounds and 14 taxoids as characteristics. The formation of distinct clusters in accordance with botanical classification proves the suitability of PCA for differentiating varieties of Taxus.

Rosmarinic acid content in antidiabetic aqueous extract of Ocimum canum sims grown in Ghana

Rosmarinic acid (RA) is an important antioxidant polyphenol that is found in a variety of spices and herbs, including Ocimum canum Sims (locally called eme or akokobesa in Ghana). Aqueous extracts from the leaves of O. canum are used as an antidiabetic herbal medicine in Ghana. Analytical thin-layer chromatography was used to examine the composition of the polyphenols in leaf extracts. The polyphenol content in the aqueous and methanol extracts from the leaf, as determined by the Folin-Ciocalteu method, were 314 and 315 mg gallic acid equivalent/g leaf sample, respectively. The total flavonoid concentration as determined by the aluminum(III) chloride method was 135 mg catechin equivalent/g leaf sample. High-performance liquid chromatography coupled to an electrospray Quadrupole time-of-flight mass spectrometer was also used to determine the polyphenol fingerprint profile in the leaf extracts of O. canum. Although the average RA concentration in the O. canum leaf extracts from Ghana was 1.69 mg/g dry weight (reported values range from 0.01 to 99.62 mg/g dry weight), this polyphenol was still a prominent peak in addition to caffeic acid derivatives.

Flavonoid content and antioxidant activity of vegetables from Indonesia

Extracts from 11 vegetables of Indonesian origin were screened for flavonoid content, total phenolics, and antioxidant activity. The flavonols myricetin, quercetin, and kaempferol and flavones luteolin and apigenin were quantified by HPLC. Flavonoid content in mg/100 g fresh weight (fw) was apparently initially reported for Cosmos caudatus H.B.K. (52.19), Polyscias pinnata (52.19), Pluchea indica Less. (6.39), Nothopanax scutellarius (Burm.f.) Merr (5.43), Talinum triangulare (Jacq.) Willd. (3.93), Pilea melastomoides (Poir.) Bl. (2.27), and Etlingera elatior (Jack) R.M.Sm (1.18). The flavonoid content of the vegetables studied were mainly quercetin and kaempferol and ranged from 0.3 to 143 mg/100 g fw, with the highest level found in Sauropus androgynus (L) Merr. C. caudatus H.B.K. had the greatest total phenols among the vegetables analysed, with 1.52 mg GAE/100 g fw. P. indica Less. and C. caudatus H.B.K. had the highest antioxidant activity as measured by ferric cyanide reducing power, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) scavenging, and inhibition of linoleic acid oxidation. Therefore, S. androgynus (L) Merr, C. caudatus H.B.K., and P. pinnata were identified as potentially rich sources of dietary flavonoids and antioxidants.

In vitro antiplasmodial activity of medicinal plants native to or naturalised in South Africa

The increasing prevalence and distribution of malaria has been attributed to a number of factors, one of them being the emergence and spread of drug resistant parasites. Efforts are now being directed towards the discovery and development of new chemically diverse antimalarial agents. The present study reports on the in vitro antiplasmodial activity of 134 plant taxa native to or naturalised in South Africa, representing 54 families, which were selected semi-quantitatively using weighted criteria. The plant extracts were tested for in vitro activity against a Plasmodium falciparum strain D10 using the parasite lactate dehydrogenase (pLDH) assay. Of the 134 species assayed, 49% showed promising antiplasmodial activity (IC(50)< or = 10 microg/ml), while 17% were found to be highly active (IC(50)< or = 5 microg/ml). Several plant species and genera were shown for the first time to possess in vitro antiplasmodial activity. These results support a rational rather than random approach to the selection of antiplasmodial screening candidates, and identify a number of promising taxa for further investigation as plant-based antimalarial agents.