MK Langat

MK Langat
Royal Botanic Gardens, Kew · Natural Capital and Plant Health

PhD, FHEA

About

105
Publications
17,047
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Citations
Introduction
MK Langat currently works at the Royal Botanic Gardens, Kew. His current role is a Research Leader for Natural Product Chemistry at the Biological Chemistry and In Vitro Studies Research group. He leads the Natural Product Research at Kew and is the keeper of the Avance Bruker NMR 400 MHz. His research work is domiciled at the Jodrell Laboratory of Kew Science.
Additional affiliations
July 2018 - present
University of Surrey
Position
  • Lecturer
July 2018 - present
Royal Botanic Gardens, Kew
Position
  • Research Leader for Natural Product Chemistry, Chemical Ecology and IVB
June 2009 - present
University of Surrey
Position
  • Teaching Research Fellow

Publications

Publications (105)
Article
Full-text available
Antimicrobial nectar secondary metabolites can support pollinator health by preventing or reducing parasite infections. To better understand the outcome of nectar metabolite–parasite interactions in pollinators, we determined whether the antiparasitic activity was altered through chemical modification by the host or resident microbiome during gut p...
Article
Reported herein is an anti-HIV monochlorinated compound, 1β-acetoxy-3β-chloro-5α,6α-dihydroxycrotocascarin L (1), of the rare crotofolane diterpenoid class. Compound 1, a suspected artifact of extraction, along with the previously undescribed 11β-acetoxycrotocascarin L (2) and a known compound, crotocascarin K (3), were isolated from the bark of Cr...
Article
Full-text available
Croton macrostachyus is an important plant in traditional African medicine, widely utilized to treat a variety of diseases. In Kenya, HIV-infected patients use leaf and root decoctions of the plant as a cure for cough, back pain, bleeding, skin diseases, warts, pneumonia, and wounds. This study aimed to evaluate the anti-HIV activities and cytotoxi...
Article
The stem bark of Citrus × paradisi Macfad. (Rutaceae) gave (23S)-isolimonexic acid (1), limonin (2), citracridone II (3), citpressine II (4), citpressine I (5), grandisine (6), 2-hydroxynoracronycine (7), citracridone I (8), 5-methoxyseselin (9), umbelliferone (10), scopoletin (11), naringenin (12), apigenin (13), friedelin (14), agrostophyllinone...
Article
Full-text available
Background Euphorbia grandicornis is widely utilized in traditional medicine for the treatment of microbial infections including sexually transmitted diseases such as syphilis, gonorrhoea and for healing of wounds. Objective The aim of this work was to isolate and evaluate the antibacterial and anticancer activities of Euphorbia grandicornis chemi...
Article
Full-text available
In our continued study on the anti-HIV activity of compounds present in CareVid TM , we report the HIV-1 integrase ((HIV-1 IN) inhibitory effects of pellitorine (1), oleuropein (2), magnoflor-ine (3), crotepoxide (4), ent-kaurane-16β,17-diol (5), crotocorylifuran (6), lupeol (7), betulin (8), and ellagic acid (9) in an in vitro enzyme assay, and in...
Article
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A chemical investigation of the leaves of Tabernaemontana inconspicua Stapf. led to the isolation of a new phenylpropanol derivative, namely irisdichototin G (1), together with nine known compounds, including one polyol derivative, dambonitol (2); three alkaloids, 10-hydroxycoronaridine (3), voacristine (4) and vobasine (5); two triterpenes lupeol...
Article
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The stems and leaves of robusta coffee, Coffea canephora Pierre ex A. Froehner, one of the traded Coffea species, yielded caffeine (1), lupeol (2), ursolic acid (3), 3β-acetyl oleanolic acid (4), friedelin (5), asperphernamate (6), squalene (7), stigmasterol (8), stigmasterol�3-O-β-D-glucopyranoside (9) and chlorophyll a (10). The structures of the...
Article
Chemical investigation of the roots of Trichilia welwitschii yielded a cycloartane type terpenoid 28,29-bis-norcycloart-24-en-3 β ,4 α ,6 α -triol ( 1 ), isolated as pure compound for the first time, three coumarins and three sterols. New cycloartane derivatives ( 1a ) and ( 1b + 1c ) were obtained by hemi-synthetic reaction of compound 1 . The str...
Article
Full-text available
CareVid is a multi-herbal product used in southwest Kenya as an immune booster and health tonic and has been anecdotally described as improving the condition of HIV-positive patients. The product is made up of roots, barks and whole plant of 14 African medicinal plants: Acacia nilotica (L.) Willd. ex Delile (currently, Vachelia nilotica (L.) P.J.H...
Preprint
Full-text available
Continuing a survey of the chemistry of species of the largely continental African genus Vepris, we investigate a species previously referred to as Vepris sp. 1 of Congo. From the leaves of Vepris sp. 1 we report six compounds. The compounds were three furoquinoline alkaloids, kokusaginine (1), maculine (2), and flindersiamine (3), two acridone alk...
Article
Full-text available
Euphorbia species have a rich history of ethnomedicinal use and ethnopharmacological applications in drug discovery. This is due to the presence of a wide range of diterpenes exhibiting great structural diversity and pharmacological activities. As a result, Euphorbia diterpenes have remained the focus of drug discovery investigations from natural p...
Article
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Vitex doniana Sweet is an African medicinal species that is prescribed as an aqueous bark extract to be applied topically or orally to achieve anti-infective outcomes. In select regions it is also taken orally as an antimalarial agent. The aim of the current study was to explore the biological properties of V. doniana and isolated compounds in the...
Article
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Australia’s endemic desert shrubs are commonly aromatic, with chemically diverse terpenes and phenylpropanoids in their headspace profiles. Species from the genus Eremophila (Scrophulariaceae ex. Myoporaceae) are the most common, with 215 recognised taxa and many more that have not yet been described, widely spread across the arid parts of the Aust...
Article
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Colorectal cancer (CRC) represents the third leading cause of death among cancer patients below the age of 50, necessitating improved treatment and prevention initiatives. A crude methanol extract from the wood pulp of Artocarpus heterophyllus was found to be the most bioactive among multiple others, and an enriched extract containing 84% ( w / v )...
Article
An aromatic alkaloid-rich ‘absolute’ extract from Vepris gossweileri inhibited Saccharomyces cerevisiae at 62.5 μg.mL−1 and Bacillus subtilis at 500 μg.mL−1. A loss of activity upon fractionation indicated possible synergistic effects. Three new acridones, gossweicridone A (3), B (4) and C (5) and known compounds from the extract were inactive. Com...
Article
Full-text available
We describe two new terpenoids, 3′',5′'-dihydroxycinnamoyl-3β,28,30-dihydroxylup-20(29)-ene (1) and 6S,9S-dihydroxycasbe-3E,7E,11E-trien-5,10-dione (2) and ten known asperglaucide, aridanin, isoscopoletin, maslinic acid, ursolic acid, oleanolic acid, lupeol, sitosterol, stigmasterol and stigmasterol-glucoside from a West African, Guineo-Congolian m...
Article
This study analyzed the antimicrobial effects of compounds present in the roots and leaves of Citrus x limon (L.) Osbeck to help understand how this plant (1) ecologically modulates microbial defense in the rhizosphere and (2) protects against food-borne bacterial pathogens. Antimicrobial effects of C. limon collected from a farm in Foumban in Came...
Article
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Andrographolide, the major constituent from the terrestrial plant Andrographis paniculata is a much-studied bioactive ent-labdane diterpene lactone and has become an important medicinal intermediate. As determined by X-ray crystallography, its structure has been applied in molecular docking studies to explain biological activities. Nevertheless, re...
Article
The bulbs of the South African Drimia altissima (Asparagaceae or Hyacinthaceae sensu APGII) have yielded a range of previously undescribed bufadienolides, drimianins A-G (1-7), the known bufadienolides bovogenin A (8), 3β-O-β-d-glucopyranosylbovogenin A (9), scillaren F (10), and altoside (11), the known homoisoflavonoid (3S)-3-(4'-methoxybenzyl)-5...
Article
Full-text available
Background Annona muricata L. was identified as a popular medicinal plant in treatment regimens among cancer patients in Jamaica by a previously conducted structured questionnaire. Ethnomedically used plant parts, were examined in this study against human prostate cancer cells for the first time and mechanisms of action elucidated for the most pote...
Article
Five homoisoflavonoids, (3S)-3,5-dihydroxy-7‑methoxy‑3-(3′,4′-dimethoxybenzyl)-4-chromanone, 1, (3S)-3,5-dihydroxy-7,8-dimethoxy-3-(3′‑hydroxy‑4′‑methoxy)-4-chromanone, 2, (3R)-7,8-dimethoxy-5‑hydroxy‑3-(4′-hydroxybenzyl)-4-chromanone, 3, and (3R)-5‑hydroxy‑7‑methoxy‑3-(3′,4′-dimethoxybenzyl)-4-chromanone, 4, (3S)-3,5,7-trihydroxy-3-(3′‑hydroxy‑4′-...
Article
Full-text available
The highly aromatic Australian mint bushes from the genus Prostanthera Labill. produce a high yield of essential oil on hydrodistillation. Together with its rich history, horticultural potential, iconic flowers, and aromatic leaves, it achieves high ornamental and culinary value. Species in the genus express highly diverse and chemically unique ess...
Article
The stem bark and root bark extracts of Croton dictyophlebodes (Euphorbiaceae) yielded seven undescribed ent-clerodanes: 15,16-epoxy-17,12(S)-olide-ent-cleroda-1,3,13(16),14-tetraen-18-oic acid methyl ester (crotodictyo A), 3β,4β:15,16-diepoxy-ent-cleroda-13(16),14-dien-20-al (crotodictyo B), 3β,4β:15,16-diepoxy-ent-cleroda-13(16),14-dien-19,20-dio...
Article
Five previously undescribed compounds, megalocarpoidolide I (1), megalocarpoidolide J (3), 12-epi-crotonzambefuran A (4), megalocarpoidolide K (5), 1-trans-p-hydroxycoumaroyl–geranylgerani-1-ol (6) were isolated from the stem bark of Croton megalocarpoides Friis & M. G. Gilbert. The known ent-trachyloban-18-ol, megalocarpoidolide B, megalocarpoidol...
Article
The leaf extract of Croton haumanianus J. Léonard (Euphorbiaceae) yielded twenty-six compounds, including eight previously reported ent-kauranes and an ent-labdane and eight undescribed ent-kauranes, ent-16R-kauran-17-al, ent-3β-hydroxy-16R-kauran-17-al, ent-16S,17-epoxykauran-19-ol, ent-16S,17-epoxykauran-3β-ol, ent-17-palmityloxykaurane-3β,16β-di...
Article
Full-text available
Bioenergy is a major component of the global transition to renewable energy technologies. The plant and fungal kingdoms offer great potential but remain mostly untapped. Their increased use could contribute to the renewable energy transition and addressing the United Nations Sustainable Development Goal 7 "Ensure access to affordable, reliable, sus...
Book
Full-text available
Kew’s State of the World’s Plants and Fungi project provides assessments of our current knowledge of the diversity of plants and fungi on Earth, the global threats that they face, and the policies to safeguard them. Produced in conjunction with an international scientific symposium, Kew’s State of the World’s Plants and Fungi sets an important inte...
Article
A systematic analysis of the root bark of Zanthoxylum chalybeum was conducted to establish the antidiabetic potential of isolated compounds based on its ethnomedicinal use to manage diabetes. Chromatographic separation of alkaloid extracts led to isolation of three undescribed amides, chaylbemide A (1), chalybemide B (2) and chalybemide C (3) along...
Article
Full-text available
The genus Euphorbia is one of the largest genera in the spurge family, with diversity in range, distribution, and morphology. The plant species in this genus are widely used in traditional medicine for the treatment of diseases, ranging from respirational infections, body and skin irritations, digestion complaints, inflammatory infections, body pai...
Article
Full-text available
Bioenergy is a major component of the global transition to renewable energy technologies. The plant and fungal kingdoms offer great potential but remain mostly untapped. Their increased use could contribute to the renewable energy transition and addressing the United Nations Sustainable Development Goal 7 “Ensure access to affordable, reliable, sus...
Article
A phytochemical investigation of the roots and twigs of Penianthus zenkeri Diels led to the identification of twenty four compounds including one previously undescribed C-28 ecdysteroid (1) and previously described phytosteroids (2–5, 20, 22, 23), phenolic compounds (6–8, 12), diterpenoids (9–11), alkaloids (13,14, 18, 19), a dipeptide (15), ursane...
Article
Ethnopharmacological relevance The Zulu and Xhosa people of South Africa use the stem bark of Cassipourea flanaganii as a skin-lightening cosmetic. Aim of the study To isolate and identify compounds responsible for the skin lightening properties from the stem bark of Cassipourea flanaganii and to evaluate their cytotoxicity towards skin cells. Ma...
Article
The stem bark of Ancistrocarpus densispinosus Oliv. exhibited triterpenoids, including the rare fernane-type, fern-9(11)-ene-2α,3β-diol (1) a possible chemotaxonomically distinct biomolecule for the genus. Other triterpenoids that were isolated from this plant include the ursane-type ursolic acid (2) and corosolic acid (3), friedelane-type friedeli...
Article
We report the chemistry and biological activities of a Cameroonian Citrus clementina Hort. Ex Tanaka, a vegetatively propagated species. The compounds isolated from this plant were determined to be the known 5-hydroxy-6,7,8,3’,4’-pentamethoxyflavone (1), tangerine (3), nobilletin (4), 5,7,8,4’-tetramethoxyflavone (5), citracridone I (6), 5-hydroxyn...
Article
The emergence of antibiotic resistant pathogens has continuously increased, leading to a growing worldwide health threat due to infectious diseases. And therefore in our search for antibacterial and antifungal compounds from the polypore Ganoderma adspersum, the dried, ground fruiting bodies of G. adspersum were extracted with methanol and solvent...
Article
The phytochemical investigation of the methanolic extracts of roots, stem bark, leaves and twigs of Manilkara obovata has led to the isolation of one new friedelane triterpene, lacefriedelic acid or 3β,23-dihydroxy D:A-friedooleanan-28-oic acid (1) and one new prenylated xanthone, lacexanthone or 4,7-dihydroxy-2,3,3,9,9-pentamethyl-2,2-dihydrofuran...
Article
The sap of the tree Lepiniopsis ternatensis is used as a topical treatment for cutaneous leg ulcers in Papua New Guinea. This study, which is the first investigation of this medicinal plant, examines the effect of the sap on wound healing biology using human-derived primary cell lines. NMR spectra from 1D and 2D experiments revealed the sap to cont...
Article
Full-text available
Ziziphus mucronata is a medicinal plant used traditionally for treating various diseases. The antioxidant assay for the crude extracts obtained from the berries of Ziziphus mucronata was carried out using DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Purified antioxidant compounds were obtained by chromatographic methods and were subjected to struct...
Article
The structure elucidation of three new alkaloids named isoformosaninol (1), formosaninol (2), and longiflorine (3), isolated from the leaves of Uncaria longiflora var. pteropoda (Miq.) Ridsdale, along with their biosynthetic pathways are discussed. Their absolute structures were determined through a combination of physical data interpretation and q...
Article
The phytochemical study of the roots, leaves and twigs of Penianthus camerounensis Dekker (Menispermaceae) has led to the isolation and the characterization of 20 compounds. A ceramide, camerounamide ( 1 ), and a furoclerodanediterpenoid, camerounin ( 2 ), have not been described previously, while the compounds xylopic acid ( 3 ), syringaresinol (...
Article
Full-text available
Plant phytochemicals can act as natural "medicines" for animals against parasites [1-3]. Some nectar metabolites, for example, reduce parasite infections in bees [4-7]. Declining plant diversity through anthropogenic landscape change [8-11] could reduce the availability of medicinal nectar plants for pollinators, exacerbating their decline [12]. Ex...
Article
Full-text available
Cassipourea congoensis (syn. Cassipourea malosana) is used in African countries as a skin-lightening agent. Two previously unreported cycloartane triterpenoids, 26-hydroxy-3-keto-24-methylenecycloartan-30-oic acid 1 and 24-methylenecycloartan-3β,26,30-triol 2 along with the known mahuannin B 3, 7-methoxymahuannin B 4, 7-methoxygeranin A 5, methyl-3...
Article
Aims: The medicinal plant Oncoba spinosa is used by the local communities in Butebo County in Eastern Uganda for treatment of malaria and other diseases. In vitro antiplasmodial activities of the crude extracts and isolated compounds were screened against chloroquine sensitive 3D7 and resistant Dd2 strains. In vivo acute toxicity of the extracts an...
Article
Three new homoisoflavonoids, (3R)-3,5-dihydroxy-7-methoxy-3-(4′-hydroxybenzyl)-4-chromanone, 4, and its 5-O-β-D-glucopyranoside and 5-O-β-D-gentiobiose derivatives, 5 and 6, along with the known homoisoflavonoids, (3S)-5-hydroxy-7-methoxy-3-(4-methoxybenzyl)-4-chromanone, 1, (3R)-5-hydroxy-7-methoxy-3-(4-methoxybenzyl)-4-chromanone (2)and (3S)-5-hy...
Article
Full-text available
Excessive blood vessel formation in the eye is implicated in wet age-related macular degeneration, proliferative diabetic retinopathy, neovascular glaucoma, and retinopathy of prematurity, which are major causes of blindness. Small molecule antiangiogenic drugs are strongly needed to supplement existing biologics. Homoisoflavonoids have been previo...
Article
Fourteen compounds were isolated from the roots, leaves and twigs of Penianthus longifolius Miers (Menispermaceae), including two previously unreported neo-clerodane diterpenoids, penianthin (1), its C-8 epimer (2). In addition, the previously reported O-methylmoschatoline (3), taraxerol (4), taraxerone (5), rubrosterone, (6), panuosterone (7), 22-...
Article
A phytochemical investigation of the stem barks of the Malaysian Croton oblongus Burm.f. (Syn. Croton laevifolius Blume) (Euphorbiaceae) yielded seven previously undescribed ent-neo-clerodane diterpenoids, laevifins A - G and the known crovatin (3). Structures were established by a combination of spectroscopic methods including HRESIMS, NMR spectro...
Article
Pumilol (1), a strobane diterpenoid, reported herein for the first time was isolated from the bark of Pinus pumila (Pall.) Regel (Siberian Dwarf Pine or Japanese Stone Pine), along with seventeen known compounds including serratane triterpenoids, not previously reported from this species, and four ferulate derivatives. The stereostructure of pumilo...
Article
The stem bark extract of Suregada zanzibariensis afforded a previously undescribed ent-abietane diterpenoid trivially named mangiolide (1) and a known jolkinolide B (2) via anticancer bioassay-guided fractionation. The CH2Cl2:MeOH extract of S. zanzibariensis was initially analysed for its anticancer properties against three cancer cell lines, rena...
Article
Three previously unreported triterpenoids 2α,3β,11α-trihydroxyolean-18-ene 1, 3β-acetoxy,2α,11α- dihydroxyolean-18-ene 2 and 2α-acetoxy,3β,11α-dihydroxyolean-18-ene 3 were isolated from the chloroform extract of aerial parts (leaves and flowers) of Salvia phlomoides collected from the Constantine region in the east of Algeria. Structures were deter...
Article
The Hyacinthaceae family (sensu APGII), with approximately 900 species in around 70 genera, plays a significant role in traditional medicine in Africa as well as across Europe and the Middle and Far East. The dichloromethane extract of the bulbs of Massonia pustulata (Hyacinthaceae sensu APGII) yielded two known homoisoflavonoids, (R)-5-hydroxy-3-(...
Article
A C-25 terpenoid, pseudopulchellol, a rare example of a compound formed by the combination of a mono- terpenoid and a sesquiterpenoid unit, was isolated along with eudesm-4(15)-en-1β,6α-diol, its likely precursor, and nine known compounds, including six ent-kaurenoic acids, from the leaves of Croton pseudopulchellus. The Logic for Structure Determi...
Article
Five ergostanes, dimethylincisterol (1), 5a,8aeepidioxy-(22E,24R)-ergosta-6,9(11),22-trien-3b-ol (2), 5a,8aeepidioxy-(22E,24R)-ergosta-6,22-dien-3b-ol (3), 5a,6a-epoxy-(22E,24R)-ergosta-8(14),22-diene-3b,7a-diol (4), (22E,24R)-ergosta-7,22-diene-3b,5a,6b-triol (5) and betulinic acid (6) were isolated from the fresh fruiting bodies of the edible mus...
Article
The phytochemistry of two Madagascan Crinum species, Crinum hardyi Lehmiller and Crinum pronkii Lehmiller were investigated and compared to that of Crinum firmifolium Baker which has been investigated previously. In addition to hippadine, lycorine, hippeastrine, masonine and crinine from C. firmifolium, lycorine, crinine, and 6-hydroxycrinamine fro...
Article
Background: Plant extracts might provide sustainable alternatives to copper fungicides, which are still widely used despite their unfavourable ecotoxicological profile. Larch bark extract and its constituents, larixyl acetate and larixol, have been shown to be effective against grapevine downy mildew (Plasmopara viticola) under semi-controlled con...
Article
Downy mildew caused by the oomycete Plasmopara viticola is the most devastating pathogen of grapevine. In this study, extracts of the bark of eight important northern forestry species were screened to find extracts showing activity against this pathogen and to identify the active compounds. Extracts from all eight species showed activity against P....
Article
Four previously undescribed diterpenoids including two crotofolanes, crotodichogamoin A and B, and two halimanes, crothalimene A and B, a new sesquiterpenoid, and fifteen previously reported compounds , including the crotofolane, crotohaumanoxide, the casbane, depressin, a further seven fur-anohalimane diterpenoids, three patchoulane and two furthe...
Article
Full-text available
The bulbs of Eucomis bicolor (Hyacinthoideae) yielded fourteen novel natural compounds, including (17S)-3-oxo-24,25,26,27,28-pentanorlanost-8-en-23,17α-olide, whose structure was determined using the logic for structure determination program, and nine novel lanosterol glycosides. Compounds were screened against the NCI-59 cancer cell panel but show...
Article
Two new acridone alkaloids, verdoocridone A (1) and B (4), together with fifteen known compounds were isolated from methanol extracts of the roots and leaves of Vepris verdoorniana. The structures of all compounds were determined by comprehensive spectroscopic analyses (1D and 2D NMR, EI- and ESI–MS). The 13C NMR values of 1,2,3,5-tetramethoxy-N-me...