Propolis produced by the stingless bee Lisotrigona cacciae was studied for the first time. Using different chromatographic procedures, a total of eighteen constituents (phenols and triterpenes) were isolated, among which flavane 1 , homoisoflavanes 2 – 4 , and xanthones 5 and 6 were new for propolis. Propolis extract was also characterized by gas chromatography/mass spectrometry and other fifteen constituents were identified. The xanthone α -mangostin ( 8 ) demonstrated significant activity against Staphylococcus aureus with MIC and MBC 0.31 μg/ml, followed by 7,4'-dihydroxy-5-methoxy-8-methylflavane ( 1 ) with MIC 78 μg/ml and MBC 156 μg/ml. 10,11- Dihydroxydracaenone C ( 4 ), a component bearing ortho -hydroxyl groups, was the only compound displaying radical scavenging ability. Triple botanical origin of the sample was defined, consisting of Dracaena cochinchinensis , Cratoxylum cochinchinense and Mangifera indica . D . cochinchinensis is a new resin source of propolis.

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The chemical investigation of Homotrigona apicalis propolis collected in Binh Dinh province, Vietnam, led to the isolation of nine compounds, including four sesquiterpenes: spathulenol (1), 1αH,5βH-aromandendrane-4β,10α-diol (2), 1β,6α-dihydroxy-4(15)-eudesmene (3), and 1βH,5βH-aromandendrane-4α,10β-diol (4); three triterpenes: acetyl oleanolic acid (5), 3α-hydroxytirucalla-8,24-dien-21-oic acid (6), and ursolic acid (7); and two xanthones: cochinchinone A (8) and α-mangostin (9). Sesquiterpens 1–4 and triterpene 6 were isolated for the first time from stingless bee propolis. Plants in the Cratoxylum and Aglaia genus were suggested as resin sources of the propolis sample. In the antibacterial activity evaluation, the EtOH extract only showed moderate activity on S. aureus, while the isolated compounds 7–9 showed good antibacterial activity, with IC50 values of 0.56 to 17.33 µg/mL. The EtOH extract displayed selective cytotoxicity against the A-549 cancer cell line, with IC50 values of 22.82 ± 0.86 µg/mL, and the xanthones 8 and 9 exhibited good activity against the KB, HepG-2, and A-549 cancer cell lines, with IC50 values ranging from 7.55 ± 0.25 µg/mL to 29.27 ± 2.07 µg/mL. The cytotoxic effects of xanthones 8 and 9 were determined by the inhibition of the EGFR and HER2 pathways using a molecular docking study. Compounds 8 and 9 displayed strong binding affinity with EFGR and HER2, with values of −9.3 to −9.9 kcal/mol. Compounds 5, 8, and 9 showed potential α-glucosidase inhibitory activities, which were further confirmed by computational studies. The binding energies of compounds 5, 8, and 9 were lower than that of arcabose.

The present study aimed to analyze and compare the chemical profile and antioxidant capacity of propolis from different bee species and different regions. The chemical profiles of propolis from six stingless bee species (Tetragonula iridipennis, T. laeviceps, Lepidotrigona terminata, L. ventralis, Lisotrigona carpenteri and Homotrigona apicalis) collected from a total of eight locations in Vietnam were investigated by gas chromatography–mass spectrometry (GC-MS). More than 70 compounds were identified, amongst which phenolic lipids (cardanols, resorcinols and anacardic acids), aromatic acids, triterpenes and xanthones. Taxonomic markers for Mangifera indica (phenolic lipids and cycloartane triterpenes) were detected in propolis from bees of the genera Tetragonula and Lepidotrigona, although in different amounts, whereas propolis from H. apicalis was characterized by triterpenes of the amyrine type, typical of dipterocarp trees. A clear discrimination between both groups was observed by principal component analysis (PCA) and partial least squares–discriminant analysis (PLS-DA). Propolis from Tetragonula and Lepidotrigona spp. and from Lisotrigona carpenteri, which is rich in xanthones, possesses higher radical scavenging and ferric-reducing capacity than that from H. apicalis. Propolis produced by all six stingless bee species in Vietnam was analyzed for the first time. In addition, this is the first report on L. carpenteri propolis.

Chromatographic separation of ethyl acetate extract of the stingless bee Lisotrigona furva propolis, that collected in Khanh Hoa province, led to isolation of five cycloartane‐type triterpenes including cycloartenone (1), cycloartenol (2), (24E)‐3β‐hydroxycycloart‐24‐en‐26‐al (3), mangiferonic acid (4) and mangiferolic acid (5). Mango plant (Mangifera indica) was suggested to be a resin source of the propolis. The propolis EtOH extract showed good antimicrobial activity on Gram (+) strain E. feacalis and fungus C. albicans. Among the isolated compounds, compound 3 displayed selective activity against three Gram (+) strains and C. albicans over Gram (‐) strains with all MIC values of 64 μg/mL. However, the propolis EtOH extract was not active against LU‐1 and MCF‐7 cancer cell lines. Only compound 5 exhibited moderate activity on LU‐1 cancer cell line with IC50 of 13.33 μg/mL.

Knema (Myristicaceae family) is a large genus, comprising over 100 species found in of South East Asian countries, among that over 10 species was found in Vietnam. Knema pachycarpa is a native tree distributed in central provinces of Viet Nam. Until now, only few chemical studies of Knema species in Viet Nam have been reported. Phytochemical study of Knema pachycarpa leaves led to the isolation of seven known compounds including six flavonoids 5,7,3′-trihydroxy-5′-methoxy isoflavone (1), luteolin (2), (-)-narigenin (3), (+)-catechin (4), isoquercetrin (5), and nicotiflorin (6), and a biphenyl compound  3,3',4,4'-tetrahydroxybiphenyl (7). Their structures were elucidated by MS and NMR data analysis and compared with those previously reported. Compounds 3 and 6-7 were found from Knema genus for the first time. In the cytotoxic assay, biphenyl compound (7) exhibited strong cytotoxicity to KB cancer cell line with IC50 value of 2.38 ± 0.11 mg/mL. Compound 7 also displayed showed activity against HepG2, Lu and MCF7 cancer cell lines with IC50 ranges from 18.25 ± 0.92 mg/mL to 35.56 ± 1.17 mg/mL, whereas flavonoids 1-6 were weakly active or inactive against tested cell lines.