Conamomum rubidum

Conamomum rubidum (Lamxay & N.S.Lý) Škorničk. & A.D.Poulsen, Taxon 67(1): 20 (2018).

its native range is Vietnam.

Vietnamese name: 

Sa nhân. 

Latin Name: 

Conamomum rubidum (Lamxay & N.S.Lý) Škorničk. & A.D.Poulsen

Synonym Name: 

Amomum rubidum Lamxay & N.S.Lý, Edinburgh J. Bot. 69(1): 166 (-169, 165; figs. 25-26) (2012).

Family: 

Zingiberaceae

Description: 

Clump-forming herb, c.1.5 m tall with 12–19 leaves per pseudostem; rhizome branched, c.1.3–1.7 cm, externally yellowish brown, internally cream, slightly aromatic; stilt roots absent; interval between pseudostems c.5–10 cm, scales broadly triangular, 1–1.2 3 1 cm, brown, papery, apex acute. Pseudostem c.1.5 cm diameter, pink when young then green; ligule ovate, c.0.6–1.2 cm long, green then brown, shortly hairy, margin of leaf sheaths dark brown; petiole canaliculate, c.0.5–0.9 cm long, glabrous; blade oblong-linear, c.30–45 3 4.5–7 cm, dark green and glabrous above, pale green with purplish-red below, glabrous, base oblique, apex acuminate to long caudate, margin hairy. Inflorescence obovoid, arising from the base, creeping vertically then curved upwards; flowering part ovoid, c.5–7 3 4–5 cm; peduncle c.4–7 3 1 cm, hairy; scales ovate-triangular, 0.5–3.6 3 1–3 cm, reddish-purple then brown, coriaceous at base, papery above, hairy, apex cucullate with spur c.0.2 cm long; bracts obovate, 3.6–4.1 3 1.5–3.5 cm, greenish-red then dark brown, rotting soon, tomentose at base, apex acute and slightly mucronate or rounded, margin ciliate; bracteole tubular, c.2.4–3.1 3 1.1–1.3 cm, membranous, 2-toothed, c.4–6 mm long, hairy at base. Calyx tubular, c.2 3 0.5 cm; calyx tube c.1.5 cm; teeth c.0.5 cm, coriaceous, glabrous. Corolla tubular, corolla tube c.1.5 3 0.3 cm, glabrous; lateral corolla lobes oblong, 2–2.3 3 0.6–0.8 cm, membranous, reddish, glabrous, apex rounded; central corolla lobe oblong, c.2–2.5 3 1–1.1 cm, reddish, membranous, glabrous, apex rounded, slightly cucullate; labellum reniform, c.3–3.7 cm long, base c.1.3 3 0.9 cm, yellow with red stripe on margin, glandular hairy at base, apical part broadly semi-circular, trilobed, c.1.7–2.4 3 3 cm, yellow, margin undulate, reflexed; lateral staminodes triangular-linear, c.0.7–0.9 3 0.1–0.2 cm, sometimes with a few tiny teeth at base, pink-red at base, yellowish-white towards apex. Filament flat, c.0.7–0.8 3 0.2 cm, white, glandular hairy; anther yellowish-cream, c.0.8–0.9 3 0.4 cm, with glandular hairs on the connective tissue; anther crest trilobed, lateral lobes linear, horn-shaped, c.0.5–0.6 3 0.1–0.2 cm, white at base, turning yellow at tip, with a few glandular hairs, central lobe bidentate, inflexed, c.0.4–0.5 3 0.35 cm, yellow, glabrous. Stigma cup-shaped, cream white, ciliate; style c.3.5 cm, white, sparsely hairy; epigynous glands 1 pair, 0.4 cm long, white; ovary c.0.6 3 0.4 cm, ovoid, glabrous, trilocular; ovules many; fruiting part ovoid, c.7 3 4.5 cm, bracts persistent, brown, papery; fruits ovoid, c.1.7 3 1.3 cm, smooth, light red. Seeds not seen.

Flowers: 

Apr-May

Distribution: 

Vietnam (Lam Dong, Bi Doup-Nui Ba N.P.).

Ecological: 

Along streams in montane evergreen forest, at 1775–1869 m altitude.

Chemical constituents and Pharmacology:

The compositions and antimicro- bial activity of the leaf and stem essential oils from A. rubidium were reported. 1,8-Cineole (37.7 %), δ-3-carene (19.5 %) and limonene (16.3 %) were the main compounds in the leaf oil, while δ-3- carene (21.9 %), limonene (17.8 %) and β- phellandrene (14.6 %) occurred in higher quan- tity in the stem essential oil 2. The leaf and stem essential oils of A. rubidium displayed strong antimicrobial activity towards Pseudomonas aeruginosa (ATCC 25923) with minimum inhibitory concentration (MIC) of 25 μg/mL and 50 μg/ mL respectively. The stem essential oil was also active against Candida albicans (ATCC 10231, MIC, 50 mg/mL) while both essential oils inhibited the growth of Fusarium oxysporum with MIC 50 μg/mL2. Also, the rhizome oil of A. rubidium was recently reported to exhibited antimicrobial activity against Escherichia coli (ATCC 25922) and Fusarium oxysporum (ATCC 48112) with Minimum inhibitory concentration (MIC) values of 50 μg/mL 3. Till moment no information could be seen on either the chemical constituents or lar- vicidal activity of essential oil from the rhizome of A. rubidum.

The chemical constituents and larvicidal activity of essential oil from Amomum rubidum Lamxay & N. S. Lý. The essential oil was extracted from the air-dried rhizome in an all-glass Clevenger-type apparatus and characterized by gas chromatography (GC-FID) and gas chromatography/mass spectrometry (GC/MS) on HP-5 column. The larvicidal property was evaluated against the fourth-instar larvae of Aedes aegypti according to the protocols of the World Health Organization. A. rubidum essential oil was characterized by high amounts of β-phellandrene (16.1 %), limonene (14.4 %), and δ-3-carene (13.9 %). The oil displayed larvicidal activity against Ae. aegypti with minimum lethal concentration, LC50 values of 22.85 and 22.62 μg/mL respectively at 24 h and 48 h, while the LC90 values of 31.44 μg/mL and 31.03 μg/mL were obtained respectively at 24 h and 48 h. 

Uses:

The plant has been used ethnomedically to ameliorate inflammation-related disorder, treat microbial infections, and act as an insect repel- lant

Typus:

holotype VNM – isotype E – isotype SING

Proposed IUCN status. 

LC. This species is known from three localities with an extent of occurrence of only 159 km2 but there is no continuing decline in extent and quality of habitat. The species is therefore assessed as Least Concern.

References

1. Lamxay, V., Newman, M.F. (2012). A revision of Amomum (Zingiberaceae) in Cambodia, Laos

and Vietnam. Edinburgh J. Bot. 69: 99-206.

2. Le T. Huong, Ly N. Sam, Cao N. Giang, Do N. Dai & Isiaka A. Ogunwande (2020) Chemical Composition and Larvicidal Activity of Essential Oil from the Rhizomes of Amomum rubidum Growing in Vietnam, Journal of Essential Oil Bearing Plants, 23:2, 405-413, DOI: 10.1080/0972060X.2020.1756425